Method and equipment for measuring laser line width

Abstract

The invention discloses a method and equipment for measuring laser line width. The method comprises the following steps of: combining a first laser output by a first laser device with a second laser output by a second laser device; dividing a combined beat note signal fb into a first beat note signal and a second beat note signal; mixing the first beat note signal fb and an ideal signal of which the frequency is f0 to obtain a difference frequency signal, namely the absolute value of fb-f0; due to a controllable bandwidth follow-up oscillator, generating a follow-up signal ft equal to the absolute value of fb-f0 under the follow-up bandwidth set by the follow-up oscillator; mixing the second beat note signal with the follow-up signal ft to output a difference frequency signal f0; and analyzing the difference frequency signal f0 to obtain the laser line width of the first laser device and / or the second laser device. Due to a circuit which is relatively simple, and by changing the servo bandwidth of the bandwidth-variable follow-up oscillator, the laser line width under a certain bandwidth of a narrow line width laser device and an ultra-narrow line width laser device can be measured.

Description

technical field [0001] The invention relates to laser line width measurement technology, in particular to a laser line width measurement method and equipment. Background technique [0002] Laser is widely used as a light source in various fields due to its characteristics of good monochromaticity, high brightness, strong directionality and strong coherence. The above characteristics of the laser can be attributed to its excellent narrow linewidth and good coherence compared with other light sources, so the output laser linewidth has become one of the important indicators for evaluating lasers. [0003] At present, the methods commonly used to measure the laser line width are as follows: [0004] (1) beat frequency measurement method [0005] Detect the beat frequency signals of the two lasers, and measure the linewidth of the beat frequency signals through a spectrum analyzer (spectrum analyzer, hereinafter referred to as: SA) or a dynamic signal analyzer (FFT), such as f...

AI Technical Summary

Problems solved by technology

[0019] However, for lasers with a wavelength that does not have a corresponding fiber amplifier, the linewidth cannot be measured by the loss-compensated time-delay self-heterodyne method

In addition, the line width broadening brought by the fiber amplifier, such as spontaneous emission, will reduce the accuracy of the line width measurement, and the phase noise brought by the fiber itself will also affect the line width measurement results

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