Utilizing a theoretical model and Taylor expansion, the formula of cross-sensitivity, which can evaluate the practical elliptical-core fiber sensor for simultaneous measurement of strain and temperature, is presented. Physical meaning of the cross-sensitivity is given. With the experimental data the errors induced by the crass-sensitivity are calculated and some conclusions are obtained.

The characterization and design of LiNbOa optical modulators of novel electrode structures are discussed by using the finite-clement method (FEM) and the incremental inductance formula. Loss coefficients are verified in this paper. The calculation results show that the structures can realize microwave-optical velocity match easily and reduce microwave electrode losses drastically, so the modulators employing such structures are candidate devices for future ultra- high- speed optical fiber transmission systems. The electrode structures are optimized by using the ratio of the 3 dB optical bandwidth to driving power as a standard. The results of optimization show that the properties of the modulators can be improved by increasing the electrode gaps. As an example, an electro-optic modulator, whose bandwidth is 100 GHz, half wave voltage is 6 and driving power is 0.48 W, is designed.

Based on the dual transverse Pockcls effect in some crystals, a novel Electro-Optic Crystal Multiplier (EOCM) is advanced. The multiplying operation between two electric signals can be done by an electro-optic crystal in a light carrier. It is experimentally verified that EOCM is capable of being applied to make the amplitude modulated optical signal and to measure the electric power. The nonlinearity error in measuring the DC electric power by a lithium niobite crystal is less than 3.3%.

In this paper, a novel sensitive photothermal interferometric detection technique, which is based on the interference of the two reflected probe beams from the front and rear surfaces of a plate sample, is developed. Both theoretical intensity profile of the interference fringe pattern and experimental measurement are presented. The signal expression for modulated photothermal interferometric detection scheme is given and the photothermal measurement is carried out with the fluoroaluminate glass plate as the sample. The potential applications of this sensitive photothermal interferometric detection scheme to material characterization, weak absorption measurement, as well as microvolume trace analysis are discussed.

The band transport model is now a widely accepted photorefractive theory. In this model, diffusion mechanism acts as a main role and in some cases two modifications, i. e. , drift under an applied field and the photovoltaic effect, are added. Actually, the photovoltaic effect should aloways be considered as important as the diffusion, and in the case of fcrroelectrics, e. g. , LiNbO3, this effect often dominates over the latter and thus becomes the main photorefractive mechanism. In this paper, the phenomenological theory of photovoltaic effect was developed and an all-around analysis for the formation of the photorefractive grating is given.

When a yellow pcntoxide vanadium sample is explored to a proper fluence excimer laser, its electric conductivity changes remarkably. So, it changes from an insulator to a semiconductor, besides its color changes too. The pentoxidc vanadium sample, before and after being acted, is analysed with the X-ray diffraction (XRD) , X-ray photoclectronic spectrum (XPS), and microscopy. It can be determined that the procedure takes place because the proper flucncc excimer laser illuminates the surface of the pentoxide vanadium sample, the temperature on the surface rises quicikly, and a thin layer of the illuminated area is molten and then resolidifies quickly, which leads to the chemical ratios change of the sample surface.

A low-pump-power self-mode-locked Ti:sapphire laser is demonstrated with a tight focusing geometry, and results as the shortest pulses of 15 fs and an average output power of 42 mW at a threshold pump power of 710 mVV are obtained.

A mode program is established to investigate the thermal distortion of the Nd : glass rod amplifier from its deposited energy distribution. This program can be used to calculate the temperature profile, stresses distribution, refractive index distribution, depolarization and phase aberration during the pumping and the cooling down processes. The influence of the pumping on laser wavefront has been measured with a Hartmann wavefront sensor. Meanwhile, the transient temperature profile has also been measured by the Hartmann wavefront sensor. The experiment is in good agreement with the calculation.

In a Ce : KNSBN crystal, two-wave coupling was carried out using two laser beams from a frequency-doubled cw modelocked Nd:YAG laser, with 82 MHz repetition rate and a pulse duration Δt =60 ps. When the time delay t of the pump laser pulses with respect to the probe ones is >0, the average gain of the probe beam is ≥0. And when t<-Δt, the average gain can be <0. A physical explanation is put forwards.

We use an analysical model to Calculate superthcrmal electron energy deposition in the main fuel under different main compressed laser energy conditions in the fast ignition concept. It is conduced: (1) During the fast ignition process, most superthermal electron energy will be deposited near the edge of the main fuel. (2) This energy deposition is the slowing down process for higher main laser energy.

Under the conditions that the incidence angle, incidence position and the intensity of the pump wave ensure a stable phase-conjugate wave output, the effect of the pump wave intensity change on the stability of the phase- conjugate wave is investigated. The experimental result shows that for some pump wave intensity, when the phase-con jugate intensity reaches its saturation value, the change of pump wave intensity may induce an instable phase-conjugate output.

The present study describes the principle and performance of the intracavity laser absorption spectrometer. It was shown that the detection limit of this setup reaches 10-10cm-1. The vibration-rotation spectrum of HDO (500) band was recorded by ICLAS and analysed, yielding a set of vibration-rotation parameters.

In this paper, the upconversion luminescence from Er3+ doped ZnS pumped by a 960 nm laser diode was studied. The results show that ZnS:Er3+ is an efficient infrared-visible upconversion material. In our experiments, the effect of Er3+ions cluster, which comes from the aggregation of Er3+ ions, on the upconversion luminescence from ZnS:Er3+ was studied too.

By solving the time-dependent Schrodinger equation with a one-dimensional short range potential, the effect of initial population on the high harmonics generation was studied. The results reveal that when a moderate intensity laser acts on an atom or ion of high ionizational potentials, if the initial population is on the ground state, the atom or ion will not be ionized, only lower harmonics can be obtained. If the initial population is partily on the ground state and partly on the excited states, the atom will be ionized partily, and the lower harmonics will be weak and the high harmonics be increased. If the initial population is on the excited states, the atom will be ionized completely, and the orders and the conversion efficiency will be lower. These results show that partial ionization of the atom will enhance the harmonic generation, and the two-step semiclassical model is confirmed to some extent.