Optical frequency comb Fourier transform spectroscopy of formaldehyde in the 1250 to 1390 cm−1 range: Experimental line list and improved MARVEL analysis

We use optical frequency comb Fourier transform spectroscopy to record high-resolution, low-pressure, room-temperature spectra of formaldehyde (H212C16O) in the range of 1250 to 1390 cm−1. Through line-by-line fitting, we retrieve line positions and intensities of 747 rovibrational transitions: 558 from the ν6 band, 129 from the ν4 band, and 14 from the ν3 band, as well as 46 from four different hot bands. We incorporate the accurate and precise line positions (0.4 MHz median uncertainty) into the MARVEL (measured active vibration-rotation energy levels) analysis of the H2CO spectrum. This increases the number of MARVEL-predicted energy levels by 82 and of rovibrational transitions by 5382, and substantially reduces uncertainties of MARVEL-derived H2CO energy levels over a large range: from pure rotational levels below 200 cm−1 up to multiply excited vibrational levels at 6000 cm−1. This work is an important step toward filling the gaps in formaldehyde data in the HITRAN database

Fiber-based laser frequency combs

For the last decade a very attractive field of laser physics, namely the optical frequency comb technique, has been intensively developed. Fiber lasers play particular role in that area. The motivation of their development is obtaining broadband comb systems with well-defined and stable mods (comb teeth). This paper presents a basic overview devoted to the fiber-based optical frequency combs

Measurement and Assignment of Hot-Band Methane Transitions with Sub-MHz Accuracy

International audienceWe use double-resonance spectroscopy with cavity-enhanced comb probe to measure sub-Doppler transitions in the 3ν3←ν3 band of CH4. We assign the final states using different pump/probe combinations reaching the same state, and the dependence of line intensities on relative pump/probe polarization. © Optica Publishing Group 2022, © 2022 The Authors

Measurement and Assignment of Hot-Band Methane Transitions with Sub-MHz Accuracy

International audienceWe use double-resonance spectroscopy with cavity-enhanced comb probe to measure sub-Doppler transitions in the 3ν3←ν3 band of CH4. We assign the final states using different pump/probe combinations reaching the same state, and the dependence of line intensities on relative pump/probe polarization. © Optica Publishing Group 2022, © 2022 The Authors

Sub-doppler optical-optical double-resonance spectroscopy of methane using a frequency comb probe

International audienceWe use a 3.3 µm high-power continuous wave pump and a 1.67 µm comb probe to detect transitions in the 3ν3 ← ν3 range of methane with sub-Doppler resolution over 6 THz of bandwidth. We achieve high absorption sensitivity for the comb probe using an enhancement cavity and a Fourier transform spectrometer with auto-balanced detection. © OSA 2021, © 2021 The Author(s

Synthesis and Characterization of Antimony Telluride for Thermoelectric and Optoelectronic Applications

Antimony telluride (Sb2 Te3 ) is an intermetallic compound crystallizing in a hexagonal lattice with R-3m space group. It creates a c lose packed structure of an ABCABC type. As intrinsic semiconductor characterized by excellent electrical properties, Sb2 Te3 is widely used as a low-temperature thermoelectric material. At the same time, due to unusual properties (strictly connected with the structure), antimony telluride exhibits nonlinear optical properties, including saturable absorption. Nanostructurization, elemental doping and possibilities of synthesis Sb2 Te3 in various forms (polycrystalline, single crystal or thin film) are the most promising methods for improving thermoelectric properties of Sb2Te3.Applications of Sb2 Te3 in optical devices (e.g. nonlinear modulator, in particular saturable absorbers for ultrafast lasers) are also interesting. The antimony telluride in form of bulk polycrystals and layers for thermoelectric and optoelectronic applications respectively were used. For optical applications thin layers of the material were formed and studied. Synthesis and structural characterization of Sb2 Te3 were also presented here. The anisotropy (packed structure) and its influence on thermoelectric properties have been performed. Furthermore, preparation and characterization of Sb2 Te3 thin films for optical uses have been also made