Wide-Band Inline-Amplified WDM Transmission Using PPLN-Based Optical Parametric Amplifier

This article proposes an optical parametric amplifier (OPA), as an inline-repeater, using a periodically-poled-LiNbO3(PPLN) waveguide with over-10-THz amplification bandwidth, and also presents wide-band wavelength-division-multiplexing (WDM) inline-amplified transmission with the OPA. Our PPLN-based OPA is polarization-independent and has a spectrally efficient configuration by filtering phase-conjugated signals (idlers). We implemented our PPLN-based OPA with half its ideal configuration with an over-10-THz amplification bandwidth because of the limited number of PPLN waveguides. The implemented OPA had 5.125-THz amplification bandwidth, gain of beyond 15 dB, and noise figure of less than 5.1-dB. The gain excludes the 5.6-dB loss of an idler rejection filter employed in the transmission experiment so that the implemented OPA can compensate 9.5-dB link loss of transmission fibers and optical components. A 3 × 30.8-km inline-amplified transmission with 41-channel 800-Gbps WDM signal in 125-GHz spacing was successfully demonstrated using our PPLN-based OPA as an inline-repeater. The results also indicate that the OPA's amplification bandwidth can potentially be extended to 10.25 THz.