300 K operation of a GaAs-based quantum-cascade laser at λ≈9 μm

Abstract

The room-temperature (300 K), pulsed mode operation of a GaAs-based quantum-cascade laser is presented. This has been achieved by the use of a GaAs/Al0.45Ga0.55As heterostructure which offers the maximum Γ–Γ band offset (390 meV) for this material system without inducing the presence of indirect barrier states. Thus, better electron confinement is achieved, countering the loss of injection efficiency with temperature. These devices show ∼100 K increase in operating temperature with respect to equivalent designs using an GaAs/Al0.33Ga0.67As heterostructure. We also measure 600 mW peak power at 233 K a temperature readily accessible by Peltier coolers.

Numerical simulation of GaAs-based mid-infrared one-phonon resonance quantum cascade laser

“…Reasonable choice of D and K is further confirmed by the calculated gain spectrum gðhmÞ (see Fig. 1b) which (i) peaks at hm ¼ 0:127 meV, corresponding very well to the experimental wavelength of k ¼ 9:6 lm, and (ii) has the FWHM of 13 meV in close agreement with the measured FWHM = 12 meV of electro-luminescence (Page et al 2001). The value of the gain peak can be traced as a function of bias.…”

“…2c). The lifetime s 3 ¼ 0:66 ps we get is significantly shorter than the value s 3 ¼ 1:4 ps calculated from the form factors and assumed in the designing process (Page et al 2001). In spite of this, as shown in Fig.…”

“…Simulations were made for the device designed by Page et al (2001): The GaAs/AlGaAs layer sequence 4.6, 1.9, 1.1, 5.4, 1.1, 4.8, 2.8, 3.4, 1.7, 3.0, 1.8, 2.8, 2.0, 3.0, 2.6, 3.0 nm defines one QCL period (barriers are in bold, underlined layers are n-doped). Most of the parameters in the formulations of scattering self-energies are material-dependent.…”

Self-consistent scattering theory of transport and output characteristics of quantum cascade lasers

“…͑1͒. The equations describing the rates dn i /dt in the collector region (iϭ1,2,3,5,7) are symmetric with those in the injector region (iϭ8, 10,11,13,15), and when the system reaches a steady state, the collector subbands population should equal those in injector subband. This implies that the injection rates on each side of the active region are equal.…”

“…6 The midinfrared GaAs/AlGaAs QCLs have not yet achieved the temperature range of InGaAs/AlInAs devices, but a lot of successful experimental work is currently under way to extend the operating temperature. [7][8][9][10][11][12][13] On the other hand, GaAs/ AlGaAs cascade structures may play an important role in producing stimulated radiation in the far-infrared region, which is also the topic of recent investigations, both experimental 14 -16 and theoretical. 17,18 The rapid experimental development has stimulated interest in theoretical work to explain the physical processes involved, [19][20][21] including the principles of carrier transport in devices, and hence, indicate routes to optimized layer design for improved output characteristics.…”