Research On Technology Of Frequency Stabilization Of Semiconductor Laser Based On F-P Cavity

Since the advent of semiconductor lasers, with the advantages of small size, theconversion efficiency, long service life, wide range of wavelengths, direct pumpedby low-power and low-current, working voltage and current compatible withintegrated circuits, they has been widely used in optical fiber communication, atomicfrequency standards, laser ranging, high-resolution laser spectroscopy, nuclearphysics, etc. But the laser output frequency to the driving current and work are verysensitive to temperature, spectral lines wider, stability is poorer, these weaknessesseverely restricting its practical application.In order to improve the stability of output frequency of semiconductor laser,according to the external cavity optical feedback frequency stabilization technique, afrequency stabilization control system based on F-P confocal interferometer has beendevised. The control system based on MSP430microcontroller takes the centerfrequency output by F-P confocal interferometer as the base frequency and has mainparts.1. F-P confocal interferometer control part. As the laser frequency is too highthat they can’t be measured directly, so frequency need be modulated. In this section,the interferometer will be given an auto scanning voltage. The laser frequency willbe modulated when the cavity length of the interferometer has been modulated.2. Optical receiving part. A PIN silicon photodiode has been used in the systemto convert the optical signal of the modulated spectrum. The converted signal wouldbe sent to lock-in amplifier to get laser frequency deviation. At last, the deviationwill be sent to SCM.3. The power supply system. A controlled current source has been designed forlaser. At the same time, this current source can adjust the size of the currentaccording to the feedback of the spectrum signal to realize the laser frequencystability. 4. Temperature control part. This part based on semiconductor cooler and SCMdrives by PWM and makes temperature stability by PID algorithm.Finally, the entire system is connected and tested in different environment. Thesystem frequency stability reached on10-7, and the reproducibility is also high.