External cavity terahertz quantum cascade laser with a metamaterial/graphene optoelectronic mirror
External cavity terahertz quantum cascade laser with a metamaterial/graphene optoelectronic mirror
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DOI：
10.1063/5.0014251
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发表时间：
2020-07-27
影响因子：
4
通讯作者：
Ritchie, David A.
中科院分区：
文献类型：
--
作者：
Almond, Nikita W.;Qi, Xiaoqiong;Ritchie, David A.
量子级联激光器（QCL）的太赫兹发射的光子工程是在无数应用中开发这种独特光源的基础，在这些应用中可以实现，例如光谱学，成像和传感。频率、功率、偏振和光束轮廓的主动控制已经通过各种方法实现。特别是，发射频率的主动控制，很难先验地确定，已经通过光子结构的集成和/或使用外部腔布置来实现。在这项工作中，提出并演示了一种外腔布置，该布置实现了超材料/石墨烯光电反射镜作为外部反馈元件。通过静电门控石墨烯调节外有源镜的反射率和色散特性。通过机械地改变由Au反射镜形成的外腔长度，可以通过电子方式再现类似于2.8THz发射的QCL中的模式开关。在自混合理论的框架下对外腔的排列进行了研究和描述。这些结果为利用快速可重构外镜实现QCL发射的全电子工程开辟了道路。这种方法可以独特地解决功率和频率控制，使用集成的外部元件，具有类似于100MHz的重新配置速度。此外，超材料/石墨烯反射镜的强色散特性可能用于太赫兹量子激光器的主动模式锁定。最后，该方法提供了一个独特的机会来研究自混合反馈体制下太赫兹量子激光器的激光动力学和模式竞争。
Photonic engineering of the terahertz emission from a quantum cascade laser (QCL) is fundamental for the exploitation of this unique source in a myriad of applications where it can be implemented, such as spectroscopy, imaging, and sensing. Active control of the frequency, power, polarization, and beam profile has been achieved through a variety of approaches. In particular, the active control of the emitted frequency, which is difficult to determine a priori, has been achieved through the integration of a photonic structure and/or by using external cavity arrangements. In this work, an external cavity arrangement, which implements a metamaterial/graphene optoelectronic mirror as an external feedback element, is proposed and demonstrated. The reflectivity and dispersion properties of the external active mirror were tuned via electrostatically gating graphene. It was possible to electronically reproduce the mode-switch occurring in a QCL emitting similar to 2.8THz by mechanically changing the external cavity length formed by an Au mirror. The external cavity arrangement was investigated and described in the framework of the self-mixing theory. These results open a way for the all-electronic engineering of the QCL emission by the use of a fast reconfigurable external mirror. This approach can uniquely address both power and frequency control, with similar to 100MHz reconfiguration speeds, using an integrated external element. Furthermore, the metamaterial/graphene mirror's strong dispersive properties might be implemented for the active mode locking of THz QCLs. Finally, this approach offers a unique opportunity to study the laser dynamics and mode competition in THz QCLs in the self-mixing feedback regime.