Photonic mixer for photonically multiplying two electrical signals in two optically interconnected interferometric modulators operated at modulation outside the linear range

摘要

A Mach-Zehnder modulator (MZM), which divides a CW laser beam into two optical portions, is biased at a 180° phase difference between the two optical portions. An RF signal and an LO signal are simultaneously applied to one of the optical portions of the laser beam to produce phase changes between the two optical portions. The two optical portions of the laser beam are then recombined into an optical output beam, which is detected by a photodetector. The photodetector generates a photocurrent, which contains a component at a beat frequency-- i.e., the frequency difference between the RF and LO frequencies. The waveform of the photocurrent component at the beat frequency is substantially the same (except for amplitude and a fixed phase shift) as the waveform of the RF signal.