Abstract
In this article, we report the demonstration of a quantum cascade laser emitting at λ ≈ 4.9 μm with a wall-plug efficiency of ∼31% and an output power of ∼23 W in pulsed operation at room temperature with 50 cascade stages (Ns). With proper fabrication and packaging, this buried ridge quantum cascade laser with a cavity length of 5 mm delivers more than ∼15 W output power, and its wall-plug efficiency exceeds ∼20% at 100 °C. The experimental results of the lasers are well in agreement with the numerical predictions.
Highlights
AFFILIATIONS Center for Quantum Devices, Department of Electrical and Computer Engineering, Northwestern University, Evanston, Illinois 60208, USA
Since the demonstration of the first quantum cascade lasers (QCLs) grown in a single step by gas-source molecular beam epitaxy (GSMBE),3 improving the wall-plug efficiency (WPE) of QCLs has been a hot topic in the QCL community
Despite constant efforts devoted to this objective, there has been no considerable improvement in the WPE of QCLs in the past ten years
Summary
It can reduce the threshold current density by increasing the modal confinement factor and decreasing the waveguide loss.9 Besides, it has the potential to increase the WPE by increasing the voltage efficiency and quantum efficiency, owing to the decrease in the proportion of parasitic resistance and cladding-core interface voltage offset with the increase in Ns. In order to achieve a high WPE and, maintain high temperature performance, we take advantage of the QCL design in Ref. 4. The waveguide loss drops more than 36% by increasing the number of QCL stages from 40 to 50.
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