Self-calibrated electrical spectrum measurement of optical frequency comb based on segmental electro-optic up-conversion

A self-calibrated method is proposed for electrical spectrum measurement of optical frequency comb (OFC) based on segmental electro-optic up-conversion. In the method, every N comb teeth of OFC are divided into one segment in the frequency domain, and M segments are investigated with the measuring frequency range of M×N×fr (fr is the repetition frequency of the OFC). Through symmetric frequency modulation, intra-segment measurement and seamless stitching between different segments are performed. Finally, only a low-frequency microwave source is required to achieve the electrical spectrum measurement of OFC within ultra-wideband frequency range, and the measuring frequency range can be 2M-fold expanded with respect to the modulation frequency rang. Meanwhile, the frequency responses of MachZehnder modulator and photodetector are fully cancelled out, realizing the self-calibrated electrical spectrum measurement of OFC within ultra-wideband frequency range.