Rebalancing of internally generated carriers for mid-infrared interband cascade lasers with very low power consumption

Abstract

The interband cascade laser differs from any other class of semiconductor laser, conventional or cascaded, in that most of the carriers producing population inversion are generated internally, at semimetallic interfaces within each stage of the active region. Here we present simulations demonstrating that all previous interband cascade laser performance has suffered from a significant imbalance of electron and hole densities in the active wells. We further confirm experimentally that correcting this imbalance with relatively heavy n-type doping in the electron injectors substantially reduces the threshold current and power densities relative to all earlier devices. At room temperature, the redesigned devices require nearly two orders of magnitude less input power to operate in continuous-wave mode than the quantum cascade laser. The interband cascade laser is consequently the most attractive option for gas sensing and other spectroscopic applications requiring low output power and minimum heat dissipation at wavelengths extending from 3 µm to beyond 6 µm.

Single-mode interband cascade lasers emitting below 2.8 μm

“…The electron injector region was grown with six InAs/AlSb layers with thicknesses of 4.3 nm/1.2 nm, 3.4 nm/1.2 nm, 2.5 nm/1.2 nm, 1.9 nm/1.2 nm, 1.5 nm/1.2 nm, 1.4 nm/2.5 nm, where the five InAs wells closest to the W-QW were highly Si-doped with 6Á10 18 cm À3 for carrier rebalancing. 23 Fig. 1 shows the band structure of the conduction and valence band for one and a half stages, containing two W-QWs and the respective hole and electron injector.…”

InAs-based distributed feedback interband cascade lasers

“…Three InAs-quantum wells were used in the electron injector, two of which were Si-doped at a concentration of 1.0 Â 10 18 cm À3 for carrier rebalancing. 20 The total layer sequence of the active region, starting with the first InAs layer in the electron injector, is 4.2 nm InAs/1.2 nm AlSb/3.6 nm InAs/1.2 nm AlSb/3.1 nm InAs/2.5 nm AlSb/2.9 nm InAs/3.0 nm Ga 0.24 In 0.76 Sb/2.5 nm InAs/1.0 nm AlSb/3.0 nm GaSb/1.0 nm AlSb/4.5 nm GaSb/ 2.5 nm AlSb. To compensate for the compressive strain introduced by the AlSb, GaSb, and Ga 0.24 In 0.76 Sb layers, As soak-times were inserted in the shutter sequence at the AlSb/ InAs layer transitions in the electron injector to enforce highly tensile strained AlAs interfaces.…”

Demonstration of the self-mixing effect in interband cascade lasers

“…With their input-power requirements almost two orders of magnitude lower than those now attainable for QCLs, ICLs are well positioned to become the lasers of choice for all applications which require long-term continuous-wave room temperature operation at relatively low output powers. 1,4 The resulting SM system yields a low input-power, self-aligned compact sensor with coaxial optical geometry that can continuously operate at room temperature for extended periods of time.…”

“…[1][2][3][4] The recent availability of MIR ICLs has driven the development of new chemical sensing systems that make use of unique molecular spectroscopic signatures in the MIR. 5 With envisaged applications in chemical analysis and biomedicine, MIR ICLs present a viable alternative to MIR quantum cascade lasers (QCLs) due to their much lower input-power requirements.…”

“…5 With envisaged applications in chemical analysis and biomedicine, MIR ICLs present a viable alternative to MIR quantum cascade lasers (QCLs) due to their much lower input-power requirements. [1][2][3][4]6 Furthermore, high sensitivity MIR detectors usually require active cooling to be effective (and even cryogenic cooling at longer wavelengths).…”