介绍了一种高精度1.55μm全光纤激光相干测速实验系统。实验系统采用光纤激光器作为激光源,利用光纤环行器与望远镜构成收发合置的光学天线,所有光学器件由单模光纤连接。数据处理采用快速傅里叶变换(FFT)频谱分析方法检测信号多普勒频移。利用该系统对转盘进行多次测速实验,速率测量的相对误差小于0.2%。同时对基于光纤激光器相干探测的主要低频噪声本振光强度噪声进行详细讨论,通过抽运驱动电流内调制法抑制本振光强度噪声后,系统的低速多普勒信号探测能力可提高2个数量级。 A high-precision 1.55μm all-fiber laser coherent speed experimental system is introduced. Experimental system uses fiber laser as a laser source, the use of fiber optic circulators and telescopes to form a combined receive and transmit optical antenna, all optical devices connected by a single-mode fiber. Data processing uses Fast Fourier Transform (FFT) spectral analysis to detect signal Doppler shift. Using this system to test the turntable several times, the relative error of the rate measurement is less than 0.2%. At the same time, the main low-frequency noise local light intensity noise based on the coherent detection of fiber laser is discussed in detail. By suppressing the local light intensity noise by the pumping internal current modulation, the low-speed Doppler signal detection capability of the system can be increased by two orders of magnitude .