Long-term measurement of high Q optical resonators based on optical vector network analysis with Pound Drever Hall technique.

An optical vector network analysis (OVNA) based on double sidebands (DSB) modulation and the Pound Drever Hall (PDH) technique is proposed and demonstrated. The frequency responses measurement of the high Q optical device with high stability are achieved by transmitting the DSB modulation signals through the device. The high stability can be realized by using the PDH feedback loop. Compared with the conventional DSB-based OVNA, the proposed scheme with only one step measurement avoids the complex post-processing. Moreover, the long-term measurement with high stability can also be realized. A proof-of-concept experiment is carried out, which achieves the magnitude and phase responses of the Fabry-Perot interferometer, and there is no frequency response shift even though the test time is up to 90 minutes. The proposed method is simple and stable, which can be potentially applied in characterization and fabrication of high Q optical devices.