Cavity-enhanced absorption detection of H2S in the near-infrared using a gain-switched frequency comb laser

A custom-designed gain-switched frequency comb laser was passively coupled of to a medium-finesse cavity in the region between 6346 and 6354 cm−1 for the development of a prototype cavity enhanced absorption setup. The setup was applied to static gas detection of hydrogen sulfide at the parts per thousand level in a laboratory environment. A Fourier transform spectrometer was used for signal detection. The experimental performance of the setup was characterized in this proof-of-principle investigation; advantages, drawbacks and future scope of the approach are discussed in this article

Compact gain switched optical frequency comb generator for sensing applications

We present a novel InP photonically integrated optically injected device that is gain switched for the generation of an optical frequency comb. Using this technique, an optical frequency comb with a free spectral range of 6.25 GHz and nine spectral lines within a 3 dB spectral window is obtained. Such a device provides tunability of both the free spectral range and the centre emission wavelength, which facilitates the matching of the wavelength to the signature of a target gas. The stable spacing and high phase correlation between the comb lines confirms the potential of the device to be used in various applications such as spectroscopy, telecommunications and gas sensing

Zeroth Poisson Homology, Foliated Cohomology and Perfect Poisson Manifolds

International audienceWe prove that for regular Poisson manifolds, the zeroth homology group is isomorphic to the top foliated cohomology group and we give some applications. In particular, we show that for regular unimodular Poisson mani-folds top Poisson and foliated cohomology groups are isomorphic. Inspired by the symplectic setting, we define what is a perfect Poisson manifold. We use these Poisson homology computations to provide families of perfect Poisson manifolds