title: Intra-cavity absorption spectroscopy with narrow-ridge microfluidic quantum cascade lasers.
abstract: We demonstrate microfluidic laser intra-cavity absorption spectroscopy with mid-infrared lambda approximately 9mum quantum cascade lasers. A deepetched narrow ridge waveguide laser is placed in a microfluidic chamber. The evanescent tails of the laser mode penetrate into a liquid on both sides of the ridge. The absorption lines of the liquid modify the laser waveguide loss, resulting in significant changes in the laser emission spectrum and the threshold current. A volume of liquid as small as ~10pL may, in principle, be sufficient for sensing using the proposed technique. This method, similar to the related gas-phase technique, shows promise as a sensitive means of detecting chemicals in small volumes of solutions.
authors: Mikhail A
authors: MA
authors: Belkin
authors: Marko
authors: M
authors: Loncar
authors: Benjamon G
authors: BG
authors: Lee
authors: Christian
authors: C
authors: Pflugl
authors: Ross
authors: R
authors: Audet
authors: Laurent
authors: L
authors: Diehl
authors: Federico
authors: F
authors: Capasso
authors: David
authors: D
authors: Bour
authors: Scott
authors: S
authors: Corzine
authors: Gloria
authors: G
authors: Hofler