Room temperature continuous wave operation of InAs/AlSb‐based quantum cascade laser at λ ∼11 µm

Abstract

The InAs/AlSb quantum cascade lasers (QCLs) operating ∼11 µm in the continuous wave (cw) regime at room temperature are reported. The lasers with cleaved Fabry-Perot resonators demonstrated pulsed threshold current densities below 1 kA/cm 2 at 300 K and operated in a cw up to 320 K that is the maximum temperature of such regime of operation for InAs-based QCLs. Distributed feedback lasers fabricated from the same wafer exhibited single frequency emission near 11 µm and operated in the cw regime up to 295 K.

InAs-Based Quantum Cascade Lasers with Extremely Low Threshold

“…The threshold current density of the fabricated laser was lower reported InAs-based QCLs [2][3][4][5]. In devices of 3.6 mm long, it range kA/cm 2 with the ridge width decreasing from 20 to 7 µ m (Figure 2).…”

“…InAs-based QCLs demonstrated room temperature (RT) continuous wave (cw) operation at wavelengths up to 17.7 µm with a pulsed threshold current density J th as low as 1.0 kA/cm 2 [2]. Low values of J th were also achieved in InAsbased QCLs emitting in other spectral regions: 0.715 kA/cm 2 at 15 µm [3], 0.99 kA/cm 2 at 11 µm [4] and 0.75 kA/cm 2 at 7.7 µm [5] (QCL grown on InAs). These performances are significantly better than those demonstrated in QCLs based on other materials.…”

Unintentional As incorporation into AlSb and interfacial layers within InAs/AlSb superlattices

“…As a result, they were able to obtain wavelengths as short as 2.63 -2.65 µm, operating at around 175 K [1]. Baranov's group reported that they achieved room temperature CW operation in InAs/AlSb based QCLs up to 15 µm [2] and 11 µm at 320 K [3], in 2016 and 2018, respectively. Those QCLs were the most recent InAs/AlSb reported before the writing of this thesis.…”

“…At low temperature, wavelengths as short as 2.63 -2.65 µm can be obtained from an InAs/AlSb based QCL [1]. At room temperature, continuous-wave (CW) operation was reported with wavelength up to 15 µm [2], while the highest CW operating temperature of 320 K was demonstrated for devices lasing at 11 µm [3]. The advantage of InAs/AlSb structure is its very large conduction band offset up to 2.1 eV and a large Γ-L distance of 0.73 eV in InAs [4].…”

Long Wavelength (λ > 17 µm) Distributed Feedback Quantum Cascade Lasers Operating in a Continuous Wave at Room Temperature

“…DFB QCLs operating in pulsed mode were demonstrated at wavelengths of 13.8 [18] and 16 µm [17]. Using the alternative InAs/AlSb materials, CW operation at room temperature above a wavelength of 11 µm [19] and up to a wavelength of 15 µm [20] was demonstrated. With this technology, we achieved room temperature operation above 20 µm [3], and lasing was obtained up to 25 µm [21].…”