Contents
2004
Volume: 24 Issue 1
28 Article(s)
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Fiber Optics and Optical Communications
Moment Method Study for the Scattering Loss Caused by a Point Defect in a Planar Waveguide
[in Chinese], and [in Chinese]
simple and effective method for calculating the scattering from a point defect (like an air bubble or a dust grain) in a planar waveguide is presented. The method is based on the theory of Green′s function. To improve the calculation efficiency,the corresponding integral equation is converted into a matrix equation by simple and effective method for calculating the scattering from a point defect (like an air bubble or a dust grain) in a planar waveguide is presented. The method is based on the theory of Green′s function. To improve the calculation efficiency,the corresponding integral equation is converted into a matrix equation by using the method of moment and the method of blocked matrix is also used. A silica planar waveguide is considered as an example;the scattering loss as a function of the size of the point defect is analyzed for both an air bubble and a dust grain. The results indicate that the scattering loss depends on the size of the defect and optical property rather than its situation in the waveguide. It is also shown that a point defect of a certain size may cause some strong resonances at some special wavelengths and will result in a large scattering loss. For the same reason, point defects with some special sizes should be avoided in the fabrication in order to reduce the scattering loss at an optical communication wavelength windows.
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 11 (2004)
Effect of Third-Order Dispersion on the Soliton Propagation in Birefringent Optical Fiber
[in Chinese], and [in Chinese]
Propagation of short pulses in the birefringent single-mode fiber near the zero-dispersion wavelength is discussed. Initial pulses are assumed to be linearly polarized at π/4 angle with respect to the polarization axes. With numerical method,it is found that the third-order dispersion,as a small perturbation,does not aPropagation of short pulses in the birefringent single-mode fiber near the zero-dispersion wavelength is discussed. Initial pulses are assumed to be linearly polarized at π/4 angle with respect to the polarization axes. With numerical method,it is found that the third-order dispersion,as a small perturbation,does not affect the threshold of the soliton trapping. But,pulse width of one polarization broadens quickly;another broadens slowly. Meanwhile the shapes and the spectra of the pulses,are not any longer symmetric in the two polarizations. Under the certain condition, the radiation of the soliton is dominantly in one polarization..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 16 (2004)
Optical Fiber Bragg Sensors Based on Ordinary WDC and LED
[in Chinese], and [in Chinese]
A technique for detecting Bragg wavelength shift using ordinary wavelength division coupler (WDC) as wavelength discriminator is presented. The WDC is used to transform the wavelength shifts to intensity changes. Double differential amplifiers are used to get rid of interference induced by light source and surroundingsA technique for detecting Bragg wavelength shift using ordinary wavelength division coupler (WDC) as wavelength discriminator is presented. The WDC is used to transform the wavelength shifts to intensity changes. Double differential amplifiers are used to get rid of interference induced by light source and surroundings. LED is used as the source to reduce the system cost,so the demodulated source and AC amplifiers are available. The strain resolution of 10 με and temperature resolution of 0.2 ℃ are achieved in the experiment. This is one of the cheapest fiber Bragg grating sensors till now..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 21 (2004)
PECVD Deposition and Characterization of Thick Silica Film for Optical Waveguide
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Without doping,plasma enhanced chemical vapor deposition (PECVD) of silica films on Si substrates with gas mixtures of SiH_4 and N_2O is considered. Various factors affecting the refractive index and the deposition rate of the deposited film are studied in order to optimize the growth process of the films. The microstrWithout doping,plasma enhanced chemical vapor deposition (PECVD) of silica films on Si substrates with gas mixtures of SiH_4 and N_2O is considered. Various factors affecting the refractive index and the deposition rate of the deposited film are studied in order to optimize the growth process of the films. The microstructures and optical properties of the films are examined by a prism coupler,a Fourier transform infrared spectroscopy (FTIR) and an atom force microscopy (AFM). The results show that a thick film with a uniform surface and small loss for infrared light can be rapidly deposited by the PECVD technology and refractive index of the film can be controlled accurately..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 24 (2004)
Chaos Synchronization Through Reverse-Phase and Its Encoding in Erbium-Doped Fiber Lasers
[in Chinese], [in Chinese], and [in Chinese]
A chaotic synchronization method of the optical intercross-injecting and reverse-phase between dual-ring and two rings is presented,based on the nonlinear kinetic characteristic of two lasing fields coupling each other in erbium-doped fiber dual-ring laser. Numerically simulations show that the synchronous systems withA chaotic synchronization method of the optical intercross-injecting and reverse-phase between dual-ring and two rings is presented,based on the nonlinear kinetic characteristic of two lasing fields coupling each other in erbium-doped fiber dual-ring laser. Numerically simulations show that the synchronous systems with two absolute single-mode erbium-doped fiber single-ring lasers and a single-mode erbium-doped fiber dual-ring laser can be chaotic synchronization. Two channels of the chaotic secure communications systems of dual-ring-two-rings are presented and numerically simulated, which mask two sinusoidal frequencies of 0.5 kHz and 10 kHz modulated signals. Their encoding quality is very good and security is robust. They can be well applied in multi-channel chaotic secure communications..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 29 (2004)
Temperature Stability of the Central Wavelength for WDM Thin Film Bandpass Filters
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The factors influenced central wavelength shift of wavelength division multiplexing (WDM) narrow-band filters are discussed. The temperature stability for such filters is emphasized. Based on Takashashi model,the effect of the temperature coefficient of refractive index,coefficient of linear expansion and Poisson ratioThe factors influenced central wavelength shift of wavelength division multiplexing (WDM) narrow-band filters are discussed. The temperature stability for such filters is emphasized. Based on Takashashi model,the effect of the temperature coefficient of refractive index,coefficient of linear expansion and Poisson ratio on temperature stability of the central wavelength of the filters is analyzed and calculated by using authors′ software. The temperature coefficient of refractive index,linear expansion coefficient and Poisson ratio of the Ta2O5/SiO2 narrow-band filters are 1×10-7 ℃-1 and 0.12 respectively. These three parameters are most important factors for the temperature stability of the filters, especially for the temperature coefficient of refractive index. For given substrate with certain linear expansion coefficient, the filter with a nearly zero wavelength shift is expected by means of adjusting interference order, cavity number and spacer material of the filters..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 33 (2004)
A Study of Address Recognition by All-Optical Method
[in Chinese], [in Chinese], and [in Chinese]
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 37 (2004)
Optimal Design and Analysis of Broadband Fiber Raman Amplifier
[in Chinese], and [in Chinese]
Based on the standard coupled equations describing fiber Raman amplifiers (FRAs),a generalized automatic algorithm with the help of Genetic algorithm and global convergent Broyden method is proposed for the design of broadband backward pumped FRAs. The main advantages of this algorithm are higher efficient,easier conveBased on the standard coupled equations describing fiber Raman amplifiers (FRAs),a generalized automatic algorithm with the help of Genetic algorithm and global convergent Broyden method is proposed for the design of broadband backward pumped FRAs. The main advantages of this algorithm are higher efficient,easier convergent and wider suitable. The numerical calculation illustrates that the gain flatness for 10 THz gain bandwidth is well within ±0.6 dB for three kinds of FRAs: discrete amplifiers with different gain values, single-fiber and dispersion-managed distributed amplifiers with different structures. These results how the flexibility of the proposed design algorithm. The comparison of OSNR between linked amplification units of SMF+DCF and DMF shows the potential application merit of DM-FRA..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 42 (2004)
Fourier Optics and Signal Processing
Three-Zone Complex Pupil Filter
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
It is an alternative means of changing the distribution of light beam at the focusing spot and realizing optical superresolution by the pupil filter. For the difficulty of fabrication,the current pupil filters are always phase-only pupil filter or amplitude-only pupil filter. Compared with them,complex pupil filter is It is an alternative means of changing the distribution of light beam at the focusing spot and realizing optical superresolution by the pupil filter. For the difficulty of fabrication,the current pupil filters are always phase-only pupil filter or amplitude-only pupil filter. Compared with them,complex pupil filter is more powerful in superresolution. Because of fabrication difficulty,practical application of complex pupil filter is limited. A new way to realize a class of complex pupil filter is proposed. Three-zone complex pupil filter is analyzed by numerical computation. The result shows that M of this complex pupil filter is decreased 50% than phase-only pupil filter with the same G and strehl ratio S, the axial deterioration of phase-only pupil filter is also improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 1 (2004)
Image Description with Jacobi-Fourier Moments
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Jacobi-Fourier moments (JFM),which choose Jacobi polynomial as radial function and Fourier factor as angle function are proposed. The new moments are generalized Orthogonal Fourier-Mellin moments. Jacobi-Fourier moments can be normalized to be invariant for shifting,scaling,rotation and intensity distortion of an imageJacobi-Fourier moments (JFM),which choose Jacobi polynomial as radial function and Fourier factor as angle function are proposed. The new moments are generalized Orthogonal Fourier-Mellin moments. Jacobi-Fourier moments can be normalized to be invariant for shifting,scaling,rotation and intensity distortion of an image. The normalized image reconstruction error (NIRE) and noise sensitivity of Jacobi-Fourier moments are also investigated. Results show that Jacobi-Fourier moments are good image feathers with strong image description ability andn noise resistange power. Compared with other researches, the research view is extended from reconstructing a certain function to reconstructing a function family..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 5 (2004)
Instrumentation, Measurement and Metrology
Refraction Index Measurement of Transparent Materials by Using Diffraction Grating and CCD
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An experimental method for the refraction index measurement of transparent materials is described,based on the interference of expanded and collimated laser beams that are diffracted by a grating. The interference pattern is captured by a CCD camera,and processed with a home-made software. The optical arrangement is siAn experimental method for the refraction index measurement of transparent materials is described,based on the interference of expanded and collimated laser beams that are diffracted by a grating. The interference pattern is captured by a CCD camera,and processed with a home-made software. The optical arrangement is simple and easy to manipulate. The precision of the refraction index measurement is of the order of 10 -4 . Two ways have been provided to carry out the measurements,the second seems to be better in our case, and the angle measurement accuracy is more important than fringe movement positioning. Its application to isotropic polymetric thin film is also presented..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 99 (2004)
Analytical System of Trajectory Camera Photo Plates and Accurate Calibration of Common Flat Scanners
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The system is developed to digitize the trajectory camera photo plates and analyse the images accurately and automatically to replace the manual work which is poorly efficient. The system digitizes the plates by common flat scanner,calibrates the scan images accurately and analyses the images with digital image processThe system is developed to digitize the trajectory camera photo plates and analyse the images accurately and automatically to replace the manual work which is poorly efficient. The system digitizes the plates by common flat scanner,calibrates the scan images accurately and analyses the images with digital image processing technology. The method of full-field accurate calibration only with orth-crossed griddings around the measuring images is described and the experimental results are shown. After the calibration, the full-field standard deviation is less than 2～3 μm. The system and the method of scanner calibration realizes the trajectory camera photo plates' digital, automatic and accurate analysis and makes it possible that common scanners is used in the engineering measurement, where high precision is demanded..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 104 (2004)
Lasers and Laser Optics
Study on Diode Laser End-Pumped Yb:YAG Rod Laser
[in Chinese], [in Chinese], and [in Chinese]
The facts associated with the efficiency of Q- switched Yb∶YAG are overviewed. The rate equation of laser diode end pumped Yb∶YAG is given. The net pumping quantum yield under two-pass end-pumped condition is deduced. With the numerical method,the relationship between the net pumping quantum yield and the length of cryThe facts associated with the efficiency of Q- switched Yb∶YAG are overviewed. The rate equation of laser diode end pumped Yb∶YAG is given. The net pumping quantum yield under two-pass end-pumped condition is deduced. With the numerical method,the relationship between the net pumping quantum yield and the length of crystal,the duration of pumping are simulated,and it is concluded that the optimization of the length of crystal is very important for improving the output efficiency of Yb∶YAG laser. The maximum gain, maximum stored energy are also calculated, and the influence on stored energy by amplified spontaneous emission is considered. The optimized design method for Q-switched laser diode end pumped rod Yb:YAG laser is proposed. The analysis and simulation result is helpful for the development of a practical laser system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 48 (2004)
Experimental Study of Microchip (Tm,Ho):YLF Laser Pumped by Laser Diode
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The relation of gain coefficient to crystal temperature of quasi-three-level (Tm,Ho)∶YLF laser system was analyzed theoretically,with the conclusion that lower temperature and shorter crystal would reduce the reabsorption loss for lower threshold and high efficiency. A microchip Tm(0.06 in number fraction of atoms),Ho(The relation of gain coefficient to crystal temperature of quasi-three-level (Tm,Ho)∶YLF laser system was analyzed theoretically,with the conclusion that lower temperature and shorter crystal would reduce the reabsorption loss for lower threshold and high efficiency. A microchip Tm(0.06 in number fraction of atoms),Ho(0.004 in number fraction of atoms)∶YLF laser end-pumped by a continuous-wave laser diode with 2.7 W at 792 nm wavelength was conducted in experiment. Up to 328 mW of output power at 2.06 μm with TEM00 mode was obtained with 1.88 W pumping power onto (Tm,Ho):YLF crystal. The pumping threshold was 450 mW, the slope efficiency of the laser was 22.5% and total optical-optical conversion efficiency was 17.4%. To achieve the optimized condition, the effects of pumping wavelength, polarization direction, crystal temperature on the performance of laser were studied..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 79 (2004)
Study of Laser Diode End-Pumped (Tm,Ho):YLF Laser
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The laser properties of laser diode end-pumped (Tm,Ho)∶YLF laser are studied. Based the characteristics of laser diode pumped quasi-three-level system,the energy transfer between Tm 3+ and Ho 3+ is discussed and the rate equations of (Tm,Ho)∶YLF laser are given. The influences of up-coversion effect and reabsorption loThe laser properties of laser diode end-pumped (Tm,Ho)∶YLF laser are studied. Based the characteristics of laser diode pumped quasi-three-level system,the energy transfer between Tm 3+ and Ho 3+ is discussed and the rate equations of (Tm,Ho)∶YLF laser are given. The influences of up-coversion effect and reabsorption loss on operation of laser diode pumped (Tm,Ho)∶YLF laser are analyzed theoretically,and the analytical expressions of threshold pump power and slope efficiency are gotten. At the same time, the experiment of (Tm,Ho):YLF microchip laser is conducted, when three crystal is kept at 29 ℃, the threshold pump power is 425 mW, the slope efficiency is 22.5%, the maximum optical-to-optical efficiency is 17.4%, and the relation between the input power and the output power at four different temperature is obtained. The experimental results are in good agreement with theoretical results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 88 (2004)
Effect of Yb:Er Codoping on Suppressing Self-Pulsing in Er-Doped Fiber Laser
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
To improve the practicability of the Er∶Yb co-doped fiber laser,the self-pulse phenomena is discussed theoretically. Based on two theories a system model is setup. One is the saturable absorption of the Er ion-pair in the co-doped fiber will lead to self-pulsing;the other is the interplay between the ion-pairs. The effTo improve the practicability of the Er∶Yb co-doped fiber laser,the self-pulse phenomena is discussed theoretically. Based on two theories a system model is setup. One is the saturable absorption of the Er ion-pair in the co-doped fiber will lead to self-pulsing;the other is the interplay between the ion-pairs. The effective pump rate for Er-doped fibers by Yb codoping is analyzed. It is shown that the level of the pump power required to suppress the ion pair induced self-pulsing in Er-doped fiber lasers can be significantly decreased by using Yb:Er codoped fiber due to the increased effective pump rate. The output pump power of the laser diode is high enough to restrain this kind of self-pulse, which support stable laser operation. The result shows that the potential of developing stable single-frequency or high-repetition-rate mode-locked fiber lasers by using high gain Yb:Er codoped fibers with laser diodes as pump sources..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 94 (2004)
Materials
Optical and Structural Properties of GaN1-xPx Ternary Alloys
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
X-ray diffraction (XRD) and Photoluminescence (PL) spectra for a series of high phosphorus compositional GaN_ 1-x P_ x films grown by means of light-radiation heating,low-pressure metal-organic chemical vapor deposition have been investigated. Photoluminescence spectra for GaN_ 1-x P_ x layers with P/N composition ratiX-ray diffraction (XRD) and Photoluminescence (PL) spectra for a series of high phosphorus compositional GaN_ 1-x P_ x films grown by means of light-radiation heating,low-pressure metal-organic chemical vapor deposition have been investigated. Photoluminescence spectra for GaN_ 1-x P_ x layers with P/N composition ratios of 15%,11% and 3% show the red-shifts of 100 meV,78 meV and 73 meV,respectively,from that of GaN due to a large bowing of band gap energy. X-ray diffraction results show that (0002) peaks of GaN1-xPx samples have shifted to smaller angles compared with that of an undoped GaN sample, and the linewidth of the (0002) peak becomes broader with increasing P composition in the samples, indicating that the crystal lattice distortion is produced due to the P incorporation into the GaN host lattice. Not peak related to GaP is observed in X-ray diffraction and photoluminescence spectra, which indicates that the phase separationb etween GaN and GaP has not occurred in our GaN1-xPx samples..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 137 (2004)
Photosensitivity of Lead Silicate Glass
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
UV-visible absorption spectra for the bulk lead silicate glass with different lead concentrations (mole fraction of PbO change from 0.30 to 0.50) were measured before and after irradiation with the frequency-quadrupled output of a Q -switched YAG laser (266 nm,10 Hz repetition rate). Different UV-visible spectra changeUV-visible absorption spectra for the bulk lead silicate glass with different lead concentrations (mole fraction of PbO change from 0.30 to 0.50) were measured before and after irradiation with the frequency-quadrupled output of a Q -switched YAG laser (266 nm,10 Hz repetition rate). Different UV-visible spectra changes were observed after exposure to laser beam with different energy density. Exposed to the 266 nm laser beam with high energy density (150 mJ/cm 2), a visible brown spot could be seen on the surface of the exposed region, and the absorption coefficient increases evidently in wavelength range measured. Exposed tot he 266 nm laser beam with low energy density (50 mJ/cm2), no visible spot was observed, but the absorption spectra showed that the absorption coefficient increased slightly over the wavelength range observed, and the refractive index decreased evidently. The largest refractive index change Δn is -0.25. Irradiating a sample with different energy density, the absorption coefficients in visible wavelength increased suddenly when the energy density was larger than a threshold value. This may be caused by the structural changes of lead silicate glasses induced by the increasing of the temperature in local region of the lead silicate glass..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 140 (2004)
OPTOELECTRONICS
A White Organic Light Emitting Diode Based on Blue Emitting Material DPVBi
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
White organic electroluminescence is one approach to achieve full-color flat panel display. A white organic light emitting diode(OLED) with the emitting layer consisting of blue emitting material DPVBi doped with red dye DCJTB is reported. According to the photoluminescence of DPVBi doped by DCJTB with different mass fWhite organic electroluminescence is one approach to achieve full-color flat panel display. A white organic light emitting diode(OLED) with the emitting layer consisting of blue emitting material DPVBi doped with red dye DCJTB is reported. According to the photoluminescence of DPVBi doped by DCJTB with different mass fractions,the OLEDs are demonstrated with the structure of ITO/CuPc/NPB/DPVBi∶DCJTB%/Alq_3/LiF/Al. White light emission can be produced when the mass fractions of DCJTB is 0.0008%. Although the white emission can be produced when the mass fractions of DCJTB is 0.0008%. Although the shite device shows a little increase in relative intensity of blue emission with increasing applied voltage, the consistent results of photoluminescence and electroluminescence indicate that the white light emission mainly originates from energy transfer from DPVBi to DCJTB. For the white light device with CIE coordinates x=0.25, y=0.32, the maximum luminance, the luminance under current density of 20 mA/cm2 and the maximum luminous efficiency are 7822 cd/m2, 489 cd/m2 and 1.75 lm/W, respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 70 (2004)
Double Mode Emitting from a Novel Organic Microcavity Diode
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The organic microcavity light emitting diode was fabricated using structure Glass/DBR/ITO/NPB/NPB:Alq/Al. Here NPB and Alq were mixed as the emitting material. In order to compare its performances with those of conventional MOLEDs,a heterostructure MOLED was also fabricated. There are many differences between the spectThe organic microcavity light emitting diode was fabricated using structure Glass/DBR/ITO/NPB/NPB:Alq/Al. Here NPB and Alq were mixed as the emitting material. In order to compare its performances with those of conventional MOLEDs,a heterostructure MOLED was also fabricated. There are many differences between the spectrum of the original microcavity light emitting diode and the conventional one. The voltage barrier was eliminated by mixing hole transport material and emitting material,thus recombination efficiency was enhanced and double modes emitting were realized and their FWHM (full width half maximum) were 8 nm and 12 nm respectively. White light emission from organic microcavity can be realized by optimizing the device structure and adopting new materials..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 75 (2004)
Physical Optics
The Influence of Vectorial Effect on the Non-Paraxial Propagation of Ultrashort Pulsed Beam in Free Space
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Starting from the intrinsically vectorial non-paraxial propagation equations,and employing the Fourier transforming and the angular spectrum formalization,the influence of the vectorial effects on the non-paraixal propagation of ultrashort pulsed beam in free space is analyzed. The result shows that the non-paraxial coStarting from the intrinsically vectorial non-paraxial propagation equations,and employing the Fourier transforming and the angular spectrum formalization,the influence of the vectorial effects on the non-paraixal propagation of ultrashort pulsed beam in free space is analyzed. The result shows that the non-paraxial correction is greatly influenced by the vectorial effect. While the non-paraxial propagation of pulsed beam is dealt,the vectorial effect should be considered. Based on the above analyses,An integral solution of the vectorial non-paraxial propagation equations is obtained. Then an correspondingly simple approach to the vectorial non-paraxial correction to the paraxial pulsed beam solution is developed by use of a Taylor expansion..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 52 (2004)
Transparency of an Overdense Plasma Layer
[in Chinese], and [in Chinese]
The transition from opacity to transparency of overdense plasma layers for the propagation of high-intensity laser pulses of circular polarization is investigated theoretically and by simulation. At some points,fluid equations cannot give a stationary solution,and then the kinetic aspects of the interaction should be cThe transition from opacity to transparency of overdense plasma layers for the propagation of high-intensity laser pulses of circular polarization is investigated theoretically and by simulation. At some points,fluid equations cannot give a stationary solution,and then the kinetic aspects of the interaction should be considered. It is found that the regions where stationary solutions exist and therefore the plasma layer is opaque. It is also found that the opacity depends not only on the electron density and the laser intensity but also on the thickness of the plasma layer. The plasma layers become transparent where stationary solution do not exist, defined as absolute transparent. The electron density hardly changes because there is no light pressure acting on the plasma layer wehn the plasma layer is opaque..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 57 (2004)
Optical Tomography Based on Fresnel Zone Plate Scanning Holography
[in Chinese], [in Chinese], and [in Chinese]
An imaging technique for three-dimensional objects termed Fresnel zone plate scanning holography based on the principle of optical scanning holography and the tomographic technique of coded aperture imaging is proposed. The scanning hologram of an object is the convolution of the transmittance of the object with the inAn imaging technique for three-dimensional objects termed Fresnel zone plate scanning holography based on the principle of optical scanning holography and the tomographic technique of coded aperture imaging is proposed. The scanning hologram of an object is the convolution of the transmittance of the object with the intensity distribution of the Fresnel zone plate and the reconstruction of the hologram is obtained by correlation operation. The system based on Fresnel zone plate scanning holography is simple and compact. Especially, it can realized optical tomograms of an object. A method of high-pass filtering is proposed to reduce the background noise of the reconstruction. Both the computer simulation and the experiments demonstrate that the principle of the technique is right, the tomograms of an object is obtained using the technique, and the contrast of the reconstruction is improved with high-pass filtering..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 110 (2004)
Alignment of a Three-Mirror Off-Axis Aspherical Optical System by Using Gradual Abberration Optimization
[in Chinese], [in Chinese], and [in Chinese]
By collecting interferograms of several fields of optical system by means of autocollimating interferometry,aberrations including spherical,coma,astigmatism,could be obtained from those interferograms. The misalignments of the system are then corrected according to the misalignment values calculated by gradual aberratiBy collecting interferograms of several fields of optical system by means of autocollimating interferometry,aberrations including spherical,coma,astigmatism,could be obtained from those interferograms. The misalignments of the system are then corrected according to the misalignment values calculated by gradual aberration optimization. This way is feasibility for correcting the misalignment of optical system. A three-mirror,unobscured,high-resolution optical system with large aperture,long focal length was aligned and the results of 0° field wavefront error of 0.094λ rms, +1° field of 0.106λ rms and -1° field of 0.125λ rms at λ=632.8 nm are obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 115 (2004)
Hybrid Diffractive-Refractive Optical System Design of Head-Mounted Display for Augmented Reality
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
By introducing diffractive surface,with the particular negative dispersive and the power of realizing random-phase modulation,in optical system,a hybrid diffractive-refractive optical system of see-through head-mounted display for augmented reality with 26 mm eye relief,12 mm exit pupil and 20°(H)×15.4°(By introducing diffractive surface,with the particular negative dispersive and the power of realizing random-phase modulation,in optical system,a hybrid diffractive-refractive optical system of see-through head-mounted display for augmented reality with 26 mm eye relief,12 mm exit pupil and 20°(H)×15.4°(V) field-of-view is designed. The utilization ratios of energy of real world and virtual world are 1/4 and 1/2,respectively. The resolution of display,determined by the system resolution power,is 800×600 and the pixel size is 33 μm. The diameter of this system is less than 46 mm, and it applies the binocular. This head-mounted display not only satisfies the demands of user;s factors in structure, but also with high resolution, very small chromatic aberration and distortion, and the system satisfied the need of augmented reality..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 121 (2004)
Study of the Color Film Graininess--Print Grain Index
[in Chinese], [in Chinese], and [in Chinese]
The graininess of the color film is one of its important quality factors,and it is usually indicated by the RMS granularity. Actually,the RMS granularity does not always represent the graininess feeling of human on the color print,for only one gray channel (white light) densities are sampled in it. In this work,red,greThe graininess of the color film is one of its important quality factors,and it is usually indicated by the RMS granularity. Actually,the RMS granularity does not always represent the graininess feeling of human on the color print,for only one gray channel (white light) densities are sampled in it. In this work,red,green and blue channel densities are all counted,resulting in three granularities. Then they are transformed into three printing granularities involving properties of the printing machine and the color paper. Finally they are resembled in a print grain index involving characteristics of human eye as well as psychology. The print grain index represents the graininess on the color paper that a color film is printed. Some Kodak films assample films have been measured and observed. The results give the measuring accuracy and coincidence between the print grain index values and the perceptible graininess on the prints, proving the efficiency of the method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 125 (2004)
Data Fusion of the Two Hartman-Shack Wavefront Sensors in the Common Path/Common Mode Adaptive Optics System
[in Chinese], [in Chinese], and [in Chinese]
In the common path/common mode(CP/CM) adaptive optics(AO) system,two Hartman-Shack (H-S) wavefront sensors are used to realize the aberration sensing in the whole light path,controlling of a set of wavefront corrector and compensation of the aberration in the whole light path. Here the data fusion methods of the two H-In the common path/common mode(CP/CM) adaptive optics(AO) system,two Hartman-Shack (H-S) wavefront sensors are used to realize the aberration sensing in the whole light path,controlling of a set of wavefront corrector and compensation of the aberration in the whole light path. Here the data fusion methods of the two H-S sensors in the CP/CM AO system are studied and the effects of the disturbance of the vector of slope data and the Reconstruction matrix to the controlling voltage are analyzed through the condition number of the reconstruction matrix. Corresponding formula are given. The close loop experiment of CP/CM is achieved. Modified slope and voltage data fusion methods are suitable to the engineering under the exising technology condition. They are equivalent in the finding of the controlling voltage, but the wavefront processors will be different..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 131 (2004)
Thin Films
Design of Interleaver with Cascaded Thin Film Filter
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A novel designing method for optical interleaver based on cascaded solid thin film Fabry-Perot filter is presented. It′s easy to control the thickness of the spacer of the device when employing the fused quartz as the material of the spacer,so the thin film interleaver can satisfiedly meet the demand of the narrow waveA novel designing method for optical interleaver based on cascaded solid thin film Fabry-Perot filter is presented. It′s easy to control the thickness of the spacer of the device when employing the fused quartz as the material of the spacer,so the thin film interleaver can satisfiedly meet the demand of the narrow wavelength gap for the DWDM system. The analysis on how to ascertain the thickness of the spacer,the numbers of thin film Fabry-Perot filters and the match of the reflective index of each Fabr-Perot filter's mirrors are given. The experimental result is coincident with the designed one well, and the device achieves to 100 GHz spaced channels, at wavelength around C band, with adjacent channel's cross-stalk less than -24 dB and the minimum insertion loss nearly 0.4 dB or so..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 24, Issue 1, 62 (2004)
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