Terahertz attenuators based on dielectric stacks with alternating refractive indices

Abstract

This article demonstrates the design of dielectric terahertz (THz) attenuators comprising of periodically placed x-cut and z-cut ion-sliced lithium niobate dielectric layers. Changes introduced in the propagating wave due to alternating refractive indices of a ferroelectric material have been exploited for the design of an effective attenuator. The electrical and optical properties gathered from experimental investigations have been used to study the influence of different crystalline orientations on the design. The conduit comprising the periodically placed dielectric slabs has been configured as a tristate switch by modulating the amplitude of the traversing THz wave by altering its angle of incidence. Full-wave finite-element simulations have been conducted over a series of parametric configurations to come up with the optimized design. A modulation depth as high as 94.76% is achieved. The proposed low-cost, easily configurable THz dielectric attenuators operating around 0.625 THz can be potentially used as an external modulator for THz quantum cascade lasers.