A novel solution of frequency locking in homodyne coherent receiver

A novel solution of frequency locking based on beat frequency detection in homodyne coherent receiver is presented and experimentally demonstrated. The beat frequency detection, using two beat frequency signals generated by a balance detector module, is easily to eliminate the noise introduced during long distance transmission. Furthermore, FPGA, as the core of the control unit, is adopted to change the resulting frequency of OVCO on the basis of the frequency deviation. The proposed scheme is tested more efficiency and higher stability than the previously single path feedback loop.