In this paper, a testing system for groove geometry of CD R substrates by measuring diffraction orders is introduced. This testing is of particular importance in CD R disc manufacture process because the results fed back from the testing can be used to help optimize recording, developing, metalizing, electroplating and replicating processes. Even if the width and depth of groove are not accurately obtained by this system, it is also valuable in CD R disc manufacturing process because the system, which can be used to judge the quality of substrates, is simple, sensitive, quick and non destructive. The results of a same sample tested by our system and an AFM microscope are presented simultaneously.

It is suggested in this paper that the simple beam and the cantilever beam used for tuning FBG will make the FBG chirping. A novel tuning method utilizing the beam under pure bending is introduced. It is proved experimentally and theoretically that this new method will tune the Bragg wavelength without chirp. The FBG external cavity semiconductor laser using this new method has achieved the tuning wavelength of ±1 nm continuously and steadily.

A novel fiber electro optic phase modulator has been fabricated with the thermal poling of polarization maintaining fiber. A PANDA polarization maintaining fiber polished and deposited with micro strip electrode was poled as applied DC 3000 V voltage on its both sides at temperature 280 ℃. The electro optic coefficient of the electro optic phase modulator is 0.47±0.05 pm/V. Because built from polarization maintaining fiber, the phase modulator may be used in all fiber device based on fiber interferometer with polarization stability.

In this paper, the time delay of input optical pulses after passing through Fabry Perot filters has been investigated theoretically in detail. The results show that the time delay depends on the input pulse width. Also, the difference between the central frequency of the input pulse and the resonant frequence of the filter has intense influence on the time delay.

The laser of Nd:YAP at 1341.4 nm transferred by fiber has not only coagulation and vaporization in tissue, but also weaker penetrability than that of the laser at 1064 nm, so it has high safety. By using the Nd:YAP laser with endoscope to treat 45 patients with gastroenteric hyper plasic diseases, the results showed that the laser of Nd:YAP at 1341.4 nm is a suitable laser for cavum organs by endoscope.

The true image that can be used for recording microscopic objects in digital holography is improved by elimination of zero order image with a digital way. The processing is done by mathematical methods without phase modulator or any other extra equipment. The basic principle and the verifying experiment are described too.

A laser based technique is proposed which is able to measure and supervise the mass concentration and particle size of smoke and dust in emissions. It is characterized by fast, non contact, on line and continuous measurements and gives a direct results of mass concentration in mg/m 3. Experimental studies proved that the proposed method is correct in principle and accurete in the measurements.

In this paper author describes the result of an experiment which illustrates the effect of laser beam incident angle on laser cutting quality. The experiemnt shows the possibility to get a satisfying cutting quality with the non vertical laser beam to work piece surface. This is quite different from the traditional ideas which the laser beam must be vertical to work piece surface for laser cutting. In three dimensional laser cutting author gives the way to obtain good cutting quality when the laser beam is not vertical to work piece surface.

The effects of curvature radius(pipe diameter) and laser beam diameter on the initial instantaneous absorptivity of laser cutting for 304 stainless steel pipe and plate were investigated theoretically. The theoretical analysis showed that the pipe diameter D and the laser beam diameter d had important effect on the initial instantaneous absorptivity of laser cutting as the ratio of d to D is bigger than 0 866, and the initial instantaneous absorptivity of laser cutting increases with the pipe diameter (curvature radius) decreases or the laser beam diameter increases.

Surface crack of steel components was repaired with two bundle of laser. There was an obvious joined band between filled region and substrate of component. The microstructures of repaired region were adnate cellular crystal, dendrite crystal, and needleshaped crystal. The phases of dendrite crystal in repaired region were consisted of γ Ni which contained plenty of Cu, Fe. The phases in the gaps among dendrite crystals wereγ Ni, NiSi 2, Cr 3Ni 2, CrSi. The hardness of filled layer in repaired region were HV 0.2 400～HV 0.2 450, then the hardness values decreased from the surface to transition region.

In this paper, the influence of surfacing technology and material on the quality of light beam Ni based alloy powder surfacing layer was investigated. In order to acquire surfacing layer of quality, the width of pre coating must be smaller than that of light spot. Too big thickness of pre coating can result in the poor bond between surfacing layer and base metal. While the pre coating is too thin, the macrohardness of surfacing layer decreases obviously owing to high dilution of base metal. By means of multi layer and multi pass lap surfacing, the surfacing layer with big thickness and area can be acquired. The transverse crack in surfacing layer, porosity in bead edge and non fusion between layers are the defects that are liable to produce when multi layer surfacing is used. When multi pass lap surfacing is used, non lap in the toe of weld can arise because of selected moisture. The reasonable control of heat input, cleaning of former weld and good protection of molten pool are the crucial factors of acquiring surfacing layer with big thickness and area. When adding wettable ceramics (WC with Ni coating) with Ni-based alloy and controlling the content of WC with Ni coating, the high quality of surfacing layer with higher hardness can be acquired.

The experimental results of the thermal recovery of the wavefront distortion using the single segment amplifier (SSA) test bed and the Hatamann wavefront sensor are reported. The results indicate that the largest values of peak to valley and RMS of the optical wavefront are 1.1λ and 0.13λ (λ=632.8 nm), respectively. The experimental results agree well with the numerical simulations.

A new method to improve laser beam quality by using intracavity phase modulation is presented. The phase modulation is fulfilled by LiNbO 3 electro optic crystal driven by high voltage. The laser used is CW Nd:YAG solid state laser pumped by Krypton lamps. The experimental results show that intracavity phase modulation can transfer effectively the laser oscillation mode from multi mode to fundamental mode like beam with smooth intensity profile.

Using the mode selection property of the etalon inserted inside the laser resonator a LD pumped single frequency and intracavity frequency doubled CW Nd:YVO 4/KTP laser with fold cavity has been designed and experimentally studied. The maximum single frequency green output power of about 40 mW was obtained at the LD pumping power of 1.5 W. The maximum tunable frequency range for green light is about 200 GHz.

Output characteristics of laser diode pumped Nd:YVO4 plane parallel cavity laser at different thermal lenses are researched. The dips in the output power curves are found and analyzed. The effects of thermal lens effect and resonator lengths on the output characteristics are put forward.

The non collinear optic parametric amplification using BBO crystal with type Ⅰ phase matched geometry is investigated theoretically. For the certain pump wavelength and signal wavelength, it is indicated that the non collinear incident angle exists with the maximum gain bandwidth and the higher gain. The temperature also effects the gain spectrum partly. The theoretical analysis is useful to optimize the optic parametric amplification of the short pulse.

The traditional slowly varying envelope method can′t be used for propagation of femtosecond pulse with duration of several optical oscillation periods. By simplifying the electric field's wave equation with unidirectional wave approximation and incorporating the material equation the propagation equation of electric field of such extremely short optical pulse can be attained. With this method the new propagation equation of extremely short optical pulse with arbitrary polarization state in isotropic medium has been presented. The interaction between two polarization parts has also been studied numerically.

Some features of the closed aperture Z-scan transmittance curves of nonlinear optical materials with Gaussian beam have been studied theoretically when the nonlinear refraction and the nonlinear absorption coexist. It is found that the peak valley or valley peak structure depends on the ratio ρ of the real part to the imaginary part of the third order nonlinear susceptibility. The exact critical value ρc, which determines whether the peak valley or valley peak structure exists or not, is given; the ρ dependences of some parameters of the transmittance curves are obtained numerically, and the scope of applications for the results is also discussed. The Z-scan experiment of CS 2 is consistent with the theoretical results obtained here.

Based on the transform of phase aberrations in third harmonic generation, the focusing properties of third harmonic beam with nonlinear crystals having periodic surface ripples were theoretically investigated. A diffraction model has been developed, which can analytically calculate the intensity and angular distributions of multi diffraction orders. It provides the design criteria for the third harmonic generation of high energy laser drivers.

The spontaneous emission is studied with non rotating wave approximation in a three level atom embedded in a photonic band gap structure (PBGS). And the edge of the gap is not located at the center of the two upper levels. Intense quantum interference occurs between the virtual and real photons with a set of suitable parameters. A new localized field is found in the spontaneous emission field, while the atom is partly trapped in the upper levels.

A novel method of all optical subharmonic frequency clock extraction at 2.5 GHz and group clock extraction at 5GHz and 10GHz is demonstrated from 4×2.5 GHz unequal amplitude sequence multiplexed OTDM signals that include dark frame pulses. The dark frame pulses used in OTDM signals can not only be used for data recognition, but also improve the quality of extracted optical clock.

The investigation on the characteristics of L Band erbium doped fiber is reported. At the optimum population inversion level (N=0.39), the flattened amplification bandwidth of 22 nm(±0.5 dB) and linear relation between pump power and signal power were demonstrated theoretically and experimentally. Small signal gain of 33 dB was achieved at 1572 nm.

Application of interleaver in DWDM fiber communication system is introduced. By means of birefringence crystal plate and polarization beam interference, principle of birefringence crystal type interleaver is analyzed. It is mentioned that a hybrid structure of birefringence crystal type interleaver and film filter is applied in DWDM fiber communication system.

The Raman gain coefficients of TrueWave TM , DCF and DSF fibers, which are pumped by 1480 nm LD are Measured and compared. Because these distributed fiber Raman amplifiers are usually wanted as the pre amplifiers of optical receiver, the noise figures of the fiber Raman amplifier are measured and calculated.

After getting rid of the interference of RF, automatically rotation speed controlled layer thickness is realized, which not only can accurately fabricate ultra thin multilayers, but also can record the thickness of every layer and automatically change rotation speed and automatically stop rotation after fabrication is over. Compared with the rotation speed controlled layer thickness monitoring, it′s useful to reduce the intensity of labor and improve the rate of finished products. The advantage is especially obvious in fabricating complicated multilayers.