Transmission degradation and preservation for tapered optical fibers in rubidium vapor

TL;DR

This paper investigates how rubidium vapor causes transmission loss in tapered optical fibers and demonstrates heating as an effective method to extend fiber lifetime in such environments.

Contribution

It provides direct measurements of transmission degradation timescales and introduces a heating technique to mitigate loss in rubidium vapor environments.

Findings

Transmission degrades rapidly with increased rubidium density.

Heating the fiber significantly prolongs transmission lifetime.

Immediate transmission loss occurs upon vapor introduction.

Abstract

The use of sub-wavelength diameter tapered optical fibers (TOF's) in warm rubidium vapor has recently been identified as a promising system for realizing ultra-low-power nonlinear optical effects. However, at the relatively high atomic densities needed for many of these experiments, rubidium atoms accumulating on the TOF surface can cause a significant loss of overall transmission through the fiber. Here we report direct measurements of the time-scale associated with this transmission degradation for various rubidium density conditions. Transmission is affected almost immediately after the introduction of rubidium vapor into the system, and declines rapidly as the density is increased. More significantly, we show how a heating element designed to raise the TOF temperature can be used to reduce this transmission loss and dramatically extend the effective TOF transmission lifetime.