CC BY
17'22
ALT' THz-l-11
NONLINEAR AND TERAHERTS PHOTONICS
THz quantum cascade lasers with two-photon emission in the gain module
grown by MBE and MOCVD
R.A. Khabibullin1, S.S. Pushkarev1, R.R. Galiev1, D.S. Ponomarev1, I.S. Vasil'evskii2, A.N. Vinichenko2, A.N.
Klochkov2, T.A. Bagaev3, M.A. Ladugin3, A.A. Marmalyuk3, K.V. Maremyanin4, V.I. Gavrilenko4, D.V. Ushakov5, A.A. Afonenko5
1- VG. Mokerov Institute of ultra-high frequency semiconductor electronics of RAS, Moscow, Russia 2- National research nuclear university Mephi, Moscow, Russia 3- POLYUS Research Institute of M.F. Stelmakh, Moscow, Russia 4- Institute for Physics of Microstructures of RAS, Nizhny Novgorod, Russia 5- Belarusian State University, Minsk, Belarus khabibullin@isvch.ru
The possibility of implementing two radiation transitions in the gain module for THz QCL has been shown many times [1,2]. However, the activation of these transitions is achieved at different bias points, which corresponds to the optimal alignment of energy levels for each transition. We propose to add an additional step to the ladder of energy levels in the gain module, equal to the energy of THz photon. Due to the low energy of THz photon, it becomes possible to design the gain module based on the conventional GaAs/Al015Ga085As heterojunction with two-photon emission at one bias point.
A new lasing scheme with sequential two-photon emission in the gain module for terahertz quantum cascade laser (THz QCL) is proposed and experimentally demonstrated. Unlike the conventional lasing scheme with only one pair of laser levels, here electrons pass through an additional laser level, which is the lower laser level for the first radiation transition and upper laser level for the second one, forming a sequence "resonant tunneling - photon - photon - phonon" (see Fig. 1). The presence of two-photon emission in the gain module reduces the gain saturation with an increase in photon density, which should potentially increase the radiation power. An optimized two-photon design based on GaAs/ Al015Ga085As As four-quantum wells was developed using the balanced equation method [3,4] and grown by two epitaxial techniques - molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD). THz QCLs based on both MBE and MOCVD structures have a lasing frequency of 3.8 THz (see Fig. 2) and maximum operation temperature around 100 K.
one-photon design
two-photon design
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Fig. 1. Schematic diagram of one- and two-photon designs with resonant phonon depopulation mechanism of lower laser level.
3,6 3,7 3,8 3,9 4,0 4,1 4,2
Frequency, THz
Fig. 2. Emission spectra of MBE- and MOC-VD-grown THz QCLs with two-photon design.
[1] S. Kumar, C. Chan, Q. Hu, J. Reno, "A 1.8-THz quantum cascade laser operating significantly above the temperature of #ra/kB," Nature Phys., vol. 7, pp. 166-171, (2011).
[2] B. Wen, C. Xu, S. Wang, K. Wang, M. C. Tam, Z. Wasilewski, D. Ban, "Dual-lasing channel quantum cascade laser based on scattering-assisted injection design," Opt. Express vol. 26, pp. 9194-9204, (2018).
[3] D. V. Ushakov, A. A. Afonenko, A. A. Dubinov, V. I. Gavrilenko, O. Yu. Volkov, N. V. Shchavruk, D. S. Ponomarev, R. A. Khabibullin, "Balance-equation method for simulating terahertz quantum-cascade lasers using a wave-function basis with reduced dipole moments of tunnel-coupled states," Quantum Electronics, vol. 49, pp. 913-918, (2019).
[4] D. Ushakov, A. Afonenko, R. Khabibullin, D. Ponomarev, V. Aleshkin, S. Morozov, A. Dubinov, "HgCdTe-based quantum
cascade lasers operating in the GaAs phonon Reststrahlen band predicted by the balance equation method," Opt. Express, vol. 28, pp. 25371-25382, (2020).
