A Frequency Shifting Scheme for On-chip Optical Frequency Transfer

SummaryWe report a frequency shifting scheme for on-chip optical frequency transfer with low external circuit requirements. Serrodyne modulation method is used to achieve frequency shifting with high carrier and sideband suppression ratios for optical carriers, and the method is also suitable for a wide range of integrated platforms. We first demonstrate the feasibility of the scheme using a commercial phase modulator, which is able to produce a frequency shift of over 1 MHz, a carrier suppression ratio of over 50 dB, a sideband suppression ratio of over 37 dB and a conversion loss of about 0.08 dB. We also design a phase modulator on thin film lithium niobate platform with a low half wave voltage about 2.18 V, which greatly reduces the requirements of the external circuit voltage for frequency shifting, and can achieve a frequency shift above 1 GHz. Our proposed scheme verifies the feasibility of on-chip frequency shifting with low loss and high suppression ratio, and paves the way for the integration of optical frequency transfer systems.