高功率表面发射太赫兹激光与混合二阶和四阶布拉格光栅。

High power surface emitting terahertz laser with hybrid second- and fourth-order Bragg gratings.

机构信息

Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, PA, 18015, USA.

Sandia National Laboratories, Center of Integrated Nanotechnologies, MS 1303, Albuquerque, NM, 87185, USA.

出版信息

Nat Commun. 2018 Apr 11;9(1):1407. doi: 10.1038/s41467-018-03697-9.

DOI:10.1038/s41467-018-03697-9

PMID:29643341

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC5895695/

Abstract

A surface-emitting distributed feedback (DFB) laser with second-order gratings typically excites an antisymmetric mode that has low radiative efficiency and a double-lobed far-field beam. The radiative efficiency could be increased by using curved and chirped gratings for infrared diode lasers, plasmon-assisted mode selection for mid-infrared quantum cascade lasers (QCLs), and graded photonic structures for terahertz QCLs. Here, we demonstrate a new hybrid grating scheme that uses a superposition of second and fourth-order Bragg gratings that excite a symmetric mode with much greater radiative efficiency. The scheme is implemented for terahertz QCLs with metallic waveguides. Peak power output of 170 mW with a slope-efficiency of 993 mW A is detected with robust single-mode single-lobed emission for a 3.4 THz QCL operating at 62 K. The hybrid grating scheme is arguably simpler to implement than aforementioned DFB schemes and could be used to increase power output for surface-emitting DFB lasers at any wavelength.

摘要

具有二阶光栅的面发射分布式反馈（DFB）激光器通常会激发具有低辐射效率和双叶远场光束的反对称模式。对于红外二极管激光器，可以通过使用弯曲和啁啾光栅、等离子体辅助模式选择对于中红外量子级联激光器（QCL），以及对于太赫兹 QCL 的渐变光子结构来提高辐射效率。在这里，我们展示了一种新的混合光栅方案，该方案使用二阶和四阶布拉格光栅的叠加来激发具有更高辐射效率的对称模式。该方案针对具有金属波导的太赫兹 QCL 实施。在 62K 下工作的 3.4THz QCL 检测到峰值功率输出为 170mW，斜率效率为 993mW/A，具有稳健的单模单叶发射。与上述 DFB 方案相比，混合光栅方案更容易实现，并且可以用于提高任何波长的面发射 DFB 激光器的功率输出。