A novel technique for the simultaneous generation of bright and dark soliton trains from continuous wave (CW) light is proposed and demonstrated numerically. It is based on the optical switching characteristics of a nonlinear optical loop mirror (NOLM) through which the CW signal is switched by a pump pulse train at another wavelength by the creation of cross phase modulation induced phase bias between the counter propagating CW components. The transmitted and reflected signals exiting from the NOLM can then evolve, respectively, into bright and dark soliton trains in fibers with the appropriate group velocity dispersion at the signal wavelength. Numerical simulations indicate that the generated solitons can be narrower than the pump pulse and that the repetition rate of the soliton trains can be higher than that of the pump pulses. Moreover, this technique permits the conversion of nearly all of the CW energy into the soliton train energy without generating pulse pedestals.

The Yb 3+ doped double clad silica fibers with rectangular and other novel inner cladding have been made by using modified chemical vapor deposition process, solution doping and optical machining altogether. The operation of these cladding pumped fiber lasers is demonstrated. The maximal laser output of rectangular fiber laser is 84 mW at the wavelength 1075.6 nm, and a slope efficiency of 77% has been achieved.

By using a beam of uniform strength, bi directional chirp free tuning of center wavelengths of the fiber grating is realized, and the tuning range up to 12.52 nm is obtained. The experimental results accord well with the theoretical analyses. The beam of uniform strength is simple in configuration, low cost and is easy to be operated. It has been used in our homemade tunable fiber lasers, sensors and add/drop multiplexers etc..

The measurement of optical signal noise ratio (OSNR) degradation of optical network elements is analyzed theoretically and experimentally. The formula denoting the difference of OSNR detected at input port and output port of the element is derived. Theoretical results show that the difference can not reflect the effect of the element on signal in optical domain under general condition, and can not be taken generally as OSNR degradation for evaluation in the element until the element system meets the demands of condition C=1 given in the paper. Experimental results support the theory and show that for an optical network element with OSNR degradation of 4.5 dB at C=1, when C decreases from 3 to 0.16, the difference of OSNR detected at its input port and output port varies from 1.8 dB to 11.3 dB.

Optical image reconstruction of absorption distribution by use of differential time resolved measurements from a 32 channel optical tomography system is reported for two cylindrical phantoms which have optical properties in the range of these expected for living tissue. Images with different heterogeneity locations, sizes, and absorption coefficients have been achieved with good qualities. Simulated and experimental reconstructions show that the 2 D, semi 3 D algorithms are effective. Two heterogeneitis which are 20 mm apart are distinguished more clearly by using mean time as the data type from 32 channel measurement than that by using intensity as data type or from 16 channel measurement. Results suggest that qualitative images can be achieved in terms of heterogeneities locations, sizes, and the change of absorption from this system. Some of the existing problems associated with the multi channel time resolved system are discussed.

With four step phase shifting method the 3 D surface profile of a coin was measured using sinusoidal fringe projection produced by a liquid crystal display (LCD) projector. The phase unwrapping problems are discussed. A new method for detection of the phase discontinuity area and a new technique for phase unwrapping are presented. The experimental results are given.

The high frequency double modulation and lock in technique was attached to the normal Fourier transform infrared spectrometer to eliminate the huge influences of the room temperature background blackbody emission on the measurement of the infrared photoluminescence spectra. The experimental method was optimized by adjusting the modulation frequency, choosing the suitable band pass filter and phase correction. The photoluminescence spectra in 10 μm long wave infrared band without the influences of the background blackbody emission were obtained.

The method to realize a beacon of small area on an uncooperative and extended target by using stimulated Brillouin scattering (SBS) threshold effect is presented. The process of laser propagation through 10km atmospheric path with SBS is simulated in cases of different atmospheric turbulence (C 2 n=10 -16 ～10 -12 ). The distribution of the phase conjugate light on the target was obtained from the simulation. The experiments of laser propagation with SBS are made in cases of different environments. The maximum distance is 250 m. The results indicate the laser propagation with SBS effect and the method to realize the beacon of small area on the target are feasible.

A new ionization model based on the interaction of ultrashort, ultrahigh intensity laser with atoms pondermotive is proposed. It is possible to generate an extremely non equilibrium plasma by this novel ionization mechanism.

A kind of double disk gold targets were irradiated by 0.35 μm intense laser at "XINGGUANG Ⅱ" laser facilities and X ray spectra emitted from primary and secondary disk were measured by two soft X ray spectrometers. The properties of X ray spectra modified on secondary disk were investigated. The experimental results were physically analyzed and showed that the X ray spectra emitted from secondary are softened. An X ray streak camera was used to obtain time spatial images emitted from laser plama of double disks targets. The streaking images indicated that collision of plasmas produced by primary and secondary disks occurred because the short distance between double disks.

A stable mode locked fiber ring laser with large dispersion cavity is demonstrated. In this laser, the instability caused by cavity length excursion is suppressed. At the same time, the super mode noise is suppressed too. A 10 GHz mode locked erbium doped fiber ring laser using a large dispersion cavity developed, in which the pulse repetition rate is 10 GHz with sech 2 profile, the pulse width (FWHM) measured by autocorrelation meter is 7.6 ps, and the time bandwidth product is approximately 0.335.

Several pulse compressing techniques of 10 GHz gain switch semiconductor laser output pulses are stuided via methods of theoretical analysis, numerical simulation and experiment. A novel three stage compressing technique is proposed which includes 1) compensation by normal dispersion fiber, 2) compressing by normal dispersion fiber followed by anomalous dispersion fiber, 3) compressing by comb like dispersion profile fiber (CDPF). In this experiment, the compressed pulse width of 2.8 ps is obtained and the total compressing factor is 9. This technique is important for implementation of 80 Gb/s optical time domain multiplexing system.

Based on the steady state master equation of actively mode locked fiber ring laser, the relationship between pulse parameters and the cavity parameters including gain, gain dispersion of Er doped fiber, filtering of band pass filter, modulation effect of amplitude modulator, GVD and SPM of single mode fiber is investigated theoretically and numerically. The conditions for generating transform limited soliton pulses is analyzed.

Tunable amplitude squeezed light is experimentally generated at low temperature (80 K) in a laser diode with light injection locking from Ti:sapphire laser. The amplitude squeezing of the output light from the laser diode can be obtained at 1.1 dB (lower than shot noise limit) throughout a tunable range 13 GHz. The amplitude squeezed light generated by injection locking is compared with that by external grating feedback.

The electronic structure of Ce:YIG is calculated by using DV Xα (discrete variational Xα)method. The results indicate that the couple orbits among 5d, 4f, and 3d orbits are existent because of the substitution of Ce 3+ ion. The couple orbits have large spin orbit interaction. The results also show that there are electronic transitions Fe 3+ (3d) →Ce 3+ (4f) that may be the origin of transition centers of 1.5 eV and 2.1 eV shown the large optical absorption. The density of transition center is proportional to cerium content. The optical absorption spectra of Y 3-x Ce x Fe 5O 8 on x=0, 0.3, 0.7, 1.0, 2.0 are calculated between 1.0 eV～3.2 eV. The calculated results are consistent with experimental data.

With a broadband mutilmode electro optically Q switched Cr:LiSAF laser pulse passing through several dispersion prisms, its frequency band is dispersed. Then by focuing it into CS 2 cell the backward stimulated Brillouin scattering is produced. Experimental results show that in comparison with case of no-dispersing prism frequency band dispersing method can efficiently reduce the broadband SBS energy threshold, raise pulsewidth compression ratio by more than 5 times, and improve beam quality of pump light.

Nonlinear evolution of filaments is investigated by taking into consideration of the energy exchange between background and modulational field. It is found that a modulated beam may experience a periodical filamentation. Bespalov Talanov (B T) theory gave the same results of the fastest growing frequency and the cutoff frequency as the nonlinear theory; but a different result of the fastest growth rate. Initially, the modulations grow exponentially, and afterwards, they grow slower than exponential.

Applying the scalar diffraction theory, the problems of energy transmission have been studied. The transmission coefficient as well as the energy flux density vector on the axis has been calculated. For the diffraction of a small aperture, above problems have been discussed by the vector diffraction theory.

Based on couple modes theory and acoustic optic effect, a monolithic single mode fiber acousto optic intensity modulation based on fused taper coupler is demonstrated at a wavelength of 1310 nm. About 64% modulation was achieved at a modulation frequency of 20.19 kHz, for an electrical drive power of about 2.6 mW.

The teleportation of an unknown quantum state from one observer to another is of great importance in quantum information. A scheme is presented for the teleportation of an unknown atomic state through the Raman interaction of V type three level atom with a coherent state cavity field of large amplitude.

Fourier transform profilometry (FTP) is used for dynamic liquid surface shape measurement. A sequence of dynamic deformed fringe images can be grabbed by CCD camera and saved on disk rapidly. By Fourier transform, filtering, inverse Fourier transform and unwrapping these phase maps in 3 D phase space, the shape of a vortex at different times is obtained. The experimental results show that FTP can efficiently deal with the dynamic liquid surface shape measurement.

A rapid and accurate model used to study microscopic imaging through turbid medium is presented which combines traditional Monte Carlo with two dimensional point spread function (PSF). The research shows that the rapid model is much faster than a pure Monte Carlo method with the help of convolution operation, when it is used to simulate multi photon excitation (MPE) fluorescence scanning microscopic imaging through turbid medium. Besides, one run instance illustrates that higher transverse resolution can be obtained in imaging through turbid medium by MPE than by confocal fluorescence microscopy.

A novel tunable distributed Bragg reflection (DBR) laser using metal coated fiber Bragg grating as the external cavity was demonstrated. It realized single mode output with narrow line width and high side mode suppression ratio (SMSR). By tuning electrical current of the metal tube coating the fiber grating, wavelength switches among six wavelengths spanning 5 nm were achieved.

High power quasi CW diode laser pumped acoustic optically Q switched intracavity frequency doubled Nd:YAG and Nd:YVO 4 laser are demonstrated. Average power of 3.5 W and 3.2 W at 532 nm with a repetition rate of 22 kHz was generated respectively.

The InGaN/GaN films were grown on (0001) sapphire substrates by metalorganic chemical vapor deposition (MOCVD) at atmospheric pressure. Properties of these films were investigated by Rutherford backscattering/channeling measurements and photoluminescence technique. The study indicated that there was an optimum TMIn/TEGa ratio to obtain high In mole fraction In x Ga 1-x N films. The In mole fraction in In x Ga 1-x N films will increase by decreasing the TMIn/TEGa ratio in some range. Surface minimum yields χ min of In x Ga 1-x N films changed from 4.1% to 11.0% when the x value of In x Ga 1-x N varied from 0.04 to 0.10.

Amorphous selenium alloy (a Se alloy) is currently of great interest as X ray imaging receptor due to its high resolution. The a Se alloy films are deposited by vacuum evaporation, the transport properties of hole and electron are measured by time of flight technique. Some factors, which affect the properties of a Se alloy film, are discussed. X ray photocurrent is measured by using 400μm thick film. The results show that linear photoelectric conversion existed in a Se alloy film, and its sensitivity to X ray irradiation depends on electric field. The calculation indicates that about 45 eV is needed for X ray to release an electric hole pair in a Se alloy film at 10 V/μm electric field.