A Research Of Time-domain Microtechnique Basing On The Nonlinear Optical Crystal

With the rapid development of laser, from picosecond to femtosecond, the pulse width of the laser becomes more and more narrow, so higher and higher detection technology for the ultra-short pulse is required. Because of the high power and ultra-short pulse width in time domain, detection of the ultra-short pulse cannot be completed by direct measurement method, we must use the indirect measurement method.In recent years, the technology of indirect measurement in time domain mainly are autocorrelation measurement method, frequency resolved optical gating(FROG) method, spectral phase interferometry for direct electric-field reconstruction(SPIDER) method and time lens method. This paper is mainly focus on the method of time lens. Based on the space-time duality, we have designed a time lens analogy to the space lens, and the time lens can be used to complete for expanding or compressing the optical pulse. The methods of achieving time lens include electro-optic phase modulation, cross-phase modulation, sum- and difference- frequency method, and four-wave mixing technology. This paper is mainly based on four-wave mixing technology to achieve time lens.Based on the nonlinear effect of nonlinear optical materials depending on the intensity of the incident light, we study on the four-wave mixing effect in silicon waveguide, analyze the dispersion characteristics and the electric field distribution of silicon waveguide by the finite element method. Then we design different size of silicon waveguides to study the dispersion curves. In a waveguide, we set different pump wavelength and pump power to study the phase matching condition of the four-wave mixing.This paper analyzed the time lens temporal imaging by system simulation. Firstly by numerical calculation simulation, we have achieved the waveforms expanding of Gauss short pulse and arbitrary waveform pulse in time domain. Then we used the system software to simulate the temporal imaging system in time domain. In the process, appearing new spectral components, which shows that the four-wave mixing effect have happened and proved the correctness of the theory.We have built the experimental platform, done the expanding waveform experiment of optical pulse which is emitted by femtosecond laser, and introduced the main optical components and instruments. Because of the limited conditions, in the experiment, we used the high nonlinear fiber instead of silicon waveguides in the four-wave mixing effect experiment. The comparison among the theoretical calculation results, simulation results and the experimental results verified that the results are reliability and validity, at the same time, we also analyzed some problems. At last, we analyzed some shortcomings in this paper and the field needed to be studied on continually.