The waveguide losses from a range of surface plasmon and double metal waveguides for Ge/Si1−xGex THz quantum cascade laser gain media are investigated at 4.79 THz (62.6 µm wavelength). Double metal waveguides demonstrate lower losses than surface plasmonic guiding with minimum losses for a 10 µm thick active gain region with silver metal of 21 cm−1 at 300 K reducing to 14.5 cm−1 at 10 K. Losses for silicon foundry compatible metals including Al and Cu are also provided for comparison and to provide a guide for gain requirements to enable lasers to be fabricated in commercial silicon foundries. To allow these losses to be calculated for a range of designs, the complex refractive index of a range of nominally undoped Si1−xGex with x = 0.7, 0.8 and 0.9 and doped Ge heterolayers were extracted from Fourier transform infrared spectroscopy measurements between 0.1 and 10 THz and from 300 K down to 10 K. The results demonstrate losses comparable to similar designs of GaAs/AlGaAs quantum cascade laser plasmon waveguides indicating that a gain threshold of 15.1 cm−1 and 23.8 cm−1 are required to produce a 4.79 THz Ge/SiGe THz laser at 10 K and 300 K, respectively, for 2 mm long double metal waveguide quantum cascade lasers with facet coatings.

Design and simulation of losses in Ge/SiGe terahertz quantum cascade laser waveguides / Gallacher, K.; Ortolani, M.; Rew, K.; Ciano, C.; Baldassarre, L.; Virgilio, M.; Scalari, G.; Faist, J.; Gaspare, L. D. I.; Seta, M. D. E.; Capellini, G.; Grange, T.; Birner, S.; Paul, D. J.. - In: OPTICS EXPRESS. - ISSN 1094-4087. - 28:4(2020), pp. 4786-4800. [10.1364/OE.384993]

Design and simulation of losses in Ge/SiGe terahertz quantum cascade laser waveguides

Ortolani M.
Secondo
;
Ciano C.;Baldassarre L.;
2020

Abstract

The waveguide losses from a range of surface plasmon and double metal waveguides for Ge/Si1−xGex THz quantum cascade laser gain media are investigated at 4.79 THz (62.6 µm wavelength). Double metal waveguides demonstrate lower losses than surface plasmonic guiding with minimum losses for a 10 µm thick active gain region with silver metal of 21 cm−1 at 300 K reducing to 14.5 cm−1 at 10 K. Losses for silicon foundry compatible metals including Al and Cu are also provided for comparison and to provide a guide for gain requirements to enable lasers to be fabricated in commercial silicon foundries. To allow these losses to be calculated for a range of designs, the complex refractive index of a range of nominally undoped Si1−xGex with x = 0.7, 0.8 and 0.9 and doped Ge heterolayers were extracted from Fourier transform infrared spectroscopy measurements between 0.1 and 10 THz and from 300 K down to 10 K. The results demonstrate losses comparable to similar designs of GaAs/AlGaAs quantum cascade laser plasmon waveguides indicating that a gain threshold of 15.1 cm−1 and 23.8 cm−1 are required to produce a 4.79 THz Ge/SiGe THz laser at 10 K and 300 K, respectively, for 2 mm long double metal waveguide quantum cascade lasers with facet coatings.
2020
quantum cascade laser; waveguides; terahertz
01 Pubblicazione su rivista::01a Articolo in rivista
Design and simulation of losses in Ge/SiGe terahertz quantum cascade laser waveguides / Gallacher, K.; Ortolani, M.; Rew, K.; Ciano, C.; Baldassarre, L.; Virgilio, M.; Scalari, G.; Faist, J.; Gaspare, L. D. I.; Seta, M. D. E.; Capellini, G.; Grange, T.; Birner, S.; Paul, D. J.. - In: OPTICS EXPRESS. - ISSN 1094-4087. - 28:4(2020), pp. 4786-4800. [10.1364/OE.384993]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1407458
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