Simultaneous Raman spectra measurement using Power Build-up Cavity (PBC)

Raman spectroscopy using a simple external Power Build-up Cavity (PBC) pumped with a diode laser was demonstrated. The PBC is very simple configuration consisted of anti-reflection coated low power (10mW, lambda=670nm) laser diode, Graded index (GRIN) lens, and extremely high finesse external cavity, where the beam intensity can reaches up to 100W intracavity beam. Such a high finesse external cavity could optimized parameter attribute to high spectral brightness mostly suitable for a compact Raman light source without any sophisticated temperature and/or current injection control. PBC pumped Raman spectrum was measured by on optical fiber coupled optical multi-channel analyzer (OMA), The Raman signal from intracavity beam was imaged on the optical fiber by two focusing lenses (f=38mm, 50mm) located in perpendicular to the optical axis. Stokes Raman spectra of N-2 and O-2 of gas mixture were simultaneously measured with real time operation, approximately.