Journals >Infrared and Laser Engineering
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2020
Volume: 49 Issue 9
32 Article(s)
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Imaging experiments for weak small target in low-light-level background
Haili Hu, Lei He, Yong Zhang, Zhen Yang, Xinmin Guo, and Jianlong Zhang
Weak small targets, such as unmanned aerial vehicles, have the characteristic of low flight height, small reflection cross-section and weak thermal information, which are difficult to detect and recognize in low-light-level background by a single imaging method. The visible light, low light night vision, long wave infrWeak small targets, such as unmanned aerial vehicles, have the characteristic of low flight height, small reflection cross-section and weak thermal information, which are difficult to detect and recognize in low-light-level background by a single imaging method. The visible light, low light night vision, long wave infrared and laser active illuminated imaging experiments were carried out, to study the suitable detection and recognition methods by comparing of weak small target images in different low-light-level background. In the field experiment, the target was a small four rotor UAV with the size of 290 mm×290 mm×196 mm, and the environmental illumination was between 10-2 lx and 10-4 lx. The working distance was from 0.5 km to 2 km. The experimental results show that simple visible light system cannot image under 10-2 lx environment illumination; the recognition distance of low-light night vision and long-wave infrared system is only 0.5 km when the environment illumination is 10-4 lx; the active imaging method combining near infrared (central wavelength 808 nm) laser illumination and low-light night vision can increase the recognition distance of weak small targets; under the same condition, the active illuminated imaging working distance is 3 times of the dynamic imaging..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20190569 (2020)
Research on the bandpass filter used for single-exposure multi-spectral ghost imaging system
Meixuan Li, Siqi Zhang, Hong Li, Nan Li, Yuxuan Ren, and Jialong Tian
Different from the traditional point-to-point imaging, multi-spectral ghost imaging retrieve the image information of the target by means of modulation and demodulation. In this paper, a single-exposure multi-spectral ghost imaging system based on a fixed phase modulator was built, and the development of thin-film deviDifferent from the traditional point-to-point imaging, multi-spectral ghost imaging retrieve the image information of the target by means of modulation and demodulation. In this paper, a single-exposure multi-spectral ghost imaging system based on a fixed phase modulator was built, and the development of thin-film devices in the system was completed. In the thin film, BK7 glass was chosen as the substrate, niobium oxide (Nb2O5) and silicon dioxide (SiO2) were used as the high and low refractive index materials, respectively. Based on the basic theory of optical thin film, the simulation analysis and the film system design were carried out by the film system design software, through setting up evaluation function for film optimization, the design of 450-700 nm band-pass film filter with an incidence angle of 0°-30° was realized and the research and development of this film was completed on OZZSQ900 box-type vacuum coating machine. Through optimizing deposition rate of SiO2 film, the surface defects and scattering loss of film were reduced. The residual evaporation deposition of film was analyzed, the fitting function between film thickness and residual evaporation deposition by least square method was established, monitoring ways was adjusted, residual evaporation deposition was reduced and the accuracy of film thickness control during preparation process was improved. From the test performed by Agilent Cary5000 spectrophotometer, the transmittance is less than 0.5% in the bands of 350-440 nm and 710-800 nm, and higher than 98% in the range of 450-700 nm at the incident angle of 0°-30°, which meets the requirements of the imaging system. The study has important practical significance and engineering value..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200169 (2020)
Nonlinear metasurfaces: harmonic generation and ultrafast control
Yun Zhao, and Yuanmu Yang
Metasurfaces refer to the optical nanoantenna arrays composed of subwavelength structures. Nanoantennas can have resonances under appropriate excitation conditions, to achieve near-field enhancement, and thus enhancing nonlinear optical effects. Compared with conventional nonlinear optical crystals, metasurfaces are moMetasurfaces refer to the optical nanoantenna arrays composed of subwavelength structures. Nanoantennas can have resonances under appropriate excitation conditions, to achieve near-field enhancement, and thus enhancing nonlinear optical effects. Compared with conventional nonlinear optical crystals, metasurfaces are more compact, with the possibility for on-chip integration. Due to the subwavelength light-matter interaction length, for applications such as nonlinear harmonic generation, metasurfaces does not suffer from the limitation of phase-matching. In addition, metasurfaces own the subwavelength spatial resolution. By designing and arranging the meta-atoms, metasurfaces can realize flexible control of the phase, polarization, and amplitude of the harmonic wave. Recent works on nonlinear metasurfaces for applications in optical frequency conversion, nonlinear wavefront control and ultrafast all-optical modulation were reviewed, the challenges and perspectives for the practical application of metasurfaces were presented..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201037 (2020)
Ultrathin invisibility cloaks based on metasurfaces
Hongchen Chu, and Yun Lai
The invisibility cloak as a longstanding fantastic dream for humans is now within the realm of possibility, thanks to the development of metamaterials. Transformation-optics-based invisibility cloaks have been proposed and realized in many frequency ranges by utilizing gradient-index metamaterials. However, due to the The invisibility cloak as a longstanding fantastic dream for humans is now within the realm of possibility, thanks to the development of metamaterials. Transformation-optics-based invisibility cloaks have been proposed and realized in many frequency ranges by utilizing gradient-index metamaterials. However, due to the large size of device and difficulty in fabrication, transformation-optics-based invisibility cloaks are significantly limited in practical applications. Recently, metasurfaces as the 2D counterpart of metamaterials have attracted tremendous interests because of its thin thickness and strong capability in manipulating the electromagnetic waves. Ultrathin invisibility cloaks based on metasurfaces release the demand on bulky sizes and extreme parameters, thus promoting further development of invisibility cloaks. This review overviewed recent progress in ultrathin invisibility cloaks based on metasurfaces, focusing particularly on the working principles, implementation methods, advantages and disadvantages. Finally, some advice was put forward on the trends of this fast-developing research field..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201038 (2020)
Lasers & Laser Optics
Influence of phase additive effect on beam smoothing character of continuous phase plate
Chunlin Yang
During the operational process of high power laser system, the uniformity of focal spot will impact the experiment and application seriously. To improve the focal spot quality, a continuous phase plate (CPP) should be used in the light path for far field beam smoothing. As a phase element CPP has different functions, sDuring the operational process of high power laser system, the uniformity of focal spot will impact the experiment and application seriously. To improve the focal spot quality, a continuous phase plate (CPP) should be used in the light path for far field beam smoothing. As a phase element CPP has different functions, such as decoherece and beam shaping. In this paper the smoothing performance of CPP was concerned. Good performance of beam smoothing depended on a reasonable surface figure distribution. According to the random characteristic of phase plate surface, the statistical method was employed to study the beam smoothing mechanism. According to the relationship between the probability density and far field histogram of the surface of CPP, the expression of the superposition intensity envelope of distorted beam and CPP surface figure was deduced. The formula proved that the function of a CPP for focal spot was just a convolution filtering. So the mathematical explanation on the beam smoothing mechanism was achieved. Furthermore, using this analysis model the reason that the CPP with short correlation length will have the capability of better beam smoothing was explained theoretically. Numerical simulations were done to show the beam smoothing performance of CPP. The far field histograms with different distorted beams are calculated and compared. The results show that after the phase additive of the distorted beam and CPP a new wavefront was generated. If the law of large numbers is satisfied, when the correlation length and the gradient of the wavefront is small, the light focus spot distribution is smooth and uniform. The statistical geometrical optical method used in this paper can reduce the analysis difficulty on the phase additive effectively..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20190515 (2020)
Tunable light absorption in Ru atomic vapor driven by three coherent fields
Dongkang Li, Liyuan Gao, Tao Wang, Xingxia Tian, and Changbao Fu
In recent years, based on the intense interaction between coherent light and matter, the controllable quantum interference phenomena, such as coherent population trapping, electromagnetically induced transparency and electromagnetically induced absorption, optical hole-burning, have attracted a comprehensive concern. FIn recent years, based on the intense interaction between coherent light and matter, the controllable quantum interference phenomena, such as coherent population trapping, electromagnetically induced transparency and electromagnetically induced absorption, optical hole-burning, have attracted a comprehensive concern. For exploring the controllable characteristics of light absorption involving the coherent hole-burning, a four-level N-type atomic system was proposed, which was driven by a strong coherent light field and two coupling fields with the Doppler broadening thermal rubidium vapor. Via introducing the coupling fields and then adjusting the intensity of the coupling field in such an atomic system, some interesting quantum optical phenomena can be observed. Based on the design of this atomic model, the expression of absorption spectrum of the weak probe light fields was derived via the Laplace transform with the system Hamiltonian equation and density matrices. In the design of optical scheme, the saturated light field was inputted with the same or opposite propagating direction as that of the two coupling light fields, which was opposite the weak probe light field. In such a scheme, six coherent optical hole-burnings and one window based on electromagnetically induced transparency may be realized. With the adjustment of the relevant parameters in terms of the intensities and frequencies of the light fields, the enhancement or weakening of the light absorption can be realized in the absorption spectrum, including the change of the position and number of the optical hole-burning. By the transition of atoms excited by the fields, both electromagnetic induced transparency and electromagnetic induced absorption appeared at the same time. Through the adjustment of light field and the comparison of simulation results, the generation and conversion of the two quantum coherence effects were deeply studied. It is concluded that these results may have a good theoretical guidance for the popular optical quantum storage..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20190528 (2020)
Scattering properties of non-spherical cluster core-shell structure particle laser
Shenhe Ren, Ming Gao, Mingjun Wang, Xiujuan Bao, and Yan Li
On the basis of heterogeneous nucleation theory of ice crystal particles, three types of ice crystal particle models were established with nucleation-shell structures of ellipsoid, hexagonal flat plate and hexagonal prism. The extinction, absorption and scattering efficiency of these three special cluster-shaped core-sOn the basis of heterogeneous nucleation theory of ice crystal particles, three types of ice crystal particle models were established with nucleation-shell structures of ellipsoid, hexagonal flat plate and hexagonal prism. The extinction, absorption and scattering efficiency of these three special cluster-shaped core-shell structures were numerically calculated by discrete dipole approximation (DDA) method. Under the same incident wavelength, the effect of effective size on the extinction efficiency, absorption efficiency and scattering efficiency of core-shell ice crystal particles, the influence of the intermediate uniform mixing layer on the scattering intensity of core-shell ice crystal particles, and the variation of Mueller matrix elements with the scattering angle were calculated. The numerical results show that the extinction coefficient, absorption coefficient and scattering coefficient of ice crystallites with three clusters of ellipsoidal, hexagonal and hexagonal prisms show different trends with the increase of effective size. Under the condition of equal size, the scattering intensity with the change of the scattering angle and particle shape have close relations, and compared with the ellipsoid and hexagonal flat two cluster core-shell structure of ice crystal particles, core-shell structure of ice crystal particles hexagonal prisms forward scattering intensity, the largest scattering intensity curve along with the change of the scattering angle oscillation is more obvious. According to the distribution of the Mueller matrix elements with the scattering angle, it can be seen that the scattering direction of the hexagonal prism cluster ice crystal structure is the most obvious, and the forward scattering intensity is the largest. The Mueller matrix elements of the hexagonal plate and hexagonal prism cluster ice crystal structure are relatively spherical and the deviation of the ellipsoid in the backscattered field area is more obvious. The research results of the thesis provide support for further analysis of the scattering characteristics of complex ice crystal particles, and the research and analysis of the scattering characteristics of various complex geometric clusters of ice crystal particles in high-altitude clouds..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20190545 (2020)
Band gap and local electric field characteristics of surface waves in left-handed and right-handed materials of photonic crystal
Jiangyong Xu, Bo Zhou, An Su, Chengju Meng, and Yingjun Gao
The energy band structure and the surface wave local electric field distribution of the left-handed and right-handed photonic crystals materials, were studied based on parameter matching by using the transmission matrix theory of plane wave and Bloch theorem in order to study and design novel optical waveguide and optiThe energy band structure and the surface wave local electric field distribution of the left-handed and right-handed photonic crystals materials, were studied based on parameter matching by using the transmission matrix theory of plane wave and Bloch theorem in order to study and design novel optical waveguide and optical sensor. The results show that there are semi closed and closed band gap structures in the energy band of the left-handed and right-handed materials with zero mean refractive index, and the energy level curve in the transmission band attenuates from high frequency to low frequency with oscillation. After the surface coating medium is added, the discrete energy level of forward and reverse waves appear in the partially semi-closed and closed band gap of the photonic crystal, the discrete energy level moves to lower wave vector with the increase of the coating thickness, and the discrete energy level in the semi-closed band gap splits when the coating thickness is at a certain value. In the band gap, the maximum value of the local electric field of the forward surface wave and the highest light intensity are near the junction of the coating and the surface of the photonic crystal, and decay with the coating thickness increasing or away from the junction. The response sensitivity of the maximum value of the local electric field corresponding to the closed band gap to the coating thickness is weaker than that of the semi closed band gap. In the band gap, the local electric field, the maximum value of the local electric field of the reverse surface wave and the highest light intensity are in the the photonic crystal, and increase with the coating thickness. The local restriction of the closed band gap on the reverse surface wave, the coupling effect of the surface wave and the incident light, and the response sensitivity of the local electric field to the coating thickness are stronger than those of the semi-closed band gap..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200052 (2020)
Laser polarization characteristics of visible light band in different humidity environments
Juntong Zhan, Su Zhang, Qiang Fu, Jin Duan, Yingchao Li, and Huilin Jiang
Haze weather interferes with the visible light imaging effect, and the polarization characteristic of visible light can effectively improve the detection efficiency. Haze environment is affected by aerosol particle humidity, which is an important physical parameter of haze environment. In order to obtain the polarizatiHaze weather interferes with the visible light imaging effect, and the polarization characteristic of visible light can effectively improve the detection efficiency. Haze environment is affected by aerosol particle humidity, which is an important physical parameter of haze environment. In order to obtain the polarization characteristics of visible light in haze environment, the influence of humidity in haze environment on polarization characteristics was analyzed. Based on the single particle scattering characteristics of non-polarized light aerosol, the polarization transmission model was established by improved Monte Carlo method, research on transmission characteristics of polarized light in visible bands under different humidity and water mist was conducted, the influence of humidity change in water mist environment on polarization characteristics of polarized light in different visible bands was analyzed, and a near-real water mist environment was built. The polarization model was verified by laboratory experiments, the change of polarization degree and polarization state of linear polarized light on 450, 532 and 671 nm was compared and analyzed under different humidity conditions, the confidence of simulation model was more than 60%. The results show that the polarization degree of polarized light decreases with the increase of humidity of water-fog environment. With the increase of the wavelength, the polarization tends to be flat, while the exit polarization degree increases with the increase of wavelength. The humidity values of the descending point of polarization degree are 50%, 70% and 90% when the laser wavelengths are 450, 532, 671 nm, respectively. For water mist, which is easily affected by humidity, polarized light with longer wave length should be selected as far as possible for transmission detection in visible band. Because humidity has a greater influence on shorter wavelengths than longer wavelengths, circularly polarized light with longer wavelengths has the best polarization retention characteristics in environments with higher humidity. In the environment with high humidity, polarized light imaging with long wavelength should be selected as far as possible to achieve better imaging effect..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200057 (2020)
Laser-induced transformation of carbon nanotubes into graphene nanoribbons and their conductive properties
Zhi Liu, Jimin Chen, Dongfang Li, and Chenyu Zhang
GNRs can be readily produced by unzipping the nanotubes because CNT structure can be analogically considered as graphene sheets rolled up. This is a special 2D graphitic structure performing the exceptional properties. Due to the unique structure and the outstanding properties, GNRs have been used in a vast range of apGNRs can be readily produced by unzipping the nanotubes because CNT structure can be analogically considered as graphene sheets rolled up. This is a special 2D graphitic structure performing the exceptional properties. Due to the unique structure and the outstanding properties, GNRs have been used in a vast range of applications, including transistors, optical and microwave communication devices, biosensors, chemical sensors, electronic memory and processing devices, nano electromechanical systems, and composites. The morphology of the fiilms was observed by scanning electron microscopy (SEM), and the properties of graphene were characterized by Raman spectroscopy. The conductivity of the fiilms was measured by a semiconductor parameter measurement system. Raman spectroscopy showed that the Raman characteristics of graphene characterized by optimized process were enhanced. Laser energy and irradiation time were two important parameters for the preparation of graphene from carbon nanotubes. In this study, to open carbon nanotubes by laser, graphene nanoribbons were produced by excimer laser irradiation of carbon nanotubes thin films. The experimental results show that, with the laser energy 150 mJ, the carbon nanotubes are not opened while the connection is observed. With the energy 450 mJ, the carbon nanotubes can be effectively destroyed, and graphene strips can be partially opened to form. At this time, the conductivity of the fiilm reaches the maximum value. Due to the thermal accumulation effect, a large number of porous structures appear on the wall of carbon nanotubes..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200298 (2020)
Longitudinal forced convection heat transfer for high power slab laser media
Jianguo He, Ming Li, Zeqiang Mo, Jinduo Wang, Jin Yu, Shoujun Dai, Yanzhong Chen, Wenqi Ge, Yang Liu, and Lianwen Fan
Thermal problem becomes more prominent in the highly-pumped laser gain mediums, for which, the forced convective heat transfer with the advantages of reliability and durability is widely used. However, a flow direction induced temperature gradient always appears within the laser operating substance during the convectivThermal problem becomes more prominent in the highly-pumped laser gain mediums, for which, the forced convective heat transfer with the advantages of reliability and durability is widely used. However, a flow direction induced temperature gradient always appears within the laser operating substance during the convective heat transfer. Subsequently, it is significantly responsible for the detrimental thermal stress which mainly cause the wave front distortion. Herein, considering the idea of temperature matching between flow field and the operating substance, a cooling configuration for double face pumped slab crystal based on longitudinal forced convective heat transfer was presented, which showed a more efficient cooling and achieved a most homogeneous temperature distribution within the crystal. The influences of flow rate, state of flow field and surface roughness were systematically studied that a fully developed flow state, higher flow rate and rougher surface lead to an improvement in cooling capability. In the simulation with 30 L/min flow rate, the calculated convective heat transfer coefficient was as high as 104 W·m-2·K-1, and even higher when a more coarse surface was implemented. Furthermore, a module based on the configuration was fabricated and the experimental results agree well with the simulation, which shows a good temperature distribution and very weak thermal lensing is achieved..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200556 (2020)
Optical Design
Vibration isolation system for transportation of main mirror of a large Antarctic telescope
Zhongyu Yue, Xiangqun Cui, and Bozhong Gu
The Antarctic Observatory of China contains an optical/infrared telescope with a diameter of 2.5 m primary mirror. The telescope is made in China and needs to be transported to the Antarctic Observatory in the form of large assembly. From Zhongshan Station in the edge of the Antarctic continent to Kunlun Station in theThe Antarctic Observatory of China contains an optical/infrared telescope with a diameter of 2.5 m primary mirror. The telescope is made in China and needs to be transported to the Antarctic Observatory in the form of large assembly. From Zhongshan Station in the edge of the Antarctic continent to Kunlun Station in the interior of the continent, the telescope needs to be transported by sled, which vibrates violently in some regions. In this paper, the vibration isolation system of the telescope's 2.5 m primary mirror module for transportation was researched. Firstly, the theoretical model of vibration isolation system was established and the performance of two-stage vibration isolation system was analyzed by the four-terminal parametric method. Secondly, the historical data from the Antarctic inland expedition team in the sled transportation was studied and the allowable dynamic condition of the primary mirror module was calculated by finite element method(FEM) considering the non-uniformity of the bottom supporting force. Thirdly, a two-stage vibration isolation system consisting of a leverage buffer structure and a polyethylene foam structure was proposed. Finally, the performance of this vibration isolation system was researched with FEM simulation and multi-body system simulation. The results show that the vibration isolation system proposed in this paper can meet the requirement of the mirror's transportation. In the finite element model, when the most extreme impact signal is loaded which is acquired by the Antarctic inland expedition team form the sled transportation, the maximum acceleration of the primary mirror module is less than 5 times acceleration of gravity which is a security value coming from the dynamic analysis of primary mirror module, and the Z-direction moving range of the module is about 1.2 m. So the vibration isolation system has practical value. This system can be used in the transport of the primary mirror module of the 2.5 m telescope to the Antarctic inland. The vibration isolation system proposed in this paper is valuable for transportation of other fragile structures..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20190517 (2020)
Control method of adaptive optical system based on conjugate combined model of aberration
Jiawei Yong, Youming Guo, and Changhui Rao
In the concentric aperture circle of the unit circle, some special Zernike modes have interrelated relationship. When the modes with strong negative correlation is superposed with a certain coefficient, the aberrations in a certain concentric aperture will cancel each other and the wave surface will become smoother. ThIn the concentric aperture circle of the unit circle, some special Zernike modes have interrelated relationship. When the modes with strong negative correlation is superposed with a certain coefficient, the aberrations in a certain concentric aperture will cancel each other and the wave surface will become smoother. This phenomenon is called the conjugate property between modes. In this paper, a set of distorted wavefront was set up, and the residual error was corrected by adaptive optical system. Then Zernike polynomials were used to decompose the corrected residual of deformable mirror. Through analysis, it was found for the first time that there was an obvious negative correlation between the lower and higher order aberrations in the residual wavefront with large mean square error. The aberration coefficients of the two parts will change regularly with the adjustment of the control signal of the deformable mirror, and in a certain combination of the coefficients, the two parts of aberrations will show conjugation. Based on the above research results, a control method was proposed. By optimizing the control voltage of the deformable mirror, the shape of the mirror surface can be adjusted so that the low-order and high-order aberration coefficients in the residual error can achieve the best matching. In this way, the root mean square (RMS) of the aberration in the concentric aperture circle of the pupil can be reduced, and the imaging quality of the system within this aperture range can be improved. The point target imaging and extended target imaging were simulated respectively. The results show that compared with the traditional closed-loop conjugate correction method, this method can obtain better optical imaging quality in the face of complex aberrations, and can effectively expand the application range of traditional adaptive optical system. This control method has a good application prospect when the deformable mirror has large fitting residual..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20190534 (2020)
Development of pressure control system for laser infrared multipass cell using Ziegler-Nichols-PID algorithm
Huixiang Xu, and Guoli Kong
In order to realize the high performance detection of CO2 gas isotope, a multi-pass gas cell pressure control system with high precision and stability was developed in this paper. In terms of hardware, the pressure sensor was connected to the front and back end of the multi-pass gas cell to measure the inside pressure In order to realize the high performance detection of CO2 gas isotope, a multi-pass gas cell pressure control system with high precision and stability was developed in this paper. In terms of hardware, the pressure sensor was connected to the front and back end of the multi-pass gas cell to measure the inside pressure of multi-pass gas cell. The main controller regulated the proportional valves that were at the front and back end of the multi-pass gas cell via PWM signal, so as to realize the closed loop of pressure control. In terms of software, Ziegier-Nichols engineering setting method was adopted to determine three parameters P, I and D. The results show that the control accuracy is ±0.04 Torr (1 Torr=133.322 Pa) when the pressure of the multi-pass gas cell is 60 Torr. In experiment, the developed pressure control system of multi-pass cell was used to measure the absorption spectra of 13CO2 and 12CO2 gas molecules at 4.3 μm. With the increase of gas pressure from 0.026-0.066 atm(1 atm= 101 325 Pa), the peaks of the absorption spectra of 13CO2 and 12CO2 gas molecular increased with the increase of pressure, the width of the absorption spectra also increased with the increase of pressure. Meanwhile, an infrared gas measuring system was used to measure the CO2 isotope abundance during two hours. The average isotope abundance of CO2 is -9.081‰, and the fluctuation of measured values is between -8.351‰ and -9.736‰, with the maximum deviation of 0.73‰. It can be proved that the system provides reliable guarantee for high performance detection of infrared CO2 gas isotope..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20190551 (2020)
Design and realization of light and small long-wave infrared optical system
Siyuan Hao, Jianan Xie, Maoxing Wen, Yueming Wang, and Liyin Yuan
The requirements on its load volume and weight are strict for unmanned airborne photoelectric pod. In order to meet the needs of 8-12.5 μm infrared detection, a lightweight and compact long-wave infrared optical system was designed and realized. The F number of the system was 2, the diameter was 150 mm, and the total fThe requirements on its load volume and weight are strict for unmanned airborne photoelectric pod. In order to meet the needs of 8-12.5 μm infrared detection, a lightweight and compact long-wave infrared optical system was designed and realized. The F number of the system was 2, the diameter was 150 mm, and the total field of view was 2.34 °. A twice focusing reflection-refraction structure was used as the optical system structure. It simplified the commonly used Cassegrain-type main system into a folded Newton-type main system, and simplified the spherical secondary into a plane mirror folding optical path. The off-axis aberrations were corrected by the aspherical correction lens group. An all-aluminum optical-mechanical structure was designed for the main system, combined with the optical-mechanical material matching of the rear optical path. In the temperature range of the working environment, the designed MTF of the system was more than 0.41@17 lp/mm, with 100% cold stop efficiency, and the volume was only Φ152 mm×125 mm. After final alignment, the MTF of the instrument was more than 0.24@17 lp/mm, and the image quality was clear and met expectations. The optical system was smartly designed, so the structure was light and compact, and the cost of manufacture and alignment was low. The design ideas and development methods can provide a reference for the optical systems of long-wave infrared instruments of unmanned airborne photoelectric pods for similar applications..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200031 (2020)
Optical system design of star sensor with long focal length and athermalization
Yanxiong Wu, Jian Qiao, and Liping Wang
Optical system is the core component of autonomous navigation star sensor to realize the collection of star light and high-precision attitude measurement. In this paper, the optical system of high precision star sensor was taken as the research object, the influence mechanism of the accuracy of optical system for detecOptical system is the core component of autonomous navigation star sensor to realize the collection of star light and high-precision attitude measurement. In this paper, the optical system of high precision star sensor was taken as the research object, the influence mechanism of the accuracy of optical system for detecting different color temperature stars were studied and analyzed. It is difficult to suppress the centroid drift caused by the changes of star color temperature and ambient temperature through later calibration, which needs to be controlled under the stage of optical design. The calculation model and allocation method of optical system design wavelength weight were established, and the performance evaluation was carried out. In addition to the conventional energy concentration, distortion and asymmetric aberrations, the centroid drift of star color temperature and ambient temperature change were proposed as the main index of accuracy evaluation. According to the application requirements, a long focal star sensor optical system based on space satellite platform was designed, with the focal length of 95 mm, the relative aperture of f2.4, the field view of 8°× 8°, the spectrum range of 450-1 000 nm, and the energy concentration of more than 85% in 3×3 pixels. Based on the regular glass materials, the lateral color aberration of the optical system was corrected under ultra-wide spectral range and long focal. The lateral color aberration of the full field was less than 0.9 μm; The results of accuracy analysis show that the accuracy of centroid position is less than 0.36 μm in the range of 2 600-9800 K, and the change of focal length is less than 2.7 μm in the range of 0-40℃, and the accuracy of centroid position caused by temperature is less than 0.45 μm..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200061 (2020)
Optical Imaging
Research progress of APD three-dimensional imaging lidar
Jie Cao, Qun Hao, Fanghua Zhang, Chenyu Xu, Yang Cheng, Jiali Zhang, Yu Tao, Dong Zhou, and Kaiyu Zhang
Due to the advantages of rich information, strong anti-interference ability and high resolution, three-dimensional (3D) imaging lidar has been widely used in defense and civil fields, such as geomorphology surveys, autopilot, smart transportation and visual tracking. With the development of avalanche photodiode detectoDue to the advantages of rich information, strong anti-interference ability and high resolution, three-dimensional (3D) imaging lidar has been widely used in defense and civil fields, such as geomorphology surveys, autopilot, smart transportation and visual tracking. With the development of avalanche photodiode detector (APD) and the multiplicities of 3D lidar (e.g., MEMS, optical phased array, flash, etc.), the performances of lidar has been greatly improved compared with that of initial 3D systems. According to the new requirements on 3D lidar for the military and civilian fields, novel methods and mechanisms were proposed to improve comprehensive performances of 3D imaging. First of all, the three key technologies of APD-based 3D imaging lidar were analyzed, including the transmitting unit, the receiving unit, and the algorithm unit (data processing unit). Then, 3D imaging lidar was classified and discussed according to the different applications for loading. Among them, 3D imaging lidar based on unmanned vehicle was selected as the typical example for illustrating the application status and the difficulties faced with military and civilian applications. Based on the diversified development of 3D imaging methods, two novel 3D imaging methods (heterogeneous resolution and ghost imaging) suitable for APD devices were discussed. Finally, based on the analysis of the research status of 3D imaging lidar, it is concluded that 3D imaging lidar is developing towards the large field of view, high resolution, high precision, real-time, modularity and intelligence, which paves the way for developing high performances of 3D imaging lidar..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20190549 (2020)
Photoelectric Measurement
Dual linear array laser thermography detection of arbitrary direction cracks on cylindrical surface
Xinhao Zhu, Dexin Hou, and Shuliang Ye
Cylinder ferrite magnetic core is a batch of black cylindrical samples and its crack contrast is low. The crack imaging result of traditional machine vision is not good. Laser infrared thermography detection technology relies on the sample surface temperature distribution to detect the crack defects, which solve the prCylinder ferrite magnetic core is a batch of black cylindrical samples and its crack contrast is low. The crack imaging result of traditional machine vision is not good. Laser infrared thermography detection technology relies on the sample surface temperature distribution to detect the crack defects, which solve the problem of low contrast micro crack detection. When the crack is detected by line laser or point laser, the cracks parallel to the laser scanning direction is hard to detect because of the small heat flow on both sides. Dual linear array laser thermography system with dislocation arrangement creates multi-direction heat flow, which can detect arbitrary direction cracks. In order to verify the feasibility of dual linear array laser to detect arbitrary direction cracks, simulation took the laser scanning process of 0°, 45° and 90° cracks. Linear array laser had great non-uniformity in the power distribution of each spot, so different parameter design had great influence on crack detection. Therefore, the design parameters such as spot radius, spot center distance, linear array laser dislocation distance, linear array laser distance, and motion velocity were optimized to improve the SNR in crack detection. Crack imaging algorithm generated cracks based on temperature spatial gradient. Due to the non-uniformity of the laser spots, the gradient of the crack at different relative positions between two laser beams was different. Algorithm selected the position of the cracks with large relative gradient between two laser beams. Through the fusion of multiple gradient images, crack imaging algorithm achieved arbitrary direction crack detection. The imaging algorithm was designed according to the crack spatial temperature gradient characteristics excited by dual linear array laser. Four cylinder ferrite samples with horizontal, vertical and inclined natural cracks were tested, and the imaging results showed all the cracks clearly and intuitively..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200097 (2020)
3D trajectory planning for gliding vehicle using linear pseudospectral model predictive control
Jianbo Sun, Xinghua Pan, Liang Yang, Wanchun Chen, and Yushan Zhao
A new entry guidance law for the high lift to drag ratio gliding vehicle was proposed on the basis of the linear pseudospectral model predictive control method. Adopting this approach, the vehicle can arrive at the end of the entry flight with the specific heading angle. Moreover, all the typical constraints such as teA new entry guidance law for the high lift to drag ratio gliding vehicle was proposed on the basis of the linear pseudospectral model predictive control method. Adopting this approach, the vehicle can arrive at the end of the entry flight with the specific heading angle. Moreover, all the typical constraints such as terminal state constraints and path constraints can be satisfied as well. Firstly, the agent technology using high dimensional polynomials was applied to generalize the lift to drag ratio, hence the analytical expression of the lift to drag ratio was obtained with respect to the energy and the angle of attack. Therefore the angle of attack was designed online to adjust the lift to drag ratio, which can enhance the trajectory planning capacity. The whole entry flight was divided into two phases noted as the descent phase and the gliding phase respectively. In the descent phase, in order to limit the maximum heating rate, the angle of attack remains the maximum allowance value and the bank angle was set to zero. During the gliding phase, the linear pseudospectral model predictive control method was applied. The reduced order dynamic model was formulated to predict the terminal state deviation, and the reduced order dynamic equation was linearized to obtain the error propagation equation. Due to the complexity of the integral calculation, Gauss pseudospectral method was used to derive the correction of the control variables. Finally, terminal state deviations involving final position and heading angle can be efficiently eliminated by modifying the angle of attack parameters, the bank angle parameters and the energy parameters of two bank reversal points. This method is simple and easy to implement with high accuracy, and it is convenient for on-line calculation. The simulation results also show that the planning requirements can be satisfied well through this method..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200279 (2020)
Design of information processing system for photoelectric seeker
Xianzhi Chen, Zhenbao Luo, Xu Yang, Tao Chen, and Jingtong Zhao
The photoelectric seeker is an important part of intelligent ammunition, and information processing is the core key technology of its precision guidance. From the perspective of engineering application, the main tasks and technical requirements of the information processing of the photoelectric seeker were systematicalThe photoelectric seeker is an important part of intelligent ammunition, and information processing is the core key technology of its precision guidance. From the perspective of engineering application, the main tasks and technical requirements of the information processing of the photoelectric seeker were systematically analyzed, and the classic distributed modular information processing design technical schemes were sorted out, and its significant advantages and main disadvantages were summarized. With the changes in the requirements of precision guided weapons in future combat objectives, environments and missions, in order to adapt to the development trend of multi-mode composite, intelligent, miniaturized, lightweight and low-cost photoelectric seekers, better meet the constraints of the missile environment urgent needs, make full use of the innovative results of VLSI and information processing technology, in the overall architecture of the photoelectric seeker system, the design ideas of integrated and miniaturized information processing were put forward, and typical application schemes was got, and the core performance was designed. It has significant advantages in terms of comprehensive cost and power consumption, and has strong versatility, which is conducive to the integration of missile guidance platform architecture, missile serialization and upgrading, and provides a reference for the development of a new generation of advanced photoelectric seeker engineering..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20200312 (2020)
Special Issue-Metasurface Empowered Manipulation of Wavefront
Nonlinear optics and quantum optics based on metasurface
Mingqian Shi, Jun Liu, Zhuo Chen, Shuming Wang, Zhenlin Wang, and Shining Zhu
In recent years, metasurface has received extensive attention in the field of classical light control, and excellent results have been obtained. At the same time, the application of metasurface in nonlinear optics and quantum optics has also attracted more and more interest. The basic principles and applications of nonIn recent years, metasurface has received extensive attention in the field of classical light control, and excellent results have been obtained. At the same time, the application of metasurface in nonlinear optics and quantum optics has also attracted more and more interest. The basic principles and applications of nonlinear metasurface and quantum metasurface were introduced, and the related reports in recent years were summarized, including the harmonic generation and enhancement, the relationship between harmonic generation and symmetry, the nonlinear phase control and holography, and the generation, measurement and manipulation of entangled photon based on metasurface. Finally, the potential application of metasurface in these two fields were prospected..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201028 (2020)
Exceptional points in metasurface
Huixin Qi, Xiaoxiao Wang, Xiaoyong Hu, and Qihuang Gong
Exceptional points are special points in non-Hermitian systems, and there are many novel physical phenomena in the parameter space near the exceptional points. In recent years, metasurface has been a popular topic in physics. A large number of devices with superior performance have been designed based on metasurface plExceptional points are special points in non-Hermitian systems, and there are many novel physical phenomena in the parameter space near the exceptional points. In recent years, metasurface has been a popular topic in physics. A large number of devices with superior performance have been designed based on metasurface platform. The appearance of the metasurface provides an easy platform for the study of exceptional points. By precisely controlling the structural parameters of the metasurface, it is convenient to study the parameter space of the exceptional points. The research on exceptional points in non-Hermitian metasurface also provides a foundation platform for studying new laws of physics. Firstly, the basic theory of exceptional points and the exceptional point in metasurface was introduced. Secondly, the recent research on the exceptional points in metasurface was introduced. Finally, the current problems needing to be solved were analyzed and the development of the field in the future was prospected..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201029 (2020)
Large field-of-view and compact full-Stokes polarimetry based on quadratic phase metasurface
Yaxin Zhang, Mingbo Pu, Yinghui Guo, Jinjin Jin, Xiong Li, Xiaoliang Ma, and Xiangang Luo
Polarization is one of the inherent characteristics of light, but the polarization information of electromagnetic waves is lost by traditional intensity and spectral detection technology. At the same time, not only the devices and technologies based on polarimetry have the problem of limited field of view, but also thePolarization is one of the inherent characteristics of light, but the polarization information of electromagnetic waves is lost by traditional intensity and spectral detection technology. At the same time, not only the devices and technologies based on polarimetry have the problem of limited field of view, but also the measuring systems are complicated. In this paper, a compact large field-of-view polarimeter was designed based on dielectric metasurface, which realized the detection of the angle and polarization state of the incident light. The device was composed of 2×2 quadratic phase metasurfaces, each of which realized the symmetry transformation for a specific polarization, that is, the rotational symmetry of the incident angle was converted into the translational symmetry of focus in the focal plane. The theory of the symmetry transformation of the quadratic phase made it possible to characterize the angle of incidence by measuring the offset of the focus over a wide angle range (-40°—+40°). On this basis, the influence of oblique incidence on the measurement of Stokes parameters was elaborated, and the modified Stokes formula was obtained. The Stokes parameters of the incident light can be calculated by utilizing the intensities of the four focal points and the modified Stokes formula. The measured Stokes parameters agree well with the theoretical values, when the field-of-view is 0°, 20°, and 40°..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201030 (2020)
Complex amplitude modulation of light fields based on dielectric metasurfaces and its applications
Xuyue Guo, Bingjie Li, Xinhao Fan, Jinzhan Zhong, Sheng Liu, Bingyan Wei, Peng Li, and Jianlin Zhao
Metasurface is an artificially ultrathin material with two-dimensional nanostructure array, which can achieve flexible modulation on amplitude, phase and polarization of light field in a sub-wavelength scale, providing a new possibility for the miniaturization and integration of modern optical devices. With the developMetasurface is an artificially ultrathin material with two-dimensional nanostructure array, which can achieve flexible modulation on amplitude, phase and polarization of light field in a sub-wavelength scale, providing a new possibility for the miniaturization and integration of modern optical devices. With the development of optical imaging, display and so on, the requirement of miniaturized optical devices with high efficiency in visible light band is becoming conspicuous. In recent years, optical metasurfaces fabricated by dielectric materials with high refractive indices and low losses have been extensively studied, showing application prospects in achromatic metalens, polarization-dependent holographic display, et al. Around the research on the metasurface of dielectric, firstly, the generalized Snell's law and the modulation principle of nanostructures in dielectric metasurface on amplitude, phase and polarization of light field were introduced. Then the research progress of dielectric metasurfaces in holographic display and structural light field generation, based on single- and multi-parameters modulation of light field was reviewed. At last, the possible challenges and prospects of dielectric metasurfaces were discussed..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201031 (2020)
Design and parametric analysis of the broadband achromatic flat lens
Xingjian Xiao, Shining Zhu, and Tao Li
The design of large scale, high numerical aperture, and broadband achromatic flat lens is a bottleneck of imaging technology and also a big challenge in metalens researches in recent years. The major reason is that there are some internal constraints between these parameters. In this paper, considering both the group dThe design of large scale, high numerical aperture, and broadband achromatic flat lens is a bottleneck of imaging technology and also a big challenge in metalens researches in recent years. The major reason is that there are some internal constraints between these parameters. In this paper, considering both the group dispersion theory and the phase distribution of the flat lens, the semi-quantitative relationship between these parameters was derived. Then, the achromatic flat lenses (including metalenses and multi-level diffractive lenses) with different parameters were designed by using directly binary search and topology optimization. It was found that under the condition of maintaining an efficiency of 80%, when doubling the size of flat lens (i.e., the diameter), the numerical or achromatic bandwidth was cut in half, and the thickness of lens increased linearly with lens scale. The results definitely show that these two types of flat lenses have the same internal constraint relations in parameters, that is, as that the lens size has negative correlation with the numerical aperture and achromatic bandwidth, while positive correlation with the thickness of the lenses. This result is in coincidence with the theoretical prediction..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201032 (2020)
Development of metasurfaces for wavefront modulation in terahertz waveband
Jingwen He, Tao Dong, and Yan Zhang
Metasurface is an ultrathin planar device composed of artificial microstructures, which can be used to manipulate the amplitude, phase, and polarization of electromagnetic (EM) waves. Metasurface has the advantages of small volume, light weight, highly integrated, flexible manipulation of EM waves, so it plays an imporMetasurface is an ultrathin planar device composed of artificial microstructures, which can be used to manipulate the amplitude, phase, and polarization of electromagnetic (EM) waves. Metasurface has the advantages of small volume, light weight, highly integrated, flexible manipulation of EM waves, so it plays an important role in the field of EM wave spectrum and wavefront modulation. In this paper, the research progresses of metasurface for wavefront modulation in the terahertz (THz) waveband were reviewed. The amplitude and phase modulation mechanisms of three kinds of microstructure units in the metasurface, including the microstructure based on Pancharatnam-Berry (PB) phase, localized surface plasmon resonance (LSPR) and Mie resonance were summarized, and the methods for realizing metasurface with high efficiency were discussed. After that, the pure phase and complex amplitude modulation methods for designing the wavefront modulation metasurface were introduced. Specifically, the typical functions, including single function and multifunction and tunable function, of the wavefront modulation metasurfaces in the THz waveband were reviewed. In the early research, metasurfaces were used to realize beam focusing, beam deflection, holographic imaging, and special beam generation such as vortex beam, Airy beam, and Lorentz beam in the THz region. In order to improve the utilization of a THz component, multifunctional metasurfaces, such as metasurfaces with polarization and wavelength multiplexing were proposed. With the requirement of dynamic control of the THz wavefront, some active metasurfaces were proposed and demonstrated. There were two kinds of active metasurfaces. One of the active metasurfaces was formed by combining the metasurface with semiconductor or phase transition materials, and the other was the all-optical metasurface formed by a silicon wafer with pump beam. The all-optical metasurfaces can be reused without reprocessing. The THz wavefront can be modulated dynamically by adjusting the image of the metasurface projected on the silicon wafer. Thus, the all-optical metasurface had the ability to dynamically control the beam steering and focusing, and it can be applied in THz communication, THz radar and other fields. At the end, the development trend and application prospects of the metasurfaces for wavefront modulation in the THz waveband were discussed..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201033 (2020)
Multi-dimensional metasurface and its application in information encryption and anti-counterfeiting
Zilan Deng, Qing'An Tu, and Xiangping Li
Metasurface is an artificial layered material with a subwavelength or wavelength-scale thickness. By adjusting the size, shape, orientation angle, displacement, etc. of the metasurface nanostructures, dimensions of electromagnetic wave including frequency, amplitude, phase, polarization, wavelength, etc. can be flexiblMetasurface is an artificial layered material with a subwavelength or wavelength-scale thickness. By adjusting the size, shape, orientation angle, displacement, etc. of the metasurface nanostructures, dimensions of electromagnetic wave including frequency, amplitude, phase, polarization, wavelength, etc. can be flexibly and effectively controlled. Metasurface has various characteristics including the ultra-thin thickness, broadband, low loss, easy processing, flexible design and powerful functionalities. This paper reviewed metasurfaces capable of one-dimensional, two-dimensional, multi-dimensional, and active light field manipulations and their applications in information encryption and anti-counterfeiting. An outlook was given for the future development trend of multi-dimensional metasurfaces. Compared with the traditional information encryption and anti-counterfeiting technology, the metasurface has the superior advantages in sub-wavelength pixels, precise controlling and ultra-secure factor in information encryption and anti-counterfeiting. Its bright future to replace the traditional information encryption and anti-counterfeiting technology was envisioned, and its broad application prospects were underpinned..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201034 (2020)
Progress of micro-nano fabrication technologies for optical metasurfaces
Yueqiang Hu, Xin Li, Xudong Wang, Jiajie Lai, and Huigao Duan
The metasurface is composed of carefully arranged sub-wavelength units in a two-dimensional plane, which provides a new paradigm for designing ultra-compact optical elements and shows great potential in miniaturizing optical systems. In less than ten years, metasurfaces have caused extensive concern in multidisciplinarThe metasurface is composed of carefully arranged sub-wavelength units in a two-dimensional plane, which provides a new paradigm for designing ultra-compact optical elements and shows great potential in miniaturizing optical systems. In less than ten years, metasurfaces have caused extensive concern in multidisciplinary fields due to their advantages of being ultra-light, ultra-thin and capable of manipulating various parameters of light waves to achieve multi-functional integration. However, in the optical band, high-degree-of-freedom, aperiodic, and densely arranged metaunits put forward many extreme parameter requirements for fabrication, such as extremely small size, extremely high precision, high aspect ratio, difficult-to-process materials, cross-scale, etc. This poses a great challenge for metasurfaces from laboratory to practical applications. Here, the principles, characteristics and latest developments for micro-nano fabrication of metasurfaces in recent years were summarized, including small-area direct writing methods, large-area template transfer methods, and some emerging fabrication methods. Finally, the current challenges and future development trends of metasurface fabrication were summarized and prospected..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201035 (2020)
Advances in the research of multifunctional metasurfaces merging computer-generated holography and nanoprinting
Zile Li, Zhou Zhou, Congling Liang, and Guoxing Zheng
Computer-generated holography and nanoprinting are two typical applications of optical metasurfaces. Recently, merging holography and nanoprinting into a multifunctional metasurface becomes an emerging research hotspot, which has prospective applications in multi-folded anti-counterfeiting, information decoding and mulComputer-generated holography and nanoprinting are two typical applications of optical metasurfaces. Recently, merging holography and nanoprinting into a multifunctional metasurface becomes an emerging research hotspot, which has prospective applications in multi-folded anti-counterfeiting, information decoding and multiplexing, multi-channel image display and VR/AR, etc. In this paper, based on the features of metasurface-based nanoprinting and computer-generated holography, the advances in the research of merging them were classified and characterized in detail. Specifically, the merging methods were discussed in detail which included orthogonal-polarization multiplexing scheme, in-plane arrangement scheme, multilayer-stacking scheme, simultaneous spectrum and phase control scheme, complex amplitude modulation scheme, orientation degeneracy scheme. The future development of multifunctional metasurfaces was prospected..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201036 (2020)
From subwavelength grating to metagrating: principle, design and applications
Rui Chen, Xia Liu, Hong Wang, Weiyi Shi, Weinan Liu, Shaoji Jiang, and Jianwen Dong
With the development of nanophotonics, optical structures, such as optical microcavity, waveguide structure, photonic crystal, subwavelength gratings and metasurfaces, can realize light transmission and manipulation at nanoscale, which promotes the development of optical integration. Subwavelength grating has been wideWith the development of nanophotonics, optical structures, such as optical microcavity, waveguide structure, photonic crystal, subwavelength gratings and metasurfaces, can realize light transmission and manipulation at nanoscale, which promotes the development of optical integration. Subwavelength grating has been widely studied by scientists because of its simple structure and low cost. It has gradually formed a mature theoretical system of grating analysis model when applied to various optical devices. Combined with the coupling of periodic structure and scattering modulation characteristics of meta-atoms, the metagrating derived from subwavelength gratings can improve the efficiency by using periodic Bragg scattering, thus avoiding the efficiency reduction and energy loss caused by the phase discretization. Scientists have studied and designed metagratings, and more physical phenomena and applications have been explored. In this paper, the basic theory, design and application of subwavelength gratings and metagratings were summarized. Based on the basic principle, the characteristics of subwavelength gratings and metagratings were discussed, the theoretical and unit design methods were also outlined and their applications in biosensing, spectral control of filter and absorption film were introduced. Finally, the future development was prospected..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201039 (2020)
All-optical image processing technology and applications based on micro-/nano-devices
Weiwei Fu, and Kun Huang
The rapid development of nanotechnology has promoted the processing and manufacturing of micro-nano structures, scientific research and industrial applications. The investigation on optical properties of micro-nano structures has recently been one of the hotspots in the field of optics, which has driven emerging discipThe rapid development of nanotechnology has promoted the processing and manufacturing of micro-nano structures, scientific research and industrial applications. The investigation on optical properties of micro-nano structures has recently been one of the hotspots in the field of optics, which has driven emerging disciplines such as nanophotonics, surface plasmonic optics, metasurface/metamaterial optics, topological photonics, and non-Hermitian optics. It provides the important technical fundamentals for full control of light with high precision. This article focused on the edge detection in all-optical image processing. The fundamentals, principles, technologies and applications of micro-/nano-scale structures and devices were discussed to realize optical mathematical computing (such as differential, convolution), followed by a detailed prospect about its future applications in ultrafast image processing, high-contrast microscopic imaging, convolutional neural networks and intelligent optics..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201040 (2020)
Progress of polarization-information detection technology based on manipulations of metasurface
Zhongyi Guo, Qianlong Kang, Zhiyong Peng, Yuemeng Cui, Huasong Liu, Jun Gao, and Kai Guo
Polarization is an inherent property of light. By deconstructing the relation between the incident and transmitting polarization states, the crucial information about the composition and structure of the interacting materials can be obtained, and thus polarization information shows high research value and application pPolarization is an inherent property of light. By deconstructing the relation between the incident and transmitting polarization states, the crucial information about the composition and structure of the interacting materials can be obtained, and thus polarization information shows high research value and application potential. In recent years, research areas, such as polarization imaging and polarization information, are flourishing and attracting wide attention of scholars all over the world. A key of these research fields is the acquisition of polarization information with high efficiency. However, conventional methods for acquisition of polarization information have various shortcomings, restricting the development of polarization information. Metasurface technology provides people with an opportunity to artificially change the phase, amplitude and polarization of light wave, with characteristics of miniaturization and integration. Firstly the polarization-information acquisition and the circular-polarization detector based on Archimedes spiral structure were introduced. Then the progress of polarization-information acquisition based on metasurface in recent years, including metal metasurface polarization detector, all-dielectric metasurface polarization detector, and polarization imagings was summarized. At last, the research status and development trend of the polarization-information acquisition technology based on metasurface were discussed..
Infrared and Laser Engineering
- Publication Date: Sep. 25, 2020
- Vol. 49, Issue 9, 20201041 (2020)
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