Linear Up-conversion of Orbital angular momentum

We experimentally demonstrated that infrared light imprinted with orbital angular momentum (OAM) was linearly converted into visible light using four-wave mixing (FWM) via a ladder-type configuration in 85Rb atoms. Simultaneously, we theoretically simulated this linear conversion process, and the theoretical analysis was in reasonable agreement with the experimental results. A large single-photon detuning process was used to reduce the absorption of the atoms to the up-converted light and to avoid pattern formation in the FWM process. The multi-mode image linear conversion process is important for applications including image communications, astrophysics and quantum information.Comment: Accepted by O

Room temperature mid-IR single photon spectral imaging

Spectral imaging and detection of mid-infrared (mid-IR) wavelengths are emerging as an enabling technology of great technical and scientific interest; primarily because important chemical compounds display unique and strong mid-IR spectral fingerprints revealing valuable chemical information. While modern Quantum cascade lasers have evolved as ideal coherent mid-IR excitation sources, simple, low noise, room temperature detectors and imaging systems still lag behind. We address this need presenting a novel, field-deployable, upconversion system for sensitive, 2-D, mid-IR spectral imaging. Measured room temperature dark noise is 0.2 photons/spatial element/second, which is a billion times below the dark noise level of cryogenically cooled InSb cameras. Single photon imaging and up to 200 x 100 spatial elements resolution is obtained reaching record high continuous wave quantum efficiency of about 20 % for polarized incoherent light at 3 \mum. The proposed method is relevant for existing and new mid-IR applications like gas analysis and medical diagnostics

Identification and Properties of New Flavins in Electron-Transferring Flavoprotein from Peptostreptococcus elsdenii and Pig-Liver Glycolate Oxidase

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65168/1/j.1432-1033.1974.tb03515.x.pd

Limits of amplification of weak images

International audienceOptical amplification of a signal or an image is always accompanied by amplification of quantum noise with a mean rate corresponding to, in the limit of high gain, the input noise of one photon per spatio-temporal mode. We show that an image of dye fluorescence can be retrieved with good contrast after parametric amplification, even if the level of the input image corresponds to significantly less than one photon per mode. Theoretical limits are assessed

Picosecond fluorescence lifetime imaging by parametric image amplification

We report a new method of fluorescence lifetime imaging that uses the ultra-fast optical temporal gating properties of parametric image amplification. Images with different lifetimes in the picosecond range are resolved with reliable and reproducible results

Revisiting the Young's Double Slit Experiment for Background-Free Nonlinear Raman Spectroscopy and Microscopy

International audienceIn the Young's double slit experiment, the spatial shift of the interference pattern projected onto a screen is directly related to the phase difference between the fields diffracted by the two slits. We apply this property to fields emitted by nonlinear processes and thus demonstrate background-free coherent anti- Stokes Raman scattering microscopy near an axial interface between a resonant and a nonresonant medium. This method is relevant to remove the nonresonant background in other coherent resonant processes

Absolute radiance imaging using parametric image amplification

International audienceWe show that parametric image amplification can be used to achieve a 2D radiance map directly expressed in photons per spatiotemporal mode. Radiance images of incoherent signals with less than one photon per mode (typically 10-2) are resolved