Terahertz Waveguiding in Silicon-Core Fibers

TL;DR

This paper explores silicon-core fibers as a new waveguide for terahertz radiation, demonstrating through simulations that they can effectively confine and transmit THz waves with low absorption over a broad frequency range.

Contribution

It introduces silicon-core fibers for THz waveguiding and provides simulation-based analysis of their propagation characteristics and mode confinement.

Findings

Silicon-core fibers can confine THz waves effectively.

Propagation loss is comparable to bulk silicon.

Mode confinement improves with core diameters of 140-250 microns.

Abstract

We propose the use of a silicon-core optical fiber for terahertz (THz) waveguide applications. Finite-difference time-domain simulations have been performed based on a cylindrical waveguide with a silicon core and silica cladding. High-resistivity silicon has a flat dispersion over a 0.1 - 3 THz range, making it viable for propagation of tunable narrowband CW THz and possibly broadband picosecond pules of THz radiation. Simulations show the propagation dynamics and the integrated intensity, from which transverse mode profiles and absorption lengths are extraced. It is found that for 140 - 250 micron core diameters the mode is primarily confined to the core, such that the overall absorbance is only slightly less than in bulk polycrystalline silicon.