Plasmonic lasers suffer from low output power and divergent beams due to their subwavelength metallic cavities. We developed a phase-locking scheme for such lasers to significantly enhance their radiative efficiency and beam quality. An array of metallic microcavities is longitudinally coupled through traveling plasmon waves, which leads to radiation in a single spectral mode and a diffraction limited single-lobed beam in the surface normal direction. We implemented our scheme for terahertz plasmonic quantum-cascade lasers (QCLs) and measured peak output power in excess of $2\,\,{\rm{W}}$ for a single-mode $3.3\,\,{\rm{THz}}$ QCL radiating in a narrow single-lobed beam, when operated at $58\,\,{\rm{K}}$ in a compact Stirling cooler. We thereby demonstrated an order of magnitude increase in power and thirty-times higher average intensity for monolithic single-mode terahertz QCLs compared to prior work. The number of photons radiated from the cavity outnumber those absorbed within its claddings and semiconductor medium, which constitutes ${\gt}50 \%$ radiative efficiency and is significantly greater than that achieved for previous single-mode mid-infrared or terahertz QCLs.

中文翻译：

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单光谱模式下具有2 W输出功率的锁相太赫兹等离子体激元激光器阵列

等离子激光器由于其亚波长金属腔而遭受低输出功率和发散光束的困扰。我们针对此类激光器开发了一种锁相方案，以显着提高其辐射效率和光束质量。金属微腔阵列通过行进的等离激元波纵向耦合，从而导致单光谱模式的辐射和表面法线方向上受衍射限制的单瓣光束。我们为太赫兹等离子体激元量子级联激光器（QCL）实施了我们的方案，并针对单模$ 3.3 \，\，{\ rm {THz }测量了超过$ 2 \，\，{\ rm {W}} $的峰值输出功率}} $以$ 58 \，\，{\ rm {K}} $操作时，QCL以窄单瓣波束辐射在紧凑的斯特林冷却器中。因此，我们证明了与以前的工作相比，单片单模太赫兹QCL的功率增加了一个数量级，平均强度提高了三十倍。从空腔辐射的光子数量超过了在其包层和半导体介质中吸收的光子数量，构成了50％的辐射效率，并且大大高于以前的单模中红外或太赫兹QCL。