When a fiber Bragg grating is subject to an uneven strain, both of the fiber core index and the grating pitch will experience an uneven variation and therefore the resonant wavelength will vary along the grating. The interaction model between fiber Bragg grating and uneven strain field is established, and the relationship of the fiber Bragg grating reflective spectrum response to the uneven strain is deduced. The results of interaction experiments between linear distribution strain field and fiber Bragg grating are given.

An analysis is presented for etched optical fiber Bragg reflectors using the normal mode based orthogonal coupled mode theory for the grating assisted coupling of forward and backward modes and, using waveguide mode based non orthogonal coupled mode theory for the mode excitation at the input/output junction. The analysis shows that three are three kinds of Bragg reflections in the reflector, which means six distinct peaks in the reflective spectrum when its polarization sensitivity taken into account. It agrees well with the experimental result. The power reflectivity depends on not only coupling coefficients but also structure parameters, especially the depth of the Al 2O 3 layer, the distance between the Al 2O 3 layer and the fiber core, and the refractive index of the index matching layer.

By using the Monte Carlo simulation method the physical factors influencing on time resolution of scintillating fiber have been studied, which include the emission, transportation, and absorbability of photons in the fiber, the pulse formation in the photomultiplier and so on. The results are compared to that of experimental measurements.

A method of direct retrieval of deformed wavefront by phase unwrapping using 2 D Fourier transform is presented. The projection data of any axial cross section can be extracted to implement 3 D tomography in full meaning. A simulated temperature field experiment proved that the projection data extraction method based on the phase unwrapping succeeded in facilitating computation of tomography.

Synthetic holography faces the difficulty of recording tremendous number of pictures. The presented idea of interpolation aims toward resolving it. The spatial relationship required by algorithm of interpolation has been given. The scheme greatly reduces the number of pictures which have to be photographed, and makes real time recording possible. Experimental results show that the idea is feasible.

The theoretical model of measurement of small signal gain by ASE method with a spherical mirror was presented. Corresponding formula of small signal gain coefficient was given which is precise, compact and explicit. This model has the mechanism of suppressing th measuring error from the transverse distribution of spontaneous emission magnified.

The fringe pattern connection method (FPCM) is an effective method in 3 D shape measurement of a large object without annoyance of illumination and readout shadows. It has shown that the main factors that effect the final accuracy of 3 D shape measurement using the fringe pattern connection method include the measurement error of subapertures the overlap coefficient K D , the order N f of polynomial fitting and the mode of aperture connection.

A basic conception of laser interferometric imaging from the point of view of a hologram, when an object travels through an interference field produced with coherence light including a plane and spherical waves, is discussed. The time varying signal scattered by the object is detected and then recorded spatially so that the recording is a one dimensional hologram of the object.

The technology of using computer processing image to get rid of air disturbance in astronomy mirror surface testing is presented. With this method, the quality of astronomy mirror surface testing is improved and the polishing period is greatly shortened.

According to the rate equation of quasi three level system, the threshold power, slope efficiency and optimum length of the crystals of longitudinally pumped Tm:YAG lasers have been calculated and discussed. The influence of temperature on the Tm:YAG lasers has been studied.

An injection seeded Nd:YAG laser that incorporates an interference scheme to lock the frequency of a slave cavity mode to the seed frequency is described. On this basis, the method of compensating the retardation caused by the signal processing through deflecting polarizer is presented. This offers a new way for an injection seeded laser to improve the technique of locking the frequency of a slave cavity mode to the seed frequency, and the high quality output of the slave oscillator can be controlled simply and effectively.

The transmission spectra and optical absorption edges (OAEs) of some scheelite structured crystals, such as undoped CaWO 4, PbWO 4, CaMoO 4 and PbMoO 4 crystals, were comparatively studied. It was found that the relative location of their OAEs can not be explained from a widely adopted viewpoint that the OAEs originate from electron transfer from t 1 orbital to 2e orbital of W(Mo)O 2- 4 group with T d symmetry. But it can be explained with the electron transfer from 1a 2 orbital to 2b 1 orbital within the W(Mo)O 2- 4 group with D 2d symmetry. The OAEs of the above mentioned crystals and the PbWO 4 crystals doped with lanthanum, niobium and molybdenum respectively were interpreted briefly from the present viewpoint and the ion polarization model.

A laser non contact surface sensor for measuring 3D free form surface is proposed. This sensor is simple in structure and its output is linearly proportional to the measured displacement in optical principle. Because this sensor can receive the diffused light of the object in 360° direction, the inclination effect is very small. Problems of shadow effect and inclination influence are solved. The measurement range of the sensor is 4 mm, resolution is 2 μm. When object is inclined to ±85°, measurement error is about 20 μm.

A systematical analysis and design have been made for 1.30 μm/1.55 μm Si 1-x Ge x/ Si filters based on multi mode interference. Using the mode propagation analysis, transmission characteristics of the device were investigated. The results show that: 1) for 1.30 μm filter, the optimum coupler length is 2302.5 μm, and the contrast and insertion loss are 31 dB and 0.01 dB, respectively; 2) for 1.55 μm filter, the optimum coupler length is 2512.5 μm, and the contrast and insertion loss are 16 dB and 0.09 dB, respectively. For both of the filters, the Ge content x, rib height, and interfernce width are 0.04, 6.35 μm, and 8 μm, respectively.

The reflection induced phase retardation between p and s components of reflected light can reduce the sensitivity and stability of bulk glass optic current sensors. The influence of the reflection induced phase retardation is theoretically analyzed and the results of numerical simulation are given.

The principle of phase discrepancy compensation of the tetragonal OCT (Optic Current Transducer) sensor head with dual layer optic circuit is analysed as well as its existing proplem. A new kind of the OCT sensor head is designed, of which the structure is simpler and the performance is better. It is demonstrated that the phase discrepancy caused by optical dispersion of this new kind sensor head is very small and its influence on measurement can be ignored, showing practical significance.

The results on fabrication of refractive microlens arrays using heat forming and reactive ion beam etching (RIBE) techniques are presented. RIBE, with high etching rate and flexible etching ability, is a novel dry etching technique for manufacturing micro optical element. The principle of the method and the controlling of etching selectivity are described. In experimetns, we have fabricated F/2 microlens array with 100 μm diameter in the surface of silicon. An accurate control of etching rate ratio between positive photoresist and silicon was obtained by adjusting multiple etching parameters. The measurement of microlenses showed that the lenslet profile was very close to the standard spherical surface profile. The duplicating ratio is 1:1.03.

With the requirement for modern infrared optics system, a method for designinghybrid diffractive refractive off axis optical system in infrared region is introduced. An optical system thus designed is simple in structure and possesses high optical and mechanical quality.

The interaction of three energy level system and tricolor phase coherent laser is systematically studied, and the state population probabilities depending on phases and amplitudes of fields are demonstrated. As a conclusion, we referred to that it is possible to fulfil state selected excitation by using coherent lasers. Virture and feasibility of using coherent lasers to perform overtone excitation are proposed.

The phase fluctuations and higher order fluctuations in odd and even coherent states have been discussed via the measured phase operators introduced by S. M. Barnett and D. T. Pegg. Based on the uncertainty relation and higher order uncertainty relation, two kinds of definitions of squeezing and higher order squeezing for the measured phase operators are introduced. Using these definitions, the squeezing and higher order squeezing of measured phase operators in odd and even coherent states have been studied.

The coherence between the two lower levels via incoherent pumping of these two levels to a fourth auxiliary level is considered to investigate the optical bistability in unidirection ring cavity with a lower level doublet atomic sample. It is shown that the optical bistability can be controlled via the interference of incoherent pump processes. It is discovered that the incoherent pump field can even lead to multistability. The optical bistability can be controlled by choosing the appropriate parameters.

Dispersion compensation experimental result on 103 km long standard fiber link is presented. The chirped fiber Bragg grating used in our experiment is obtained by chirping a 10 cm long uniform grating into a chirped one.

An efficient method to write long period fiber grating using a micro lens array is reported. It is possible to using several hundred excimer laser pulses to write a long period grating by using this method.

The ultraviolet visible photoabsorption spectrum of the Ag particles matrix (BaO) thin film deposited by vacuum evaporation was measured. The transmission electron micrograph indicated that in the matrix Ag formed particles with a mean diameter of 15 nm. There is a clear absorption peak of surface plasmon mode at 410 nm wave length. This is the absorption of electric dipole oscillation. The results were compared with those in previous literatures. The dependence of absorption on the particle size was discussed.

The attenuated total reflection technique was used to excite surface plasmon. We have measured the efficiencies of the surface plasmon energy emitted through surface roughness into air side, for prism/LB film or Ag film /Ag film/ air and prism/Ag film/air structures. Depending on the distribution of scattering light intensity, the surface roughness parameters, i. e. the transverse correlation length σ and the surface corrugation depth δ of air/Ag film interface were simultaneously evaluated. Then we calculated the emission efficiency of the surface plasmon polariton energy from σ and δ. The calculated efficiency corresponds with that of experiment.