Self-Calibrated Coherent Optical Vector Analysis With High Resolution and Sensitivity

Measurement of the frequency response of sensors and devices with high-frequency resolution and sensitivity is of great importance for high-sensitive trace gas detection, high-quality photonic circuit fabrication, etc. Optical vector analysis (OVA) based on microwave photonics (MWPs) offers outstanding frequency resolution. However, the sensitivity of the incoherent detection system is usually limited. This article proposes a self-calibrated coherent OVA system that leverages MWP technology. The laser phase noise, which is the leading challenge in coherent detection, is compensated through a self-calibration process. Employing precise microwave sweeping paired with a highly stable laser, the proposed system achieves a theoretical frequency resolution at the level of hertz. In the experiments, we demonstrate a sensitivity improvement of at least 35 dB over the incoherent system. In addition, the proposed OVA system offers superior frequency resolution and accuracy compared to commercial coherent OVA products.