Thermally activated resonant grating using a vanadium dioxide waveguide

Abstract

In this work, we report on the design of a one-dimensional subwavelength resonant grating comprised of a fused silica substrate and a bi-layer waveguide, consisting of a solgel synthetized anatase TiO2 layer followed by a thin VO2 layer that is applied using pulsed laser deposition and rapid thermal annealing. A TE waveguide mode is excited under normal incidence in the VO2/TiO2 bi-layer via a positive photoresist based grating printed on top, leading to high resonant reflection at room temperature. Increasing the temperature to about 68°C causes the VO2 to undergo a dielectric to metallic transition accompanied by optical modifications in the IR region, canceling the resonance effect. This thermally triggered absorber/emitter tunable configuration enabling the on and off switching of optical resonant excitation in a reversible manner is proposed for passive Q-switching self-protecting devices for high power lasers in the IR wavelength range. Modeling of the optimized temperature dependent resonant waveguide and preliminary experimental results are presented.

A tunable broadband terahertz metamaterial absorber based on the vanadium dioxide

“…All of these metals have intrinsic absorption characteristics that limit the tunability of surface plasmon resonance. More precisely, it can be said that in these absorbers, depending on the material and their dimensions of layers, the periodicity of the upper metal array, the magnetic resonances will be stimulated along certain wavelengths, and the amount of absorption and the frequency position of the resonant peaks will be constant [10,11]. Therefore, the idea of designing tunable absorbers using semiconductors, liquid crystals, graphene, and phase change materials (PCM) has always been raised [3,[12][13][14].…”

SiN/VO2/SiN Sandwich‐Based Resonant Waveguide Grating to Produce Thermally Activated Optical Components

“…The design of the resonant grating aims to maximize the reflectance (the intensity of the zeroth reflected order) for normal incidence at 1500 nm, that is, around the wavelengths usually used in telecom applications. The idea is to achieve maximum reflection for the cold state of VO 2 (at room temperature) and to reduce the resonance when the structure is heated, as described in our previous paper, [ 20 ] where the use of the TE 0 guided symmetric mode in the structure led to high losses even when the vanadium dioxide was in the cold state.…”

“…[19] Recently, our group demonstrated for the first time a VO 2 /TiO 2 based optical switch device that uses a resonant reflection for a TE 0 mode propagating along a thermally activated bi-layer for optical switching. [20] The structure was based on PLD fabricated VO 2 film grown on TiO 2 thin film deposited on a SiO 2 substrate with Table 1. Refractive indices of some used materials with VO2 for the thermal activated device components fabrication.…”

“…[ 19 ] Recently, our group demonstrated for the first time a VO 2 /TiO 2 based optical switch device that uses a resonant reflection for a TE 0 mode propagating along a thermally activated bi‐layer for optical switching. [ 20 ] The structure was based on PLD fabricated VO 2 film grown on TiO 2 thin film deposited on a SiO 2 substrate with a positive sinusoidal photoresist placed on top of the VO 2 /TiO 2 bilayer as a waveguide resonant grating filter. For that structure, a single‐guided mode TE 0 was selected in the waveguide layer.…”

“…This sandwich structure uses a TE 1 guided mode to minimize the amplitude of the electric field in the VO 2 layer embedded in the SiN layers, thereby insuring minimal absorption and losses. Furthermore, compared to the previously reported approach, [ 20 ] the new design embeds the VO 2 layer in the high index SiN layers. The reason for using SiN material is that the refractive index of SiN (≈2 @633 nm wavelength) is very close to that of VO 2 helping to produce a high‐ index homogenous optical layer as presented in Table 1 .…”