Abstract
Very low power-consumption distributed feedback (DFB) quantum cascade lasers (QCLs) at the wavelength around 4.9 μm were fabricated by conventional process without lateral regrowth of InP:Fe or using sidewall grating. Benefitted from the optimized materials and low waveguide loss, very low threshold current density of 0.5 kA/cm2 was obtained for a device with cavity length of 2 mm. Combined with the partial-high-reflection coating, the 1-mm-long DFB QCL achieved low power-consumption continuous wave (CW) operation up to 105 °C. The CW threshold power-consumptions were 0.72 and 0.78 W at 15 and 25 °C, respectively. The maximum CW output power was over 110 mW at 15 °C and still more than 35 mW at 105 °C. At 15 °C, wall-plug efficiency of 5.5% and slope efficiency of 1.8 W/A were deduced, which were very high for low power-consumption DFB QCLs.
Highlights
In recent years, quantum cascade lasers (QCLs) have proven to be very efficient coherent light sources in the mid-infrared region with a wide variety of applications, such as trace gas sensing, high-resolution spectroscopy, and free space communication [1–3]
We demonstrated the very low threshold operation of QCL in continuous wave (CW) mode with the Threshold current density (Jth) of 0.56 kA/cm2 at 20 °C by optimizing growth parameter of
The maximum CW output power was over 110 mW at 15 °C and still more than 35 mW at 105 °C
Summary
Quantum cascade lasers (QCLs) have proven to be very efficient coherent light sources in the mid-infrared region with a wide variety of applications, such as trace gas sensing, high-resolution spectroscopy, and free space communication [1–3]. The input electrical power consumption of the DFB QCL is required to be as low as possible, so that the total volume and power consumption of the system can be minimized. In order to obtain stable and narrow line-width single-mode emission, continuous wave (CW) operation of DFB QCL above ambient temperature is desired. Several works on the demonstration of room temperature, low powerconsumption DFB QCLs have been reported, in which narrow ridge and short cavity device structure are the. We demonstrated the very low threshold operation of QCL in CW mode with the Jth of 0.56 kA/cm at 20 °C by optimizing growth parameter of. The very low Jth is encouraging for developing low power-consumption DFB QCLs without a very narrow ridge
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