Enhanced stimulated four-wave mixing in a bipartite silicon resonator for phase mismatch switching

Four-wave mixing (FWM) in integrated photonic platforms requires phase matching, which typically limits the bandwidth and conversion efficiency. In this work, we experimentally demonstrate, for the first time, enhanced stimulated FWM in a bipartite silicon microring resonator, which maintains constructive accumulation of the FWM conversion in one segment and reduces the length of the destructive cancelation of the other when there is more than π phase difference between pump and signal/idler. The resonator is designed with two different segments to ensure the phase mismatch, thereby extending the effective interaction length for idler generation. The device achieves a maximum conversion efficiency improvement over a conventional resonator of 10.75 dB in the O-band and 4.94 dB in the C-band, with idler-pump frequency detunings of 11.4 and 10.8 THz, respectively. Moreover, the peak enhancement frequency can be tuned from 10.3 to 17.3 THz by adjusting the cavity length. The phase-mismatch switching (PMS) scheme exhibits robustness against dimensional variations and flexibility in pump wavelength selection. These results validate the PMS theory and highlight its potential for enhancing a wide range of nonlinear processes. The scheme is also applicable to other platforms like SiN and AlN, enabling wider use.