title: Application of Balanced Detection to Absorption Measurements of Trace Gases with Room-Temperature, Quasi-cw Quantum-Cascade Lasers.
abstract: Distributed-feedback quantum-cascade (QC) lasers are expected to form the heart of the next-generation mid-IR laser absorption spectrometers, especially as they are applied to measurements of trace gases in a variety of environments. The incorporation of room-temperature-operable, single-mode QC lasers should result in highly compact and rugged sensors for real-world applications. We report preliminary results on the performance of a laser absorption spectrometer that uses a QC laser operating at room temperature in a quasi-cw mode in conjunction with balanced ratiometric detection. We have demonstrated sensitivities for N(2)O [10 parts in 10(6) volume-mixing ratio for a 1-m path (ppmv-m)] and NO [520 parts in 10(9) volume-mixing ratio for a 1-m path (ppbv-m)] at 5.4 mum. System improvements are described that are expected to result in a 2 orders of magnitude increase in sensitivity.
authors: D M
authors: DM
authors: Sonnenfroh
authors: W T
authors: WT
authors: Rawlins
authors: M G
authors: MG
authors: Allen
authors: C
authors: C
authors: Gmachl
authors: F
authors: F
authors: Capasso
authors: A L
authors: AL
authors: Hutchinson
authors: D L
authors: DL
authors: Sivco
authors: J N
authors: JN
authors: Baillargeon
authors: A Y
authors: AY
authors: Cho