Tunable ultra-fast infrared generation in a gas-filled hollow core capillary by a four-wave mixing process: erratum

This erratum reports corrections to the temporal axes in Figs. 12 and 13 of J. Opt. Soc. Am. B 39, 662 (2022)JOBPDE0740-322410.1364/JOSAB.444574

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Art Painting Testing with Terahertz Pulse and Frequency Modulated Continuous Wave

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Frequency modulated continuous wave terahertz imaging for art restoration

Art and heritage analysis techniques are important in the framework of restoration and conservation. Usual techniques for painting analysis are X-ray imaging and infrared raking light. We propose in this paper to present a case study of a painting analyzed by conventional methods and by terahertz imaging

Tunable ultra-fast infrared generation in a gas-filled hollow core capillary by a four-wave mixing process

International audienceIn this manuscript, we numerically and experimentally investigated the four-wave mixing process in a gas filled hollowcore capillary in the femtosecond regime. The interaction between a visible broad-band continuum and a chirped pump pulse resulted to the generation of a tunable near infrared pulse of 1.2 to 1.5 µm, and with the potentiality to reach the mid-infrared range. Numerical simulations were performed in order to fully understand the role of key parameters such as the gas pressure, chirps and relative delays of the involved pulses. The experimentation which demonstrated and highlighted the feasibility of the tunable femtosecond source, led to the generation of an idler at 1.2 µm with a duration of ~220 fs at the direct output of the capillary. The duration can ultimately be reduced to 45 fs in the presence of phase compensators

Frequency modulated continuous wave terahertz imaging for art restoration

Art and heritage analysis techniques are important in the framework of restoration and conservation. Usual techniques for painting analysis are X-ray imaging and infrared raking light. We propose in this paper to present a case study of a painting analyzed by conventional methods and by terahertz imaging

Optical parametric amplification in gas-filled hollow core capillary for the generation of tunable pulses in the infrared

International audienceUltrashort pulses in the near-infrared (NIR) to mid-infrared (MIR) are widely used for laser matter interaction experiments, e.g. the relaxation process of carrier semiconductors and chemical dynamics at the femtosecond and attosecond time scale [1,2]. Many different approaches based on nonlinear processes or laser devices can be found to generate pulses in theses spectral ranges. Recently, four wave mixing (FWM) based parametric amplification in gas-filled hollow core capillary (HCC) has been used to create a tunable source of ultrashort pulses. For example, pulses can be generated in the visible with an energy at the 10 µJ level [4] and in the near infrared at ~1.4 µm with an energy of 5 µJ and a pulse duration of 45 fs [5]. Here, we present an implementation of a scheme to generate tuneable pulses from the NIR to the MIR toward a high-power level. The general principle of the FWM process relies on the combination of two pulses: a strong pump and a weak signal which co-propagate in a gas filled HCC. According to the phase matching condition, a part of the pump energy is transferred from the pump to the signal and an idler is created. In our experiment, this process was driven by pulses from a 1 kHz, Ti: Sapphire laser (800 nm, 120 fs) in combination with a weak continuum tunable from 420 to 650 nm (the signal) obtained by focusing a part of the 800nm laser into a 5 mm thick Sapphire plate. The relative delay between the pump and the seed pulses was controlled by a translation stage. Both beams were focused in a 30 cm long argon filled HCC with an inner core diameter of 150 µm. In parallel, we firstly achieved numerical simulations to predict the optimal pressure when the three waves propagate in the fundamental modes. From the computed total phase mismatch (Figure 1.a), we determine that tunable pulses in the near/mid infrared with high gain can be obtained from a pressure < 2 bar. Figure 1.b-c shows the experimental spectrum for a pressure of ~2 bar and an energy in the capillary of 146 µJ, when the pump pulse and the continuum signal are temporally overlapped. The tunability was obtained by changing the relative delay between the signal and the pump with the translation stage. In this condition, the idler is found to be tuneable from 1µm to 1.3 µm. Others simulations and experiments are in progress to extend the bandwidth toward the mid-infrared. a) b) c) Fig. 1 (a) Total phase mismatch in a Ar filled HCC. The core diameter is 150 µm. The pressure is tuned from 0.5 to 2 bar. The pump energy is 250 uJ.at 800nm b) Continuum spectrum (black line). Amplified spectrum for several delays, (color lines). c) Infrared spectrum generated by the FWM for a pressure of 2 bar. To summarize, we have shown that FWM based parametric amplification in gas filled hollow core capillary is an efficient method to generate tuneable pulses in the infrared band with a promising potentiality to reach the mid infrared. References [1] B

Tunable source of infrared pulses in gas-filled hollow core capillary

International audienceWe report a tunable source that generates pulses in the infrared from an optical parametric amplification in a gas-filled hollow core capillary based on four-wave mixing process, in which the phase matching strongly depends on the gas pressure and the pump. In our case, we have generated pulses from 1 to 1.6 m in the sub-µJ level together with a parametric amplification in the visible