Research On Self-injection And Optical Phase-Locked Loop Locking Of Distributed Feedback Semiconductor Laser

Semiconductor lasers have many advantages,such as small size,low cost,easy adjustment,easy integration with other electronic devices.Distributed feedback(DFB)semiconductor lasers with good single longitudinal mode and narrow linewidth characteristics are widely used in coherent communication,high-precision detection and other fields.However,ordinary DFB semiconductor lasers still cannot meet the requirements of many applications such as ultra-narrow linewidth and high frequency stability.In this thesis,self-injection locking of DFB semiconductor laser based on fiber optical ring Resonator(OFRR)and optical phase-locked loop(OPLL)are studied.Based on the basic theory of optical feedback semiconductor laser,the influence of feedback power and feedback phase on laser output is calculated,and the corresponding influence laws are summarized.Considering the limitation of the optical feedback semiconductor laser theoretical model,we numerically solved the rate equations of semiconductor laser under OFRR self-injection locking,simulated the output characteristics of free running and self-injection locking semiconductor lasers,calculated the influence of feedback power and feedback phase on the output light of the laser,and summarized the corresponding influence rules.Self-injection locking of DFB semiconductor laser based on OFRR is investigated experimentally,the DFB semiconductor laser with 4MHz free running linewidth is reduced to about 20 k Hz after self-injection locking,the influence of feedback power and injection current on the output light of the laser is measured and analyzed,the locked time without mode hopping is measured.Based on the basic principle of optical balanced phase-locked loop,an optical balanced phase-locked loop based on real-time data acquisition and identification is designed.The scheme has the advantages of simple loop design,easy adjustment of feedback adjustment parameters and avoiding the influence of periodic sliding on phase demodulation.Two narrow linewidth fiber lasers are used to verify the feasibility of the OPLL design,the two lasers remain locked for more than 2 hours in the experiment,and the frequency stability is improved by three orders of magnitude compared with the free running condition.Applying the optical phase locked loop scheme designed in this paper to the locking of DFB semiconductor laser,it is necessary to overcome the difficulty that the output frequency is too sensitive to the change of current.