In this paper we successfully apply the modified genetic algorithm to the optimal design of diffractive phase optical elements with high demension. Its comparison to simulated annealing algorithm is also discussed. The results show that genetic algorithm not only can be applied to the optimal design of diffractive optical element with ninary phase, also with the multi-level phase. Especially, it suits to implement in an optoelectronic hybrid system.

The differential integral equation derived from Maxwell's equations was used to rigorously deal with the wavelength- sized surface relief trapezium- shaped reflecting grating in TE (transverse electric) polarization. Numerical analyses of the surface electric field show that the effect of edge and wall of the grating has significant influence on the surface field of metallic materials, e. g. gold and aluminium. Particularly, for the incident wavelength λ=1.0 μm when gold is in strong metallic nature, the edge and wall effect becomes more apparent. The oscillating characteristics of the surface field at the bottom of the grooves and the far field diffraction efficiency against the groove depth are explained by its physical mechanism of the edge and wall effect. This technique can be used to tackle the diffraction problem for arbitrary shapes of grating or single scattering obstacle in arbitrary angles of incidence and polarization.

Numerical modelling has been used to investigate the behaviour of O+7 recombination X-ray lasers produced by Mylar (C10H8O4) fibre or slab target irradiated by ultrashort pulses. Feasibility of experiment on saturated gains has been discussed. The theoretical results show that saturated recombination X-ray laser are possible by using ultrashort pulses.

Under a continuum approximation we derive a complex Ginzburg-Landau equation to describe the the fast- time dynamics of a set of locally coupled lasers. Its spatio-temporal behaviour has been studied analytically and numerically. Spatial soliton solutions have been derived.

In this paper, effects of one of the fibre nonlinearities, four-wave mixing, in long distance coherent multichannel optical fibre transmission are studied. An optical frequency division multiplexed system with 9 erbium doped fibre amplifiers, transmitting over 550 km of fibre is used in the expreiment. The nonlinear interactions between the channels due to the four-wave mixing are clearly observed. Experimental results are well agreed with the theoretical analysis and calculations. Results show that for multichannel transmission at several Gbit/s with conventional non-return to zero data, transmission performance is significantly affected by the four-wave mixing.

We present a practical model for optical amplifier noise amplifier noise analysis and its application in conventional intensity modulation- direct detection (IMDD) optical transmission systems. In particular, a general sensitivity calculation formulae for optically pre-amplified receiver is derived and the impact of different system parameters on BER performance is discussed. Measurements on a experimental system with a 2. 5 Gb/s optically pre-amplified receiver show the good coincidence between the theoretical calculation and the experimental results. By using an optical pre-amplifier, the receiver sensitivity of the experimental system improved from -26.5 dBm to -39.5 dBm.

A novel photonic switching device based on polarisation switching by optical injection in fibre lasers is investigated. An all-optical switching device with an extremely low threshold (0.1 μW) has been demonstrated. The mechanism of operation, experimental realisation and device characteristics are persented.

Electric current may be measured optically by utilising the Faraday megnetic-optic effect. Devices using optic fibre or optical bulk glass as their sensing elements have been intensively researched and developed. This paper outlines the main problems associated with Fibre optic current sensors and reviews recent development in the optic bulk glass current sensors based upon the Faraday effect.

A quantitative wavefront analysis method for star testing is proposed. Both computer simulation and laboratory experiment results of the proposed method are presented.

Through correlation calculation and filtering analysis, statistical distribution of fringe intensity in speckle-shearing interferometry has been established, so that more general characteristics of this kind of fringe have been obtained.

According to the process of the mutual reaction of the population number at each energy level of the un-equilibrium mixed gases flowing in flow laser and the intensive emission reaching the stable oscillation, and the numerical simulated calculation results of the corresponding 3-dimensional distribution states, the simplified calculation formulae of the basic properties of the corresponding oscillator and amplifier are developed. The calculation results of these formulae are agree well with the experimental measures of many kind devices with various cavities. Concretely comparing and analyzing the basic properties of flow laser oscillator and amplifiers, some basic principles are gained for providing the theory basis of the optimum design of the corresponding devices.

Multiline osciilation of the dye laser with four prisms and a grating has been observed and studied. The results are shown that the output spectral features, such as wavelength interval of the neighboring lines, distributive bandwidth of the multiline and singlet width, are in agreement with the theory of compound cavity with multisurface reflector and grating combination.

We report an observation of optical phase conjugate in LB films of pure purple membrane for the first time. The dependence of intensity of the optical conjugate wave upon the total incident intensity has been deduced, based on the simplified model of photo-cycle of bacteriorhodipsin [bR(570) M(410)]. The fitting restults of the saturated absorption intensity of the LB films and the life time of the intermediate M (410) are 0.49 W/cm2 and 2.5 ms, respectively.

By using two crystals series, temperature tuning and optical wedge complement, the simultaneous resonance of three modes for pump and two nondegenerate subharmonic field in optical parametric oscillator (OPO) cavity has been experimentally demonstrated. The classical gain of subharmonic field has been measured and calculated with semi-classical theory. The experimental results are in agreement with the theoretical analyses.

By using the principles of diffuse reflection laser phase ranging with non-cooperation turget to analyze and to design the key unit techniques, a prototype of laser phase imaging radar is developed which is suilable for the visual guiding system of autonomous carriage.

As a modified heterodyne profilometer the heterodyne common path surface profilometer for measuring surface roughness is described. The profilometer is not sensitive to mechanical instability and temperature variations. The actual height resolution is 0. 1 nm and this system could be developed into a standard instrument for surface roughness measurement.