We demonstrate that electrically pumped random laser resonators, operating at terahertz (THz) frequencies, and comprising a quantum cascade laser heterostructure, can operate as sensitive photodetectors through the self-mixing effect. We devise two-dimensional cavities exploiting a disordered arrangement of surface holes that simultaneously provide optical feedback and allow light out-coupling. By reflecting the emitted light back onto the surface with random holes pattern, and by varying the external cavity length, we capture the temporal dependence of the laser voltage, collecting a rich sequence of interference fringes that follow the bias-dependent spectral emission of the laser structure. This provides a visible signature of the random laser sensitivity to the self-mixing effect, under different feedback regimes. The latter effect is then exploited, in the near-field, to demonstrate detectorless scattering near-field optical microscopy with nanoscale (120 nm) spatial resolution. The achieved results open up possibilities of detectorless speckle-free nano-imaging and quantum sensing applications across the far-infrared.

中文翻译：

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太赫兹频率的量子级联随机激光器中的自混合干涉法和近场纳米技术

我们证明，以太赫兹（THz）频率运行并包括量子级联激光异质结构的电泵浦随机激光谐振器可以通过自混合效应作为灵敏的光电探测器运行。我们设计了二维空腔，这些空腔利用了无序排列的表面孔，可以同时提供光学反馈并允许光输出耦合。通过用随机的孔图案将发射的光反射回表面，并通过改变外腔长度，我们捕获了激光电压的时间依赖性，收集了一系列随激光的偏光光谱而变化的干涉条纹。结构体。这提供了在不同反馈机制下随机激光对自混合效应的灵敏度的可见特征。然后，在近场中利用后一种效应来证明具有纳米级（120 nm）空间分辨率的无检测器散射近场光学显微镜。所获得的结果为跨远红外的无探测器无斑点纳米成像和量子感测应用打开了可能性。