Comb operation in terahertz quantum cascade ring lasers
Abstract
Ring resonators are an interesting alternative cavity solution to the commonly used ridge-type waveguide for terahertz (THz) quantum cascade lasers. They either support a standing-wave pattern showing spatial hole burning if there are defects implemented or a traveling mode in a defect-free cavity. Here, we report on ring-shaped THz quantum cascade lasers emitting between 3.2 and 4.1 THz operating in four different emission regimes. The presence of defects in the cavities force the THz quantum cascade laser into a standing-wave pattern. The measurements show a complex behavior highlighting the effect of strong confinement and the optical nonlinearities leading to the generation of a harmonic state, as well as to a fundamental comb, exhibiting over 30 equidistant modes and covering a bandwidth of 622 GHz. The results are explained by numerical calculations based on the Maxwell–Bloch formalism, including the linewidth enhancement factor and reflection points. The compact geometry and high output power (4 mW detected) make these devices extremely appealing for on-chip frequency comb applications in the terahertz region.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 24, 2021
- Source ID
- 10.1364/optica.420674
Entities
People
- Aaron Maxwell Andrews
- B Limbacher
- Benedikt Schwarz
- Dominik Theiner
- Gottfried Strasser
- J Darmo
- K. Unterrainer
- Martin A Kainz
- Maximilian Beiser
- Michael Jaidl
- Miriam Giparakis
- N. Opačak
- S Schönhuber
Organizations
- Air Force Office of Scientific Research
- Austrian Research Promotion Agency
- Austrian Science Fund
- European Research Council
- TU Wien