Phase-sensitive cascaded second-harmonic generation and difference-frequency generation in a periodically poled lithium niobate waveguide allow converting two orthogonal quadratures of an optical field to different wavelengths, thus enabling simultaneous quadrature phase-shift keying-to- \(2\times \) binary phase-shift keying modulation format and wavelength conversions. Static phase-sensitive extinction ratios above 20 dB are obtained for both quadratures, resulting in error-free dynamic operation with low penalty (BER (10-9) ) at 10 Gbaud.
- Phase shift keying
- Nonlinear optics
- Periodically poled lithium niobate (PPLN)
- Phase-sensitive amplification