Alkaline oxide interface modifiers for silicon fiber production

Erlend F Nordstrand,Andreas J Eraker,Ursula J Gibson,Andrew N Dibbs

doi:10.1364/ome.3.000651

Erlend F Nordstrand, Andreas J Eraker + Show 2 more

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https://doi.org/10.1364/ome.3.000651

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Abstract

We demonstrate the ability to pull small diameter silicon-core fibers with low oxygen content by using interface modifiers between the silica cladding and the semiconductor. Alkali earths scavenge oxygen and form a fine-structured eutectic that accommodates thermal strain and may be useful as an intermediate index cladding layer for optical applications. NaO, MgO, SrO, CaO and BaO interface modifiers were tested. CaO coated fibers were made with core diameters down to 10 microns, small bending radii, low oxygen incorporation, and optical losses below 4 dB/cm at 1.55 microns.

Highlights

Fiber materials for the infrared are of increasing importance as new laser sources are developed throughout the region from 1 to 10 microns
We present studies on the use of alkaline-earth interface modifiers to improve the mechanical properties of silicon-based fibers, demonstrating low-oxygen core content, core diameters down to 10 microns and low damage to the silica cladding, as evidenced by small bending radii
We demonstrate the ability to pull small diameter silicon fibers with good flexibility when using an interface modifier to scavenge oxygen from the core, relieve thermal mismatch, and decrease the viscosity of the boundary between the molten silicon and the silica glass

Summary

Introduction

Fiber materials for the infrared are of increasing importance as new laser sources are developed throughout the region from 1 to 10 microns. Scott [6] and Ballato [7] published results on the use of molten core fiber-optic pulling techniques to form silicon and germanium [8] fibers encased in glass. We present studies on the use of alkaline-earth interface modifiers to improve the mechanical properties of silicon-based fibers, demonstrating low-oxygen core content, core diameters down to 10 microns and low damage to the silica cladding, as evidenced by small bending radii. This technique should be adaptable to the production of high quality optical fibers when performed in a commercial drawing tower, when employing MOCVD-deposited oxide interface modifiers

Experimental

Results and discussion

Conclusions