In this paper, the effect of impurities in the vacuum chamber during the deposition of optical coatings on laser induced damage threshold (LIDT) of films is analysed. The quantity of impurity is tested by second ion mass spectroscopy (SIMS). By comparing the testing result, it shows that getting rid of every kinds of factors which produce impurities in the thin films is a promising way to improve the LIDT of optical coatings.

Aluminum foils were fabricated by two different methods——evaporation and extrusion moulding. Depth distribution of surface elements and chemical components were analyzed by Auger Electron Spectroscopy (AES). Also the thickness of the oxidation layer exposed in ambient with different times was measured. According to the experimental results, the oxidation layer with saturated oxidation is mainly composed of Al2O3 and its thickness is about 7.5 nm. The throretical transmittance of the foil is then modifed by the formula I=I0.exp［-μ(E).(ρd)］. For comparison, experimental measurements of the transmittance are done on the Beijing synchrotron radiation facility, which are consistent with the throretical value within a maximum difference of 11%.

Observations of free turbulence by means of small angle collective scattering with a CW argon laser (λ=0.514 μm) have been realized. It is demonstrated that the visible laser scattering is useful in studying density fluctuation with wavelengths between 0.02 mm and 0.26 mm in the atmosphere air turbulence.

A careful analysis demonstrated that when optical beams propagated with the wave vector parallel to the some orientations in biaxial crystals, they would not exhibit the first-order thermal-induced static phase retardation. These orientations were now called NTSPR directions of the crystals. In this paper, taking some approximations, we theoretically founded the NTSPR directions in KNbO3 and KTP crystals, with the help of the relative data from the literature. Also, the EO figure of merits at these NTSPR directions in KNbO3, KTP crystals is discussed. The calculations implied that with the large EO figure of merits at these NTSPR directions in some biaxial crystals, the novel single-crystal EO switches would have short propagation length and need not to be temperature-controlled compared to EO switches of traditional structure.

In this paper, the relationships between the device reliability and the electrical derivative curves and the electrical derivative parameters of oxide stripe structure GaAs/GaAlAs high power quantum well semiconductor lasers are discussed. Then it is pointed out that the quality and the reliability of the devices can be evaluated by electrical derivative parameters (m, h, b). In short, the electrical derivative measurement can be applied to screen high-power semiconductor lasers rapidly.

In this paper, the magnetic hysteresis curves of In-BiCaVIG crystal are given. The effects of magnetic hysteresis and saturation effects on a magneto-optic fiber sensor is analyzed in detail. Magnetic hysteresis affects the phase delay mainly, and less the amplitude and frequency spectrum when the measured magnetic field signal is an alternating quantity. Magnetic saturation effects not only decrease the amplitude, but also change the frequency spectrum obviously.

Characteristics of phase-shifted fiber Bragg gratings are analyzed by coupled mode theory. A transmission type fiber filter has been made experimentally using photo-imprinting.

A General discrimination function used to classify 3-D objects is proposed in this paper. The computer simulation shows that the general discriminal function which is constructed by RBF function is very effective for classifying 3-D objects. It has not only short learning time but also short classifying time when the information is processed parallelly in the system. An optoelectronics system is proposed to implement this general discrimination function.

Employing a liquid crystal modulator and CCD camera, a phase-sensitive images system has been investigated experimentally for various fluorescence lifetimes. The images have been obtained with the time resolution up to sub-millisecond.

This paper describes a fly′s eye homogenizer for excimer laser micromachining. It has high performance in averaging the strong intensity fluctuations of the incident excimer laser beam and low transmitting loss. The dimension of the output beam can be adjusted continuously.

The concepts of laser beam permeability and absorbed line density are proposed. A theoretical model is esdablished. The beam permeability and the absorbed line density of laser energy were determined by means of metallography. The theoretical and experimental results coincide well with each other quantitatively and are consistent in reflecting the objective reality of the process. A reasonable explanation on why a maximum is observed in the relationship between the effective powder feeding rate and the scanning speed is presented.

By combining a digital counting processing method and the computer sampling technique, a real-time signal processing system is realized to construct a laser sweeping technique (LST) with real-time ability to measure the instantaneous closing velocity of mechanical heart valve prosthesis. After a brief review of LST, the effect of the positions of the collimating lens and the moving grid on the measurement results is analyzed. A practical grid construction is presented, and the principle and the construction of the signal processor are discussed in detail. The statistical behavior of MHV closure can be drawn out from real-time realization of instantaneous closing velocity obtained by using the new laser diagnostic system. The system has been used for the diagnostic of leaflet closing velocity of a monoleaflet type MHV, and the experimental results are given.

A high efficient diode laser pumped Nd:YVO4 1.34 μm laser is reported. The maximum output power of 2.27 W at 1.34 μm is obtained under the pump power of 6.6 W, the optical-to-optical conversion efficiency is up to 34.4%. Using a KTP crystal as the intracavity frequency doubler, a 70 mW, 0.67 μm red light at the pump power of 4.1 W is obtained.

For quantum structure lasers, including quantum well, quantum wire and quantum box lasers, a simple method is presented to obtain the optimized structure of the active region for low threshold condition. A logarithmic description is used to describe the relationship between the material gain and the injected carrier density. Taking the InGaAs(P)/InP quantum-well laser and the InAs/GaAs self-assembled quantum box laser as examples, the optimal condition to obtain the lowest threshold current is provided, including the number of quantum wells, the area density of quantum boxes, and the cavity length.

The multiphoton ionization (MPI) efficiencies and laser power indexes versus laser powers of different laser beam′s spatial and temporal structures were calculated for the three-level systems. The results were compared with those of the square wave approach. Based on the comparison, it was found that the laser beam′s temporal structure and spatial structure in the lower laser power region have very little effect on the laser power index, but the laser beam′s spatial structure exerts great influence on the multiphoton ionization processes in the higher laser power range. This analysis was supported by the experimental results.

A theoretical model of wavelength conversion based on cross-gain saturation in a semiconductor optical amplifier (SOA) has been established. The wavelength conversion characteristics under the small-signal modulation and the converted waveform distortion under the large-signal modulation are discussed respectively. The results show that the SOA carrier lifetime is the main factor that produces converted waveform distortion.

It analyzes the interaction of a double-mode stationary field with a 3-level atom in the quantum cavity. The condition of trapping of the atom is discussed. The influence on trapping of the atom of overlapping of states, which occurs in the case when the photon number is large, is also presented.

Two He-Ne lasers in the far field acted as simulated light sources carried out self-pumped phase conjugation in BaTiO3:Ce crystal. By studying the changes of their conjugate intensity, especially the response time differences of their grating build-up with different incident light intensities, it was found that the conjugate light produced by the non-single intensity distribution light in far field can be separated in time sequence. With these specific properties, the problem of how to make the beacon light on a uncooperative target become a light spot used for an adaptive optical system may be dealt with tentatively.

The ultrafast modulation spectroscopy of a four-level system (UMSFS) has been studied in which the linewidths of the pump beams are either narrow or broad and it was found that for both cases a Doppler-free precision in the measurement of the energy-level difference can be achieved. In the condition that a beating occurs, the energy-level difference could exceed the laser linewidth, and the measurement accuracy could reach the same order of magnitude as the laser linewidth.

Based on Huygens-Fresnel diffraction integral, an expression describing the focused field of Gaussian beams focused by a lens with spherical aberration is derived. The numerical results show that when the coefficient of the spherical aberration is negative, one can get subdiffraction-limited focusing, that is, one can achieve a smaller focused beam radius than that of no spherical aberration (SA) cases. The larger the coefficient of negative SA, the smaller the focused beam radius. On the contrary, when a Gaussian beam is focused by lenses with positive SA, the focused beam radius is larger than that of no-SA cases. And, the larger coefficient of positive SA, the larger the focused beam radius. The effect of the SA coefficient on the positions where the axial focused intensity is maximum (best focal point) is also discussed.

Dye-doped and SiO2-based blue band solid laser materials were synthesized by the sol-gel technique. With a 308 nm XeCl laser as the pump source, the laser output at 440 nm wavelength was obtained from the materials under transverse pumping. In the case of 7 mJ pump energy, the derived blue laser energy can be up to 0.38 mJ.