A new kind of a radio frequency (RF) excited diffusively cooled gain slab waveguide CO2 laser was presented. In this type of laser,to improve the quality of output laser beam and enhance the mode coupling between multi-waveguide sub-channels, grooves were made on the top electrode to form a list of parallel sub-electrodes, which can produce the periodically gain distribution along the transverse direction of waveguide. A phase-shifted totally reflecting copper mirror with periodically grooves on the surface was employed and the interference superposition of far-field sub-laser-beams was obtained.The near-field and spatially compressed single peak far-field intensity distributions of output laser beam were studied at pressures of 10.0 kPa and 10.7 kPa, respectively.

The Hartmann wavefront sensor is commonly used in adaptive optical (AO) system to measure the wavefront aberration. Noise and assembly errors decrease the accuracy of a Hartmann wavefront sensor, thus degrade the quality of the AO system. The moment theory, which has its origin in digital graphic discipline, is introduced into AO system. The Zernike moment is utilized as pre-processing filter because it is insensitive to noise and rotationally invariant. Hence the AO system becomes less sensitive to noise, and no high assembly precision is required.

Performance optimization is one of important facets for the investigation of laser thruster. Due to the limitation of hardware, effects of laser pulse waveform on lightcraft performance have not been carried out widely in the field of laser propulsion. Based on actual pulse waveform of two CO2 lasers, two groups of energy injecting models are formed, whose temporal waveforms are similar, single pulse energies are the same, but peak powers and pulse durations are different. Performances of parabolic laser thruster obtained by numerical calculations are compared under the conditions of different pulse waveforms. The results indicate that peak power and pulse duration are important parameters in determining the lightcraft performance and waveform with shorter duration and higher peak power is more efficient in improving impulse coupling coefficient and force. The numerical results of impulse coupling coefficient with two actual pulse waveforms are 40.9×10-5 N·s/J and 30.0×10-5 N·s/J respectively, which are consistent with experimental ones reported by other literatures. The presented method and investigative idea can be used in pulse waveform design of CO2 laser and provide some reference for laser propulsion research.

A scheme of long-distance fiber Bragg grating (FBG) sensor system based on linear-cavity fiber Raman laser is proposed and demonstrated. The cavity of the laser consists of the sensing FBG and the tunable FBG, of which the Bragg period is tunable through a one-dimensional (1D) adjustor. The 1D adjustor, which is connected with a step motor that is controlled by a programmable logic controller (PLC), can control the Bragg period of the tunable FBG to match the Bragg period of the sensors, which decide the wavelength of the laser output. The tuning module, the optical/electrical circuit, the detecting-and-controlling system and the fiber Raman laser construct a close loop, which performs the wavelength demodulation. Experimental results show that the demodulation sensor system can accomplish sensing and detecting of long-distance distributed sensing signal. Signal-to-noise ratio of stable Raman laser output is greater than 40 dB with 30 km non-zero dispersion shifted fiber (NZDSF), and the precision of the proposed system is about 0.05 nm in a demodulation range of 4.2 nm.

Polarization-maintaining fibers (PMF) are widely used in coherent optical communication systems, optical fiber sensors, optical fiber lasers, optical fiber gyros, and so on. The temperature stability is one of the key factors for the application of such fiber. In this paper, the characteristics of the fiber Bragg grating(FBG) fabricated in the PMF are analyzed by both of the theory and experiments. The results show that the higher of the temperature, the narrower of the polarization peak space. This is the theory basis of the high resolution new method to get the temperature characteristic of PMF. The experiments for the PMF at temperature range from -40 ℃ to 130 ℃ are measured, and the results agree well with the theory analysis.

The research results of a novel kind of side-hole fiber and side-hole fiber grating are reported. The finite element method is used to analyze the interior stresses distribution and the birefringence values of side-hole fiber, which is also measured by wavelength scanning method, both the theoretical and the measurement results show that the birefringence of side-hole fiber reaches 4×10-5. Utilizing the property that the polarizations of the two reflection peaks are orthogonal, the article has presented a novel scheme based on polarization detection to measure peak separation. The experimental results show that the temperature sensitivity of peak separation is 0.05 pm/℃, which is only 1/184 of the normal single-mode fiber grating. A novel transversal load sealing method is first presented in this paper, with a pressure sensitivity of 119.14 pm/MPa, which is 21 times of the pressure sensitivity of bared side-holes fiber grating 5.6 pm/MPa. The temperature-insensitive high sensitivity pressure sensing can be realized with the side-hole fiber grating.

Supercontinuum spectra can be generated in a novel multi-core microstructure fiber (MF) with random air lines. Over 600-nm-wide broadening spectrum (400～1000 nm) is obtained after the 20 fs laser pulse train from a Ti∶sapphire laser oscillator at 820 nm wavelength transmitting a 40-cm-long multi-core MF. The visible light can be tuned by adjusting input end of the MFs. The experimental results show that super non-linearity occurs as the MFs with random air lines are used for generation of supercontinuum.

Based on the computer aided design (CAD) digital base of complete denture model, a titanium base was made with the RS-850 laser rapid forming system, which processing parameters were suitable. The method made the Ti-base faster comparing with the traditional one, and the shape of the complete denture base was very well. The success development of the titanium base provided a new method for the automatic manufacture of titanium prosthetic replacement, and would make the foundation for the clinical application in the future.

The technology of fingerprint identification is a convenient, reliable, noninvasive and cheap scheme for biometrics. A method that adopts surface plasmon resonance imaging (SPRI) to collect fingerprints utilizing surface plasmon resonance (SPR) phenomenon is put forward to improve the quality of images in this paper. The principles and the structure of SPRI system are introduced. SPR is stimulated by a Kretschmann prism couple configuration. The cover glass coated with a 50 nm gold film serves as a sensor chip. The fingerprint is then imprinted on the gold film. Polarized monochromatic light is projected on the sensor through the prism, where the SPR phenomenon occurs. The reflected fingerprint image is collected by CCD. The images are collected by SPRI and conventional optic method for the same fingerprint, two different contrast gradients in which the fingerprint ridges are compared with the valleys of the main parts of the two images are 0.2014 and 0.0516 respectively. The contrast and clarity of the image collected by SPRI are much improved.

The control effects of the main insect of fruits—drosophila melanogaster were studied with the semiconductor laser in this paper. The experiment was designed with response surface method to investigate the biological effects on drosophila melanogaster with different laser power and irradiation time. The results showed that the death rate was above 99% to the larva of drosophila melanogaster under the conditions of laser power of 60 mW and irradiation time of 1282 s, with semiconductor laser at wavelength of 650 nm. At the same time, the weight of drosophila melanogaster was reduced, and the required eclosion time was decreased. Therefore, the semiconductor laser has strong biological effects to larva of drosophila melanogaster. However, when the power was below 40 mW, the laser light has the effect of promoting the growth of drosophila melanogaster. The experiment demonstrated that drosophila melanogaster did not show anti-laser effects in the third generation under the same experimental conditions compared with the control groups, it is suggesting the possibility of the semiconductor laser application on pest control of fruits.

The characteristics of polymer dispersed liquid crystal (PDLC) and holographic polymer dispersed liquid crystal (H-PDLC) volume grating are introduced. Based on the novel H-PDLC volume gratings, series-connecting dynamic gain equalizer design is provided. Furthermore, simulations are made about wavelength selectivity of H-PDLC grating at 1550 nm and the function of H-PDLC dynamic gain equalizer. The calculation results show that when suitable grating parameters of H-PDLC are selected, half spectral width of grating is about 10 nm at central wavelength of 1550 nm. And the fluctuation of spontaneous emission spectra of erbium-doped fiber amplifier (EDFA) can decrease from 3.3 dB to 0.1 dB within 1530 nm to 1560 nm based on H-PDLC dynamic gain equalizer.

The influences of laser welding velocity, flow rate of side-blow shielding gas, defocusing distance and other parameters on the full penetration laser weld seam of K418 and 42CrMo were experimentally investigated using continuous wave Nd∶YAG laser. Results show that the asymmetric cross-sections of weld seams exhibit X shape or T shape. With increasing welding velocity, the linear heat input and dimension of weld seam decrease, and the shape of it changes from X shape to T shape. Meanwhile, the rate of change in dimension of weld bottom region is larger than that of weld top region. The change of the top surface width of the weld seam is small under the condition that defocusing distance changes within the range of Rayleigh length; the top surface widths of the weld seam increase quickly under the condition that defocusing distance changes out of the range of Rayleigh length with enough density of laser power. The high-quality of weld seam with constant 3 kW laser power and 35° angle of side-blow shielding gas can be obtained by optimizing welding velocity, flow rate of shielding gas, defocusing distance and other parameters.

Based on the relationship between the features of laser ultrasonic waveform and the spatial distribution, temporal distribution of the laser pulse as well as the material physical properties, a model for the thermoelastic generation of ultrasonic wave in metals and non-metals is established by using finite element method (FEM). The temperature distributions in metal and non-metallic materials excited by laser pulse are obtained, and the ultrasonic waveforms at the epicenter caused by thermoelastic expansion are calculated by utilizing the temperature distributions as ultrasonic force source. The generation reason and rules of precursor are analyzed according to the waveforms at the epicenter. The results show that, because of the thermal diffusion, a force source is excited on the metal surface, whereas a body force source with relatively large depth is caused due to the optical penetration in non-metals. The stresses normal to surface are excited by rapid expansion of material heated by laser pulse, but the location that the stresses act on is below the surface in the case of non-metals, so the precursor is monopolor in metals and it becomes dipolar in non-metals. The precursor waveforms include the material physical properties and parameters, so this research is useful for nondestructive materials test and evaluation by utilizing the characteristic of precursor.

Based on many experiments of CO2 laser welding of 1.5 mm zinc coated high strength steel to vehicle body, joint microstructure and stress-strain curve of specimen are acquired. Given special welding technology, theoretical Pc-v curve and Pc-Δf curve of stable deep penetration laser welding are deduced. The unstable sharply gasification of zinc enlarges heat-affected zone (HAZ), debases welding stability and increases the difficulty of protecting condenser. Through optimizing technology parameter, adopting coaxial and side blown protective gas, deep penetration laser welding can effectively avoid softening HAZ of welding of zinc coated high strength steel and can control the gas hole. The experimental result indicates that the content welding quality can be gained on the condition of using N2 as protective gas ,the laser power at 1300 W, the welding speed at 0.8～1.1 m/min and defocusing amount at Δf=-0.4 mm, the hardness of welding seam is twice as that of base material.

The development of a new side-sliding discharge scheme can provide efficient uniform ultraviolet (UV) preionization for transverse excitation (TE) CO2 laser. The use of the scheme has resulted in the successful generation of CO2 laser discharges between electrodes separated by 5.5 cm, total cross section is 27.5 cm2. The laser is modular in construction, under the condition of V(CO2)∶V(N2)∶V(He)=1∶1∶4 mixtures and 60 kPa gas pressure, a modular with active discharge volume 5.5 cm×5 cm×90 cm has yielded output energy of 53 J, the specific output energy ratio is 3.46×10-4 J/(L·Pa). When a pair of discharge modulars are employed in series in a simple oscillator configuration, output energy of 103 J is yielded. An effect of laser energy enhancement occurs in dual-modular, the output energy of dual-modular is 15% higher than twifold energy of single modular.

InGaAlAs/AlGaAs/GaAs strained double quantum well (DQW) linear array diode lasers with asymmetric wide waveguide have been successfully fabricated by pulse anodic oxidation process upon molecular beam epitaxy (MBE) material growth, high efficiency and high power quasi-continuous-wave (QCW) output has been realized at 808 nm wavelength. The pulse anodic oxidation process is used to etching and insulating film preparation in QCW device process with electrolyte solution of 4∶20∶1∶1 ratio of glycol∶deionization water∶phosphoric acid∶2% hydrochloric acid. The fill factor of the prepared linear array is about 72.7%, the threshold current and slope efficiency of the prepared devices are 24 A and 1.25 W/A respectively under QCW operation condition of 100 Hz repetitive frequency and 200 μs pulse width, a maximum electrical-optical conversion efficiency of 51% has been achieved.

An average power of 138 W green beam operation by intracavity frequency doubling of acousto-optic Q-switch solid-state Nd∶YAG laser is reported. An U type resonator is designed and optimized in order to compress pulse-width and increase the average power. Two Nd∶YAG rods were employed and a type Ⅱ phase matched KTP crystal (=25°, θ=90° under the condition of 24 ℃, the size is 7 mm×7 mm×7 mm) was applied for frequency doubling. Under the pumping currents of 18.5 A and 20.5 A, a maximum green power of 138 W was generated at 10 kHz repetition rate and 49 ns pulse-width, leading to 14.1% of optical-optical conversion efficiency and ±2.8% instability.

An all fiber laser based upon nonlinear polarization rotation as an effective fast saturable absorber for mode-locking is reported. The absorber can act as passive Q-switching and modelocking. The ring laser with a highly Yb3+-doped fiber as the gain medium, pumped by a semiconductor laser of 976 nm wavelength, can operate in three different stable regimes by proper adjustments of pump power and polarizer orientations: Q-switched, Q-switched mode-locked and continuous wave (CW) mode-locked. The center wavelength of the CW mode-locked pulse is 1.05 μm with a full width at half maximum (FWHM) spectrum of 13.8 nm, the pulse repetition rate is 20 MHz, and an average output power is 15.82 mW with 270 mW pump power. In Q-switched regime, the laser generates 8 μs duration pulses of 4.7 nm FWHM spectrum at a repetition rate of 17.54 kHz. The Q-switched repetition rate is 300 kHz in Q-switched mode-locked regime.

A method of controlling chaos is presented by phase conjugation feedback (PCF) in a semiconductor laser. The physical model of controlling chaos produced by modulating the current of semiconductor laser is set up under the condition of PCF. The physical mechanism is found that the nonlinear gain coefficient and linewidth enhancement factor of laser are affected by PCF, the system dynamical behavior and its frequency characterization can be changed and controlled. The effect quantity relates to the feedback coefficient, the delay time and the linewidth enhancement factor. Numerical simulations show that chaos is controlled into the periodic state, the dual-periodic state, the multi-periodic state respectively by controlling PCF light delay time under the conditions of different PCF light intensity. And the laser emitting power is increased by PCF when chaos are controlled in all kinds of periodic states because that the performance characterization of the PCF light can produce the coherent function on the laser emitting light to realize controlling chaos in PCF controlling chaos processes.

The optic-acoustic reaction relationship is analyzed to noncollinear acousto-optic tunable filter (AOTF) under normal phase matching condition in this paper. To the generally designed AOTF, the diffracted o and e rays have different wavelengths. The two rays cannot be used simultaneously in practice. In order to magnify the intensity of light that can be used, the two diffracted rays should have same wavelength. The main research content of the paper is how to get two rays with same wavelength in normally produced AOTF crystal. For the AOTF crystal not produced by equivalent point theory, the incident light can be deflected a small degree with the normal of the crystal plane. By normal phase match condition it can be found that certain degree can diffracted the same wavelength rays. Experiments have validated the method. The deflected degree is called equivalent offset angle. For different diffracted wavelengths, there are corresponding different equivalent offset angles. Finally the variation rule of equivalent offset angle with diffracted wavelength is given.

A wave coupling theory of linear electro-optic effect is used to investigate the temperature properties of electro-optic modulator made by a uniaxial crystal LiNbO3. The dependence of output intensity on the incident direction and the temperature is characterized by numerical calculations. It is found that along some directions, the output intensity of the modulator is insensitive to the temperature within a range of angles. Further, when the polar angle θ is set to 0, azimuth angle  changes from 0 to π/2 and the temperature T changes from 243 to 343 K, the modulator presents perfect temperature stability. In addition, when  is set to π/8 and θ changes from 0 to 0.0032π, the temperature scarcely has effect on the ratio of output intensity to input intensity. Therefore, the temperature stability can be ensured by adjusting the incident direction of the beam, which can be obtained from the wave coupling theory of linearly electro-optic effect.

The transmission spectra and defect mode properties of the one-dimensional (1D) photonic crystal with Bragg microcavity are studied, where the Bragg reflectors are composed of alternately arranged different dielectrics with positive and negative indices. The transfer matrix is expanded in Taylor series near the central frequency, and the formulae of transmission and the quality factor are obtained with the first order approximation. Frequency variance of the defect mode near the central frequency caused by change of the thickness of defect layer material (DLM) can be well explained with the method of the first order approximation. The formula of the quality factor is almost identical with the result of numerical calculation. The quality factor at the central frequency is higher, and increasing defect layer thickness and the number of period can enhance the quality factor of the defect mode.

To investigate the dispersive character of cylindrical Rayleigh wave, a finite element model is developed to simulate laser inducing cylindrical Rayleigh waves on the surface of an isotropic cylinder. This model is based on the thermoelastic mechanism and can take the temperature dependence of material properties into account. Verifying the correctness of the model, the waveforms of cylindrical Rayleigh waves induced by laser on the cylinders with different radii was calculated, and quantitatively analyzed the influence of the cylinder′s diameter on the dispersion character of cylindrical Rayleigh waves by the phase spectral analysis method. The results show that with the frequency increasing, the phase velocity of cylindrical Rayleigh wave rapidly increases to the maximum value CRmax, and then gradually decreases to that of plane Rayleigh wave CPR. Moreover, as the radius of cylinder increases, the dispersion of cylindrical Rayleigh decreases, until the radius increases to ∞ (plane), the dispersion will vanish.

The Raman and infrared spectra of tellurite glasses were studied, and the influence mechanism of OH- on upconversion luminescence of Er3+-doped tellurite glasses was analyzed. The experimental results showed that the phonon energy of oxyfluoride tellurite (60TeO2-40PbF2-0.5Er2O3, TPF) glass was higher than that of oxychloride tellurite (60TeO2-40PbCl2-0.5Er2O3, TPC) glass, but upconversion luminescence intensity of Er3+-doped TPF glass was also higher than that of Er3+-doped TPC glass. It is considered in the removing water experiment that this phenomenon could be mainly attributed to the effect of OH-. With decreasing concentration of OH-, both the fluorescence lifetime and upconversion luminescence of Er3+ were enhanced. In this experiment, the effect of OH- on upconversion luminescence of Er3+ was bigger than that of phonon energy, and thus resulted in upconversion luminescence intensity of Er3+-doped TPF glass higher than that of Er3+-doped TPC glass. The research results were conducing to increase luminescence efficiency of Er3+.

The absorption spectra, infrared (IR) absorption spectra and upconversion fluorescence spectra of a series of Er3+/Yb3+-codoped 46Bi2O3-44GeO2-10Na2O (B46G44N10) glasses were investigated, and upconversion luminescence mechanisms of Yb3+ sensitize Er3+ were analyzed. Upconversion fluorescence intensities of Yb3+ sensitize Er3+ were measured, the optimal doping ratio of Er3+ and Yb3+ was 1∶6 for this glass, which resulted in the strongest upconversion fluorescence intensities. An upconversion efficiency of 2.27×10-4 was calculated for green emission from the B46G44N10 glass with 0.5 wt.-% Er2O3, and 3.0 wt.-% Yb2O3 pumped by 980 nm. Results indicated that this kind of bismuth glasses might be potential materials for developing upconversion optical devices.

It is a rising non-contact measuring method to detect minor distortions and displacements using digital laser speckle images. To improve the speed of this measurement method, a new speckle tracking method—digital speckle marginal correlation (DSMC) method is presented after the research of digital speckle correlation measurement (DSCM) method and speckle images′ characteristic. The speckle images′ pixel sum of every line and column is computed to make the light energy accumulated to the margin, and then uses only the two sequences to find the displacement of speckle images by correlation and interpolation method. And the displacement of speckle image reflects the distortion or displacement of objects. The theory and experiment proves that this method is feasible and it reduces computing time greatly without damaging the computing precision, because the precision of the measurement is mainly determined by the number of interpolation points and the synthesis noise of the digital speckle images themselves.

A dual-wavelength microarray scanner based on laser confocal principle is constructed to detect two-color (Cy3/Cy5) fluorescence. Volume holographic filters are employed. It is not necessary to switch filters when samples tagged with Cy3 and Cy5 are scanned because of diffraction and band elimination property of volume holographic filter. Filter and gridding of microarray images based on order morphological methods are presented. Experimental result shows that sensitivity of the system is 0.1 fluo/μm2. The gridding algorithm is simple and effective.

Micro-digital speckle correlation method (DSCM) is used to measure the mechanical property of advanced thin film material. From the high-quality displacement fields obtained by CCD camera, the mechanical property of the material can be achieved. In this application, the modulus of elasticity of the composite material of polyimide/SiO2 is obtained by use of DSCM. The out-plane displacement is achieved through the measurement of in-plane displacement, then the electrostrictive strain is evaluated by adding an electric field repeatly, and the electrostrictive coefficient of the sample can be obtained. In order to improve the accuracy of the measurement, the curved surface fitting algorithm is used to obtain the sub-pixel gray values. The results show that DSCM is an efficient and feasible method to analyze static and dynamic mechanical property of thin film material.

A new algorithm of nondestructive, automatic and high-speed inspection is proposed for dark-field image to be used to inspect online optic component damage on high power laser system. This algorithm is based on the theory of clustering in pattern recognition. The position of the damage can be automatically analyzed according to this algorithm from its dark-field image. Then, according to the characteristics of damage image, the two-directional (2D) scanning way can be used to obtain a continuous damage block without leaving out any damage pixel. Theories analysis and experiment show that the algorithm can determine the position of optical component damage and analyze the damage dimensions accurately and automatically.