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A broadband active metasurface is designed around quantum‐cascade (QC) gain material for use in a broadband tunable QC vertical external‐cavity surface‐emitting laser (VECSEL). The metasurface is based on a unit cell containing two resonant waveguide elements that couple with the periodicity of the metasurface to produce a multi‐resonant reflection spectrum. Simulated reflectance spectra exhibit full‐width half‐maximum bandwidths up to 50% of the centre frequency. The tested QC‐VECSEL demonstrates up to 15 mW of peak pulse power at 77 K and supports multimode lasing from 2.85 to 3.9 THz (>30% fractional bandwidth around 3.37 THz). The frequency coverage is limited by how short the cavity can be made, rather than the metasurface bandwidth. Consistent multimoding results from non‐uniform distribution of spectral energy across the surface.
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Tunable quantum-cascade VECSEL operating at 1.9 THz
We report a terahertz quantum-cascade vertical-external-cavity surface-emitting laser (QC-VECSEL) emitting around 1.9 THz with up to 10% continuous fractional frequency tuning of a single laser mode. The device shows lasing operation in pulsed mode up to 102 K in a high-quality beam, with the maximum output power of 37 mW and slope efficiency of 295 mW/A at 77 K. Challenges for up-scaling the operating wavelength in QC metasurface VECSELs are identified.
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- Award ID(s):
- 1810163
- PAR ID:
- 10305912
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 29
- Issue:
- 21
- ISSN:
- 1094-4087; OPEXFF
- Format(s):
- Medium: X Size: Article No. 34695
- Size(s):
- Article No. 34695
- Sponsoring Org:
- National Science Foundation
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