https://doi.org/10.1051/epjconf/202328707009
Broadband THz quantum cascade laser frequency combs with surface emission and inverse-designed facet reflectors
Quantum Optoelectronics Group, Institute of Quantum Electronics, ETH Zürich, 8093 Zürich
* Corresponding author: usenica@phys.ethz.ch, scalari@phys.ethz.ch
Published online: 18 October 2023
We present a planarized waveguide cavity with an integrated broadband output coupler that improves both the output power and far-field properties of THz quantum cascade laser frequency combs. The laser mirror reflectivity can be tuned by the shape of the end facet, which is obtained with an efficient inverse design algorithm, where the structure is iteratively updated to match the desired figure of merit. Surface emission is achieved with a broadband patch-array antenna, and all the components have been optimized for octave-spanning emission spectra (2-4 THz). Experimentally, we demonstrate a broadband surface-emitting THz quantum cascade laser frequency comb with optical bandwidths of up to 800 GHz, surface emission into a narrow beam with divergence below (20° x 20°) and a peak power of 13 mW.
© The Authors, published by EDP Sciences, 2023
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
