Multi-spectral optoacoustic microscopy driven by gas-filled hollow-core fiber laser pulses.

Multi-spectral optoacoustic microscopy (MS-OAM) requires high-performance light sources capable of delivering multiple intense spectral lines precisely matched to the absorption characteristics of selected biomolecules. We present a gas-filled anti-resonant hollow-core fiber (ARHCF) laser source optimized for near-infrared (NIR) MS-OAM. The hydrogen (H)-filled ARHCF laser emits multiple spectral lines with high pulse energy and narrow linewidths (<0.1 nm) across a broad spectral range (∼1100 nm to ∼2200 nm). Several Raman laser lines were generated to overlap with key biomolecular absorption bands, including lipids (1210 nm and 1700nm), collagen (∼1540 nm), and water (∼1400 nm and ∼1900 nm). We demonstrate the system's performance by mapping absorbers in the first and second overtone regions of hair, pig tissue, and collagen samples. This work aims to bring the gas-filled fiber technology into MS-OAM applications and paves the way for high-resolution, label-free bio-imaging across extended infrared and ultraviolet regimes.