For the coupled effects of the fluid flow,convective-diffusive and transient thermal conduction happened in the process of pumping and cooling,a flow-thermal-solid interaction model for calculating the temperature distribution in the laser crystal has been established based on the coupled analysis of multi-physics fields. The transient temperature distribution of a laser slab pumped by high-power repetitive pulses is obtained by using the finite element method. The proposed method precludes the influence of the inaccurate film coefficient of the cooling water on the calculation results. Therefore,for the purpose of reducing the thermal effects in the laser crystals,it provides a new effective way to assess and improve the cooling process.

In order to solve thermal effect of laser medium end-pumped by laser diode (LD),a thermal analysis model of YAG-Nd:YAG composite crystal rod with adiabatic end faces,fixed boundary temperature and consecutive heat flow interface was established. A general analytical temperature field expression of YAG-Nd:YAG composite crystal rod end-pumped by super-Gaussian beam was obtained by the methods of eigen-function and constant variation. Meanwhile,some factors,such as the super-Gaussian beam with different spot radius,different orders and the length of YAG crystal,which influenced the temperature distribution of YAG-Nd:YAG composite crystal rod,were quantitatively analyzed. The results showed that when the output power of LD was 50 W,the transmission efficiency of optical focusing coupler was 82%,the maximal temperature rise of the YAG-Nd:YAG composite crystal rod,in which the length of YAG crystal is 1.5 mm,the length of Nd:YAG crystal is 5 mm and the neodymium ion doped concentration in the crystal is 1.0% (mass fraction),end-pumped by the forth super-Gaussian beam was 132.7 ℃. The results would provide a theoretical basis for reducing the thermal effect of laser crystal and reasonably designing thermally stabilized cavity of solid-state laser.

Spliting performance of two parallel plates is analyzed and a design method is presented to optimize their spliting performance. Two parallel plates parallel to each other split one incident laser beam into multiple beams which are detected by a CCD camera. Because of the use of CCD camera,difference of maximum power density between received laser faculae (DMPF) should be made as little as possible. Effect of distance between plates and incident angle on difference of laser faculae is analyzed. And the calculation results show that reasonable selection of distance between plates and incident angle can minimize DMPF. The optimum distance between plates increases as Rayleigh length of laser beam increases while the optimum incident angle keeps stable under the condition of fixed coated film and fixed central wavelength of laser beam. And DMPF under corresponding optimum conditions fluctuates as Rayleigh length increases.

Spectral beam combination of two Er3+/Yb3+ co-doped double-clad fiber (EYDF) lasers were experimentally studied through an outer resonator with a blazed grating placed in it. The outer resonator was formed by two dichroic mirrors and a partial reflector. Two EYDFs with different lengths were used as the gain element. A transform lens were employed to locate the output ends of the EYDFs in term of their incidence angle on surface of the blazed grating. The blazed grating was used to select the operating modes of the two EYDF lasers. The wavelength characteristics of a single EYDF laser were tuned experimentally. Stable output of single mode laser was achieved from 1532 nm to 1568 nm. The tunable range was about 36 nm and the 3 dB line width of the output lasers were all less then 0.08 nm. The output powers of the two EYDFs with lengths of 6 m and 8 m respectively were spectrally combined together. The combined output power of 480 mW was achieved on condition that the maximum pump powers coupled into the two fibers were 2.6 W and 4 W,respectively.

A ring-cavity fiber laser using a 973-nm laser diode (LD) as pump source and a highly Yb3+-doped fiber as gain medium is built. A laser output with a continuously-tunable width of 24 nm (1030-1054 nm) and a threshold power of 49 mW is obtained by tuning the intra-cavity polarization filter,which is made of a common fiber and some polarization elements. Moreover,we significantly expand the tunable range to 57 nm (1021-1078 nm) by introducing uniform stress in a part of cavity fiber. Compared with other tunable Yb3+-doped fiber lasers on the principle of polarization filter,this laser system has realized a much wider tunable width.

Different nonlinear dynamic behaviors of the distributed feedback semiconductor laser (DFB-SL) subjected to external optical feedback have been investigated experimentally and theoretically. The experimental results show that DFB-SL can exhibit rich nonlinear dynamic behaviors such as stable state,one-period,double-period,multi-period and chaos under different feedback strengths. For the laser operating at the series of periodic states,there are obvious characteristic frequency peaks in corresponding optical spectra and power spectra while the background noise is very low. Moreover,after increasing the feedback strength to a certain level,the coherence collapse will happen due to the strong mode competition of DFB-SL,and 10 GHz broadband chaos can be obtained experimentally. In addition,the numerical simulations are executed,and the results agree well with the experimental observations. The simulations also indicate that the feedback strength is a key parameter for controlling nonlinear dynamic behaviors of DFB-SL.

In order to study the formation and improvement of laser modes of high power transverse-flow CO2 laser,the structure of a tube-plate electrode is analyzed theoretically. A Laplace′s equation describing the electric potential in the discharge area is numerically solved,and the spatial distributions of the electric potential and field are obtained. Based on the distributions of electric field,the densities of electron,population and photon can be predicted theoretically. These results can be used to analyze the formation reasons of laser modes,as well as to explain the nonuniform characteristic of the laser spot energy. It is also shown by the calculations that with the decreasing of electrodes space and increasing of the tube diameter,the magnitudes and uniformity of electric field near the optic axis are enhanced greatly. As a result,the electron density will be increased and the laser modes can be controlled and improved. Based on the theoretical analysis,laser beam modes are improved through slightly adjusting of the electrodes and the optic axis.

Tunable reflective narrow filters have important applications in optical communication,display,optical switch,security images label and other fields. The design of narrow tunable reflective guide mode resonant filters (GMRF) using the variation of azimuthal angles was done. Through rigorous coupled-wave analysis,the structure of guided mode resonant filters whose reflective peak value depend on the azimuthal angle was obtained. For TM polarize light with 60° incident angle,the resonant peak value of guided mode resonant filters shifted to longer wavelength with the increase of azimuthal angles.

In order to investigate the application of linear phase retrieval sensor in the adaptive optics system,an experiment adaptive optics system was established based on the linear phase retrieval method. The close-loop compensation ability to the dynamic aberrations was investigated and validated by using a 19- element deformable mirror. During the experiment,it was needed to calibrate the system aberration produced by the deformable mirror first and keep its image. And then the voltage of drivers can be retrieved by utilizing the different images between the actual image and calibrated image. Finally,the unknown aberration can be corrected by controlling the deformable mirror. The results indicated that the system can correct certain size aberrations,and it had a fine compensation effect. The adaptive optics system based on the linear phase retrieval method is excellent with simple structure,low calculation cost and high speed.

Adaptive optics (AO) based on stochastic parallel gradient descent (SPGD) algorithm can be used to correct the phase aberration without the wavefront sensor,but the low speed of convergence confines its application in real-time system. Considering the relationship between the stochastic perturbation and convergence speed of SPGD algorithm,a technique is proposed to optimize the proportion of stochastic perturbation with Zernike mode. Aiming at atmospheric turbulence,a 61-element AO model based on SPGD algorithm is set up,and a group of phase aberration with the Kolmogorov spectrum is simulated numerically to research the effect on convergence characteristic resulting from this method. Results show that,comparing with the AO before optimization,the convergence speed can be improved efficiently although it gives up a little correction precision.

In order to minimize optical distortion of beam introduced by gas jet stream and improve optical transmission quality,a project of utilizing N2/He mixture as working gas is proposed based on matching index-of-refraction and equalizing pressure. The method for determining gas mixture composition is also discussed. Experiments are carried on N2 and N2/He mixture respectively,and the laser beam wavefront aberration peak-to-valley (PV) value is measured from the data collected by Hartmann sensor. The results show that the wavefront distortion PV value of aerodynamic window (ADW) is 0.18 μm approximately in case of N2;while that is 0.13 μm in case of N2/He mixture. The optical quality of the ADW can be improved by using N2/He mixture as working gas instead of N2.

Numerical simulation model of thermal loading on piston by laser is established. By virtue of the model,the influence of different cooling matters on thermal loading of piston is investigated. The results show that temperature fluctuations occur at thin-layer regional of piston top surface when cooling air is applied to piston top surface and tunnel with cessation laser heating,which is in accordance with actual stable conditions. Temperature fluctuations is not consistent with actual stable conditions of air cooling of piston inner chamber and tunnel or water cooling of tunnel. Low-cycle fatigue with air cooling of piston top surface,water cooling of inner chamber and tunnel can accelerate damage to piston. Meanwhile,these regions of concave,tunnel and inner chamber are most vulnerable to form crack due to the cool medium contacting with them. The numerical results are in agreement with the experimental results,which indicates that the established numerical mode is correct and reliable.

We investigate the lasing action of the nematic liquid crystal device,which is added laser dye DCM and chiral compound CB15. The anti-parallel rubbing device is manufactured and the planar texture state of cholesteric liquid crystal is achieved. The emission spectra is mesured and anylazed using a frequency-doubled Nd:YAG pulsed laser (λ=532 nm) as pumping source. Broad fluorescence radiation spectra of DCM is observed under lower pumping energy. When pumping energy is larger than 18.0 mJ,dramatic narrowing spectra which has the obvious threshold and the direction characteristics is observed with centre wavelength of 606 nm. The full width at half maximum (FWHM) is about 10 nm.

Observed Fraunhofer spectrums are limited by achromatic performance of waveplates in solar magnetic field telescope. Comparing to the different kinds of achromatic waveplates,one which composes of five-element of polyvinyl alcohol film is chosen due to its good performance in whole scope of visible wavelength. Analyzing the measurement datum from 486.1 nm to 656.3 nm,it is found that the maximum error of retardance is in the orders of λ/350 and λ/160 for half wave plate and quarter wave plate respectively,and the maximum error of axis azimuth is in the orders of 0.2° and 0. 6° for half wave plate and quarter wave plate respectively. From the measurement data,this kind of waveplate made of polyvinyl alcohol film can be used in the whole visible spectrum,and has good performance comparing to that of birefringent crystal which is insensitive to temperature and incident angle.

Star sensor is imaging the space weak star point. The background noise from stray light will badly affect the extracting accuracy of image. So baffle design is the key technology of the star sensor. In this paper,the principle of baffle design is listed,the formula of the optimum length for two-stage baffle is deduced and an example of baffle design of a star sensor is cited. It is indicated that the new design has shorter length and better performance in stray light attenuation than the traditional barrel baffle.

The condition of electromagnetic wave mode is obtained by restrictions condition of electromagnetic wave in the cylindrical one-dimensional (1D) doping photonic crystal. The defect modes of TE wave and TM wave are calculated by the characteristic matrix method. The new defect mode structures of cylindrical doping photonic crystal are obtained. The defect mode frequencies of TE wave and TM wave increase with increasing quantum number but decrease with increasing cylinder radius. The defect mode full-width at half-maximum (FWHM) of TE wave decreases with increasing quantum number but increases with increasing cylinder radius,while the defect mode FWHM of TM wave changes different.

The 3Λu state of Na2 is excited by using optical-optical double resonance spectroscopy. The predissociative rates and collisional transfer rates of 3Λu state are experimentally measured. The cell temperature varies between 553 K and 703 K. A continuous-wave (CW) all-solid-state green laser (532 nm) is used to pump Na2 from ground state 13Σ+u to the 13Σ+g. Then an optical parameter oscillator (OPO) laser is used to excite high-lying 3Λu state. From time-resolved fluorescence for the 3Λu→13Σ+g transition at different Na densities,the effective lifetimes of the Na2(3Λu) state are yielded. Based on the Stern-Volmer equation,the sum of the radiative and predissociative rates is obtained with (4.8±1.2)×107 s-1,and the total cross section for deactivation of the Na2(3Λu) by means of collisions with Na is (2.7±0.5)×10-14 cm2. With different Na densities,the time-integrated intensities of 3Λu→13Σ+g,5S→3P and 3D→3P radiative transition are measured. The intensity ratios versus the Na densities can be fitted by the straight lines. From the slopes and the intercepts,we obtain predissociative rate of (8.0±2.4)×106 s-1 from Na2(3Λu) to Na(3D),and the cross sections of (6.2±1.9)×10-15 cm2 and (1.1±0.3)×10-15 cm2 for collisional energy transfer from Na2(3Λu) to Na(5S) and from Na2(3Λu) to Na(3D),respectively.

Cavitation bubble characteristic through laser cavitation and high speed photography is investigated. The characteristic data of bubble dynamics,collapse lighting and bubble collapse shock wave is measured based on apparatus of laser bubble measure. It is shown that the laser bubble is a good simulation of single-bubble. The shock wave intensity of plasma bubble expansion and bubble collapse are related to liquid viscidity.The intensity of the bubble collapse lighting is dependent on bubble collapse least size. The intensity of collapse photon is pertinent with liquid surface and steam tension.

In order to study the temperature performance of polarization maintaining fiber coil which is used in middling or high precision fiber optic gyroscope (FOG),the main reasons affecting the performance of fiber coil are analyzed from the viewpoint of the manufacturing process and the temperature changes of external environment. The light wave signal’s polarization cross-coupling of the interferometer is qualitative analyzed by using coupled wave idea,and the major polarization errors which affect the performance of FOG are pointed out. According to the transient state of temperature effects of fiber coil,the temperature test system is established to study the signal polarization’s changes in fiber coil. Experimental results show that the polarization state of the optical signals is affected by temperature in fiber coil,and also is concerned with temperature distribute of the whole fiber coil. In addition,this system can be used as the performance evaluation system to filter fiber coils with outstanding performance.

We propose a novel optical element for bulk glass Faraday current sensor to avoid the influences of the reflection phase shift in traditional bulk glass current sensors. An annular graded-index magnetic-optic glass with an opening is designed as the sensing head,in which the inner and outer layers possess gradient indices,while the center layer is uniform. The theoretical analyses show that since the light propagating in the sensing head can not reach the interface between the magnetic glass and air,the reflection phase shift could be avoided essentially,resulting in dramatically enhancement of the sensitivity. The influences of the geometrical parameters on the beam traces and the effective range of the initial angle are numerically simulated. It is revealed that this sensing head with high sensitivity,large effective range of the initial angle and no reflection phase shift can be obtained by choosing proper parameters of the annular magnetic-optic glass.

The method of optimized sensitivity modulation for the resonator optic gyroscope (ROG) is introduced. ROG is a novel optical rotation sensor whose resonant frequency is changed due to the Sagnac effect. The limited sensitivity of ROG should be obtained while the modulating frequency is optimized according to frequency-modulation spectroscopy. This adjusting method which is based on the theory of modulation frequency simplifies the process of optimized sensitivity modulation in ROG system. The theory and the structure of ROG system are analyzed. The modulation method of the optimized sensitivity based on modulation frequency is presented. The actual experiment results have proved that the method can modulate ROG to the optimized sensitivity and can apply in the adjustment of ROG system.

The paper proposes octagonal structural photonic crystal fiber (PCF) with double cladding and simulated numerically its dispersion properties by the multipole method. The result shows that the dispersion properties of the octagonal structural photonic crystal fiber have large differentiation by changing Λ or d1. But they change slowly by changing d2,while they are dependent on the value of d2. When d2 is small,the dispersion properties change with d2,but when it is larger than twice of d1,the dispersion properties will no longer change. According to this characteristic,a nearly zero dispersion flattened photonic crystal fiber at 1500 nm is designed. The result has good effect on preparing the doping photonic crystal fiber which is used in the high power laser and improving the laser output quality.

Supercontinuum generation in the normal-dispersion regime of photonic crystal fibers (PCFs) with long pulse pumping has been experimentally investigated. The coupling system between laser and fibers is designed based on essential conditions of lens coupling,by which the coupling efficiency can reach 60%. Low splicing loss is realized. Splicing loss is mainly caused by modal field mismatch of conventional fiber and PCFs. Theoretic value is 5 dB,while the experimental value is 3.8 dB. Supercontinuum generation is experimentally studied as pump power increases,and supercontinuum spanning from 710 nm to 1700 nm of 10 dB bandwidth with average power up to 1.2 W is generated. The experimental results show that stimulated Raman scattering (SRS) plays an important role in the onset of spectral broadening,then fission of higher-order solitons and cross-phase modulation make supercontinuum broader and flatter.

In the coherent beam combination of lasers array,the duty ratio has influence on efficiency of coherent beam combination,which is researched with mathematic analysis. Coherent beam combination experiment with 1×2 laser arrays is carried out in self-Fourier cavity. The result of mathematic analysis shows that through increasing the duty ratio,the energy duty of the central spot increases,and the number of secondary spot decreases.It is proved by the results of experiment that the energy duty of the central spot decreases from 42% to 11.13%,when the distance of two adjacent beam increases from 2.06 mm to 6.02 mm.

A beam shaping method for laser diodes stack by superposition of tilted fundamental mode Gaussian beams to form a nearly uniform illumination is proposed. The analytical formula for average intensity of the multi-tilted Gaussian beams (MTGB) propagating is derived and used to study the uniform properties of the beam profile by the Fourier analysis method. It is found that the MTGB maintain the flat-topped shape as it propagates. And the uniform properties of the MTGB are closely related to the parameters of fundamental beams and superposition. Both analytical formula derivation and the numerical examples are illustrated. The method is then used to reconfigure the beams of a high power laser diodes stack to form a multi-tilted Gaussian beam shape for a 12°×10° field angle illumination,which is simulated in ASAP software. The shaping method with the proper uniformity and high efficiency is well suitable for laser illuminator in laser active imaging and detecting system.

Fe-based WC composite coatings are prepared on the surface of A3 steel by laser induction hybrid rapid cladding (LIHRC). Microstructure and microhardness characteristics of the composite coatings are investigated. The results show that WC particles are almost dissolved completely and interact with Fe-based alloy,so that M6C are precipitated in the Fe-based interdendrite matrix phase. The reason why the microhardness of Fe-based WC composite coating is relatively low is that WC particles are dissolved completely and the retained austenite is precipitated during laser induction hybrid rapid cladding.

The analytic solution for spatially-resolved diffuse reflectance based on the Delta-P1 approximation for the two-point-source approximation is investigated. We have derived the radiative transport equation and the expression of the effective source by using scattering phase function which contains Dirac delta function. The analytic solution RDelta-P1,2(ρ) considering two-point-source approximation to the Delta-P1 model is presented. By comparing RDelta-P1,2(ρ) with the diffusion approximation RSDA(ρ),it is demonstrated that the Delta-P1 approximation RDelta-P1,2(ρ) models the radiance in moderate albedo media or close to source (ρ about 1.5 mm) more accurately than diffusion theory with the relative errors within 15%. Furthermore,the analytic solution RDelta-P1,2(ρ) provides the prediction of the second-order parameter γ of phase function,which is important for developing the inversion algorithm to recover optical parameters from the spatially-resolved diffuse reflectance measurements with small source-detector separations.

Laser-induced breakdown spectroscopy (LIBS) is used to analyze unburned carbon in fly ash. The samples are obtained by using fast ashing method. In the experiment,the carbon line at 247.86 nm presents strong interference by iron line at 247.95 nm,which affectes the analysis of unburned carbon by using LIBS. Without strong interference of other lines,the carbon line at 193.03 nm in deep UV is used,and calibration curve is constructed. The analysis results show that C 193.03 nm line can be detected at atmospheric pressure by using spectral detection system with deep UV detector coating,short focal length collimating lens and anti-UV fiber. The correlation coefficient of calibration curve is 0.99,and the detection of limit of unburned carbon is 0.74% (mass fraction).

The morphology of surface disperse strengthening by laser-guided discharge(LGD) is investigated,including the surface morphology and the cross section morphology of the strengthened area. It is found that the arc pressure can form the special morphology on the surface of the strengthened area in the process of arc discharge. The large current with the tilted discharge is liable to blow the melted metal up and forms the pit and bulge on the surface of the strengthened area,while the small current with the perpendicular discharge structure is liable to form the flat surface of the strengthened area and to increase the thickness of layer strengthened. The ratio of diameter versus thickness of the strengthened area is decreased when the discharge pulse-width is increased. In the same thickness of the strengthened layer,the low current and the long discharge pulse-width is liable to form the small ratio of diameter versus thickness of the strengthened area,while the high current and the short discharge pulse-width is liable to form the big ratio of diameter versus thickness of the strengthened area. Under the present experimental condition,the maximum thickness of the strengthened area is 0.479 mm,and the ratio of diameter versus thickness of the strengthened area is 3.9,when the current is 150 A and discharge pulse-width is 9.83 ms.

The generation of permanent high-grade conducting layer on the surface of polyvinylidene fluoride (PVDF) was induced by 248 nm KrF excimer laser irradiation. The results of XPS and FTIR spectra indicated that the photochemical reaction was occurred on the surface of samples and the microstructure was changed by laser light to generate HF gas,then resulted in high-stability and high-uniformity conducting layer on the surfaces. After analyzing and calculating the relationship between laser processing parameters and surface conductivity,the laser energy density of 44-112 mJ/cm2 was determined. The conductivity of the changed surfaces was increased to 12 orders of magnitude which reached to 10-1 Ω-1·cm-1. Based on the discovery of conducting layer,the mechanism of electrical conduction on PVDF surface was discussed.

The influence of the total number of Si particles on the spatial density distribution of the particles (Si and He) and the velocity distribution of the Si-particles is investigated with Monte Carlo simulation. The results indicate that the maximum distance of high density peak from the target and the width of velocity distribution increase,and the time of reaching the maximum distance from the target firstly increases and then decreases with the increase of number of Si-particles. The splitting of the velocity is observed at the vicinity of 1.01×1015 and 1.01×1016 Si-particles.

The development of a new welding method for dissimilar metals is strongly required for weight reduction of automobiles. The most popular and important combination of dissimilar metals is steel and aluminum. The lap joining of steel/aluminum alloy is carried out using the continuous wave-pulse wave (CW-PW) dual-beam YAG laser welding method. The tests are also performed for the lap joints using scanning electron microscopy (SEM),electron probe microzone analysis (EPMA),micro-hardness tester,tensile testing machine. The results show that the CW laser matching the appropriate PW laser for dual-beam laser welding can effectively reduce or avoid the produce of pores,as well as the deeper penetration can be obtained using the low-power CW laser,which expands the scope of the low-power CW laser equipments. In the dual-laser beam welding process,the Fe penetrates into the Al due to the role of pulsed laser. And the irregular hook-like structure produced in the bottom of welding seam,which can enhance the Fe/Al joint strength. A brittle Fe-Al intermetallic compound (IMC) layer formed at the join interface. The shearing strength of the lap joint is 128 MPa,and the morphology is quasi-cleavage fracture.

Laser milling of micro-fluidic Grooves under vacuum condition is presented. The regularity of laser milling under vacuum condition is established according to the analysis of melting-material removal which provides a theoretical basis. Nd:YAG laser is used to mill micro-fluidic grooves of a kind steel of HPM75. The research outcomes show that when vacuum pressure is from -0.07 MPa to -0.5 MPa,the materials removal increases by 1.6% to 3.3%. Vacuum condition means that air pressure is reduced. When the parameters are preferable,the quality of groove is satisfied with width 0.225 mm and depth 0.058 mm,and materials removal increased,compared with common condition. Laser milling rate is higher and its surface quality is proved better than that of normal laser milling. It helps to control the precision of milling size,and it is an effective method to laser milling technology.

Mole fraction 9% Ho3+ doped KYb(WO4)2 (Ho:KYbW) crystal which belongs to monoclinic system is grown by top seeded solvent growth method using K2W2O7 as a suitable flux. The infrared spectrum and Raman spectrum of the Ho:KYbW crystals are measured,and the assignation of the vibrations of the peak value is determined. The absorption spectrum and fluorescence spectrum of the Ho:KYbW crystal are analyzed and the corresponding spectral parameters are calculated. The absorption spectrum shows that the highest absorption peaks of Yb3+ are located position at 930 nm and 987 nm and the full-width at half-maximum (FWHM) of the peaks reaches 93 nm. The fluorescence spectrum of the Ho:KYbW crystal indicates that the emission wavelengths of fluorescence are 1971 nm and 1988 nm,and the emission FWHM of the chief peak 1988 nm reaches 71 nm,so it is an excellent gain medium for tunable laser. Upconversion fluorescence spectrum of the crystals is measured,the upconversion green light of 542 nm and red light of 647 nm are obtained,and the corresponding upconversion mechanism is analyzed.

High quality Yb:Lu3Al5O12 (Yb:LuAG) crystal doped with 10% atom fraction Yb3+ was grown by the Czochralski method. After annealing under different atmospheres,the spectral properties of the crystal were characterized. The experiment indicates that the absorption band in 363 nm and 562 nm are connected with Yb2+. After air annealing,the intensity of fluorescence spectra is the strongest and the fluorescent lifetime is the longest. The curve of gain cross-section indicates that Yb:LuAG crystal has a wide emission band. Under laser diode (LD) pumping with 9.59 W power,the maximum output power,the slope efficiency,and the lasing threshold of Yb:LuAG crystal are 3.05 W,41.7%,and 40 mW,respectively.

The study was performed on hafnia thin films deposited with electron beam evaporation deposition before and after annealing. The transmittance,X-ray diffraction (XRD) and photoluminescence (PL) excitation spectrum of the samples were tested to analysis the property and structure of the film. Intensity of the photoluminescence increases after the annealing process. It is found that the Stokes shift is existed between excitation spectrum and emission spectrum. XRD shows that after annealing,the orientation and the crystalline are markedly improved. The annealing process has no effect upon the laser-induced damage threshold (LIDT).

Titanium dioxide (TiO2) thin films are deposited on two different roughness K9 glass and monocrystalline silicon substrates by electron beam evaporation technique and all samples are treated with oxygen ion beam. Surface roughness of substrates and all samples are measured using Talysurf CCI. The refractive index of TiO2 thin films is measured by an ellipsometer. The experimental results show that TiO2 thin films decrease the subatrate surface roughness,and ion beam post-treatment improves the surface roughness of TiO2 thin films. When the substrate roughness is larger,with the increase of ion energy,the surface roughness of TiO2 thin films decreases firstly,and then increases;with the increase of ion beam bombardment time,the surface roughness of TiO2 thin films decreases obviously. With the increase of ion beam density,the surface roughness of TiO2 thin films decreases. The surface roughness of all samples is also decreased with ion beam treatment.

A measure system for checking high reflectivity of the coating by cavity ring-down spectroscopy (CRDS) at IR wavelength has been set up. The measure precision could approximate to be 10-4 with a pair of high reflectivity concave mirror put aside to make a straight cavity. The ringdown curves have been gained in different cavity lengths,for change of cavity mode would cause different modulation depth curves. Then the reflectivity of the cavity mirror is calculated and the average square error is 2.25×10-4. Then the influence of the reflective measure precision is studied with adjusting the relative position and adding the diaphragm in optic length which could change cavity mode. The average square error is 2.55×10-5 in the adjusting range of 20 mm between two lens. The use of the diaphragm in optic length could improve the match of the cavity modes which would reduce the accord error of the ringdown time.

The wavefront collimation of the large aperture near-infrared interferometer must be controlled strictly. Scanning pentaprism system is introduced to divide the wavefront of the interferometer into a series of sub-wavefronts,and the relative positions of the spot centroid according to every sub-wavefront are recorded on the CCD camera. The normal directions of every sub-wavefront are obtained to reconstruct the tested wavefront,thus the collimation test of the wavefront can be realized. The wavefront in the horizontal direction of the collimation lens of a 210 mm aperture near-infrared interferometer is tested and reconstructed. The effect of system error on the experimental results is analyzed. This method is of low cost and high accuracy,and is particularly applicable to the collimation test of a large aperture near-infrared wavefront.

Heat bridge in the online energy measurement device for long-pulse laser enhances heat conduction effect. The research was done to assure the value of the effect on measurement result so as to correct the measurement result. Curves of temperature was divided into three parts,each part was analyzed with Fourier heat law,heat conduction equations and energy conservation law. Relationship between energy loss and device parameter was obtained,and experiment research was done. Experiment data was fitted and conclusion was drawn:heat loss rate is decided by pulse length,heat conduction coefficient of material,length of heat bridge,quality of heat absorption body,and et al.. These parameters are decided according to experiment interval and precision requirement. Theory value and experiment result have a good coherence. Its deviation is 2.9%.

An integrated radio-over-fiber (ROF) system with 60 GHz wireless mm-wave transmission by using optical carrier suppression (OCS) is proposed and experimentally demonstrated. A Mach-Zehnder single-arm intensity modulator (IM) is employed to generate 60 GHz millimeter-wave by OCS,and the 2.9-Gbit/s on-off keying (OOK) signal is modulated on mm-wave by using other IM. Then the downstream signal is transmitted from central office to base station by fiber link. In the base station,the mm-wave is detected by a high-speed optical/electrical (O/E) converter before it is amplified by an electrical amplifier and beamed by the antenna. The received wireless mm-wave is demodulated by coherent demodulate to retrieve the baseband signal. The experimental results show that the 58 GHz optical millimeter-wave will be generated by 29 GHz radio frequency resource,and 2.9 Gbit/s downstream and upstream data can be transmitted over 20 km in fiber,and 2.6 m wireless distance can be realized simultaneously.

An all-optical discrete Fourier transformer (ODFT) based on SiO2 plamar lightwave circuit (PLC) technologies and made up of optical directional couplers,phase shifters,and optical delay lines is designed. Whose principle is investigated and an ODFT chip operating at 4×40 Gb/s is designed and optimized. Detailed designation and implementation methods are also given. Based on that,an all-optical orthogonal frequency division multiplexing (OFDM) transmission system is designed,eliminating the processing speed introduced by electronics as in conventional OFDM systems. The VPItransmissionMaker V7.6 is used to evaluate system performances. Simulation results prove the effectiveness of the all-optical OFDM system. The bit error rate (BER) is lower than 3×10-11 after transmission through 320 km in the optical fibers. All-optical OFDM has been treated as a good candidate for the long-haul and high-speed transmission technology.

An optical fiber long length side-grinding device with controllable and high precision grinding thickness,and a setup for high-precision polishing of the optical fiber section by using an arc discharge method are self-made. The grinding precision is 0.01 μm,the grinding length can be longer than 100 mm,and multi-fibers can be grinded at the same time. By using the devices,the side grinding thickness of the polarization-maintaining fiber Bragg grating (PMF-FBG) can be controlled,and long length,high precision controllable PMF-FBG can be fabricated. The span of the two wavelengths of the PMF-FBG can be controlled accurately. The experiment results show that when the radius of the grinding side of the PMF-FBG changed from 125 μm to 65 μm,the wavelength span of the PMF-FBG changed from 0.34 nm to 0.208 nm.

A time-domain semi-analytical solution of nonlinear Schrdinger equation (NLSE) was obtained by using perturbation method (PM). And a modified perturbation method (MPM) was brought forward with the increase of nonlinearity. The numerical simulations of its applications in a high-speed nonlinear fiber-optic system,which is made up of multi-span each including one transmission fiber,one dispersion compensation fiber and an erbium doped fiber amplifier,proves that the MPM give a more precise semi-analytical solution of NLSE,which provides a novel solution to study the high-speed long-haul fiber-optic system.

A distributed fiber optic intrusion sensor system based on Brillouin optical time domain analysis (BOTDA) is proposed. The absolute values of temperature and strain are not required in this system. So the complicated frequency analyzer is omitted,which simplifies the BOTDA system. An optical pulsed signal is used as pump and a continuous wave optical signal in counter propagating direction is used as the detected light. It is concluded that the best sensitivity can be achieved when the frequency of continuous wave is higher than the Brillouin peak gain frequency produced by pump and there exists an optimal frequency offset that makes the highest sensitivity. When the temperature of the optical fiber changes,the optimal sensitivity can be achieved by adjusting the pump frequency.

Elimination of polarization-induced fading is one of the key technologies of interferometric fiber optic sensors.Single-mode fiber optic Michelson interferometer based on Faraday rotation mirror (FRM) is researched. The effect of FRM rotation angle error on the system performance is analyzed and simulated based on Jones matrix. When the FRM rotation angle error is less than 6°,the visibility of interferometer remains above 0.9. The effects of different wavelengths on the interferometer performance are discussed. When the wavelength is close to central wavelength,the interferometer visibility remains above 0.9. Experimental results show that at wavelength of 1495.4-1606.7 nm,the visibility of interferometer is close to 1 and the performance remanis good.

Based on the leakage and measurement of evanescent wave in side-polished fiber (SPF),an all-fiber integrated optical power monitor-controller (OPMC) is fabricated by integration of variable optical attenuator (VOA) and optical power monitor (OPM). Using common optical fiber as a substrate of waveguide,the structure of OPMC based on dual side-polished areas of side-polished fiber is designed,and its manufacture technique is developed. A VOA and an OPM are fabricated in the first and second polished areas of side-polished fiber,respectively. Both VOA and OPM are integrated in a section of optical fiber so as to become an all-fiber integrated photoelectronic component that has two functions of both monitor and controller. Experiments show that the typical characteristics of the integrated component are as follows:insertion loss of 0.7 dB,attenuation range of 0-52 dB,wavelength dependent loss of 0.2 dB,polarization dependent loss of 0.17 dB,photoelectric transition efficiency of larger than 100 mA/W,and so on. The all-fiber integrated component has many advatages,such as easy fabrication,small size,low cost ,electric control,etc.

Optical fiber lasers and amplifiers based on stimulated Brillouin scattering (SBS) in optical fibers and their applications are reviewed. Due to their intrinsicly unique characteristics,fiber Brillouin amplifier (FBA) and Brillouin fiber laser (BFL) have important applications in many fields. In particular,researches on FBA-based optical slow light buffer,ultra-narrow line-width BFL,multi-wavelength BFL and optical generation of microwave signals based on BFL have been attracting much attention in recent years. Their latest advances are focused in this review. Because of its potential applications,SBS in optical fibers may play important roles in fields of future all-optical telecommunication systems,coherent optical transmission systems and optical fiber sensing.