Pulse-stacked cavity ring-down spectroscopy

Abstract

Pulse stacking, or synchronous pumping, is a novel approach that offers important advantages in cavity ring-down spectroscopy. Using an ultrashort pulse, high repetition rate laser source we have shown that it is possible to resonantly stack pulses in a high finesse cavity, significantly enhancing the decay wave forms obtained when the laser source is abruptly terminated. We have achieved signal-to-noise ratio improvements of several orders of magnitude compared to single pulse injection systems, demonstrating a sensitivity of ${\text{2×10}}^{\text{−9}}\hspace{0.17em}{\mathrm{cm}}^{\mathrm{-1}}$ at 5.38 μm.