https://doi.org/10.1051/epjconf/202226609007
Field-enhancing tapered planarized waveguides for THz quantum cascade laser frequency combs
1 Quantum Optoelectronics Group, Institute of Quantum Electronics, ETH Zürich, 8093 Zürich
2 Istituto di Fotonica e Nanotecnologie, CNR, Via Cineto Romano 42. 00156 Rome, Italy
* Corresponding author: usenica@phys.ethz.ch, scalari@phys.ethz.ch
Published online: 13 October 2022
We present a new planarized waveguide geometry for THz quantum cascade laser frequency combs with improved waveguide losses, RF and thermal dissipation properties. Ridge devices display broadband free-running comb states, and the THz emission can be further broadened by RF injection. Tapered waveguide devices feature a strong field-enhancement effect, which results in an improved comb performance. This includes free-running comb states with strong single beatnotes up to nearly -30 dBm at 90 K, almost three orders of magnitude stronger than for ridge devices. Improved comb operation is maintained also for high operating temperatures, up to 115 K.
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