Simultaneous QPSK-to-2×BPSK wavelength and modulation format conversion in PPLN
Résumé
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×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 1e−9) at 10 Gbaud.