The optical properties of long-period fiber gratings are studied,and long-period gratings are successfully written in the hydrogen-loaded standard single-mode fibers by a KrF excimer laser and point-by-point method with a properly designed program-controlled auto-scanning exposure system.The experimental results show that this method is highly flexible in the fabrication of long-period fiber gratings.The stability of the long-period gratings written in hydrogen-loaded standard single-mode fibers are studied and discussed.

The power penalties of intraband crosstalk using directly and externally modulated lasers are compared experimentally.The results are in good agreement with theoretical analyses.The power penalty of direct modulation is smaller than that of external modulation at the same crosstalk level.

In the region beyond the turning point at the substrate side of graded-index planar optical waveguides,it is shown that the field solution is a rigorous exponential evanescent function.The attenuated coefficient can be characterized by an equivalent refractive index.

Based on the theory of wavelet matched filtering and the associative characteristic of volume holographic storage in a photorefractive crystal,a new idea for associative memory is proposed and realized.It can remember and recover a primary image from its deformed features.The photorefractive crystal in the system stands for both the cell of pattern identification and that of image restoring.Its application in face memory is studied,and experimental results are given

A more powerful tool for binary image processing,logical function morphology,is proposed.In logical function morphology,image and structuring element are considered as logic functions,and the MULTIPLY between image and structuring element in correlation are replaced by 16 logic operators.A total of 12 logical function morphological operations are obtained.The optical implementation of logical function morphology is described.The application of logical function morphology and experimental results are presented.

The accuracy of phase-measuring profilometry (PMP) is greatly influenced by the environmental light,especially in the outside of the room.The error caused by the change of the environmental light is analyzed.A method to calibrate the grey scale of the fringe pattern acquired by the CCD camera is presented.By using the method,the error is greatly restrained.

A newly developed high efficiency high resolution,large size transmission grating spectrograph for higher collection efficiency and higher spectral resolution used in laser produced plasma diagnosis is reported.The spectrograph comprises of a toroidal mirror as the collecting optics,a standing-free high-density transmission grating and a soft X-ray CCD camera.The partial coherent light diffraction theory is applied to determine the X-ray intensity distribution on the soft X-ray CCD camera.Analysis shows that the spectral resolution is better than 0.05 nm over the spectral range of 1.4～12 nm,which is successfully demonstrated in the relevant experiments.Owing to its high efficiency,it is especially suitable for the experiments of ultrashort femtosecond pulse laser produced plasmas.

The fiber-endoscope is a novel type of medical apparatus and has been used in clinical application.The designed structure and characteristics of the angioscope are described.The resolution and image magnification as a function of the working distance are given.With this system,some objects are observed,and satisfactory results are obtained.

The probability density function of time for photons is calculated.The charateristics of multi-photon correction function and its influence on the fluorescence lifetime measured by time-correlated single photon counting method are studied.The quantitative relation between multi-photon contamination and measurement errors is presented.

These isolated point measurements deserve pertain roles in the OCT reconstruction.The ART3 algorithm is a robust method dealing with practically noisy or even partly missing projections,and is friendly to integrate the information from various sources.Most of the suggestions on fusing information inevitably introduce high frequencies,which never exist in the field,into the interation.And these high frequencies over-suppress the expected low frequency components and cause the reconstraction non-stable.An adaptive way is developed to take a good use of pointwise priori.By analyzing the simulated experiments,some deserved attention to the application of priori in OCT is strongly suggested.

The method on profile-control of micro-optic element in photoresist was presented.The difference between fabrication of binary optic element and that of continuous-relief MOE may not be ignored.A reciprocal equation among the depth,exposure,density of the developer and its etching time was inferred,with the appropriate conditions that proved to be useful for the MOE fabrications.The property and treatment of the photoresist were modified in order to meet the conditions of the reciprocal equation.As the result,some MOEs having accurate depth and good surface performance,with the evaluation of a typical element,were shown.

A new method,probing model and device to measure upper atmospheric wind field is proposed by employing wide-angle Michelson interferometer without movable mirror.Variation of path difference velocity and temperature of wind field are analyzed and calculated applying interference image spectroscopy.The method has advantages of higher stability,throughput and accuracy,larger field of view and better real time measurement.

A novel practical configuration for superresolution is presented,which relies on the polar reversal property of some irradiance redistribution elements and the profile of TEM00 mode Gaussian laser beam.Gaussian peak of incident light coming into the central part of such element,may go out from near the peripheral part of element,and the skirt of Gaussian beam coming into peripheral part goes out from central part.Thus,the optical superresolution is obtained in an imaging system.Compared with the filter,the energy loss is greatly diminished and the deserted light energy is recovered.

By measuring photoluminescence spectra of each point along the slope of several polished GaP:N green light emitting liquid phase epitary (LPE) slices,the photoluminescence intensities of p- and n-type crystals are compared,it is found when nitrogen concentration is equal on two sides of p-n junction approximately,the main luminescence region is p-type region,though there is also light emitting from n-type region.The photoluminescence intensities in the former region are about 3 to 5 times of that in the latter region.

The dynamic variations of the photorefractive properties of Fe:LiNbO3 crystal via the crystal temperature were investigated.The results show that there is strong competition between the protons and the thermally excited electrons.Within the response time of the photorefractive gratings,the effect of protons on the photorefractive properties of Fe:LiNbO3 crystal is weak,and the variation of thermal excitation coefficient of electron β will be the dominate factor that affects the photorefractive properties of Fe:LiNbO3 if the crystal temperature is below 120℃.When the crystal temperature is higher than 120℃,the protons will have important effect on the photorefractive properties of Fe:LiNbO3 crystal because of its increasing mobility.

Two probe models are presented,which satisfy the conditions of high optical resolution together with high transmission efficiency.A two-step method to fabricate the two kinds of probes is proposed.First,an optical fiber probe with the transitional taper in hyperbolic or parabolic shape is produced by heating-pulling method in a simple home-made device,followed by a rapid chemical etching in 40% buffered hydrofluoric acid to sharpen the tips,keeping the shape and conic angle unchanged.The tips diameters are in the range of 20～200 nm,and the taper angle 20°～60°.To demonstrate the performance of high transmission efficiency of the tips,their spot distributions are compared with conventional taffy-pulled probes.The evanescent wave decay curve in PSTM mode and the scanning near-field image of holographic grating are given by use of transmission SNOM working in collection mode.In addition,an approach curve of shear force is shown to verify its applicability to tip-sample distance regulation based on the shear-force principle.

A theoretical analysis of the phase measurement performance of Shack-Hartmann wavefront sesnor is made based on the analysis of the subaperture centroid detecting error of atmospheric turbulence with Shack-Hartmann wavefront sensor.The phase detecting error of Shack-Hartmann wavefront sensor is not only dependent on the noise of detector,object′s stellar magnitude,but also the characteristics of object and the numbers of subaperture.A relationship of phase probe error of atmospheric turbulence with Shack-Hartmann wavefront sensor is presented in analytic form.

A detailed experimental study on the spatial filters used in the ICF Raman system has been carried out relating to their general design.From the experimental results and analysis,a considerable difference to the case of solid state laser system shows that for the design of the spatial filters used in the ICF Raman system,some special considerations must be taken.The results in this paper can provide general direction to the system design rules for the engineering project building.

Quantum interference in population trapping in a multi-level system,which is coupled by vacuum modes and driven by a coherent field,is studied in view of dressed states.The analytic expression of trapping population under interference conditions is derived.The influences on population trapping of the initial population,the Rabi frequency of the driving field and the spacing between the upper levels are explored.It is shown that the forms of the total trapping population of all energy-levels under certain initial population condition,depending on both the Rabi Frequency of the driving field and the spacing between the upper levels,are not always the monotonically increasing (or decreasing) functions.The maximum of the total trapping population in a given system can be obtained by calculating the extremal solution of its analytic equations.

The phase properties of two dipole-dipole coupled atoms interacting with two-mode strong coherent light fields via multiphoton process are studied.The influences of the initial atoms states,the intensity of initial fields and the dipole-dipole interaction between atoms on the phase probability distribution,the phase diffusion and the frequency shift are discussed.

Based on cavity quantum electrodynamics and physics of semiconductor,the micro-cavity effect in a vertical cavity semiconductor surface emitting laser has been discussed.The spontaneous emission spectra in the vertical cavity semiconductor surface emitting lasers are obtained.As a result,spontaneous emission intensity in one direction can be enhanced about 200 times by the confinement the photon with distributed Bragg reflectors because the micro-cavity effect in the lasers.

Nd:YCa4O(BO3)3,known as Nd:YCOB,is a new nonlinear multifunctional crystal.By using Datachrom-5000 dye-laser as a pumping source,a Nd:YCOB(8at%) self-frequency-doubling laser from 1.06 μm to 0.53 μm has been realized.The wavelength of the frequency-doubling laser is 530.2 nm,the lowest threshold energy is 2 mJ,the hightest conversion efficiency is 3.3%,and the highest green laser energy 1.03 mJ.The laser characteristics of Nd:YCOB self-frequency crystal are discussed.

A RF excited diffusively cooled carbon monoxide kilowatts laser is reported.In this laser,the top electrode was cooled with the tap water and the bottom electrode was cooled with the liquid nitrogen to maintain the slab waveguide gas discharge region at a low temperature.In the experiments,a slab waveguide region was excited by a RF transverse gas discharge at a frequency of 90 MHz,a new type of optical resonator consisting of a conventional unstable resonator and a flat feedback mirror was employed.The maximum laser power output of over 1 kilowatts was obtained with a gas composition of P(CO):P(He):P(Xe):P(O2) at a ratio of 24:71:4:1.

Diamond-like carbon (DLC) i.e.amorphous carbon films were grown on germanium (Ge) substrates by rf-plasma decomposition of methane.Fourier transform infrared (FTIR) spectroscopy measurement showed that the DLC films acted as the anti-reflect coatings of Ge substrates,especially,maxima of the transmission of DLC/Ge/DLC were above 99% from 1740 cm-1 to 2044 cm-1,94.5% at 945.7 cm-1(10.6 μm).IR transmission spectroscopy and improved transmission formula were used to calculate the absorption coefficient of DLC films from 2.5 μm to 12 μm.The results indicated that the absorption coefficient of the films approached 0 ranging from 1700 cm-1 to 2600 cm-1 and 230 cm-1 at 945.7 cm-1.The sp3 C-H bonds were dominate in the DLC films.All the absorption peaks were well explained by bonds.

The attenuated-total-reflections (ATR) of absorbing films contain much characteristic information about the films.Taking considerations of the prism coupling and film absorbing,the first-order perturbation theory is applied to deduce the simplified analytical expressions of the perturbed propagation constants.Based on the theory,a method is introduced for determining the complex dielectric coefficients and thicknesses by detecting and analyzing the attenuated-total-reflections of absorbing films.