Significant suppression of Rayleigh scattering loss in silica glass formed by the compression of its melted phase.

We propose the formation of silica glass with improved optical transport properties by compressing its melted phase with a hot isostatic pressure machine at high pressure and temperature. The lowest Rayleigh scattering loss was obtained for the glass held at 200 MPa and 2073 K for 4 h. The observed loss corresponds to 0.07 dB/Km at 1.55 μm, which is about half of the loss in conventional silica glass fiber. The decrease in the loss was well explained in terms of the decrease in the size of the sub-nanometer-sized structural voids observed by positron annihilation lifetime spectroscopy in silica glass. The achievement of high transparency and strong confinement of light represents a promising result for the development of future fiber-core media.