Narrow Linewidth Semiconductor Laser Based On Fiber Bragg Grating Self-injection Locking

With the development of ultra-high speed optical interconnection,coherent optical communication and coherent detection technology,more stringent requirements have been put forward for laser linewidth,phase noise,tunability and stability.Narrow linewidth semiconductor lasers are the core source of high speed optical communication,coherent space laser communication and coherent optical detection.Because of their high coherence and high monochromatic properties,they are attracting much attention in recent years.With the improvement of semiconductor laser technology,we need to filter the output light and select the frequency in order to get the ideal narrow linewidth output laser,so as to improve the linewidth characteristic.Fiber grating external cavity semiconductor laser has been widely studied in recent years due to its unique advantages such as wide spectral line width,wide tuning range,high output power,small volume and low cost.In this paper,a narrow linewidth semiconductor laser based on self-injection locking of fiber Bragg grating is experimentally studied,and the stable narrow line width output light of 1550 nm band is obtained.This paper introduces the application field of narrow linewidth laser first,makes a comparative study of the status and characteristics of narrow linewidth lasers of various structures,and then describes the locking principle and mode selection principle of narrow linewidth semiconductor laser with self-injection locking of fiber Bragg grating,analyzes the factors of the output characteristics and influence.On the basis of the related theory,the effect of using fiber Bragg grating as the external cavity selection element to narrow the line width and reduce the noise is discussed.Through the design and manufacture of semiconductor laser chip preparation,we finally get the butterfly packaged fiber grating self-injection locked semiconductor laser.Analyzing the characteristics of narrow linewidth semiconductor laser with selfinjection locking of fiber Bragg grating,including spectral characteristics,noise characteristics,I-V-P characteristics,the relationship between noise and linewidth variation with current,temperature and current,temperature and wavelength,We analyzed the influence of injection current and temperature on laser output.Under the driving current of 20-100 mA,a stable 1550 nm band,narrow linewidth and low noise laser output can be obtained,the output power is over 10 mW,the side mode rejection ratio is greater than 50 dB,and the Lorenz line width is less than 1kHz,and the performance parameters are competitive compared with the similar products on the market.Accordingly,we propose optimized schemes for the narrow linewidth laser of the structure,so that the laser can meet higher requirements in the application field.