半導体光増幅器での強度雑音と周波数雑音の理論解析

摘要

A theoretical analysis of the intensity and the frequency noise in semiconductor optical amplifiers (SOA) is given. Amplification of a traveling optical wave is formulated associating yith fluctuations on the optical intensity, the optical phase and the electron numbers based on the classical wave-equation and quantum mechanical modification. Inclusion of the amplified spontaneous emission generated in the SOA is also taken into account. Amounts of noise are expressed in terms of the relative intensity noise (RIN), the spectrum line-width and the frequency noise (FM noise). Sensitive dependency of the RIN property on the optical input power is theoretically explained. The RIN increases after passing the SOA when the optical input power is small enough, but decreases when the optical input power is rather high. On the while, the spectrum line-width is found to be scarcely changed from the input light for conventional operation of the SOA.%半導体光増幅器(SOA)における強度雑音と周波数雑音を理論解析した。揺らぎをともなった伝播光の増幅作用を古典的波動方程式に量子論的修正を加えて定式化した。SOA自身が発生する増幅された自然放出光(ASE)の混入も考慮しており、強度雑音は相対強度雑音（RIN)、周波数雑音は信号光の線幅で記述した。入射光の電力による出射光RINの変化を理論的に説明した。入射光電力が小さい場合、出射光のRINは増加するが、入射光電力がある程度大きい場合は、出射光のRINは入射光よりも減少する。また、信号光の線幅はSOAで増幅しても変化しない。