Photonic Millimeter-wave generation and transmission system applicable to the high-frequency radio interferometers

In the field of high-frequency radio interferometer, Atacama Large Millimeter/sub-millimeter Array (ALMA), its highest receiving frequency reaches 950 GHz. To receive such high frequencies, a higher reference frequency is required (as much as over 100 GHz). To maintain signal coherency, this reference signal has to be highly stable. To address these issues, we have developed a new method to generate and transmit a reference signal in the form of frequency difference between two coherent light waves. The two transmitted optical signals require phase stability better than 10^-13 (1 sec) in white phase noise in the Allan standard deviation.