Tailoring performance through loss engineering in ring-waveguide lasers for enhanced Single-Mode lasing

Loss engineering is a valuable approach for controlling the properties of ring-waveguide lasers. By carefully adjusting the waveguide’s loss parameters, it is possible to create customized lasers with improved performance for specific applications. In this study, we present the fabrication, characterization, and simulation of a ring-waveguide laser with loss-engineering capabilities. Initially, we optimized the waveguide’s cross-section to reduce scattering loss caused by side-wall roughness, achieving a low loss of 0.03 dB/cm. Next, we investigated the effect of the coupling coefficient on the lasing properties of the device by varying the gap between the waveguide and the resonator. Our experimental results demonstrate that by fine-tuning the coupling coefficient, we can achieve single-mode lasing with an impressive side-mode suppression ratio (SMSR) of over 47 dB at a wavelength of 598 nm. These findings offer valuable insights into loss-engineering techniques for ring-waveguide lasers and showcase the potential for single-mode emission lasers with high stability, which can be applied in various fields.