在光电子器件散射参量定义的基础上建立了基于直接扣除法的半导体光放大器频率响应测量系统,测量中通过扣除激光器和探测器系统的频率响应,得到放大器固有的频率响应。对InGaAsP体材料行波腔半导体光放大器样品进行了测量,得到了放大器在不同注入光功率和不同偏置电流下的频率响应曲线。这些曲线很好地反应了半导体光放大器的增益饱和和噪声特性,进一步分析发现半导体光放大器对低频调制信号的放大能力弱于对高频信号的放大能力,分析认为其原因在于半导体光放大器的载流子寿命有限导致低频信号长时间消耗载流子时,载流子数量无法及时恢复,从而使得增益降低。

A frequency response measuring system of semiconductor optical amplifiers based on direct-subtracting method is proposed according to the definition of scattering parameters of optoelectronic devices. By subtracting the frequency response of laser-photodetector system, the frequency response of an semiconductor optical amplifier its own can be obtained. With this system an InGaAsP traveling-wave semiconductor optical amplifier is measured under different input optical powers and different bias currents, and the frequency response curves are calculated. These curves indicate the gain saturation effect and the noise characters of the semiconductor optical amplifier. Moreover, it is shown that the signal gain of lower frequencies is less than that of higher frequencies. The reason is the carrier lifetime of semiconductor optical amplifier is limited. Lower-frequency signals have longer period to deplete carriers continuously, therefore the number of carriers cannot resume in time.