Quantum cascade lasers and applications in defense and security

Abstract

Quantum cascade lasers (QCL) were first demonstrated in 1994. However, it took nearly eight years before the first continuous wave, room temperature (CW/RT) operation was successful, brought about by an improved design for rapidly depopulating the lower laser level thorough the use of two phonon resonance technique. The progress since 2002 has been remarkable in improving the power output and wallplug efficiency. Furthermore, newer structure design ideas (notably the nonresonant extraction, NRE, principle for rapid depopulation of the lower laser level without the use of two phonon resonance) have emerged, which increase the structure design flexibility for simultaneous improvements in various operating parameters of QCLs. At present, CW/RT power outputs of >;3 W and wall plug efficiency in excess of 15 % have been demonstrated at 4.6 μm in the midwave infrared (MWIR) region. Using the NRE structure design ideas we have demonstrated CW/RT power output in excess of 2 W at 4.0 μm and have extended QCL operation up to 3.6 μm, were average power output of more than 300 mW has been obtained for room temperature operation. The NRE design principle is also applicable to longwave infrared (LWIR) regions to lead to improvements in power output and wallplug efficiency similar to those attained in the MWIR region. Over all CW/RT operation of QCLs now covers a wavelength region from 3.6 μm to longer than 12 μm. Pranalytica, being a vertically integrated (from fundamental design of the structure to final customer usable product, but fabless) manufacturer of QCLs, has been supplying high power CW/RT QCLs as well as cryogenically cooled QCLs producing substantially higher power output (>;7 W, CW) at very high wallplug efficiency (>;30%) to military, homeland security and civilian customers