Damage-free single-mode transmission of deep-UV light in hollow-core PCF

TL;DR

This paper demonstrates damage-free, stable single-mode transmission of deep-UV light in hollow-core photonic crystal fiber, significantly improving coherence times in trapped ion experiments by reducing beam pointing instability.

Contribution

It introduces the use of kagomé-type photonic crystal fiber for UV light transmission, achieving long-term stability and minimal degradation, which was not possible with solid-core fibers.

Findings

No transmission degradation after >100 hours at 15 mW CW power

Effective single-mode UV transmission with acceptable loss

Enhanced coherence times in trapped ion experiments

Abstract

Transmission of UV light with high beam quality and pointing stability is desirable for many experiments in atomic, molecular and optical physics. In particular, laser cooling and coherent manipulation of trapped ions with transitions in the UV require stable, single-mode light delivery. Transmitting even ~2 mW CW light at 280 nm through silica solid-core fibers has previously been found to cause transmission degradation after just a few hours due to optical damage. We show that photonic crystal fiber of the kagom\'e type can be used for effectively single-mode transmission with acceptable loss and bending sensitivity. No transmission degradation was observed even after >100 hours of operation with 15 mW CW input power. In addition it is shown that implementation of the fiber in a trapped ion experiment significantly increases the coherence times of the internal state transfer due to an increase in beam pointing stability.