Device for measuring linewidth of narrow linewidth laser based on optical fiber time-delay self heterodyne method as well as method for measuring thereof

Abstract

The invention discloses a device of measuring the line-width of a laser with narrow line-width and a method of measuring the line-width based on a optical fiber delay self-heterodyne method; in the hardware device, an optical fiber delay line is connected between a first and a second couplers; an acousto-optic modulator is connected between the first and the second couplers; the measured laser isconnected to the input of the first coupler, and a photoelectric detector is connected to the output of the second coupler; the photoelectric detector is connected with a spectrum analyzer. In the line-width measurement, simulation models of the line-width triangle v of the laser and the spectrum-width triangle f of the photoelectric current heterodyne signal are built in the frequency shift delay self-heterodyne methodology, and the function relation between the line-width triangle v of the laser and the spectrum-width triangle f of the photoelectric current heterodyne signal is obtained fitting of the three-level proportion function model. The invention presents that with the short optical fiber delay self-heterodyne method, the device can eliminate the deficiency of greatly reduced measuring precision because of not enough delayed time in the delay self-heterodyne method when the length of the delay optical fiber is less than 6 times coherence length of the laser, so as to provide an effective method of precisely measuring the line-width of the laser with narrow line-width in projects.

Description

technical field [0001] The invention relates to a method for measuring the line width of a narrow line width laser, more particularly, it refers to a method based on the principle of the fiber delay self-heterodyne method, using a shorter fiber delay line to achieve the purpose of accurately measuring the line width , the method can effectively reduce the length of the optical fiber delay line, reduce the cost and volume, and basically do not affect the original accuracy. Background technique [0002] Single-frequency lasers are one of the development directions of lasers in recent years. They are mainly used in many fields such as lidar, optical communication, gravitational wave measurement, high-resolution spectral measurement, and squeezed state research in quantum optics. [0003] Ordinary light sources emit light, which is the spontaneous emission of a large number of independent oscillators. The light waves emitted by each vibrator are composed of wave trains that las...

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