The Noise Characteristics Of External Optical Feedback Semiconductor Laser

Fiber grating external cavity optical feedback semiconductor laser is used in high speed large capacity optical communication field,space coherent laser communication and light detection field widely.The development of this laser is very important to the improvement of our country's national defence capability and our science technology.The important factor which restrict the development of laser is laser's noise.The low noise laser could not only improve the transfer-length and transmission capacity of optical communication but also improve the abilit y of optical detection.The low noise laser that used widely on the market is solid-state laser and distributed feedback laser.The major defects of those lasers are high price,high production cost,high stability requirement on the environment.Because o f the low price,low production cost,low stability requirement on the environment that fiber Bragg grating external cavity optical feedback semiconductor laser has it's own potential application value and research prospects.This article is aimed on the influence of the frequency noise and phase noise of fiber grating external cavity optical feedback semiconductor laser,and can be divided into several parts as the theory of laser modeling,physical design,preparation.To suppress the noise characteristics of the fiber grating external cavity optical feedback semiconductor laser,by using a theoretical model of the external optical feedback semiconductor laser,combining the laser rate equation and linewidth theory,this article discussed the influences o f gain chip parameter and fiber Bragg grating parameter to laser's frequency noise and relative intensity noise under different injection current.Simulated results indicated: by changing the injection current and adjusting the size of active region,the s tructure of fiber Bragg grating and coupling coefficient,the frequency noise of the laser could be decreased about 5×108 Hz,the relative intensity noise of the laser could be decreased about 8 d B/Hz and the relaxation oscillation frequency of laser could be improved about 8 GHz in theory.By using epitaxial growth,photo etching,dry etching,O hmic contact and else technology,we designed a gain chip for semiconductor laser.By theoretical analysis,we chose fiber Bragg grating.The gain chip and fiber Bragg grating are coupled and packaged together as a butterfly encapsulation laser.We tested the output spectrum,power,phase noise,frequency noise,relative intensity noise of the laser.The results show that the central wavelength of fiber grating exter nal cavity optical feedback semiconductor laser at 35.40? 100 mA is 1549.0060 nm.The power of this laser is about 11 m W.The phase noise and relative intensity noise of the laser at 100 KHz is lower than-70 d Bc/Hz and-140 d B?We designed and manufactured a fiber grating external cavity optical feedback semiconductor by using theoretical analysis.In order to reduce the phase noise,frequency noise and relative intensity noise,we have been optimized the parameters of the laser.This study provides solid foundation to the wide use of fiber grating external cavity optical feedback semiconductor.