Erlangen 2018 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 24: Experimental Techniques

MO 24.5: Vortrag

Freitag, 9. März 2018, 11:30–11:45, PA 2.150

Coherent anti-stokes Raman spectroscopy in gas-filled hollow-core PCF — •Rinat Tyumenev¹, Barbara Trabold¹, Amir Abdolvand², Luisa Spaeth¹, and Philip St J Russel¹ — ¹Max-Planck-Institut für die Physik des Lichts Staudtstraße 2 91058 Erlangen — ²Nanyang Technological University

Gas sensing and composition analysis are of great importance in numerous fields, for example environmental studies of greenhouse gases and toxic substances, medicine for detection of marker gases in human breath, chemical and industrial applications. Raman spectroscopy provides quantitative molecule-specific measurement of analytes. However, some analytes, for example gases, have relatively weak Raman gain and at low concentrations free space Raman spectroscopy yields tiny signal levels, which require very powerful pump lasers to be detectable. We present an approach that relaxes the need for high laser power and provides broadband Raman spectroscopy of gas mixtures. The approach is based on coherent anti-Stokes Raman spectroscopy in gas filled hollow-core photonic crystal fibre (PCF). The hollow core provides long interaction lengths allied to core diameters of a few tens of micrometers, dramatically increasing the CARS signal. The ability to change the dispersion of the waveguide by altering the gas pressure or (less practically) the PCF geometry permits CARS phase-matching over a broad wavelength range, so that the Raman signal can build up coherently over the whole fiber length. We report broadband (4000 1/cm) single-shot CARS with a concentration detection limit of 300 ppm.