title: First demonstration of high-order QAM signal amplification in PPLN-based phase sensitive amplifier.
abstract: We demonstrate the phase sensitive amplification of a high-order quadrature amplitude modulation (QAM) signal using non-degenerate parametric amplification in a periodically poled lithium niobate (PPLN) waveguide. The interaction between the pump, signal, and phase-conjugated idler enables us to amplify arbitrary phase components of the signal. The 16QAM signals are amplified without distortion because of the high gain linearity of the PPLN-based phase sensitive amplifier (PSA). Both the phase and amplitude noise reduction capabilities of the PSA are ensured. Phase noise cancellation is achieved by using the interaction with the phase-conjugated idler. A degraded signal-to-noise ratio (SNR) is restored by using the gain difference between a phase-correlated signal-idler pair and uncorrelated excess noise. The applicability of the simultaneous amplification of multi-carrier signals and the amplification of two independent polarization signals are also confirmed with a view to realizing ultra-high spectrally efficient signal amplification.
authors.forename: T
authors.initials: T
authors.lastname: Umeki
authors.forename: O
authors.initials: O
authors.lastname: Tadanaga
authors.forename: M
authors.initials: M
authors.lastname: Asobe
authors.forename: Y
authors.initials: Y
authors.lastname: Miyamoto
authors.forename: H
authors.initials: H
authors.lastname: Takenouchi