長距離系光ネットワークへの伝送容量拡大の要求から，全光処理によって振幅•位相雑音抑制が可能である位相感応型増幅器(PSA)の信号再生器への応用が期待されている.本研究では2つのポンプ光による四光波混合(FWM)に着目している.この手法では高非線形ファイバ(HNLF)を利用した報告がなされているが，モノリシック集積と媒体長短縮が今後期待される.これまで，半導体光増幅器(SOA)のFWMに基づく PSA動作の実現可能性を数値解析により検討してきた.位相伝達関数とPSA利得曲線からSOA-PSAの基本特性を示し，加えてSOAの利得飽和領域で動作させることで，単一のSOA内で強度雑音と位相雑音を同時に抑制する手法を述べる.また長距離伝送により劣化した信号に対して信号再生を試み，40GbpsのRZ-DPSK信号に対してSOA-PSAによる雑音抑制とEVM向上の可能性を確認したので報告する.%In recent years, internet traffic is increasing every year, and therefore higher transmission capacity system is required. In this system, signal regenerators are necessary for enlarging transmission distance. However, it becomes difficult to overcome the issue of increment of power consumption as well as speed limitation with conventional electrical signal processing. Recently, much attention has been paid to a phase sensitive amplifier (PSA) as an all-optical signal regenerator for long-haul optical transmission system. PSA operation can be achieved using four wave mixing (FWM) which strongly occurs in a highly nonlinear fiber (HNLF). However, long device length of more than 100m is required. Thus, we have been investigating downsize of a nonlinear element by using a semiconductor optical amplifier (SOA). In this report, we present the fundamental property of PSA operation with input-output phase transfer function and PSA gain, and explain the method of simultaneous phase/intensity noise suppression in a gain saturated SOA. We also discuss an effect of phase noise suppression for a degraded 40Gbps RZ-DPSK signal which is transmitted in a long haul transmission system. We confirm the possibility of noise suppression and improvement of error vector magnitude by a SOA-PSA.
展开▼
