Realizing large-scale single-mode, high-power, high-beam-quality semiconductor lasers, which rival (or even replace) bulky gas and solid-state lasers, is one of the ultimate goals of photonics and laser physics. Conventional high-power semiconductor lasers, however, inevitably suffer from poor beam quality owing to the onset of many-mode oscillation^1,2, and, moreover, the oscillation is destabilized by disruptive thermal effects under continuous-wave (CW) operation^3,4. Here, we surmount these challenges by developing large-scale photonic-crystal surface-emitting lasers with controlled Hermitian and non-Hermitian couplings inside the photonic crystal and a pre-installed spatial distribution of the lattice constant, which maintains these couplings even under CW conditions. A CW output power exceeding 50 W with purely single-mode oscillation and an exceptionally narrow beam divergence of 0.05° has been achieved for photonic-crystal surface-emitting lasers with a large resonant diameter of 3 mm, corresponding to over 10,000 wavelengths in the material. The brightness, a figure of merit encapsulating both output power and beam quality, reaches 1 GW cm⁻² sr⁻¹, which rivals those of existing bulky lasers. Our work is an important milestone toward the advent of single-mode 1-kW-class semiconductor lasers, which are expected to replace conventional, bulkier lasers in the near future.

实现大规模单模、高功率、高光束质量的半导体激光器，与笨重的气体和固体激光器相媲美（甚至取代），是光子学和激光物理的最终目标之一。然而，传统的高功率半导体激光器由于多模振荡的出现，不可避免地会出现光束质量差的问题^1,2，而且，连续波 (CW) 操作下的破坏性热效应会导致振荡不稳定^{3, 4}。在这里，我们通过开发大规模光子晶体表面发射激光器来克服这些挑战，该激光器在光子晶体内部具有受控的厄米和非厄米耦合以及预先安装的晶格常数空间分布，即使在连续波条件下也能保持这些耦合。光子晶体表面发射激光器具有超过 50 W 的纯单模振荡连续输出功率和 0.05° 的超窄光束发散度，谐振直径为 3 mm，对应于材料中的 10,000 多个波长。亮度（包含输出功率和光束质量的品质因数）达到1 GW cm ^-2  sr ^-1，可与现有的大型激光器相媲美。我们的工作是单模 1 kW 级半导体激光器问世的一个重要里程碑，预计该激光器将在不久的将来取代传统的、体积更大的激光器。