Dual-wavelength light source assisted frequency response measurement of photodetectors based on double-sideband suppressed-carrier modulation is proposed in this letter. In this method, a directly modulated laser with a modulation frequency of $f_{1}$ combined with an optical tunable filter is used to generate a dual-wavelength carrier, which can be highly stable since only one light source is introduced. The dual-wavelength carrier generates two pairs of first-order sidebands under double-sideband suppressed-carrier modulation of the Mach-Zehnder modulator at frequency $f_{m}$ . Afterwards, the modulated signal is injected into the photodetector under test, and the frequency response of the photodetector can be extracted by recording the electric power at specific frequencies. Based on this method, we used a 35-GHz modulator to measure the frequency response of photodetectors with bandwidth of 15 GHz and 43.5 GHz respectively. Moreover, a comparison of the results is performed between our method, the swept frequency method, and electro-absorption modulator deduction method. The results show that the new method extends the frequency response measurement range from $f_{m}$ to $f_{1}+2f_{m}$ , and the influence of the modulator on the frequency response measurement results is reduced simultaneously.

中文翻译：

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光电探测器双波长光源辅助频率响应测量方法

本文提出了基于双边带抑制载波调制的双波长光源辅助光电探测器频率响应测量方法。在这种方法中，直接调制的激光器的调制频率为 $f_{1}$ 结合光学可调滤光片用于生成双波长载波，由于仅引入一个光源，因此可以高度稳定。双波长载波在Mach-Zehnder调制器的双边带抑制载波调制下产生两对一阶边带频率 $f_{m}$ . 之后，调制信号注入被测光电探测器，通过记录特定频率的电功率，可以提取光电探测器的频率响应。基于该方法，我们使用35-GHz调制器分别测量带宽为15 GHz和43.5 GHz的光电探测器的频率响应。此外，在我们的方法、扫频方法和电吸收调制器推导方法之间进行了结果的比较。结果表明，新方法将频响测量范围从 $f_{m}$ 至 $f_{1}+2f_{m}$ ，同时降低调制器对频响测量结果的影响。