Abstract
We report in this paper the study of achieving low current threshold quantum cascade lasers (QCLs) by using highreflection (HR) coating to short-cavity QCLs. Experimental results show that the QCL current threshold (Ith) and injecting electrical power are significantly decreased with HR coatings applied to one side or both sides of a QCL. The QCL structures used in the experiment are strain balanced InGaAs/InAlAs supperlattices based on InP substrate with the emission wavelength at λ~4.8μm. QCL devices with 28 periods and 60 periods are studied. With HR coatings on both laser facets, a 28 periods QCL device cleaved with 1mm long cavity expresses a low current threshold of 70mA at cryogenic temperature and a 0.5mm long cavity device shows a current threshold of 65mA at 50K. A 0.5mm long 60 periods QCL device with both sides HR coated is found to have a current threshold as low as 30mA at 20K and still below 50mA at liquid Nitrogen cooled temperature.
Published Version
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