Thermally-diffused expanded core fibres for low-loss and inexpensive photonic components

Abstract

A technique is presented to locally expand the mode-field diameter of singlemode fibres. This can rapidly diffuse germanium ions into the core of silica fibres without deforming the cladding. The mode-field diameter broadens 20 μm after 5–l0 min of heating. Low-loss and inexpensive fibre-to-fibre and fibre-to-device connections are realised using the thermally-diffused expanded core fibre.