单块非平面环形腔激光器的强度噪声抑制技术研究

Suppression of the intensity noise of monolithic non-planar ring oscillator laser

研究了LD泵浦1319nm单块非平面环形腔(NPRO)激光器的强度噪声特性,发现随着输出功率的增加,弛豫振荡峰频率从100kHz向280kHz移动,同时弛豫振荡峰宽度增加但幅度降低,且在弛豫振荡峰处发生π相位跃变,在600kHz以上频率区域,噪声已经接近量子噪声极限。自行设计的噪声抑制电路在实现足够大增益的同时,在500kHz附近获得了约65°的相位超前,由此获得了优于通常同类实验的噪声抑制结果:当弛豫振荡峰频率为230kHz时,弛豫振荡峰处和低频区域的强度噪声幅度分别被抑制了45dB和20dB。

The intensity noise properties of LD-pumped Nd：YAG non-planar ring oscillator （NPRO） laser are experimentally investigated. The increase of the laser output power induces the increase of the frequency of the relaxation oscillation noise （RON） peak from 100 kHz to 280 kHz and the width of the noise spectrum increase. Simultaneously the RON peak value decreases and the phase of π changes across the RON peak. The homemade optoelectronic feedback circuit can provide an adequate gain and a big phase advance of 650 at 500 kHz. Using the circuit, a result better than common results is achieved. For the noise with a RON frequency of 230 kHz, the experiment results show that the RON peak value and low frequency intensity noise are reduced about 45 dB and 20 dB, respectively.