以光纤光栅作为反射镜，将双偏振光纤激光器的一小部分输出光经光纤延迟线延迟后再反馈回激光腔,降低了拍频信号的相位噪声。结果表明：反馈时间越长，噪声降低的幅度越大。以50 m长的单模光纤作为延迟线，降低了双偏振光纤光栅激光器拍频信号20 dB以上的相位噪声，在10 kHz偏移处相位噪声达到-92 dBc/Hz的水平；光反馈的偏振态对外部光反馈系统的噪声抑制能力有影响，并对双偏振光纤激光器的拍频频率有微弱的调谐能力。

By using a fiber grating as a reflector, a small part of the dual-polarization fiber laser is delayed by the fiber delay line, and then fed back to the laser cavity, which can reduce the phase noise of beat frequency. Results show that the longer the feedback time is, the greater the noise reduction magnitude is. With a 50 m single mode fiber as the delay line, more than 20 dB phase noise reduction is achieved for a dual-polarization fiber grating laser, and a phase noise of -92 dBc/Hz at 10 kHz offset is achieved. The polarization state of optical feedback has influences on noise suppression capability of the external optical feedback system, and it has weak tuning capability to beat frequency of the dual-polarization fiber.