28 GHz single-mode surface-grating, surface-emitting laser based on wavelength detuning for mode-hopping suppression.

The rapid growth of data traffic in artificial intelligence and data center applications is placing increasingly stringent demands on the modulation bandwidth of optical interconnects while maintaining their established transmission reach. Surface-emitting lasers have been widely deployed in such short-reach links, owing to their low cost, low power consumption, and inherent scalability. Among them, single-mode surface-emitting lasers are particularly attractive, because their narrow spectral linewidth enables higher data rates without sacrificing transmission distance in both multimode and single-mode fibers, while their stable emission wavelength facilitates wavelength-division multiplexing using multi-wavelength arrays. In this work, we propose and demonstrate a surface-grating surface-emitting laser that employs wavelength detuning in the phase-shift section of the second-order grating to suppress longitudinal mode hopping. The fabricated device achieves stable single-mode operation up to 15 mA with a side-mode suppression ratio of 55 dB, a maximum output power of 4.4 mW-a twofold improvement over previously reported horizontal-cavity surface-emitting lasers-and a small-signal modulation bandwidth of 28 GHz at a bias current of 12 mA. These results suggest that the wavelength-detuned surface-grating surface-emitting laser is a promising approach for high-speed short-reach optical interconnects.