Towards Interband Cascade lasers on InP Substrate

Krzysztof Ryczko,Janusz Andrzejewski,Grzegorz Sęk

doi:10.3390/ma15010060

Krzysztof Ryczko, Janusz Andrzejewski + Show 1 more

Open Access

https://doi.org/10.3390/ma15010060

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Abstract

In this study, we propose designs of an interband cascade laser (ICL) active region able to emit in the application-relevant mid infrared (MIR) spectral range and to be grown on an InP substrate. This is a long-sought solution as it promises a combination of ICL advantages with mature and cost-effective epitaxial technology of fabricating materials and devices with high structural and optical quality, when compared to standard approaches of growing ICLs on GaSb or InAs substrates. Therefore, we theoretically investigate a family of type II, “W”-shaped quantum wells made of InGaAs/InAs/GaAsSb with different barriers, for a range of compositions assuring the strain levels acceptable from the growth point of view. The calculated band structure within the 8-band k·p approximation showed that the inclusion of a thin InAs layer into such a type II system brings a useful additional tuning knob to tailor the electronic confined states, optical transitions’ energy and their intensity. Eventually, it allows achieving the emission wavelengths from below 3 to at least 4.6 μm, while still keeping reasonably high gain when compared to the state-of-the-art ICLs. We demonstrate a good tunability of both the emission wavelength and the optical transitions’ oscillator strength, which are competitive with other approaches in the MIR. This is an original solution which has not been demonstrated so far experimentally. Such InP-based interband cascade lasers are of crucial application importance, particularly for the optical gas sensing.

Highlights

An important class of coherent radiation sources in the mid-wave infrared have become the interband cascade lasers (ICLs) employing type II, indirect in the real space optical transitions [1,2]
The ICLs are usually based on a broken gap material system of InAs/GaInSb [1,2,3,4], which fulfills the electronic structure and technological requirements, and simultaneously allows to reach a broad range of mid infrared (MIR) [5]
These characteristics translate into numerous applications of ICLs, including in optical gas sensing [13,14], multi-gas analyzers [15], industrial process control [16,17], environmental pollution monitoring [18], medical diagnostics [19], infrared countermeasures [20], gas leakage detection [21], free space optical communication [22] with demonstrations of the efficient optical wireless link for military applications [23], combustion diagnostics [24], IR scene projection [25], and detection of explosives [26]

Summary

Introduction

An important class of coherent radiation sources in the mid-wave infrared have become the interband cascade lasers (ICLs) employing type II, indirect in the real space optical transitions [1,2]. As for the case of GaAs-substrate some preliminary demonstrations exist—an ICL in a pulsed mode and low temperatures (up to 270 K) has been reported [27], such are still missing for the case of InP-based technology The latter, which is cost-effective, offers additional advantages like simplified epitaxial structure, because the InP can serve as an optical cladding layer, improved heat dissipation material or allows considering the option of using a high-power near-IR sources to optically pump an epitaxial-side-down-mounted device through a transparent substrate [28]. Overall, such a novel ICL would be a breakthrough solution because

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