Integrated quasi-phase-matched second-harmonic generator and electro-optic phase modulator for low-noise phase-sensitive amplification.

We propose a quasi-phase-matched second-harmonic generator integrated with an electro-optic phase modulator in a directly bonded LiNbO3 (DB-LN) waveguide to obtain high signal-to-noise ratio (SNR) pump light for a phase-sensitive amplifier (PSA). This integrated device exhibits 1-MHz modulation and 1-W second-harmonic-generation properties sufficient for phase-locking between the signal and pump and for PSA gain, respectively. A novel PSA configuration based on the high-input-power tolerance of the device helps to suppress the noise from the erbium-doped fiber amplifier used for pump-light generation and leads to an improvement of the SNR of the pump light. The SNR improvement was confirmed by comparing the noise figure of a PSA employing the DB-LN waveguide with that of a PSA using a Ti-diffused LN waveguide modulator.