Efficient 4.42 Μm Raman Laser Based on Hollow-Core Silica Fiber

Abstract

In this paper we consider mid-infrared Raman lasers based on gas-filled hollowcore silica fibers and provide theoretical and experimental analysis of factors that limit the efficiency and output power of these lasers. As a result, we realized an efficient ns-pulsed 4.42 µm Raman laser based on an 1 H 2 -filled revolver silica fiber. Quantum efficiency as high as 36 % is achieved, and output average power as high as 250 mW is demonstrated. The possibilities of further improving the laser efficiency are discussed.

Photoacoustic detection of CO2 using a H2-filled mid-infrared fiber Raman laser source

“…This trend can be attributed to the known saturation of the Raman gain at high pressure [28] and decreased dephasing time of H2 (see black curve in Figure 3(a)). Remarkably, the saturation pressure here is much less compared to previous reports [29] since the transient Raman regime is well suppressed by the long pump pulse duration of 6.9 ns. Figure 3(b) depicts the spectrum at 20 bar measured using an optical spectrometer with a resolution of 0.05 nm, where a strong laser line at 4.22 µm is formed as a result of the vibrational Raman Stokes shift from the pump laser.…”

“…Figure 3(b) depicts the spectrum at 20 bar measured using an optical spectrometer with a resolution of 0.05 nm, where a strong laser line at 4.22 µm is formed as a result of the vibrational Raman Stokes shift from the pump laser. A rotational Raman line is also formed at 1.68 µm, but its intensity is negligible compared to the vibrational Raman line as a result of the optimized pump polarization [29,30]. Simulated absorbance spectrum of CO2 is also provided for comparison in this figure.…”

Gas-filled hollow-core fiber lasers for gas spectroscopy and imaging

“…Initially, only the first-order rotational Stokes line at 1683 nm was observed at the pressure of ~1 bar. Increasing the gas pressure increases the Raman gain coefficient of the steady-state Raman regime [28] and suppresses the transient Raman regime [4], which has a lower gain coefficient than the steady-state regime. As a result, the intensity of the first-order Stokes line first continuously increases until it is sufficient to serve as a new pump to generate the second-order Stokes line at 1868 nm.…”

“…The recent advent of gas-filled low-loss silica ARHCF technology opens up a promising way for the generation of broadband [1,2] or narrow line infrared (IR) Raman lasers with high pulse energy and relatively low noise [3][4][5][6][7][8][9][10]. Eficient stimulated Raman scattering (SRS) process is enabled by the intense interaction between the pump laser and the gas along the hollow core region of ARHCF that leads usually to a high quantum conversion efficiency approaching to 80% [6,7,11], while the long Raman Stokes coefficient of the gas can directly red-shift the NIR pump wavelength to MIR Raman Stokes [4,6,7]. Another remarkable advantage is that the Raman gain width of gas can be hundreds of MHz, which eventually allows the generation of very narrow Raman lasers [12,13].…”

Полые Револьверные Световоды (Свойства, Технология, Применения)

“…В работах [42,59,60] [53], посвященной газовым волоконным лазерам на основе инверсии населенностей, была продемонстрирована эффективная генерация излучения на длине волны 3,1 мкм при накачке на λ = 1,53 мкм. Несмотря на большой квантовый дефект, сопоставимый с квантовым дефектом в ВКР-лазерах, была достигнута выходная мощность более 1 Вт в непрерывном режиме.…”