Performance evaluation of an X-cut Ti: LiNbO 3 waveguide traveling-wave phase modulator

Coherent lightwave detection techniques, particularly coherent phase shift keying (PSK), offer among other advantages a significant improvement in receiver sensitivity over direct detection.1 To achieve this sensitivity gain in a coherent PSK system a low-loss broadband phase modulator is required. Recently such a modulator was successfully employed in a heterodyne differential phase-shift keyed (DPSK) experiment at data rate of 1 Gb/s.2 Both the design and fabrication of this X-cut Ti:LtNbO3 waveguide traveling-wave phase modulator were described at the Optical Fiber Conference in Atlanta, Ga., 1986,3 Here we report the performance evaluation of a similar X-cut traveling-wave phase modulator using two different