Fraunhofer IPMS, Germany
Title: Miniaturized tunable QCL - lightsource for MID-infrared spectroscopy
Biography: A Merten
Broadband tuning of MIR-infrared radiation from 3 to 10 µm is a very promising way for spectroscopic study of gaseous, liquid, or solid species or intermixtures. We report a fast broadband tunable IR-light source based on the combination of a quantum-cascade-laser and a micro-opto-electro-mechanical systems (MOEMS) with integrated diffractive grating. This concept unites the advantages of broadband sources with the advantages of coherent laser sources in a miniaturized setup. The diffraction grating is processed inline within the MOEMS production process by non-isotropic etching. Grove depth and thus maximum spectral diffraction efficiency is determined by lithographic mask and the etch-parameters. The scanning MOEMS-grating is driven electrostatically and oscillates with high repeatability at resonance frequency of 1 kHz and up to 10° deflection, which allows scanning the entire spectral range of the QCL-chip within 500 µs. This opens the way for real-time spectroscopy in the MID-IR range. We present applications in non-contact detection of hazardous species e.g. explosives and inline-detection oil contamination in water.