Laser beam shaping system based on deformable mirror has the advantages of control flexibility, good adaptability and high damage threshold. In order to enhance performance of the laser beam shaping system with a deformable mirror as the phase modulation element, a stochastic parallel gradient descent algorithm is proposed to further optimize control voltage, which takes the least square fitting control voltage as the initial value. Laser beam can be transformed to square and circular flat topped beam with different sizes by a 37 element deformable mirror. Numerical simulation results show that, for the far field intensity, both the uniformity of target area and the similarity to the theoretical intensity are improved, after the introduction of optimization algorithm, on the basis of the least square method. So the performance of the laser beam shaping system is also improved.descent algorithm

The Aerosol extinction coefficient is of crucial importance for atmospheric visibility and climate change.The aerosol extinction coefficient is measured based on the cavity ring down spectrometer using 532 nm pulsed laser.The detection limit of the aerosol extinction spectrometer is 0.3 Mm-1. Pure CO2, pure Freon R134, and different concentration NO2 are used for full scale calibration. Comparative field measurement of aerosol extinction using aerosol extinction spectrometer, nephelometer and aethalometer are carried out, and the data are in good agreement.

The balanced detection system based on Mach-Zehnder type interferometer is applied to increase the detection sensitivity in laser Doppler velometer experimental system. Based on the Doppler effect, the principle of laser velometer system and the balanced detection realization method are described, the formula of light current is derived, and its advantages compared with the conventional coherent detection technique are analyzed. The formula of the signal-to-noise, which is derived by light current, is used to attain the influence factors. The simulation results demonstrate that when the reflection coefficient is set in (0.2908,0.7092) or the conversion coefficient ratio of two detectors is set in (0.4632,1), the dual balanced detection technique offers higher signal- to- noise ratio than the conventional detection technique. The sensitivity of the Doppler velometer system is strengthened with balanced detection technique.

Aiming at the problem of oversize eigen current of resonant tunneling diode photodetector focal plane array working at near-infrared wavelengths, a method that using p-doped type in double barriers structure (DBS) of resonant tunneling diode photodetector working at near- infrared wavelengths to suppress eigen current is presented. The current-voltage characteristics are simulated by finite element software. Effects of single barrier pdoped, double barriers p-doped，DBS p-doped and concentrations of p-doping on the eigen current suppression are researched. Simulation results show that the peak tunneling current of the detector with p-doped in DBS reduces about 3 orders of magnitude compared with that of the detector with undoped DBS. It is also found that the eigen current reduces with the increasing of the doping concentration of the DBS. The proposed device has been fabricated and tested. The results demonstrate that the eigen current is effectively suppressed when the DBS is doped in p-type.

Fiber optic accelerometer receives more and more attention in recent years due to its advantages. A fiber optic accelerometer based on two-end fixed beam is presented, which is on the basis of the beam sensors. A kind of small-diameter single-mode optical fiber with high numerical aperture is wrapped on the beam as the sensing fiber. The minimum bending radius of the single-mode is analyzed, thereby more fiber can be affixed to the beam arm without any bending loss and the sensitivity is enhanced. The transverse sensitivity is greatly reduced due to the double- ended fixed structure which is convenient for the production of three- dimensional sensor. The nature frequency of the sensor and the sensitivity are analyzed theoretically. The linearity of the sensor response is analyzed by experiments. The sensor presented has the natural frequency around 360 Hz, and its sensitivity up to 3300 rad / g at 100 Hz. It can be used to detect low-frequency acceleration effectively.

Because the simple beam of traditional equal section used for tuning fiber Bragg grating (FBG) can make the FBG produce chirp, a novel tuning structure utilizing the equilateral rhombic beam under pure bending is designed, which has no chirp appearing. The experimental research is consistent with theoretical research well. The novel rhombic beam can realize the tuning wavelength of 8 nm, the linearity of 99.9%. And the 3 dB reflection bandwidth shows no change during the tuning process. The beam under pure bending has good symmetry, which realizes the linearly chirp-free central wavelength tuning of FBG.2015-12-18

Measurements of power frequency electric field are necessary to understand electromagnetic environments and optimize the high voltage electrical equipment. For this purpose, a novel fiber Bragg grating (FBG) based on the all-fiber power-frequency electric-field sensor is proposed. The sensor head actually is an optical fiber cantilever beam with a FBG, on which the polyimide resin as the electric field induction medium is multiple-layer coated. When the fiber cantilever beam is put into the electric field, the polyimide coating will produce the dynamic polarization effect under the induction of power frequency electric field because of the dielectric properties of polyimide coating materials, which, in turn, induces the fiber cantilever beam to vibrate periodically through the action of the timevarying electric field force. As a result, the Bragg wavelength of FBG also is modulated. The maximum shift of the Bragg wavelength is proportional to the applied electric-field strength. For demodulation of the detection signal, a laser source is used and its operating wavelength at the edge of the FBG reflective spectrum is selected. Through this operation, the change of optical power reflected from the FBG can be monitored and the power-frequency electric field strength can be measured. The experimental investigations prove that the proposed sensing method for power frequency electric field measurements is feasible and the prototype of the sensor had very high detection sensitivity and good measurement accuracy in the 1 kV to 4 kV voltage range.

Considering the wavefront aberration and speckle noises in long distance digital holography, the wavefront correction based on image metric optimization and speckle noise reduction based on multi-image averaging are studied, in which the multi-images are generated with aperture dividing technique. A digital off-axis holography experimental setup is established, and the wavefront aberration correction experiments are performed, in which the gradient descent algorithm is used to optimize the image sharpness metric. Multi-images with different speckle noises are reconstructed by dividing aperture into certain small parts, and average operation is performed among those multi images. The results show that the image resolution is improved effectively while the aberration is corrected with image metric optimization method, and a higher quality image is obtained after multi-images averaging.

The traditional remote sensing image fusion methods is not make good use of spatial information of the low-resolution multispectral images. To solve this problem, a novel remote sensing image fusion method based on low-resolution multispectral image super-resolution processing is proposed. The low-resolution multispectral image is processed by super- resolution based on sparse representation, which enhances spatial information while maintaining the spectral information. The intensity component Y of the enhanced multispectral image and the panchromatic image are fused using the stationary wavelet transform. The fused multispectral image is obtained via inverse YUV transform. The experimental results carried out on real remote sensing images show that the proposed algorithm is able to improve spatial details of the fused image effectively while maintaining the spectral information. The effectiveness of the proposed method is also verified by the comparable experiments.

When the number of observed stars is few, the matching number of stars and the decision conditions of boundary distance do not satisfy the requirement the grid algorithm. Meanwhile because of the principle limits of the grid algorithm, the identification rate decreases obviously. According to these problems, an improved grid algorithm is put forward, and the identification rate of observed star increases effectively in precondition of ensuring the robustness. Experimental results show that the improved grid algorithm urges the identification rate increased from 95% to 99% compared with the traditional grid algorithm, under the condition that the number of observed star is less than 10. At the same time, the non-recognition and false-recognition stars in the star chart have been carried on the analysis, it can help to promote grid algorithm for star identification further.

A robust matching algorithm based on spatial marked points is proposed to improve the reliability of threedimensional (3D) scanning registration. This methodology defines the spatial energy to describe the uniqueness of the marked points, which is based on the distance and the spatial relationship between the marked points. Besides, the uniqueness of the energy can be applied to match the marked-points and stitch them together in different views. Compared with the traditional methodology, this algorithm can significantly avoid the ambiguity problem in the process of stitching. According to the experimental results, it only takes less than 2 ms to reach the accuracy of 100% when matching the marked-points in two views, which can realize the 3D data registration of multiple-view in the real time.

Mueller matrix imaging polarimeter is an effective instrument in measuring the polarization characteristics of materials and devices as well as the polarization aberration of immersion lithography tool, which is composed by polarization state generator and polarization state analyzer. The retardance and fast axis alignmen in the quarter-wave plates and the alignment error in polarizer are the main factors in influencing the measurement accuracy of the Mueller matrix imaging polarimeter. We measure the five primary parameter errors of the Mueller matrix imaging polarimeter of our laboratory developed. The measurement accuracy can be significantly enhanced. The calibration and compensation are carried out by Fourier analysis method. The experiment results show that the measurement accuracy of Mueller matrix imaging polarimeter has been increased from 0.2015 to 0.1051, which is 47.84% better than the un-calibrated one. At last, we measure the polarization aberration of projector with the calibrated Mueller matrix imaging polarimeter. The measurement repeatability is better than 1.1%.

In order to evaluate the long term stability of opto-mechanical systems, a novel method of long term instability evaluation based on the calculation of misalignment is presented. Firstly, a model has been built to find the relationship between the misalignment of the opto-mechanical systems and the wavefront error with the aid of sensitivity matrix, and a method for the misalignment calculation based on singular value decomposition (SVD) is given. Then, a reduced projection system is illustrated to analyze the relationship between the aberration singular vector and the configuration singular vector base on the SVD of constructed sensitivity matrix. Intended misalignments are added to the actual reduced projection system and the calculated result verifies the availability of the method. Finally, the long term stability is tested and it can orientate the opto-mechanic optimization.

A common-path interferometry is proposed to measure the phase of liquid crystal spatial light modulator (LCSLM), which is based on the pricinple of liquid-crystal polarization splitted light. The linearly polarized input beam is divided into two orthogonal polarized beams by LCSLM, and then propagates to the Wollaston prism (WP) along the same direction. Two beams transmitted from the WP generate lateral shearing and a tilt modulation is introduced into the two beams, and hence a carrier-frequency interferogram is obtained after passing analyzer polarizer. The relative phase-shift between two frames of fringes is calculated accurately by using the Fourier-transform algorithm. A phase modulation experiment to the transmissive LCSLM is given. The proposed method is less sensitive to vibrations and air turbulence. Furthurmore, it can measure the whole phase modulation characteristics of LCSLM, and the measuring result is more precise and scientific.

Raman transition based on caesium atoms in the bad cavity Raman laser is put forward. The spin correlation coefficient showing the collective effects is analyzed. The photo emits in a collective way through the forbidden transition and couples into the low Q resonant cavity, with a power level of 10-9 W. The operating conditions and properties such as output power and pumping threshold changing with several parameters which can be useful for future analysis and practical experiment.

In order to improve the stability of the binocular stereo vision measuring accuracy image matching. A new robust matching algorithm based on feature point energy is proposed, the algorithm based on epipolar constraint to get the initial matching feature points around image. The energy not affected by affine transformation is defined to describe feature points based on epipolar constraint relationship among feature points, and the error matching is removed by comparing the energy of feature points. The proposed method effectively reduces the false matching rate and the false rejected rate so that it can meet the need of strictly limited false matching rate in the process of multiple angle measurement data. Experimental results show that the correct matching rate of the proposed algorithm is over 95%, and the false rejected rate is less than 2%.The algorithm has better robustness.

Aiming at realizing three-dimension reconstruction, both the high-precision calibration of the low-cost stereo-camera system and the assessment of the quantitative accuracy are accomplished. The self-calibration bundle adjustment model that can calculate the platform parameters between cameras and internal parameters of camera is deduced.Based on relative orientation of the stereo-camera,atheoretical model for accuracy evaluation of ration is established by taking advantage of total calibration parameters and its covariance matrix. A stereo-camera system is established by using low-cost web camera. The calibration and accuracy evaluation of ration of the proposed system is carried out.Experimental results show that simultaneous determination of internal parameters and platform parameters of stereo-camera can improve the calibration accuracy and the stability. Quantitative evaluation model of considering parameters relativity can reflect the calibration accuracy for the stereo-camera system robustly.

The changes of temperature may lead to the divergence of best focal plane of its optical system, which will make the imaging quality of optical system decline. In order to maintain the optical system imaging quality stable, we study the athermalization of the optical system. A new way of athermalization what is divergence of the best focal plane is studied. The surface displacement formula is studied, then the surface displacement formula is used to guide the design of athermalization compensation. For example, we study the system that reaches diffraction limit in normal temperature. When the temperature ranges from -40 ℃ to 60 ℃ , it is found that modify the four parameters in the surface displacement formula will make the surface displacement decrease or go to zero. So the optical system imaging quality gets improvement and achieves athermalization. The conclusion is that the surface displacement formula can guide the design of athermalization.

Traditional strategy of designing a two-mirror catadioptric optical system employs zero-power correcting elements to balance the residual aberrations, which usually contains two or three refracted, even asphere, lenses. The use of an axial gradient-index (AGRIN) lens can achieve the same goal of aberration correction, as well as a compact and light weight system which employs only one correction element. This paper summarizes primary aberrations theory of the two-mirror catadioptric optical system and the AGRIN lens. A method of designing a twomirror catadioptric system with an AGRIN lens instead of homogeneous lenses is presented. As an example, a twomirror catadioptricsystem, whose focal length is 3000 mm, F-number is 8, and the field of view is 1°, is promoted. The design result shows that the wavefront aberration is less than 0.07 l, the system dispersion radius is close to the radius of Airy, the transfer function at 50 lp/mm is higher than 0.35, the maximum distortion of the system is less than 0.5, the maximum field is less than 0.2, and the image quality almost reaches the diffraction limit.

In order to obtain excellent output signals from wavelength channels, the structures of reflecting splitters based on photonic crystal U- shaped resonators (PCUR) are designed. Electromagnetic wave power splitting characteristics of these structures are studied by the time- domain finite- difference method. Four symmetrical structures can split wavelength power into two equal parts, and all of them have the characteristic of high transmission efficiency in the third communication window. Five asymmetrical structures have the characteristic of low signal crosstalk at the peak wavelength. According to our needs of designs, high transmission efficiency splitters with different channel wavelength intervals can be obtained by changing radii of scattering dielectric rods or 3×2 inner rods of the two PCURs in the symmetrical structure of reflecting splitters based on 3×2 PCURs. The results show that these micro reflecting splitters based on PCURs have the advantages of excellent wavelength selectivity, flexible designs, low crosstalk at peak wavelength and so on. These structures have potentially applicable value in the fields of low loss optical integrated circuits, high density wavelength optical communication systems etc.

Origin of polarization sensitivity of the silicon cross-slot waveguide (SCSW) is analyzed. The effective refractive indices as well as the single-mode-operation conditions of SCSWs for different polarization states are calculated. A single-mode SCSW can be polarization-insensitive if its structure is designed dedicated. A polarization-independent micro-ring resonator with 3.7μm radius based on a polarization-insensitive SCSW is proposed and simulated. The polarization-independent working bandwidth of the micro-ring resonator is about 64 nm, and the free spectral range is about 35 nm.

Based on the general theoretical model of solar cell, algebraic equations are constructed by means of the derivative of the short circuit, maximum power point and open circuit of photovoltaic (PV) module. Using parameters, such as short-circuit current, open-circuit voltage, current and voltage at maximum power, given by PV manufacturer at standard test condition, five model parameters (photo current, diode saturation current, series resistance, parallel resistance, ideality factor) can be simulated by genetic algorithm. Compared with Newton iterative method, genetic algorithm can give more accurate and stable simulation results, and the relative error is about 2%. Also, PV module simulator operated in Matlab environment is constructed, and it can simulate the electric characterization of PV module in arbitrary solar radiation and temperature, which is helpful to PV systems researchers.

Laser is focused on soil samples doped with Cr and Cu elements. Signal-to-background ratio (SBR) of Cr (I) 425.435 nm, 427.481 nm and Cu (I) 324.754 nm, 327.396 nm is analyzed. The calibration curve is drawn using the intensity ratio of each line to the Fe reference line intensity, and the limit of detection is calculated. The effect of atomic configuration, angular momentum and transition probability on calibration curve and limit of detection is studied. It is indicated that the high SBR spectral line gets lower limit of detection, and is more sensitive to element detection. The spectral line SBR is independent on transition probability. The variation in SBR with element content exhibits similar characteristics for the lines with the same atomic configuration. The excitation of lines with large angular momentum is better with higher regression coefficient of calibration curves. The limit of detection of Cr (I) 425.435 nm (4-3) and Cu (I) 324.754 nm (3/2-1/2) decreases by 11% and 42% compared to the lines Cr (I) 427.481 nm (3-3) and Cu (I) 327.396 nm (1/2-1/2) respectively. The lines with large angular momentum are more sensitive and more suitable for element detection.

Using the double slit diffraction and interference principle, small fluctuation of wavelength leads to refractive index change and generates a obvious phase difference between two diffraction slits. Thus zero level of the diffraction stripe deviates from the optical axis. Small fluctuation of wavelength is monitored in realtime through the change of offset. Experimental results show that 2 pm change of the laser wavelengh can cause displacement of diffraction stripe for about 2.6 μm. Because the displacement of zero level diffraction stripe is detected, effects of light intensity change are avoided which greatly improves the wavelength monitoring resolution.

To overcome the shortage on dynamic range of the photoelectric detector, and the difficulties on accurate measurement of both the minimum and maximum intensity transmittances of the linear polarizer under the same condition, a method for extinction ratio measurement based on nonlinear fitting is proposed. The experimental system is setup. The measured polarizer is rotated only within a limited angular range to detect the transmitting intensities. Then, based on the principle of the model, the nonlinear fitting is applied on the obtained intensity data to calculate the extinction ratio. The experimental results show that the measured accuracy of 10-5 level can be achieved. Also, good repeatability and effectiveness of the proposed method are verified.

In view of the optical fiber Bragg grating(FBG) quasi distributed sensing demodulation system, a specialized study is studied. In view of mixed information, large dynamic range and other characteristics in quasi distributed sensing demodulation system, a FBG sensing demodulation system is set. Using laboratory existing composite sensor as a platform, based on the LabVIEW software, a suitable system for distributed optical fiber grating sensor demodulation is designed, which makes the temperature, pressure, flow information based on wavelength changes are distinguished intelligently and the physical quantities measured are displayed real-time through the corresponding calculation. Through this experiment, the temperature sensor, pressure sensor and flow sensor are calibrated respectively, the parameters are calculated; through the comprehensive experiment, the system identified the wavelength value of different physical quantities and displayed physical quantities directly, realized the purpose of the high precision visualization and real-time display,verified the feasibility and reliability of the system design.

AMSR-2 observations at 7.3 GHz from Aug. 1 to 16, 2014 over Japan, China and surrounding areas are carefully analyzed. The observations of 7.3 GHz channel in ascending portions of orbits are usually interfered over Japanese land, while no radio frequency interference (RFI) detected in descending passes. The signals emanating from geostationary communication and television satellites that reflect off the land surface are the major interference sources of these RFI. Besides 7.3 GHz, the measurements of 6.9 GHz and 10.65 GHz over Japan are all affected by RFI. These RFI signals are all from ground point target sources, being isolated in space and persistent in time. Strong and wide RFI are detected every day in Vietnam in both ascending and descending orbits. Both 7.3 GHz and 10.65 GHz information are all contaminated over China. The cities and areas affected by RFI at both frequencies are identical with the distribution of Chinese ground-based radar stations.

As early as 1950 s, chalcogenide glasses have aroused the interest of researchers for their special properties of broad infrared transmission band and high refractive index, especially the Te-based chalcogenide glasses whose infrared transparent wavelength can reach up to 18 μm. They may be widely applied in far infrared sensor, CO2 laser energy transmission, biosensor and alien life detection. In addition to the applications in the traditional transmission of infrared energy and infrared imaging, chalcogenide glasses also become the best candidate materials for optical switch, super-continuum sources and Raman gain applications, due to their ultra-high nonlinearity and ultra-short response time. It summarizes the nonlinear properties and applications of the common chalcogenide glasses and compares three theoretical models for chalcogenide glasses nonlinearity analysis. And then describes the most popular test method for chalcogenide glasses nonlinearity, the Z-scanning method. Prospection is given for the exploration of higher nonlinear chalcogenide materials and future directions for research.

Ince-Gaussian modes are the third complete family of exact and orthogonal solutions of the paraxial wave equation following the Hermite-Gaussian and Laguerre-Gaussian modes. Its transverse mode pattern is diversiform, and the helical Ince-Gaussian modes exist separate spiral vortex structures and carry orbital angular momentum, which makes Ince-Gaussian modes have broad prospects in the fields of particle manipulation, biomedical, optical communications and so on, and have attracted a great deal of interests. The theory of Ince- Gaussian beam is presented in the paper, the methods of generation of Ince- Gaussian mode laser are addressed, and the future development of high efficient Ince-Gaussian mode laser is disscussed.

Single- molecule optical detection has been shown as an important tool for the research in physics, chemistry and biology in recent years. Effective manipulation of single-molecule fluorescence is of great significance for the preparation of quantum devices and for the detection of chemical reactions and biological phenomena. In this review, recent studies on manipulating and controlling single- molecule fluorescence are summarized, including electric field induced single-molecule fluorescence modulation, hysteresis of single-molecule fluorescence and fabrication of single-molecule based fluorescence switch.

Continuous-wave green laser has been widely applied in various fields like optical data storage, color display, fluorescent diagnostic and optical communication. Up-conversion is one of the effective ways to achieve the continuous-wave green laser, which has become a hot research field of laser technology. Laser diode (LD)- pumped Er3+-doped material has the merits of good stability, long fluorescent lifetime and less dependence on the matrix material, which is suitable for obtaining a continuous-wave green laser output. The researches of the Er3+- doped green laser around the world are summarized and the dependence of up-conversion luminescence of rare earth ions on matrix material is discussed. Moreover, make an outlook for the research and application of the rare earth ion in terms of green up-conversion luminescence.

Accurate, rapid and non- destructive estimation of apple canopy SPAD (soil and plant analyzer development) values using hyperspectral remote sensing has important significance for monitoring the growth of apple trees. Spectral reflectance and SPAD values of 196 apple canopies are measured in 62 orchards in two years. The original spectra and the continuum- removed spectra are analyzed and correlated with SPAD values. The continuum-removed spectral indices of DVI (difference vegetation index), RVI (ratio vegetation index) and NDVI (normalized difference vegetation index) are calculated by the combination of arbitrary two bands in the range from 350 nm to 1300 nm. The stepwise regression and principal component analysis methods are used to extract the principal components as the independent variables. A support vector machine regression model for estimation of SPAD values is constructed and verified by the data collected in the second year. The vegetation indices of the biggest correlation between SPAD and the three newly built vegetation indices are NDVI (406, 563), RVI (406,565) and DVI (646,695), and the correlation coefficient (r) reaches 0.677, 0.690 and 0.711, respectively. The support vector machine regression model is verified. Relative error of prediction (REP) is 1.190%, PR2 is 0.837 and relative percent deviation of prediction (RPDP) is 2.213. The continuum-removed method and building vegetation indices can improve the correlation between spectra and apple canopy SPAD values. The spectral index which has the highest correlation with SPAD is composed of the visible bands. The support vector machine regression model has excellent ability to estimate the SPAD values of apple canopies which are growing rapidly.

Fluorescence imaging technique is an important technique for noninvasive detection of latent fingerprints. An ultraviolet (UV) laser is used as excitation light source, and the thermal treatment technique and the fluorescence imaging technique are combined to noninvasively detect and show the latent fingerprints on the surface of porous papers. By controlling the heating temperature and time in the thermal treatment period, the brightness contrast between fingerprints and background is increased, and the fresh and aged latent fingerprints on the paper surface are noninvasively detected and shown by using the fluorescence imaging technique. The study provides experimental guidance for the application of thermal treatment and fluorescence imaging techniques in the field of latent fingerprint detection.

The effect of irradiation angle on detecting apple sugar by near infrared spectroscopy is discussed, and the best irradiative way of light source is obtained. An apple is selected as the object and sugar content of the apple is measured. The apple sample is irradiated in the middle of two lights of 100 W with three irradiation angles (30°, 45°, 60°). The spectra are collected using diffuse transmittance and the partial least squares regression model (PSL) is established. When the light angle is 45°, the precision of the model is the highest. The correlation coefficient of the calibration set (Rc) is 0.91, root mean square error of the calibration set (xRMSEC) is 0.57, the correlation coefficient of the prediction set (Rp) is 0.84 and the root mean square error of the prediction set (xRMSEC) is 0.73. The results show that the irradiation angle has certain effect on the model accuracy, and the study provides a basis for selecting the best irradiation angle in the building of actual models.

The effect of dust particles on the attenuation characteristic of plasma is discussed in three kinds of situation: 1) considering the collision between particles only; 2) considering both the particles’collision and the charging of the charged particles (electrons and ions) on the dust particle; 3) considering the effect of the electrical potential based on 2). Based on the calculation of the attenuation coefficient, the rocket exhaust plume is taken as an example on further analysis and discussion. The attenuation coefficient has a critical value with temperature and pressure, when in the low frequency of microwave band, and the corresponding attenuation coefficient produces a trough. The attenuation peaks appears near the dusty plasma resonant frequency. The distance between the position of the peak value and the resonant frequency is determined by the effect of the temperature and pressure on resonance frequency. At a given temperature, pressure and frequency, the attenuation coefficient of the third is larger than the other two and in the area of the experimental data. So, the effect of the electrical potential impact factor needs to be considered in the calculation.

Thin films of GexAsySe1-x-y chalcogenide glasses with different chemical compositions are deposited by thermal evaporation from bulk material in various GexAsySe1-x-y thin films. The Raman spectroscopy of GexAsySe1-x-y chalcogenide glass films is studied to understand the influence of chemical composition on internal film structure. The evolution of Raman features in the wavenumber range from 100 cm-1 to 350 cm-1 is analyzed. The Raman features are fitted into different peak-fitting functions. The intensity of Ge-Se vibrational mode at 190 cm-1 increases with the increasing of concentration of Ge and As. With the increasing of the mean coordination number (MCN), the intensity of As-Se vibrational mode decreases. Meanwhile, the two Raman shift modes located at 225 cm-1 and 250 cm-1 gradually merge and extend to high wavenumber for high MCN samples. In addition, in the films with high Ge content, the Raman features in the wavenumber range from 170 cm-1 to 180 cm-1 is caused by the defect modes.