Experimental research shows that laser induced damage thresholds (LIDT) are strongly dependent on the beam radius. The thermo-elastic model describing the interaction of CW laser with uniform optical materials is established, and material response and structure response are studied independently. Study shows that spot size effect in material response results from the energy loss of the irradiated area. As for structure response, different mechanical boundaries result in different relationships of LIDT with radius of laser beam.

The formulation for analysing mode behavior in photonic crystal fiber is simplified, and the dispersion relations in photonic crystal fiber of hexagonal lattice are calculated. The dispersion relations in different air post radii are compared. It is found that the mode index decrease, and the wavelength of zero dispersion shifts toward long wavelength with the increase of the air post radius.

The estimation formula of transmission bandwidth of WDM system using optical phase conjugator (OPC) at the midpoint of standard fiber link for dispersion compensation is derived and verified by numerical simulation. The OPC is asymmetrically accessed in the fiber link to improve transmission bandwidth and the estimation formula of transmission bandwidth affected by OPC accessing position is derived. The results of both estimation and numerical simulation show that the transmission bandwidth of WDM system with OPC at the optimum position is increased nearly by one time as compared to that of WDM system with OPC at the midway.

Adopting a new design structure and using a single fiber Bragg grating, simultaneous measurement of two parameters for the torsion (torque or torsional stress) and the temperature have been realized. The new method can solve the temperature cross-sensitivity in torsional angel and torque sensing, and the Bragg wavelength change is linear to the torsional angel, the torque and torsional stress with the determinate arm of force. In the range of the torsional angle between -40° and +32°, the torsional angle, torque and temperature sensitivities are 0.19 nm/(°), 3.29 nm/Nm and 0.03 nm/℃, respectively. The wavelength range of linear tuning is up to 14.20 nm.

If a long-period grating is written in the hydrogen-loaded standard SM fiber, using the amplitude mask, the thermal stability will be decreased because of the presence of H 2, which makes it difficulty to fabricate an ideal long-period fiber grating (LPFG). It is pointed out both in aspects of theory and experiment that if the solubility of H 2 in the hydrogen-loaded fiber is lowered and using the technique of uniform UV exposure properly, the thermal stability of LPFG could be improved greatly.

The Investigation of pulse ranging signal for pulse coherent laser radar is presented. On the basis of the calculated pulse waveform of Q-switched laser, the waveform of pulse laser heterodyne and its frequency spectrum of Fourier transform reflected from scattered treflection object are studied theoretically. Experimental studies are made on reflected pulse laser heterodyne of tunable electrooptically Q-switched CO 2 laser and its frequency spectrum of Fourier transform. In addition, the objected range is calculated. The experimental results are consistent with the theoretical analyses.

The theory of broad-bandwidth high power laser system is given upon Maxwell equation. By simulation, the effect of gain-narrowing in broad-bandwidth and narrow-bandwidth high power laser system is demonstrated. In addition, a method to eliminate the distortion of amplified pulse shape, resulted from Ti:Sapphire′s asymmetric cross-section of stimulated emission, is proposed and verified by computer simulation.

A simple self-seeding scheme for generating dual-wavelength single mode picosecond pulses at a fixed repetition rate with a Fabry-Perot (F-P) laser diode is proposed. The F-P laser diode was self-seeded from two fiber gratings that act as wavelength filters. About 2 GHz dual-wavelength pulses were achieved in the cases of the length of exteral cavities corresponding to different wavelength were equal or different.

Efficient L-band (long wavelength band) fiber ring laser with tunable range of 43 nm (1567.1 nm～1610.1 nm) is demonstrated. Both high concentration Erbium-doped fiber and 1480 nm pump laser diode (LD) were used to depress the laser threshold pump power and to increase the slope efficiency. Output powers between 10.9 dBm and 12.1 dBm were achieved when 95 mW pump power was provided. And the signal-to-noise radio was better than 60 dB. A high slope efficiency of 0.201 was obtained at lasing wavelength of 1585 nm.

An experiment system of "pulsed light-continuous probe-light-continuous erasure light" is built. By using modulated Q pulse light of 532 nm and continuous probe light of different wavelengths, fast photoresponse characteristic of photocycle and photoabsorption of different intermediate based on bacteriorhodopsin (BR) film are studied. Microsecond optical switch is observed and BR molecule distributing of different intermediate is analyzed when the exciting pulse is over.

An Er 3+,Yb 3+ codoped phosphate glass laser pumped by LD is demonstrated. The slope efficiency of 10.2% was obtained, with thresholds of 118 mW. The maximum output power is 43 mW.The laser spectral range is from 1527 nm to 1533 nm.

Ba(PO3)2 was introduced to AMCSBY glass to substitute BaF 2, and some properties of glasses were studied. The substituting formula is 10MgF 2-20CaF 2-(10-x)BaF 2-10SrF 2-15YF 3-35AlF 3-x Ba(PO 3) 2(x=0,2,4,6,8). The results of differential thermal analysis on glasses show that the glass forming ability was improved greatly by introducing metaphosphate to AMCSBY glass. Transmission spectra of glasses were measured from UV to IR, and ultraviolet absorption spectra of some glasses were also measured . With metaphosphate′s being introduced, the middle infrared transmittance of glass reduced, and the IR cut wavelength shifted to short wavelength, but ultraviolet transmittance of glass increase, and the UV cut wavelength shifted to ultraviolet wave band. Influenced by PO - 3, the absorption peak of OH group moved to 3145 nm from 2830 nm.

The 5th～7th high order harmonics soft X-ray radiation with He in static gas target ranging from 40 nm to 160 nm driven by linearly-polarized 105 femtosecond Ti:sapphire laser at 795 nm are observed. The change of high-order harmonic intensity vs gas pressures is studied. The high-order harmonic intensity increases with gas pressures, but the optimal gas pressures have not been obtained considering the possible destruction to the detector under higher gas pressures.

Multiplexer/demultiplexer′s impact on optical network system is studied. 10 Gbit/s optical system′s degradation caused by optical nodes is identified. Noise distribution is assumed as a Gauss one. The transmission function of optical node is considered as a band pass function. The central region of this band pass function is always not as flat as the ideal function. It causes the degradation of system performance severely. The system penalty is 2 dB～6 dB on the condition of 0.2 dB～0.5 dB variation. Also the difference of the flaw makes discrimination of penalty. The discrimination is 1 dB～5 dB considering the amplitude and rank of variation.

A long-period fiber grating is simplified as a three-layer step-index waveguide. By using the concepts of scalar approximation and leaky-mode and the couple-mode theory, the influence of the change of ambient refractive index upon the LPG′s characteristics such as resonance wavelength and peak loss in detail is analyzed. Some useful conclusions are obtained which agree with the experimental results very well.

A new electric current sensor based on fiber Bragg grating tuned by magnetostrictive material rod is demonstrated. A fiber Bragg grating is firmly clung on a magnetostrictive rod that is put into the central part of a solenoid. The Bragg wavelength of the fiber grating will shift when the uniform magnetic field in the solenoid changes. The rod will have elastic lengthening along the direction of the magnetic field. The grating resonant wavelength of fiber grating will shift as consequence of the rod lengthening. The relationship between the electric current and the wavelength shift is basically linear. The wavelength range of linear tuning is about 0.9 nm. The electric current range of sensing is about 900 mA. The sensitivity is about 1000 mA/nm. The electric current can be accurate to 10 mA. The experimental result coincides with the theory.

A novel torsion sensor based on a long-period fiber grating (LPFG) written by high-frequency CO 2 laser pulses is demonstrated. The resonant wavelength shifts linearly toward longer wavelength as the LPFG is twisted clockwise, whereas it shifts toward linearly shorter wavelength as the LPFG is twisted anticlockwise. Such a torsion sensor can, not only measure the applied twist rate directly, but also determine the twist direction. Accordingly, this all-fiber absolute torsion sensor could find important engineering applications in the field of smart structures where the ability for the sensor to be embedded into the structure is critical.

An arrayed waveguide grating (AWG) demultiplexer with total internal reflection (TIR) mirrors is designed based on silicon-on-insulator (SOI) material. Fabrication technology is developed based on numerical simulation results of the device. The device has function of polarization compensation and characteristic of compact structure. The primary results show that the AWG can realize function of demultiplexing well.

A novel prism coupled device as an Fabry-Perot oscillating field sensor has been developed. In the proposed configuration, liquid or gaseous sample to be probed supports oscillating field in Fabry-Perot cavity, rather than evanescent field as in the conventional SPR sensors or the waveguide mode sensors. Because most energy of incident light is coupled in oscillating field, the sensor′s detection sensitivity is very high. Prototype sensor based on this approach has been successfully fabricated and tested. The detection limity for glucose solution is 10 -5 (mass fraction) in the experiments with the system.

Beam combiner is the key part of optical aperture synthesis telescope array. From the interferogram produced by beam combiner, the useful messages such as the central fringe phase and visibility can be extracted. With these messages, one can make it into reality to control the telescope status, compensate the path with delay lines, track fringes, beam parallel character feed back and fine control so as to get enough data used for closure phase calculating and image reconstruction. An initial result on the beam combiner for optical aperture synthesis telescope array is presented.

The application of polarizing beam splitter for projection display system was reviewed. A new method was described for the design of polarizing beam splitter to meet the requirement of wideband and wide incident angle acceptance. Multiple Macneille Pairs were used and multiple central wavelength for λ/4 layer stacks combination were adopted in the design. The experimental results illustrated that the method was practicable.

An improvement to the traditional Fabry-Perot tunable liquid crystal filter which makes liquid crystal as the intracavity dielectric layer is presented. Placing one polarizer on each side of the filter, and the angle between optical axis of the two paralleled polarizers and the molecular major axis of liquid crystal is 45°. The incident beam first generates multiple-beam interference, then polarized beam interference. It is concluded that the resonance wavelength is given by 2(n ∥-n ⊥)Lcosθ=mλ. So the disadvaisntage that the two spectra can′t be distinguished of the traditional Fabry-Perot tunable liquid crystal filter is overcomed. Near 1550 nm, the characteristics of this tunable filter is analysed under 1.6 V, 1.9 V, 2.3 V.

The formulae of second-order intensity moments of partially coherent beams passing through hard-edged apertures were given. The generalized propagation parameter M 2-factor of partially coherent beams was obtained. By taking a Gaussian Schell-model (GSM) beam as an example of partially coherent beam, the corresponding generalized M 2-factor was derived and the numerical calculation and analysis were made.

Functional derivation is employed to analyze the two-dimensional colored noise in the third-order laser model. The stationary intensity distribution is derived. The variation of the most probable intensity with pump parameter and noise intensity correlation time is investigated. With the shifted 1/N expansion, the instantaneous solution of the laser model, i.e., the change of eigenvalues with the pump parameter, is obtained. It is shown that the pump parameter and intensity noise correlation time are the major factors of the first-order-like transition. Angular noise correlation time has great influence on the linewidth in the intensity spectrum.

Optical properties of monolayer oxygen-doped Ge-Sb-Te thin films prepared by RF-sputtering method were studied in the region of 400 nm～800 nm, including refractive index, extinction coefficient, reflection and transmission spectra. The results indicated that larger reflectivity contrast can be achieved by appropriate doping of oxygen, thus the recording properties of the Ge-Sb-Te film material can be improved by the oxygen-doping.

In the phosphorescence lifetime measurements with pulse method, both the excitation light pulse parameters and initial time selected for intensity decay analysis are crucial to the accurate lifetime calculation. The relation between phosphorescence intensity decay and the parameters of the excitation light pulse is analyzed based on the linear time invariance. it is found that the phosphorescence intensity decay is independent on the parameters of the excitation light pulse after the excitation light vanishing. If the excitation light pulse vanishing moment is selected as the initial time, the accurate lifetime can be obtained. The experimental results from the Oxy-Phor R2 samples excited by different excitation light pulse have proved the above conclusion.

A 40 Gb/s optical time division multiplexing (OTDM) system is presented and discussed. Frame structure of OTDM data stream is designed based on unequal amplitude coding methods. Gain-switched distributed-feedback laser (GS-DFB) and comb-like dispersion profiled fiber (CDPF) are employed to generate the ultra-short optical pulses; chirped fiber grating for dispersion compensation; electro-absorption modulator (EAM) for de-multiplexing the 40 Gbit/s data stream. The frame clock (10 GHz) is extracted from the data stream with high Q value electronic filter. After transmission over 122 km single mode fiber (SMF), bit error rate of the whole system is less than 10 -9.

With Cr 4+:YAG as the saturable absorber and xenon flash lamp as the pumping source, passively Q-switched quasi-three-level laser operation of Nd 3+:YAG at 0.946 μm is realized. Pulses with a width of 38 ns and an energy of 1.7 mJ are obtained.

The low-loss broadband semiconductor saturable absorber mirror (SESAM) is firstly designed and manufactured in China. This SESAM has been used in self-starting mode-locked Ti:sapphire lasers.

Two-dimensional rough sea surface is generated based on JONSWAP sea spectrum, then the geometric optics approximation and Kirchhoff approximation are applied to calculate the light scattering. Each facet is treated as a surface with small roughness instead of a smooth plane, and the shadowing function for arbitrary incident and scattering angles is obtained with the projecting and ray tracing methods, hence making the results more accurate. Finally the image of sea surface is simulated in the 3 μm～5 μm band, which is of great reference value for reducing the interference to the sensor operating in the infrared by the scattering of sunshine from rough surface.