Integrated optical heterodyne interferometer in lithium niobate

A high performance integrated acousto-optical heterodyne interferometer has been developed for vibration measurement. All components including an acou sto-optical TE-TM mode converters, two electro-optical TE-TM converters, tw o polarization splitters and two phase shifters are integrated on a X-cut L ithium Niobate substrate. The fully packaged optical integrated circuit (op tical-IC) coupling with three fibers optics pigtails gave a signal-to-noise ratio of 69 dB with at 3 kHz bandwidth by using a commercial DFB laser dio de as a light source with 1561 nm emission wavelength and a PIN-FET balance d receiver.