Segmental Measurement of High-Speed Photodiodes Based on Pre-Definable Electro-Optic Frequency Comb

A segmental method utilizing a pre-definable electro-optic frequency comb (EOFC) is proposed for characterizing the frequency response of high-speed photodiodes (PDs). The EOFC is generated through frequency shifting and phase modulation of a continuous light wave, with the comb teeth defined by adjusting the electrical power applied to the electro-optic phase modulator (EOPM). By employing the Jacobi-Anger identity, the uneven comb teeth of the EOFC can be equalized. The EOFC signal is combined with a sweeping optical signal produced by an electro-optic modulator (EOM) to create a segmental up-conversion stimulus for probing the PD under test. This approach allows for scalable measurements of PDs across a frequency range exceeding ten times the sweeping frequency of the EOM. A proof-of-concept experiment demonstrates the feasibility of the proposed method, achieving a measurement frequency range of 70 GHz when the frequency is swept up to 7 GHz. The consistency observed between the proposed method and conventional techniques validates the efficacy of frequency response measurements for PDs, showcasing a segmental and scalable capacity based on the pre-definable EOFC.