In the process of high power frequency-doubling, the temperature inside the nonlinear crystal will become non-uniform because of absorbing the fundamental and second harmonic waves, leading to phase mismatch, conversion efficiency reduce and output power instability. This phenomenon appears severe in the high power high repetition rate laser system. Temperature distribution inside KTP crystal was analyzed by solving thermal conductivity equation. According to temperature distribution of KTP, we have theoretically calculated the optimal phase matching angles, tolerance angles and walk-off angles of type II KTP crystal as function of temperature.

The technology progresses of the different type high average power disk laser were summarized and its advantages, restrictions, developing potential and applications were analyzed and commented. Finally the newest progress of high average power disk type laser and heat capacity solid-state laser achieved in Institute of Applied Electronics were introduced.

The waste heat deposits into the gain medium when energy is made by optical pumping to laser. Removing this waste heat for steady state operation creates " heat effect ". The heat effect leads to degrade beam quality, reduces laser power, and possibly fractures the solid-state medium. The paper outlines the principal work, the developments and the techniques to avoid the heat effect.

The recent progress of the high power pulse double cladding fiber lasers are reviewed, the simulation calculation for pulse sharp amplified by the double cladding fiber is obtained by using small signal instantaneous gain model. The key points of the master-oscillator fiber power amplifier (MOPA) are analysied in detail. The system can emits average power up to 133.8 W at the wavelength of 1064 nm and repetition rate of 100 kHz.

Characteristics of the quasi-three-level solid-state laser doped with Nd3+,Yb3+,Ho3+ and Tm3+ etc. trivalent rare earth ions are compared, and their laser performances in solid-state laser configurations of rod, slab, thin disk and fiber are analyzed. Progresses in high average power Yb3+-doped solid-state laser are summarized. The experimental results of the Yb:YAG/YAG composite slab laser and the fiber laser in our research group are presented also.

The spectra characteristics of the Yb:YAG crystal which is an ideal gain medium of LD pumped all-solid laser were discussed. An LD end-pumped Yb: YAG laser system was described. At the pumping energy of 25 W, we obtained the output power of 6.09 W at 1030 nm, with the optical-optical and slope efficiency of 24.3% and 31.6%.

In the field of the diode-pumped solid-state laser engineering, the thermal induced distortion in laser crystal limits the output power and beam quality. We summarized the very promising properties of the concept of the slab laser with hybrid resonator. With such a diode pumped Nd:YVO4 slab laser setting 16 W CW output laser were demonstrated, the expression of the thermal lensing was obtained and the thermal effect was analyzed.

Utilizing four-level rate equation and double-frequency theory of analogous-Gauss beam, laser output power on the KTP length is calculated for LD array side-pumped 660 nm red laser. The optimal parameters are given. Theoretical analysis agrees quite well with the experimental results. With different length of KTP crystal, 3.75 W red laser power is obtained at 180 W pumping power. Using the appropriate length 5.83 W red laser is obtained at 210 W pumping power.

A laser in eye-safe spectrum region at 1.44μm was demonstrated by using LDpumped Nd:YAG. The 4F3/2→4I13/2 transition of Nd:YAG was realized by reasonable coating on the mirrors of the resonator. The CW and pulse operation switched by a new type of saturable absorber V:YAG were realized, respectively. When the incident pump power was 1.5 W, CW linear polarization output power of 268 mW was obtained with Brewster plate acting as polarizer in the cavity. The threshold was 380 mW and the slope-efficiency was 23.9%. Beam quality factor M2 was less than 1.3. When V:YAG was inserted into the resonator instead of the Brewster plate with 0?incident angle, linear polarization laser was also demonstrated. The results of average power of 36 mW, pulse duration of 106 ns and pulse repetition rate of 52 kHz were obtained. The corresponding peak power and single pulse energy was 6.5 W and 0.69 μJ, respectively.

We report the operation of a passively Q-switched diode-pumped Nd:GdVO4 laser, using GaAs as saturable absorber in a very simple compact plane-concave cavity. With 8 W incident pump power, passively Q-switched laser was obtained with an average power of 0.98 W. The shortest pulse width of 60 ns and the highest repetition rate of 240 kHz are realized.

Compress of the beam in unstable resonators by prism pair is discussed theoretically. A pair of prisms are placed into an electro-optical Q-switch Nd:YVO4 slab laser with an unstable-stable hybrid resonator. The beam is compressed in the unstable direction, which reduces the dimension of electro-optical crystal BBO and remains the large mode volume in the laser crystal. It fits high power performance. With CW pump power of 66 W, average power of pulse laser is 3.6 W at 2 kHz repetition rate, 1.8 mJ per pulse. Pulse width is 6ns. The experiment indicates that the laser can output high repetition rate and high intensity pulse with good beam quality, when the pair of prisms is in the resonator.

Several familiar methods for evaluating beam quality are discussed, and the shortcoming of them used in evaluating beam quality of laser diode is also analysed. The main factors to influence collimating the beam of laser diode with lenses are analysed. A new quality parameter(QP) lθ5(l is the size of the emitter in the direction parallel to the junction plane, 9 is the angle of the beam in the perpendicular direction.) for evaluating beam quality of laser diode is given. The difficulty of collimation is well expressed by this mean. The smaller the value of lθ5 is, the more easily the beam is collimated. Furthermore we give a reference value of the QP, when the QP value of the beam is smaller than this value, this beam can be collimated without much difficulty.

In order to ensure the accurate measurement of laser diodes (LDs), it was important to set and maintain a stable temperature. Based on the analysis of the temperature characteristics of LD, a new temperature control design with high stability was presented, which was a combination of several techniques that controlled accurately the temperature of laser diode and kept the detection and transmission of signals accuracy. Experimental results indicate that the temperature stability can attain to±0.01℃ at 10℃-40℃, and±0.005℃ at 25℃. So the design is an effective approach to enable better process control in a LD production environment. Depending on the setting of control parameter, it can also be applied to the temperature control system of other kinds of semiconductor laser.

Nd:GGG grown with Czochralski method is a very promising laser crystal used in the strong lasers. The precursor of GSGG was prepared by coprecipitatiom method, and polycrystalline material of GSGG was obtained at the lower sintered temperature. Scandium-containing garnet Nd:GSGG of (?)26 mmx45 mm, which are free of scattering, air bubbles, cloud layer and crack, was grown by Czochralski method. The phase transition of co-precipitating precursors of GSGG sintered at the different temperatures was studied by X-ray diffraction, which indicated that the precursors were converted into the polycrystalline GSGG at 900℃. The phase transition temperature is 200℃ lower than that of solid state reaction method. Meanwhile, the structure of the polycrystalline GSGG and single crystal Nd:GSGG were studied by X-ray diffraction. Their lattice parameters were computed by the least square method with the extrapolation function f(θ) = sin θ-sin1-T θ(T = 20), which are 1.257547 nm and 1.256163 nm, respectively. It is possible that the lattice parameter difference results from the difference of the ingredient Ga in the polycrystalline GSGG and single crystal Nd:GSGG.

GGG polycrystalline material was prepared by co-precipitation method with the metal Ga and Gd2O3 as the starting materials and aqueous ammonia as the preprecipitator. The X-ray diffraction spectra of GGG polycrystalline material prepared by co-precipitation method ,Nd:GGG prepared by solid-state method and the crystals GGG and Nd: GGG grown by Czochralski method were measured. Their lattice parameters were computed by extrapolation method. The lattice parameter of GGG polycrystalline material is smaller than that of Nd:GGG polycrystalline material, it is probably because the Gd3+ substitute Ga3+ and Nd3+substitute Gd3+ partly. Meanwhile, The lattice parameter of Nd:GGG crystal is larger than that of GGG crystal, from the result we know that Nd3+ substitute Gd3+. In addition, the lattice parameters of crystals are bigger than those of polycrystalline materials, which is probably caused by Gd3+ substitute Ga3+ due to Ga component vaporization. These results show that Ga component vaporization maybe exists not only in the preparation of polycrystalline materials but also in the crystal growth, so the Ga component vaporization should be considered in polycrystalline material preparation and crystal growth,The vaporization of Ga component can be controlled by using co-precipitation method

The spectral characteristics of Nd:GSGG crystal were studied, where the crystal was grown successfully by the Czochralski method. The absorption spectrum in the range of 400-2700 nm was measured. The fluorescence spectrum and lifetime were determined by exciting with 808 nm wavelength, the emission cross-section was calculated by F-L formula. These parameters were also compared with Nd:GGG and Nd:YAG crystals.

Nd:GGG laser crystal is one kind of important active material of solid state heat capacity laser. Nd:GGG laser crystals grown by using the Czochralski method were about 60mm in diameter. The macroscopical and microcosmic defects were studied with stress meter, polarization microscope, ESEM and chemical etching method. Reference could be afforded to improve growth technological parameter and grow good large diameter Nd:GGG laser crystals.

X-ray phase-contrast computed tomography (CT) is based on the difference in phase contrast of the materials during imaging by X-ray to describe the density or thickness of the materials. The use of phase contrast is suitable for weak-absorption materials and to diminish the total absorption dose, enhancing the conditions of the entire imaging procedure and decreasing the damage to the materials. In this paper, we introduce and compared three methods used for X-ray phase-contrast computed tomography, the experiments and the process of image reconstruction.

The measurement principle of gases sensors based near-infrared diode laser absorption spectroscopy was introdnced. Latest advanced of the applications in monitoring and controlling of garbage combustion processes, remote sensor of pipe leakage, monitoring of vehicle emissions etc., and developing trend of diode laser sensor were discussed.

The chemiluminescence of active nitrogen reaction with CHBr3 was investigated in a flowing afterglow reactor. Strong emission spectrum was observed in the wavelength range from 550 to 750 nm, which is ascribed to NBr(b→X) transition. Meanwhile, in the downstream of the flow tube, emission spectrum exhibits different character dominantly from excited states CN(A, B). The formation mechanism of these excited species has been analyzed, indicating that the generation channel of NBr(b) is from direct N(2D) abstraction bromine from CHBr3, and the excited CN(A, B) comes from the reaction of N(4S) with CBr, which is formed due to CHBr3 dissociation by metastable N2(A).

The new Er3+/Yb3+-codoped 70TeO2-5Li2O-10B2O3-15GeO2 glass was prepared by the technique of high-temperature melting. The thermal stability, absorption spectra, fluorescence spectra and upconversion spectra were measured and investigated. The oscillator strength, spontaneous emission probability, radiative lifetime and emission branching ratio of several Er3+ transitions were calculated according to the Judd-Ofelt theory. It is found that this glass has good thermal stability, broad FWHM and large stimulated emission crosssection. The three upconversion emissions at about 532 nm, 546 nm and 659 nm, corresponding to the 2H11/2→4I15/2, 4Ss/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, respectively, were simultaneously observed excited by 970 nm LD. The results show that this glass may be a suitable material for optical amplifiers and practical upconversion fiber optical devices.

Frequency stabilization of 1.53μm FBG ECLD on C2H2 absorption lines is reported. By choosing suitable parameters, the 1.5μm ECLD and a novel FBG tuning and modulating structure are designed. Using a lock-in amplifier to control the Bragg wavelength, the output wavelength is locked at the C2H2 absorption line of 1530.37 nm. The frequency stability reached 10-8.

The characteristics of distributed Bragg reflector(DBR) cavity are analyzed. A narrow-linewidth single-frequency ytterbium-doped fiber DBR laser is fabricated. The laser is pumped by a semiconductor laser operated at 977 nm. Its output power reaches 4 mW and the lasing linewidth is less than 8 MHz (instrument resolution limited) at free wavelength of 1052.5 nm. Up to 20.4 nm(1036.1-1056.5 nm) continuous tuning is demonstrated from this DBR fiber laser operating in single longitudinal mode using a simple beam bending tuning technique for axial extension and compression. Over the full tuning range, threshold pump power and slope efficiency vary with laser wavelength.

The polarization properties of photonic crystals were studied. Using transfer matrix method deduced from Pendry theory, we calculate transmission spectra of S-polarization and P-polarization, PBG (photonic crystal band-gap) at base frequency with different incident angle, plots of transmission efficiency dependent on the packing rate of medium a with specific incident angle and specific frequency of incident beam.

The entropy evolution properties of field in the system of two-mode squeezing vacuum field interacting with two coupling atoms are studied by means of quantum theory. The influences of the squeezed factor of light field, initial states of an atom ,the coupling constant of two atoms and the coupling constant of atom-field on the entropy evolution properties of field is also discussed.

Hydroquinone always exists in the environment by dust. For rapidly detecting it in the atmosphere, the off-line laser mass spectrometry is used to analyze the LDI mass spectra of hydroquinone firstly. And we find 110M+ is the characteristic spectrum. Then we acquire the LDI spectra of hydroquinone aerosol by aerosol time-of-flight laser mass spectrometry. Besides, no influence of impurity NaCl to the detection of hydroquinone is found, which is useful.

A new subjective wave-front aberrometer, which measures ocular wave-front aberrations, is studied. The working principle and design project are presented. The method of three optical channels is used to design the optical system. The key technologies of multi-threading, video collecting, image processing and the control of single-chip microcontroller and stepping motors are used to realize three-dimensional real time automatic tracking of pupil. All the seven order ocular aberrations are measured with the aberrometer. The ocular aberrations are described with Zernike polynomials, two-dimensional and three-dimensional wave-front aberration maps. The formula of every order wave-front aberrations' RMS is obtained. 110 eyes of 57 patients were measured three times for clinic investigation. The difference between the gradually descending values of every wave-front aberrations' RMS was not significant (P >0.05) with SPSS software. The results show that the repeatability and accuracy of the aberrometer are good.

A novel EDFA driver based on C8051F005 SCM is introduced in detail on design and development. Driving 980 nm LD with it, the output is quite stable. And when Bi-EDF is pumped, ultra-broad band ASE spectrum is obtained. At the same time, it is testified that the driver has a favorable linearity output.

Models of the dispersion-managed soliton system with third-order dispersion periodicity variaty are designed, their effects on dispersion-managed soliton propagation are investigated. The results show, time delay of soliton versus propagation distance will linearly arise mainly, and the effects independently exist. We can obtain the mean values of effects by third-order dispersion along propagation distance. The effect of third-order dispersion can be significantly suppressed if third-order dispersion of the fiber is periodically alternated between the positive and negative regimes.

The group delay and group velocity dispersion (GVD) of the fundamental mode was proposed by derivative action on the characteristic equation directly and the influence of different index contribution of doubly clad single-mode fibers on propagation constant, group delay, group velocity dispersion and the zero dispersion wavelength were studied. The research results indicate that the optical parameters, i.e., relative index of inner clad and outer clad (R) and relative index of the core and outer clad (P), have distinct impact on propagation constant, group delay, group velocity dispersion and zero dispersion wavelength and the rules of impact vary with the parameters. These rules provide theoretical basis for designing doubly clad single-mode fibers catering for different dispersion.

Nanocrystalline silicon(nc-Si) clusters can be formed by rapid thermal annealing the hydrogenated amorphous silicon (a-Si:H)films at 600℃-620℃ for about 10 s. Characterized by micro-Raman scattering, the formed nc-Si clusters are randomly distributed in the amorphous matrix of the annealed films with their sizes in the range of 1.6-15 nm in diameter. Under high power laser irradiation, in situ nanocrystallization and subsequent nc-Si growth in the a-Si:Hfilms have been demonstrated. Based on the theory of crystal nucleation and growth, the effect temperature ramp rate on the sizes of the formed silicon particles is discussed. Under high power laser irradiation, in situ nanocrystallization and subsequent ncSi clusters are small enough for visible light emission, authors have not detected any visible photolum inescence (PL) from these nc-Si clusters before surface passivation. After electrochemical oxidization in hydrofluoric acid, however, intense red PL has been detected. Cyclic hydrofluoric oxidization and air exposure can cause subsequent blue shift in the red emission．The importance of surface passivation and quantum confinement in the visible emissions has been discussed.

It is an interested question whether MCU can drive LCD directly or not. It discussed deeply by analyzing operation principle and electric characters of LCD, demonstrating specific hardware circuit and waveform of driving signal. The idea of software design is given. It. is the conclusion that MCU can drive LCD directly in practice

In visible spectral band, we measured the BHDF of grass and man-made object similar to grass with three angular sampling intervals in principal plane. Based on the experimental data, we can draw the conclusion： when the sun zenith angle is large （〉 45°）, a interval of 20° is adequate to capture the BRDF of grass in principal plane;when the sun zenith angle is small, a less angular sampling interval in zenith angle is needed in the hot spot area. The above conclusion was not only useful to the selection of angular sampling interval in satellite multi-angle remote sensing but also to reduce experimental work.

The conversion of sensor the top of the atmosphere signals （TOAS）, to reflectivity representing land surface target characters is an important sector in remote sensing information quantification. Assuming atmosphere disturbance being excluded, because of adjacency effect among pixels, the DN value of a target pixel contain the scatter contributions of background pixels. The magnitude of the contribution is directly proportional to the background pixel reflectivity and is correlative with the distance to target pixel. According to the results of carder（1995） and Christopher（1998）, the influence of adjacency effect exceeds that of mixed pixels when the spatial resolution is greater than 250 m. Along with the increase of satellite spatial resolution and remote sensing information quantification degree, adjacency effect and its correction method are paid attention to. Recently, supported by NSFC, we have carried out a research on them. Based on radiation transfer model, the adjacency effect in a scene of Landsat5 TM data of Beijing is analyzed and corrected to comprehend the general characters of adjacency effect

The contrastive experiment of back-scattering echo and beacon angle-of-arrival fluctuation was introduced. The experiment was used to validate that whether the back-scattering angle-of-arrival fluctuation can describe the atmosphere structure of refractive index Cn^2 by method of contract. The results prove that the back-scattering angle-of-arrival fluctuation can describe the atmospheric structure of refractive index Cn^2. And some contrastive parameters were analyzed.

Based on the high resolution imaging spectrometer data of OMIS I we performed a simulative calculation from 6S. Relation between radiance at satellite level and variety of zenith observation angle was discussed and correlative error in the retrieve of surface reflectance was analyzed, simultaneously. The results show that there are spectral properties about this effect, it is sensitive in the strong scattering regions and the major absorption channels by atmosphere;On the other hand, the brightness of targets and the flight elevation decides this effect. Based on this analysis a primary correction strategy was given