Enhanced Thermal Management in Semiconductor Lasers via Distributed Waveguide Design

Semiconductor lasers are indispensable in modern photonics due to their high efficiency and compact form factor. However, their performance is fundamentally constrained by self-heating, which limits output power, efficiency, and device lifetime. Although increasing cavity length can theoretically improve thermal dissipation, high-power GaAs lasers experience severe performance degradation beyond 5-6 mm due to spatial hole burning and nonlinear effects. Here, we introduce a distributed waveguide (DWG) architecture that redefines long-cavity semiconductor laser design, overcoming the traditional cavity-length barrier and enabling efficient heat dissipation without compromising optical performance. The DWG approach electrically isolates lasing and secondary sections for independent current control while preserving optical coupling, thereby extending functionality beyond conventional semiconductor laser designs. The lasing sections generate the laser output, while secondary sections, biased near the lasing threshold, act as auxiliary thermal pathways with negligible heat generation. By leveraging these secondary sections for enhanced thermal management, DWG provides unprecedented control over cavity length, heat dissipation, and potentially device reliability. Experimental and numerical results demonstrate that extending the cavity length from 4 to 8 mm using DWG reduces junction temperature rise by half, with possible further reductions through optimized DWG design. These findings establish DWG as a disruptive innovation in photonic waveguide engineering, providing a scalable platform for high-efficiency, high-reliability semiconductor laser architectures.