低噪声光纤激光器的实验研究

Experimental Study on Low-Noise Fiber Laser

光传感和光通信领域的迅速发展迫切需要相位噪声和强度噪声都很低的激光光源,为满足这一需求,设计出一种新型低噪声光纤激光器。激光器采用复合腔结构,以掺铒光纤作为工作物质,通过在未被抽运的掺铒光纤中形成的瞬态自写入光纤光栅的窄带滤波特性进行选模和压窄线宽,产生稳定的单频激光输出;经过光路改进,激光输出光谱信噪比优于62 dB;利用光电负反馈电路,弛豫振荡峰下降了约25 dB,低频段强度噪声也大为改善,有效地抑制了光源的强度噪声。激光器的输出光功率大于1 dBm,线宽小于1 kHz,边模抑制比超过50 dB。优异的低噪声特性使得该激光器在光传感和光通信领域具有重要的应用价值。

With the rapid progress of optical sensors and optical communications, the laser source with low phase noise and intensity noise is in urgent demand. To meet the needs, a novel low-noise fiber laser with compound cavity structure is designed. The stable single-mode operation is realized by using a transient self-written fiber grating, produced by the effect of saturable absorption within a section of unpumped erbium-doped fiber, as narrow band filter for mode selecting and linewidth squeezing. Through optical path modification, the spectral signal-to-noise ratio is better than 62 dB. With opto-electronic negative feedback, the intensity noise of the source is well suppressed, the intensity noise in the low frequency band is greatly improved and the relaxation oscillation peak is reduced with about 25 dB. The laser has an output power more than 1 dBm, linewidth less than 1 kHz, and side-mode-suppression ratio larger than 50 dB. The excellent noise property indicates that the source has important applications in optical sensors and optical communications.