In this paper, the amplified spontaneous emission (ASE) intensity of a distributed feedback laser diode (DFB-LD) amplified by a semiconductor optical amplifier (SOA) is calculated, and the signal-to-spontaneous emission ratio (SSER) is investigated assuming a wavelength tunable laser. Based on a formulization appropriate for an active layer under a low excitation, the theoretical limit of the SSER of the SOA is obtained, and the SSER including the ASEs from both the DFB-LD and the SOA is numerically calculated. The side mode suppression ratio (SMSR) taking the spectral distribution into consideration is also calculated by expanding the same method.

中文翻译：

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半导体光放大器辅助分布式反馈激光二极管放大自发射的理论计算

在本文中，计算了由半导体光放大器 (SOA) 放大的分布式反馈激光二极管 (DFB-LD) 的放大自发发射 (ASE) 强度，并研究了信号自发发射比 (SSER)，假设为波长可调激光器。基于适用于低激发下有源层的公式，获得了 SOA 的 SSER 的理论极限，并数值计算了包括来自 DFB-LD 和 SOA 的 ASE 的 SSER。考虑光谱分布的边模抑制比（SMSR）也通过扩展相同的方法来计算。