Study On Technology Of Frequency Stabilization Of External Cavity Semiconductor Laser

This paper emphasizes in researching the theory and experiment on utilizing acetylene's absorption optical spectrum to stabilize frequency on 1.5μm fiber grating external semiconductor laser.First, the development history and applications status of external cavity semiconductor laser are briefly introduced. Then, two primary external cavity fabrics are discussed, i.e. fiber grating external cavity as well as blazed grating external cavity. This paper demonstrates the frequency stabilization theory, including the related concepts on frequency stabilization and reproductivity, the mathematics model of frequency stabilization laser, the factors of frequency stabilization, and the measurement on frequency stabilization, etc. . Discussing and comparing on some major frequency stabilization measurements, putting emphases on acetylene molecule saturation absorption frequency stabilization theory from describing the respects of the width and shape of absorption line, the theory and advantage of saturation absorption frequency stabilization and the acetylene's molecule absorption optical spectrum line, etc. With high stability, this method combining with external cavity, can realize the characteristics of narrow line width, high stability and single-frequency laser. There is few related experiment reports on this respect inland, especially on 1.5μm fiber communication wave band.This paper designs the FBG ECSL servo circuit. The whole servo circuit includes the photo-electricity receiver, 1KHz sin wave generator, trebler, and phase discrimination. The photo-electricity receiver which has high sensibility, can output the voltage of 2.4V when the receiving power is only 0.114mW, and meantime, the noise is well depressed. 1KHz square wave is generated by dividing the frequency of crystal oscillater's output signal, and then is become 1KHz sin wave by bandpass filter whoseω0 = 1KHz,Q≈10, H 0 = 1 2.This sin wave is rather smooth and has no other resonance waves. The trebler is made up of PLL circuit. It is became sin wave by bandpass filter whoseω0 = 3KHz,Q≈10, H 0 = 1, and its frequency strictly equals to the 3 times of the 1KHz sin wave. These two signals'phase difference is zero. Double Balanced Mixer(DBM) is the core of phase discrimination, its output signals are processed by difference amplifier and lowpass filter to achieve DC error signal of 0.5VThis paper also designs the absorption cell of acetylene, Brewster angle removes...