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为了满足激光干涉成像,尤其是傅里叶望远镜成像对差频稳定的高功率光学外差干涉模式的需要,提出基于主振功放(MOPA)结构的光学外差干涉激光器的概念,并通过实验验证可行性。从原理上指出现有产生光学外差干涉模式方法的局限性,同时给出基于MOPA结构的光学外差干涉激光器的主要优点。指出基于MOPA结构的激光器可能存在明显影响相干性和产生光频漂移等的限制并设计实验验证。结果表明:功率放大过程对相干性没有明显影响,经过单级功放仍能保持线宽小于0.1GHz(根据实测相干长度计算线宽约30MHz),功放过程和倍频过程对光频漂移无影响,实测频漂小于10Hz,与声光移频器的频率稳定性相吻合,故推知频漂完全由移频器引起。
In order to meet the needs of high-power optical heterodyne interferometry with poor frequency stability by laser interferometry imaging, especially Fourier telescope imaging, the concept of optical heterodyne interference laser based on the main oscillator power amplifier (MOPA) structure is proposed and verified by experiments feasibility. The limitations of the existing methods of generating optical heterodyne interference modes are pointed out in principle, and the main advantages of the optical heterodyne interference laser based on the MOPA structure are also given. It is pointed out that the laser based on MOPA structure may have some limitations that affect the coherence and produce optical frequency drift obviously. The results show that the power amplification process has no significant effect on the coherence. The single-stage power amplifier can still keep the linewidth less than 0.1GHz (the linewidth is about 30MHz according to the measured coherence length). The power amplifier process and frequency doubling process have no effect on the optical frequency drift, The measured frequency drift is less than 10Hz, which is consistent with the frequency stability of the acousto-optic frequency shifter. Therefore, the frequency drift is estimated to be caused by the frequency shifter.