# Proca Fields in Step-index Optical Fibres

## TL;DR

This paper derives mode solutions for Proca's equation in step-index optical fibres, showing that the no-go theorem for massive photons in coaxial waveguides does not apply here, advancing understanding of photon mass effects in optical systems.

## Contribution

It provides a comprehensive derivation of Proca mode solutions in step-index fibres, challenging previous no-go results and expanding theoretical models for massive photons in optical waveguides.

## Key findings

- No-go theorem does not apply to step-index fibres
- Full mode solutions for Proca's equation derived
- Implications for photon mass in optical systems

## Abstract

The topic of a photon mass has received justified attention over the years with strong theoretical reasoning for its existence. We derive a full description of mode solutions in step-index optical fibres on the basis of Proca's equation as a model for massive photons. The no-go theorem recently found in coaxial waveguides does not appear in the optical fibre case.