Opt Lett. 2018 Jul 1;43(13):3041-3044. doi: 10.1364/OL.43.003041.
An ultrahigh-resolution optical vector analyzer (OVA) is proposed and experimentally demonstrated based on microwave photonic frequency downconversion and fixed low-frequency electrical phase-magnitude detection. In the proposed OVA, two optical single-sideband (OSSB) signals are generated by two RF signals with a fixed frequency spacing. One propagates through an optical device under test (DUT) and is then combined with the other before entering to a low-speed photodetector. By photodetection, a low-frequency and frequency-fixed photocurrent carrying the spectral responses is achieved. Hence, a low-frequency electrical phase-magnitude detector is sufficient to extract the magnitude and phase. Sweeping the frequency of the RF signals, the spectral responses of the DUT can be obtained. As compared with the conventional OSSB- and optical double-sideband-based OVA, the proposed OVA avoids the use of high-speed photodetection and broadband electrical phase-magnitude detection. In addition, it is inherently immune to the measurement errors induced by high-order sidebands and has the capability of measuring arbitrary spectral responses. In an experiment, the proposed OVA is implemented based on an electrical phase-magnitude detector working at 10 MHz. The measurement resolution is 1 MHz, and the measurement range is larger than 45 GHz.
提出并实验演示了一种基于微波光子频率下变频和固定低频电相位幅度检测的超高分辨率光矢量分析仪（OVA）。在所提出的 OVA 中，两个射频信号具有固定的频率间隔，产生两个光学单边带（OSSB）信号。一个信号通过待测试光学器件（DUT）传播，然后与另一个信号在进入低速光电探测器之前进行组合。通过光电检测，获得了携带光谱响应的低频和固定频率的光电流。因此，低频电相位幅度检测器足以提取幅度和相位。扫频射频信号，即可获得 DUT 的光谱响应。与传统的基于 OSSB 和光学双边带的 OVA 相比，所提出的 OVA 避免了使用高速光电检测和宽带电相位幅度检测。此外，它固有地对由高阶边带引起的测量误差免疫，并且具有测量任意光谱响应的能力。在实验中，基于工作在 10MHz 的电相位幅度检测器实现了所提出的 OVA。测量分辨率为 1MHz，测量范围大于 45GHz。
