Quantum cascade lasers are, by far, the most compact, powerful, and spectrally pure sources of radiation at terahertz frequencies, and, as such, they are of crucial importance for applications in metrology, spectroscopy, imaging, and astronomy, among many others. However, for many of those applications, particularly imaging, tomography, and near-field microscopy, undesired artifacts, resulting from the use of a coherent radiation source, can be detrimental. Random lasers can offer a concrete technological solution to the above issue. They, indeed, maintain a high degree of temporal coherence, as traditional lasers, while only exhibiting low spatial coherence, which can allow for the prevention of coherent artifacts, such as speckles. In this study, we report on the development of one-dimensional THz-frequency random wire lasers, patterned on the top surface of a double-metal quantum cascade laser with fully randomly arranged apertures, not arising from the perturbation of a regular photonic structure. By performing finite element method simulations, we engineer photonic patterns supporting strongly localized random modes in the 3.05–3.5 THz range. Multimode laser emission over a tunable-by-design band of about 400 GHz and with ∼2 mW of peak power has been achieved, associated with 10° divergent optical beam patterns. The achieved performances were then compared with those of perturbed Fabry–Perot disordered lasers, showing continuous-wave operation in the 3.5–3.8 THz range with an order of magnitude larger average power output than their random counterpart, and an irregular far field emission profile.

中文翻译：

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一维表面发射无序太赫兹激光器

迄今为止，量子级联激光器是太赫兹频率下最紧凑，功能最强大，光谱最纯净的辐射源，因此，它们对于计量，光谱学，成像和天文学等应用至关重要。然而，对于许多这些应用，特别是成像，断层扫描和近场显微镜检查，使用相干辐射源导致的不良伪影可能是有害的。随机激光器可以为上述问题提供具体的技术解决方案。实际上，它们像传统激光器一样，保持高度的时间相干性，而仅表现出低的空间相干性，这可以防止诸如斑点之类的相干伪像。在这项研究中，我们报告了一维太赫兹频率随机线激光的发展，图案形成在双金属量子级联激光器的顶面上，该激光器具有完全随机排列的孔径，而不是由规则光子结构的扰动引起的。通过执行有限元方法仿真，我们设计出了支持3.05–3.5 THz范围内强局部随机模式的光子图案。已经实现了在约400 GHz的可调谐设计频带上的多模激光发射，并具有约2 mW的峰值功率，与10°发散的光束图案相关。然后将获得的性能与摄动的Fabry-Perot无序激光器的性能进行了比较，显示了在3.5–3.8 THz范围内的连续波操作，其平均功率输出比其随机同类产品大一个数量级，并且具有不规则的远场发射曲线。