非均匀分布反馈半导体光放大器的动态双稳特性

Analysis on the Bistable Dynamic Characteristics of Nonuniform Distributed Feedback Semiconductor Optical Amplifiers

分布反馈半导体光放大器(DFB-SOAs)具有较低的双稳上跳阈值,因而在光学信息处理方面有一定的应用前景。引入空间相移、啁啾等非均匀性后,其双稳特性可得到进一步改善。由于系统的传输速率受到脉冲下降沿形变及开启延时的限制,因此对其动态双稳特性的研究很有必要。从耦合模方程及载流子速率方程出发,数值分析了相移、啁啾分布反馈半导体光放大器的动态双稳特性。结果表明,相移使出射脉冲下降沿的形变及开启延迟随初始失谐量的减小呈现先恶化后缓和的趋势,引入啁啾可明显抑制脉冲下降沿的形变,但是增加了开启延迟所需的功率过载量。

Distribution feedback semiconductor optical amplifiers (DFB-SOAs) have potential applications in optical signal processing because of lower switching-on threshold of bistability. By introducing spatial phase-shift and chirp, its bistable performance can be improved. If the amplifier operates at pulse state, signal transmission rate would be affected by the falling-edge distortion of output pulse and turn-on delay, so it is necessary to study its dynamic properties. In this paper, based on the coupled mode equation and carrier rate equation, the bistable dynamic characteristics of phased-shifted and chirped distributed-feedback semiconductor optical amplifiers have been investigated numerically. The results show that, the phase-shifted DFB-SOAs make the shape distortion of falling edge and turn-on delay of output pulse worsened firstly and then weakened with the decreased initial detuning, which can be suppressed by introducing chirp but being accompanied by the enhanced input peak overdrive.