Bright Spatially Coherent Wavelength-Tunable Deep-UV Laser Source Using an Ar-Filled Photonic Crystal Fiber

TLDR

Unlike supercontinuum generation in solid‑core photonic crystal fibers, the absence of Raman scattering and the ability to control dispersion with pressure enable efficient deep‑UV dispersive‑wave emission in an argon‑filled hollow‑core fiber. The study reports spectral broadening of ~1 µJ, 30 fs pulses in an argon‑filled hollow‑core photonic crystal fiber. The experiment employs less than 1 m of argon‑filled hollow‑core fiber to produce stable, bright deep‑UV light with up to 8 % IR‑to‑UV conversion efficiency. The resulting UV light, confined to the single‑lobed fundamental mode, is tunable from 200 to 320 nm by varying pulse energy and gas pressure, making it immediately useful for high‑spatial‑coherence applications such as laser lithography and confocal microscopy.

Abstract

We report on the spectral broadening of $\ensuremath{\sim}1\text{ }\text{ }\ensuremath{\mu}\mathrm{J}$ 30 fs pulses propagating in an Ar-filled hollow-core photonic crystal fiber. In contrast with supercontinuum generation in a solid-core photonic crystal fiber, the absence of Raman and unique pressure-controlled dispersion results in efficient emission of dispersive waves in the deep-UV region. The UV light emerges in the single-lobed fundamental mode and is tunable from 200 to 320 nm by varying the pulse energy and gas pressure. The setup is extremely simple, involving $<1\text{ }\text{ }\mathrm{m}$ of a gas-filled photonic crystal fiber, and the UV signal is stable and bright, with experimental IR to deep-UV conversion efficiencies as high as 8%. The source is of immediate interest in applications demanding high spatial coherence, such as laser lithography or confocal microscopy.