Low power-consumption quantum cascade lasers

摘要

Quantum cascade lasers (QCLs) are promising light sources for real time high-sensitivity gas sensing in the mid-infrared region. For the practical use of QCLs as a compact and portable gas sensor, their power-consumption needs to be reduced. We report a successful operation of a low power-consumption distributed feedback (DFB) QCL. For the reduction of power consumption, we introduced a vertical-transition structure in a core region to improve carrier transition efficiency and reduced the core volume. DFB-QCL epitaxial structure was grown by low-pressure OMVPE. The core region consists of AlInAs/GaInAs superlattices lattice-matched to InP. A first-order Bragg-grating was formed near the core region to obtain a large coupling coefficiency. A mesa-strip was formed by reactive ion etching and a buried-heterostructure was fabricated by the regrowth of semi-insulating InP. High-reflective facet coatings were also performed to decrease the mirror loss for the reduction of the threshold current. A device (5×500μm) operated with a single mode in the wavelength region from 7.23μm to 7.27μm. The threshold current and threshold voltage under CW operation at 20 ℃ were 52mA and 8.4V respectively. A very low threshold power-consumption as low as 0.44 W was achieved, which is among the lowest values at room temperature to our knowledge.