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Unraveling the scientific and technological importance of the mid-infrared (mid-IR) region remains yet a long-standing challenge. Despite the significant efforts on mid-IR light sources, development of high-energy, narrow-linewidth and compact lasers still constitutes the main obstacle towards novel spectroscopic, imaging and sensing devices. Photoacoustic modality is known as one of the most powerful tools enabling high signal-to-noise ratio gas detection and albeit its wide use in the mature near-infrared (near-IR) region, further research has to be carried out in the mid-IR in order to “unlock” its full potential. In this work, we aim on tracing CO2 based on the innovative combination of the emerging gas-filled mid-IR silica anti-resonant hollow-core fiber (ARHCF) Raman laser technology with the powerful photoacoustic modality. The laser source adopts the stimulated Raman scattering effect of H2 filled in a piece of ARHCF, to enable the generation of first-order vibrational Raman Stokes from a 1533 nm Er-doped fiber laser pump. With this configuration, a nanosecond laser pulses with micro-joule level pulse energy is achieved at ~ 4.25 μm wavelength, which is located within the strongest absorption band of CO2. The laser’s linewidth is estimated to be tens GHz level. This laser source is used to drive an in-house developed photoacoustic sensor, revealing a 1.78 ppm level CO2 detection limit in laboratory condition. This work provides a valuable reference for the development of high-sensitivity gas detectors.
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