Abstract-Electronic temperatures of terahertz quantum cascade active regions with phonon scattering assisted injection and extraction scheme

Pietro Patimisco, Gaetano Scamarcio, Maria Vittoria Santacroce, Vincenzo Spagnolo, Miriam Serena Vitiello, Emmanuel Dupont, Sylvain R. Laframboise, Saeed Fathololoumi, Ghasem S. Razavipour, and Zbigniew Wasilewski

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-21-8-10172

We measured the lattice and subband electronic temperatures of terahertz quantum cascade devices based on the optical phonon-scattering assisted active region scheme. While the electronic temperature of the injector state (j = 4) significantly increases by ΔT = T_e⁴ – T_L ~40 K, in analogy with the reported values in resonant phonon scheme (ΔT ~70-110 K), both the laser levels (j = 2,3) remain much colder with respect to the latter (by a factor of 3-5) and share the same electronic temperature of the ground level (j = 1). The electronic population ratio n₂/n₁ shows that the optical phonon scattering efficiently depopulates the lower laser level (j = 2) up to an electronic temperature T_e ~180 K.
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