Room-temperature, continuous-wave, single-mode quantum-cascade lasers at λ≃5.4μm

Key issues associated with low threshold current density for InP-based quantum cascade lasers

“…As a result, room temperature threshold current densities as low as 3.3 kA/cm 2 in pulsed, and 4.6 kA/cm 2 300 K were achieved. Very recently, InP-based mid-infrared QCLs at the wavelength region from 3 to 10 mm have exhitibed tremendous improvements in their performance [7][8][9][10][11][12][13][14][15]. For the multi-mode F-P QCLs, CW operation at room temperature with a threshold current densities of 1.5-2.8 kA/cm 2 at a wavelengths range between 4.3 and 9.3 mm have been achieved.…”

Tuning properties of mid-infrared Fabry-Pérot quantum cascade lasers for multiheterodyne spectroscopy

“…The nonlinear tuning characteristics stems from a proportionality of the optical frequency of the modes to the change of the active region temperature T, which in turn is a function of thermal resistance and electric power delivered [9], all exhibiting nonlinear behavior. Despite the model simplicity, the fit remains within excellent agreement of the experimental data (R 2 >0.994 for all investigated modes), albeit with a small sine-wave-like fit residual that occurs for all the modes with a noticeable phase shift.…”

Sub-part-per-billion monitoring of nitric oxide by use of wavelength modulation spectroscopy in combination with a thermoelectrically cooled, continuous-wave quantum cascade laser

“…[7][8][9] Only recently, cw QCLs that are able to operate in single mode at room temperature have become available. 10 Single-mode operation is an important step forward for molecular spectroscopy, because of the narrow absorption lines down to tens of megahertz. Since they are thermo-electrically cooled, these single-mode cw QCLs do not require liquid nitrogen cooling and therefore are well suited to be utilized in a compact and high-sensitivity trace-gas sensor.…”