Optical Transmission Signal Phase Compensation Method Using an Image Rejection Mixer

In the field of large-scale radio interferometers, there is a growing need for the photonic highly stable signal generation and distribution system. To maintain signal coherency of the distributed reference-frequency signal, the photonic phase compensation technique is indispensable. To address this issue, we have developed a new method to transmit a reference signal in the form of frequency difference between two coherent light waves. The proposed low-frequency signal optical transmission method is suitable for an optical transmission at a low frequency equal to or lower than 20 GHz, which optically enables a long-distance transmission by compensating a phase delay amount caused by the transmission. This method has external-influences resistance. The system can be applied to a signal transmission field with the objective of achieving high stability of the reference signal transmission, such as an interferometer, or the transmission or distribution of the highly stable signal according to, for example, the national frequency standard or applied to a field involving a problem of the transmission delay.