Development of DFB Quantum Cascade Lasers and their Applications

Abstract

We have developed single-mode quantum cascade lasers (QCLs) emitting at 5.2μm and 7.7 Em. Single-mode emission with narrow line width is achieved using a distributed feedback (DFB) technology. A narrow line width is interpreted in terms of an extremely small effective coupling efficiency of spontaneous emission, caused by ultrafast nonradiative scatterings. We have demonstrated absorption signal detection of NO, N₂O, and CH₄. The highest spectral resolution can be achieved with a CW mode DFB-QCL. We have observed lines of isotopomer of nitrous oxide, and signal detection limit is about 50 ppb.