Widely tunable raman fiber laser for hyperspectral photoacoustic imaging

Authors

Abhigyan Goswami

Sarthak Dash

VR Supradeepa

Swathi Padmanabhan

Jaya Prakash

Doi

https://doi.org/10.1117/12.3043033

[1]
A. Goswami, S. Dash, V. R. Supradeepa, S. Padmanabhan, and J. Prakash, “Widely tunable Raman fiber laser for hyperspectral photoacoustic imaging,” in Photons plus ultrasound: Imaging and sensing 2025, SPIE, 2025, p. 1331911. doi: 10.1117/12.3043033.
Abstract

We demonstrate a widely tunable pulsed cascaded Raman fiber laser (CRFL) continuously tunable in the second near infrared (NIR-II) window (1060-1600 nm) and through harmonic conversion in the visible window (530-600 nm, limited currently only by crystal availability in house) and effectively implemented it in a hyperspectral photoacoustic imaging (PAI) setup. We utilized it for PA spectroscopy of lipids in the second resonance of C-H bond in 1145-1257 nm. The CRFL operates at a tunable high repetition-rate variable from 20 kHz to 80 kHz. Pulse-duration can be changed from 40 ns to 200 ns by minor modification. The pulse energy is ⁓ 10 μJ in NIR-II window and ⁓ 0.1 μJ in the visible window. The CRFL module can provide an alternative to OPOs and supercontinuum for hyperspectral PAI applications.