Polarization selectivity in single-mode photonic molecule lasers

An efficient approach to achieve single-polarization selectivity in single-mode double microring lasers (photonic molecule lasers) is presented in this study. The fabricated microring lasers achieved polarization extinction ratios of 11.3 dB for TM polarization and -12.8 dB for TE polarization. The fabrication process was conducted by direct laser writing on SU-8 photoresist doped with Rhodamine B dye. In order to obtain an optimum single-mode operation with a specified polarization capability, the study employs Vernier effect double microring lasers and investigates the effects of geometric characteristics, surface scattering loss, and coupling efficiency on polarization performance. The finite-difference time-domain method was utilized to conduct simulations, and the results were verified experimentally. The proposed single-polarized microring lasers provide open possibilities for advanced integrated photonic systems with potential applications in quantum photonics, nonlinear optics, and optical sensors.