Chirped Periodically Poled ${\rm LiNbO}_{3}$ Wavelength Converter With Apodization Structure

We developed a periodically poled LiNbO
₃
wavelength converter with its nonlinear coupling strength changed along the propagation length to improve the quasi-phase-matched (QPM) wavelength bandwidth. The apodization is realized by sampling the QPM grating to attain fabrication easiness. The wavelength response showed a broad and flat-top wavelength conversion characteristic in a second harmonic generation. The QPM bandwidth of the wavelength conversion was 2.2 nm, which is sufficiently broad to convert optical pulses for a 160-Gb/s system.