Advances of MOEMS-based External Cavity QCLs

摘要

The combination of broadly tunable quantum cascade laser chips in an external cavity (EC-QCL) with a micro- electromechanicalsystem (MEMS) scanner with integrated diffraction grating as wavelength-selective element allows for thedevelopment of extremely compact and robust spectroscopy systems. Resonant MOEMS grating scanners enablespectral tuning rates of hundreds of wavenumbers per millisecond and consequently broad-band spectroscopy withmillisecond temporal resolution. Also non-resonant (quasi-static) MOEMS grating scanners are possible, providing scanrates of tens of Hz as well as static setting of arbitrary wavelengths, as common for mechanically driven EC lasers, whilekeeping the small MOEMS footprint, ruggedness, and low power consumption. Here, we give a progress report on thelatest developments on MOEMS-based EC-QCLs made by Fraunhofer IAF and IPMS. We will highlight two of ourlatest developments: A non-resonant MOEMS EC-QCL version that allows arbitrary scan frequencies up to few tenHertz, as well as static operation. Furthermore, we present the application of a resonantly driven cw-MOEMS-EC-QCLwith cavity-length control to enable fast high-resolution spectroscopy over a spectral range of >100 cm-1, offering newpossibilities for spectroscopy on complex gas mixtures.