Journals >Frontiers of Optoelectronics
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2016
Volume: 9 Issue 4
16 Article(s)
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Research Article
All-optical bistable switching, hard-limiter and wavelengthcontrolled power source
Mehdi SHIRDEL, and Mohammad Ali MANSOURI-BIRJANDI
In this paper, an all-optical bistable switching operation of resonant-tunneling devices with ultra-small photonic crystal cavity was demonstrated. The whole structure was based on a square lattice photonic crystal formed by rods of refractive index nr= 3.4 in an air background. The cavity was surrounded by eight nonliIn this paper, an all-optical bistable switching operation of resonant-tunneling devices with ultra-small photonic crystal cavity was demonstrated. The whole structure was based on a square lattice photonic crystal formed by rods of refractive index nr= 3.4 in an air background. The cavity was surrounded by eight nonlinear rods of refractive index nL0= 3.1 and nonlinear Kerr coefficient n2=9×10–17 W/m2. Nonlinear finite difference time domain method was used to get a bistability hysteresis loop. Next, all-optical wavelength controlled power source (WCPS), hard-limiter and switching operation based on optical nonlinearity were shown. And that small cavity structure has a small length of 12 mm. Considering the numerous applications and small length, this proposed structure has various potential function in all-optical circuits..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 560 (2016)
RESEARCH ARTICLE
Characterizing PM2.5 in Beijing and Shanxi Province using terahertz radiation
Ning LI, Honglei ZHAN, Kun ZHAO, Zhenwei ZHANG, Chenyu LI, and Cunlin ZHANG
Particles of aerodynamic diameter ≤2.5 μm (PM2.5) caused extremely severe and persistent haze pollution is of concern in many cities. In this study, samples of PM2.5 were collected from atmosphere environment of Beijing and Shanxi Province, and analyzed using terahertz (THz) radiation. The transmission spectrum of PM2.Particles of aerodynamic diameter ≤2.5 μm (PM2.5) caused extremely severe and persistent haze pollution is of concern in many cities. In this study, samples of PM2.5 were collected from atmosphere environment of Beijing and Shanxi Province, and analyzed using terahertz (THz) radiation. The transmission spectrum of PM2.5 in Shanxi Province had two distinct absorption peaks at 6.0 and 6.7 THz, and the curve was increasing on the whole. However, the transmission spectrum of PM2.5 in Beijing had obviously different variation tendency and the absorption peak was studied by monitoring PM2.5 masses in conjunction with two-dimensional correlation spectroscopy (2DCOS). By comparing the pollutant species and concentrations of Shanxi Province and Beijing over the time of collecting samples, the concentrations of sulfate and ammonium were similar, which contributed to emerge absorption bands in the same position. While the concentrations of organic matter (OM), nitrate, chloride and elemental carbon (EC) were different. Furthermore, dust and some other inorganic ion are unique to Shanxi province, which lead to different variation tendency of the transmission spectrum of PM2.5. These results will be of importance for environmental monitoring and for controlling PM emissions. According to this research, optical techniques, and especially spectral methods, should be considered for PM2.5 monitoring..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 544 (2016)
Optical performance of ultra-thin silver films under the attenuated total reflection mode
Ming ZHOU, Sheng ZHOU, Gang CHEN, Yaopeng LI, and Dingquan LIU
Ultra-thin silver films were deposited by thermal evaporation, and the dielectric functions of samples were simulated using Drude-Lorentz oscillators. When s-polarized incident light from the BK7 glass into thin silver film at 45° angle using attenuated total reflection (ATR) mode, we experimental observed that thUltra-thin silver films were deposited by thermal evaporation, and the dielectric functions of samples were simulated using Drude-Lorentz oscillators. When s-polarized incident light from the BK7 glass into thin silver film at 45° angle using attenuated total reflection (ATR) mode, we experimental observed that the reflection reach a minimum of 1.87% at 520 nm for thickness of d~6.3 nm silver film, and it reach a minimum of 10.1% at 500 nm for thickness of d~4.1 nm. Moreover, we simulated the absorption changes with incident angles at 520 nm for both p-polarized (TM wave) and s-polarized (TE wave) light using transfer matrix theory, and calculated the electric field distributions. The absorption as a function of incident angles of TM wave and TE wave showed different characteristics under ATR mode, TE wave reached the maximum absorption around the critical angle θc~41.1°, while TM wave reached the minimum absorption..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 549 (2016)
Junction temperature measurement of alternating current light-emitting-diode by threshold voltage method
Ran YAO, Dawei ZHANG, Bing ZOU, and Jian XU
Junction temperature of alternating current light-emitting-diode (AC-LED) has a significant effect on its stable light output and lifetime. The threshold voltage measurement is employed to characterize the junction temperature of AC-LED, due to its excellent merits in high efficiency and accuracy. The threshold voltageJunction temperature of alternating current light-emitting-diode (AC-LED) has a significant effect on its stable light output and lifetime. The threshold voltage measurement is employed to characterize the junction temperature of AC-LED, due to its excellent merits in high efficiency and accuracy. The threshold voltage is measured when the driving current of an AC-LED rises to a reference on-set value from the zero-crossing node. Based on multiple measurements of threshold voltage at different temperatures, a linear relationship was uncovered between the threshold voltage and the junction temperature of ACLED with the correlating factor of temperature sensitive parameter (TSP). Thereby, we can calculate the junction temperature with the TSP and threshold voltage once the AC-LED stays at thermal equilibrium state. The accuracy of the proposed junction temperature measurement technique was found to be 3.2°C for the reference current of 1 mA. It is concluded that the method of threshold voltage is accurate and simple to implement, making it highly suitable for measuring the junction temperature of AC-LED in industry..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 555 (2016)
Broadband coplane metamaterial filter based on two nested split-ring-resonators
Benxin WANG, Xiang ZHAI, Guizhen WANG, Weiqing HUANG, and Lingling WANG
Split ring resonators (SRRs)-based broadband metamaterial filters have attracted considerable attention due to their great prospect of practical applications. These filters had been usually obtained by stacking multiple different-sized metallic patterns, making their fabrication quite troublesome. Herein, we presented Split ring resonators (SRRs)-based broadband metamaterial filters have attracted considerable attention due to their great prospect of practical applications. These filters had been usually obtained by stacking multiple different-sized metallic patterns, making their fabrication quite troublesome. Herein, we presented a simple design of broadband filter composed of two nested SRRs. The resonance bandwidth of the metamaterial filter gradually increased with the decrease of the arm length of the inner SRR. The increase in the resonance bandwidth was attributed to the increase in the radiation of the entire structure. Moreover, the bandwidth of the metamaterial can be further broadened by decreasing the period of the structure. The proposed filter provides a meaningful way toward expanding the bandwidth operating range from narrowband to broadband in an effective way..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 565 (2016)
Low dispersion broadband integrated double-slot microring resonators optical buffer
Chuan WANG, Xiaoying LIU, Minming ZHANG, and Peng ZHOU
Microring resonator optical buffer is attractive in high-speed optical network system, but ordinary microring resonator use strip waveguide as its basic light guide medium, which cannot provide small footprint, low dispersion and high delay-bandwidth product (DBP) simultaneously. Double-slot waveguide structure was firMicroring resonator optical buffer is attractive in high-speed optical network system, but ordinary microring resonator use strip waveguide as its basic light guide medium, which cannot provide small footprint, low dispersion and high delay-bandwidth product (DBP) simultaneously. Double-slot waveguide structure was first proposed to construct racetrack-microring resonators. It was found that cascading multiple microrings can increase the delay-bandwidth and lower the dispersion of the resonators by optimizing the structure parameters. Optical buffer cascaded by 8 microrings with flat bandwidth of 20 GHz provided the delay of 150 ps and the dispersion of ~10– 7 ps/nm over 1530 – 1630 nm, and the footprint of each microring was about 51 μm2. This study can provide design methods and theoretical basis support for practical application..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 571 (2016)
All-optical AND/OR/NOT logic gates based on photonic crystal ring resonators
Ashkan PASHAMEHR, Mahdi ZAVVARI, and Hamed ALIPOUR-BANAEI
Photonic crystal based ring resonators are best choice for designing all-optical devices. In this paper, we used a basic structure of photonic crystal ring resonators and designed all optical logic gates which are working using the Kerr effect. The proposed gates consisted of upper and lower waveguides coupled through Photonic crystal based ring resonators are best choice for designing all-optical devices. In this paper, we used a basic structure of photonic crystal ring resonators and designed all optical logic gates which are working using the Kerr effect. The proposed gates consisted of upper and lower waveguides coupled through a resonator which was designed for dropping of special wavelength. The resonance wavelength was designed for 1550 nm telecom operation wavelength. We used numerical methods such as plane wave expansion and finite difference time domain (FDTD) for performing our simulations and studied the optical properties of the proposed structures. Our results showed that the critical input power for triggering the gate output was lower compared to previously reported gates..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 578 (2016)
Water cooling radiator for solid state power supply in fast-axial-flow CO2 laser
Heng ZHAO, Bo LI, Wenjin WANG, Yi HU, and Youqing WANG
Two different flow channel configurations on thermal resistances associated with the behavior of cooling of power device were studied in this paper. ANSYS Icepak 14.0 has been adopted as a numerical simulation tool. The simulation results from this study showed that the shapes of channels in cooling radiator play an imTwo different flow channel configurations on thermal resistances associated with the behavior of cooling of power device were studied in this paper. ANSYS Icepak 14.0 has been adopted as a numerical simulation tool. The simulation results from this study showed that the shapes of channels in cooling radiator play an important role in the thermal management of water cooling radiation system. The optimal channel design could improve the heatdissipating efficiency by 80% in water cooling radiation system. The result also indicated that the thermal resistance of heat sinks decreased with the volumetric flow rate and the number of cylindrical columns in the flow channel. Experimental results were obtained under certain channel configurations and volume rates. Moreover, the results of numerical simulation can be explained well by the experimental results..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 585 (2016)
Effect of excitation frequency on characteristics of mixture discharge in fast-axial-flow radio frequency-excited carbon dioxide laser
Heng ZHAO, Bo LI, Wenjin WANG, Yi HU, and Youqing WANG
A one-dimensional fluid model has been used to describe the effect of radio frequency (RF) on the characteristics of carbon dioxide (CO2), nitrogen (N2) and helium (He) mixture discharge at 120 mbar in fast-axialflow RF-excited CO2 laser. A finite difference method was applied to solve the one-dimensional fluid model. A one-dimensional fluid model has been used to describe the effect of radio frequency (RF) on the characteristics of carbon dioxide (CO2), nitrogen (N2) and helium (He) mixture discharge at 120 mbar in fast-axialflow RF-excited CO2 laser. A finite difference method was applied to solve the one-dimensional fluid model. The simulation results show that the spatial distributions of electron density and current density rely strongly on the modulating driven frequency. When the excitation frequency changes from 5 to 45 MHz, the plasma discharge is always in α mode. Moreover, as the excitation frequency increasing, the higher densities of COV001 2 and N*Vib 2 can be obtained, which is important to get higher excitation efficiency for the upper laser level..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 592 (2016)
Design of four mirror inverted telephoto zoom system
Jun CHANG, Guijuan XIE, Lifei ZHANG, Yao XU, Jide ZHOU, and Shengyi YANG
A novel inverted telephoto four mirror zoom system with large field of view (FOV) was designed over a wide spectral bandwidth. The initial configuration of the zoom system was obtained by applying the aberration equations under certain constraints. Then, a method was presented to correlate the aspheric coefficients witA novel inverted telephoto four mirror zoom system with large field of view (FOV) was designed over a wide spectral bandwidth. The initial configuration of the zoom system was obtained by applying the aberration equations under certain constraints. Then, a method was presented to correlate the aspheric coefficients with the aberrations of this system. By using this method, the required image quality could be achieved after optimization using the ZEMAX Optical Design Code. Besides good image quality, another benefits of using this system is the potential for using cheap optics..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 599 (2016)
Off-axis three-mirror reflective zoom system based on freeform surface
Guijuan XIE, Jun CHANG, Ke ZHANG, Jide ZHOU, and Yajun NIU
A reflective optical system is not affected by chromatic aberration, so it has a wide range of applications. Based on the design theory of reflective zoom system with three mirrors, this paper presents the simulation, optimization, and image quality evaluation of the traditional offaxis three-mirror zoom system and freA reflective optical system is not affected by chromatic aberration, so it has a wide range of applications. Based on the design theory of reflective zoom system with three mirrors, this paper presents the simulation, optimization, and image quality evaluation of the traditional offaxis three-mirror zoom system and freeform off-axis threemirror reflective zoom system.. In these systems, the optical design was aided by software CODEV. Through the analysis of aberrations and structural performance for the traditional aspherical off-axis three-mirror system, the freeform surface was introduced to the tertiary mirror to improve the balance capacity for optical aberrations. This off-axis three-mirror reflective zoom system based on freeform surface could provide technical reference to the study of such systems..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 609 (2016)
Novel frequency shift keying modulation based on fiber Bragg gratings and intensity modulators
Liu YANG, and Fengguang LUO
This paper proposed and investigated a novel frequency shift keying (FSK) modulation based on two fiber Bragg gratings (FBGs) and two intensity modulators. Then the transmission of 10 Gbit/s FSK signal after a 50 km single mode fiber (SMF) was studied in this paper. The power penalty at the bit error rate (BER) of 10–9This paper proposed and investigated a novel frequency shift keying (FSK) modulation based on two fiber Bragg gratings (FBGs) and two intensity modulators. Then the transmission of 10 Gbit/s FSK signal after a 50 km single mode fiber (SMF) was studied in this paper. The power penalty at the bit error rate (BER) of 10–9 was below 0.1 dB. The FSK modulation system can be applied to optical transmission system..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 616 (2016)
Design of temperature insensitive in vivo strain sensor using multilayer single mode optical fiber
F. MAKOUEI, and S. MAKOUEI
Bone strain measurement is a case of interest and demanding task for osteogenic adaption responses. In this paper, a novel biocompatible optical sensor for the bone axial strain measurement was proposed. In case modern multilayer single mode WII type optical fibers are well designed, they exhibit superior characteristiBone strain measurement is a case of interest and demanding task for osteogenic adaption responses. In this paper, a novel biocompatible optical sensor for the bone axial strain measurement was proposed. In case modern multilayer single mode WII type optical fibers are well designed, they exhibit superior characteristics compared to conventional metal strain gauges (SGs). Furthermore, they could be strong competitors for SGs based on fiber Bragg grating (FBG) devices. In this study, mode field diameter (MFD) was selected as the indirect parameter for sensing task, which was totally a new approach. The strain sensitivity of 70.7733 pm/με was obtained. Moreover, temperature sensitivity was –3.0031 ×10–6 pm/°C, which was negligible and removed the temperature compensation complexity for the sensor structure presented. The satisfactory property achieved for the designed sensor is as a result of multilayer fiber’s complicated structure as well as the design procedure based on evolutionary genetic algorithm (GA). In addition, the sensor demonstrated a reliable performance as its sensitivity was independent of the magnitude of the applied load..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 621 (2016)
Hyperspectral image unmixing algorithm based on endmember-constrained nonnegative matrix factorization
Yan ZHAO, Zhen ZHOU, Donghui WANG, Yicheng HUANG, and Minghua YU
The objective function of classical nonnegative matrix factorization (NMF) is non-convexity, which affects the obtaining of optimal solutions. In this paper, we proposed a NMF algorithm, and this algorithm was based on the constraint of endmember spectral correlation minimization and endmember spectral difference maximThe objective function of classical nonnegative matrix factorization (NMF) is non-convexity, which affects the obtaining of optimal solutions. In this paper, we proposed a NMF algorithm, and this algorithm was based on the constraint of endmember spectral correlation minimization and endmember spectral difference maximization. The size of endmember spectral overallcorrelation was measured by the correlation function, and correlation function was defined as the sum of the absolute values of every two correlation coefficient between the spectra. In the difference constraint of the endmember spectra, the mutation of matrix trace was slowed down by introducing the natural logarithm function. Combining the image decomposition error with the influences of endmember spectra, in the objective function the projection gradient was used to achieve NMF. The effectiveness of algorithm was verified by the simulated hyperspectral images and real hyperspectral images..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 627 (2016)
Improved accuracy of superpixel segmentation by region merging method
Song ZHU, Danhua CAO, Yubin WU, and Shixiong JIANG
Superpixel as an important pre-processing technique has been successfully used in many vision applications. In this paper, we proposed a region merging method to improve superpixel segmentation accuracy with low computational cost. We first segmented the image into many accurate small regions, and then progressively agSuperpixel as an important pre-processing technique has been successfully used in many vision applications. In this paper, we proposed a region merging method to improve superpixel segmentation accuracy with low computational cost. We first segmented the image into many accurate small regions, and then progressively agglomerated them until the desired region number was reached. The region merging weight was derived from a novel energy function, which encourages the superpixel with color consistency and similar size. Experimental results on the Berkeley BSDS500 data set showed that our region merging method can significantly improve the accuracy of superpixel segmentation. Moreover, the region merging method only need 50 ms to process a 481×321 image on a single Intel i3 CPU at 2.5 GHz..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 633 (2016)
REVIEW ARTICLE
A tutorial introduction to graphene-microfiber waveguide and its applications
Xiaoying HE, Min XU, Xiangchao ZHANG, and Hao ZHANG
Graphene-microfiber with the advantage of graphene material and the microfiber has been hailed as a wonderful waveguide in optics. A tutorial introduction to the graphene-microfiber (GMF) waveguides including the effect of graphene on waveguide, fabrication and applications has been presented. Here, we reviewed recent Graphene-microfiber with the advantage of graphene material and the microfiber has been hailed as a wonderful waveguide in optics. A tutorial introduction to the graphene-microfiber (GMF) waveguides including the effect of graphene on waveguide, fabrication and applications has been presented. Here, we reviewed recent progress in the graphene waveguides from mode-locking and Q-switching in fiber laser to gas sensing and optical modulation. A brief outlook for opportunities and challenges of GMF in the future has been presented. With the novel nanotechnology emerging, GMF could offer new possibilities for future-optic circuits, systems and networks..
Frontiers of Optoelectronics
- Publication Date: Jan. 01, 1900
- Vol. 9, Issue 4, 535 (2016)
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