Interband Cascade Active Region with Ultra-Broad Gain in the Mid-Infrared Range

Abstract

The optical gain spectrum has been investigated theoretically for various designs of active region based on InAs/GaInSb quantum wells—i.e., a type II material system employable in interband cascade lasers (ICLs) or optical amplifiers operating in the mid-infrared spectral range. The electronic properties and optical responses have been calculated using the eight-band k·p theory, including strain and external electric fields, to simulate the realistic conditions occurring in operational devices. The results show that intentionally introducing a slight nonuniformity between two subsequent stages of a cascaded device via the properly engineered modification of the type II quantum wells of the active area offers the possibility to significantly broaden the gain function. A−3 dB gain width of 1 µm can be reached in the 3–5 µm range, which is almost an order of magnitude larger than that of any previously reported ICLs. This is a property strongly demanded in many gas-sensing or free-space communication applications, and it opens a way for a new generation of devices in the mid-infrared range, such as broadly tunable single-mode lasers, mode-locked lasers for laser-based spectrometers, and optical amplifiers or superluminescent diodes which do not exist beyond 3 µm yet.

Towards Interband Cascade lasers on InP Substrate

“…More details on the calculations’ methodology can be found in Refs. [ 38 , 41 ]. All the material parameters were taken from Refs.…”

“…[ 42 , 43 ] for 300 K. The total gain was obtained by using the subband-to-subband optical transitions and which is described in Refs. [ 41 , 44 ]. We assume that the half linewidth of the Lorentzian function is equal to 5 meV, based on the transport data for n- and p-type InAs/Ga 1−x In x Sb superlattices of type II [ 45 ].…”

Continuous-Wave GeSn Light-Emitting Diodes on Silicon with 2.5 μm Room-Temperature Emission

“…The former requires emitters operating at longer wavelengths in the IR range to overlap with the molecular fingerprint. For instance, emitters in the 2.35–2.6 μm range are useful for sensing temperature and gas molecules such as CO, H 2 O, SO 2 , and HF. − These applications call for broadband emitters such as light emitting diodes (LEDs), particularly for spectroscopic detection of these critical gases generated in a chemical plant or for their atmospheric monitoring. , The commercially available LEDs emitting at the 2–5 μm wavelength range are dominated by III–V compound semiconductors. − The III–V LEDs that exhibit an emission peak below 2.35 μm are predominately made of GaInAsSb/AlGaAsSb, whereas InAsSb/InAsSbP is used for those emitting above 2.6 μm. − However, these III–V devices suffer an inherent emission gap in the 2.35–2.6 μm range due to material limitations . Additionally, the III–V LEDs emitting at wavelengths longer than 2.6 μm exhibit significantly lower output power if operated in continuous wave mode as compared to pulse mode. , Although GaSb-based lasers and superluminescent LEDs possess higher tunability of the emitted wavelength, − their narrow band emission remains less favorable for spectroscopic gas detection. , Notwithstanding the progress in developing III–V LEDs, these materials remain costly, and their direct growth on silicon is typically associated with a degradation of device performance, thus hindering their integration in large-scale applications.…”

Improving the quality and properties of GaInSb crystal with Al doping

“…And the band gap can be increased from 0.18 eV (InSb) to 0.725 eV (GaSb) [4,5], and the cutoff wavelength can be adjusted from 1.7 μm (GaSb) to 7.3 μm (InSb) [6]. Therefore, GaInSb crystals can be more widely used in epitaxial substrate materials [7], quantum well lasers [8], high electron mobility transistors [9], thermoelectric materials [10,11], as well as infrared (IR) and near-infrared (NIR) devices [12][13][14][15] and other fields.…”