Topological robustness of a high-power narrow linewidth semiconductor laser based on the Su-Schrieffer-Heeger model.

Narrow-linewidth semiconductor lasers utilizing surface high-order Bragg gratings frequently encounter the issue of reduced output power. Many microstructures are used to improve the device output power, but correspondingly, more stringent requirements are put forward for the process tolerance. Fortunately, topology theory provides a new approach to robust laser design. Here, based on the three-defect Su-Schrieffer-Heeger (SSH) model derived from the one-dimensional SSH model, a robust high-power electrically pumped laser with narrow linewidth is demonstrated by I-line lithography. By finely adjusting the adjacency distance of the three-defect waveguide, the coupling of supermodes, with the exception of the topological zero-energy state with side array, is realized. Combined with selective pumping, single-lateral mode operation is achieved. Moreover, a 27-order grating is introduced over the three-defect waveguide to ensure single-longitudinal mode operation. Then, the robustness of the designed three-defect SSH slotted laser is verified by simulation and experiment, indicating that our laser can achieve high-power narrow linewidth output, while avoiding the problem of small process tolerance caused by the added microstructure. The device exhibits an output power of 54.6 mW, a lasing wavelength of 1552.94 nm, a side-mode suppression ratio (SMSR) of 40.4 dB, and a linewidth of 2 MHz at 300 mA, thus holding significant potential for mass production of high-performance laser sources that satisfy the demands of coherent optical communication and laser radar.