Wang Zhixin, Kapsalidis Filippos, Wang Ruijun, Beck Mattias, Faist Jérôme
ETH Zürich, Institute of Quantum Electronics, Auguste-Piccard-Hof 1, Zürich, 8093, Switzerland.
Nat Commun. 2022 Jan 11;13(1):230. doi: 10.1038/s41467-021-27927-9.
Semiconductor lasers with extremely low threshold power require a combination of small volume active region with high-quality-factor cavities. For ridge lasers with highly reflective coatings, an ultra-low threshold demands significantly suppressing the diffraction loss at the facets of the laser. Here, we demonstrate that introducing a subwavelength aperture in the metallic highly reflective coating of a laser can correct the phase front, thereby counter-intuitively enhancing both its modal reflectivity and transmissivity at the same time. Theoretical and experimental results manifest a decreasing in the mirror loss by over 40% and an increasing in the transmissivity by 10. Implementing this method on a small-cavity quantum cascade laser, room-temperature continuous-wave lasing operation at 4.5 μm wavelength with an electrical consumption power of only 143 mW is achieved. Our work suggests possibilities for future portable applications and can be implemented in a broad range of optoelectronic systems.
具有极低阈值功率的半导体激光器需要小体积有源区与高品质因数腔相结合。对于具有高反射涂层的脊形激光器，超低阈值要求显著抑制激光器端面的衍射损耗。在此，我们证明在激光器的金属高反射涂层中引入亚波长孔径可以校正相位前沿，从而反常地同时提高其模式反射率和透射率。理论和实验结果表明，镜面损耗降低了40%以上，透射率提高了10%。在小腔量子级联激光器上采用这种方法，实现了在4.5μm波长下的室温连续波激光运转，功耗仅为143mW。我们的工作为未来的便携式应用提供了可能性，并且可以在广泛的光电子系统中实现。
