Employing a grating-external-cavity diode laser (ECDL) as laser source, the modulation transfer spectrum (MTS) of cesium D 2 line (6 2S 1/2 F=4→6 2P 3/2 F′=3,4,5) is obtained. Instead of using a electro-optical modulator (EOM), a directly frequency modulation to an acousto-optical modulator (AOM) in MTS device is adopted, which more or less simplifies the spectroscopic device. Under different modulation frequencies the character of MTS is investigated experimentally.

The switch-losses of one Q-switch, two Q-switches in acousto-field perpendicular or parallel are analyzed. According to the theory of acousto-optic (AO) interaction, the formulas of diffraction loss of two AO Q-switches, which acousto-field are perpendicular or parallel one another, in Raman-Nath diffraction are derived. The power divider for ensuring two AO Q-switch synchronization and effective power driving is designed. The calculation results are satisfied with Nd∶YAG laser experimental results. It is shown that two AO Q-switches, which acousto-field are perpendicular each other, switch-loss is nearly three times large than one AO Q-switch, one time large than the two AO Q-switches which acousto-field are parallel.

In order to gain uniform intensity from a high-power and high-gain CO 2 laser, an time-average approach is proposed. By periodic change of curvature of concave mirror, the modes of beams transform with time. Thus the average out at intensity profile with good uniformity is obtained.

In this paper, the distribution of two-dimensional scattering field of infinite cylinder illuminated by a plane-wave is derived, the interaction equation between cylinder-samples and sphere-probe is obtained, and the resolution of two parallel cylinder samples and simple grating is calculated. The result shows that the best resolution exists in the case of two-dimension field,and the offset of far-field component to near-field component still plays a role.

Imitated the optical system of Rowland circle structure, the Rowland sphere structure is built in this paper, the Rayleigh-Sommerfeld diffraction scalar integral formula of electromagnetic wave is simplified on the Rowland sphere structure, the computational formulas of spatial frequency spectrum and diffractional far field distribution from the weakly guiding optical fiber LP mode are derived. The concept of central disc in LP 01 mode optical fiber diffractional far field, which had analogy to the Airy disc of plane wave Fraunhofer diffraction from circular aperture, is presented, and the calculational formulas of LP 01 mode optical fiber diffractional far field divergence half width is deduced in the end of this paper.

Based on the theory of the human′s binocular vision, the information content of 3D object, its hologram and their relationships have been studied. The particular computing method and its result have been figured out. So the theoretical foundation and compression way have been offered for the hologram compression.

Photoluminescence (PL) was observed from GaAs/AlGaAs quantum wells structure excited by mid-infrared free electron laser (FEL) irradiation. The experimental results showed that the characteristic PL peak of quantum wells was shifted to longer wavelength (red shift) and the intensity was decreased much after FEL irradiation. The results are discussed and compared with that of electron irradiation.

In order to obtain the self-lubricating and antiwear composite coating with high hardness for tribological metal surfaces, especially for line—or point-contact surfaces, the technique and microstructure of the laser alloying coating of Si 3N 4/graphite composite materials on 45 # carbon steel, and the interface between the coating and substrate are studied. The distribution and content of the elements in the alloyed coating are examined and analyzed with OM, SEM and EDS, and the micro-hardness along the depth is measured. Results show that silicon nitride in the coating decomposes completely during laser scanning, but Fe, Co, Si and C distribute evenly on the cross section and the content of C reaches 15.69%. The existing form of most C is graphite, which has self-lubricating property. At the same time, the surface micro-hardness has been improved by solid solution mechanism of Si-Fe, Co-Fe and martensite.

Many experiments illustrate that He-Ne laser is unfit for the laser induced liquid-phase deposition technique. And CO 2 laser, whose output laser wavelength is in middle infrared, is also very difficult to achieve liquid-phase local deposition of metal on the right side of the substrate by the conventional methods. A novel method has been introduced in this text. The local deposition of metal copper lines on the right sides of epoxy resin has been achieved from the aqueous solution by CO 2 laser induced liquid-phase deposition technique. Meanwhile, effect of several experimental conditions on the deposition rate of copper line has been simply studied.

The Simulation and experimental results of single segment amplifier (SSA) used in high power laser system are introduced in this paper. By optimizing the pumping constructs of SSA, about 4.9%cm -1 small signal gain efficiency and 2.4% storage energy efficiency have been obtained when working voltage is about 22 kV. At the same time, the thermal distortion and wavefront changing are investigated, the changing of cleanliness in pump cavity is measured.

Pico-second gain and refractive index nonlinearities in semiconductor optical amplifiers (SOAs) were simulated using a multi-section model from the start of the rate equation. Carrier density variation induced by pulse injection, aberration of the temporal profile of the output pulse, gain and phase change induced by pulse injection, and frequency chirp on the output pulse were analyzed.

In this paper, a new way is provided to select single-longitudinal mode pulse using Q-swithed method on the decent shape of Nd∶YAG fluorescent radiation pumped with xenon lamp. A steady laser pulses are achieved which the ratios of the single-longitudinal-mode are 100%, and the output energies reach mJ with the pulse width about 18 ns. Moreover, when it is used as the source of MOPA system, a satisfied result is obtained.

A group of equations deduced from TDFA (thulium-doped fiber amplifier) rate equations and light propagation equations, introducing the overlapping factors between the (pump and signal) light intensities and the thulium dopant distributions inside the fiber core, is presented in this paper. Using the group of equations, the gain characteristics of the amplifier are calculated.

The revulsion of resonator losses during converting from the starting to the SBS phase-conjugation is carefully analyzed. Based on rate equation theory and quick Q-switching characteristic, the self-Q-switching mechanism of SBS phase-conjugation laser resonator is discussed, and a formula for estimating the Q-switching pulsewidth is given.

The principal refractive indices and the thermal refractive index coefficients for Cr 3+∶Be 3Al 2Si 6O 18 crystal dopted with 1 01 wt.-% Cr 2O 3 have been accurately measured by the auto-collimation method at the wavelengths of 0 488 μm, 0 53975 μm, 1 0795 μm and 1 3414 μm, and at the temperature of 308 2 K, 328 6 K, 359 1 K and 395 4 K, respectively. The sellmeier′s equations and the thermal refractive index coefficients were obtained, and the result was certified to be accurate by error analysis.

The Er 3+-doped and Er 3+/Yb 3+-codoped tungsten-tellurite glasses were prepared. The absorption spectra, 1.5 μm emission spectra and fluorescence lifetime of Er 3+ excited at 970 nm, were measured. The absorption and emission cross-sections were calculated. The dependence of Yb 3+ concentration upon 1.5 μm emission intensity and bandwidth of Er 3+ were investigated. Yb 3+-codoping can improve the 1.5 μm emission intensity of Er 3+ effectively and increase its FWHM. The optimum Yb 3+ concentration was 3.66×10 20 ions/cm 3 and a broad 1.5 μm emission spectrum of 81nm FWHM was demonstrated.

This paper introduces the principle of the color 3D laser scanning measurement. The light-plane-equation mathematical model of spatial 3D coordinates is derived. Optimum design for structure parameters of the measuring system is presented, experiments on the optimization of structure parameters were performed, and the structure parameters are confirmed to be the optimum from the experiment results analysis. The measurement error of the system, established on these optimum structure parameters, is less than 0.1 mm in measurement range of 250 mm×200 mm×50 mm.

The study result shows that in open resonant lower-ladder and V systems, the destabilization of the nonlasing solution can occur through a Pitchfork bifurcation giving rise to continuous wave lasing without inversion (LWI), and also through a Hopf bifurcation giving rise to self-pulsing LWI. This paper also analyzes the effect of the unsaturated gain parameter, damping rate of cavity , ratio of the atomic injection rates and atomic exit rate on the two instabilities.

The Stimulated Raman Scattering (SRS) in H 2 pumped by the third harmonic of Nd∶YAG laser (355 nm) was investigated. The wavelength of pump laser has been shifted into 204～867 nm wavelength region. When the pump laser was operated at laser energy of 70 mJ, four orders of Stokes and five orders of anti-Stokes have been observed in this experiment. The corresponding output energy of the first order Stokes (416 nm), the second order Stokes (503 nm) and the first order anti-Stokes (309 nm) was 28.7 mJ, 16 mJ and 3 mJ, respectively. The relationships between the pressure of H 2 and energy of each Stokes were investigated. Moreover, the circle beam spot and phenomena of pulse-width compressed have been observed.

A model for the treatment of amplified spontaneous emission (ASE) noise in semiconductor optical amplifiers (SOA) in the case of ultra-short pulse injected into SOA by taking not only interband effects but also intraband effects, such as carrier heating, spectral hole burning, two-photon absorption and ultrafast nonlinear refraction is proposed. The influence of ASE on the performance of terahertz optical asymmetric demultiplexers (TOAD) is also discussed. Numerical results show that the edge of switching window of a TOAD device becomes sharper and the over-shoot peak in the tailing edge of switching window becomes more obvious when the ASE noise is considered. Results also show that the signal noise ratio (SNR) of output signal of TOAD is larger than 25 dB when it is in the turn-on state.

In this paper, an atmospheric optical wireless communication system based on Turbo code is introduced and investigated. Based on analysis on losses and noises of optical wireless system, characterizations of the optical wireless communication system based on Turbo code are presented with simulations. Compared with uncoded system, the Turbo-coded optical wireless system improves the performance of optical wireless link because Turbo code compensates losses and noises of link and improves jamming-rejection capability of system.