Tunable dielectric resonators for freespace light intensity modulation
Tunable dielectric resonators for the modulation of freespace radiation and methods of using the resonators are provided. The dielectric resonators include a planar waveguide that supports a vertical Fabry-Perot resonance, a grating that supports a qBIC resonance, and a radiation absorbing material having an electronically or thermally tunable absorption at the qBIC resonant frequency. Using this resonator design, the intensity of the transmission and reflection of the qBIC resonance can be modulated by modulating the absorption properties of the absorbing material at the qBIC resonant frequency.
1. A dielectric resonator comprising:
a waveguide comprising a planar dielectric slab; and
a periodic grating on the planar dielectric slab, wherein the waveguide supports a vertical Fabry-Perot resonance and the periodic grating supports a qBIC resonance, the supported qBIC resonance having a qBIC resonant frequency corresponding to a peak in the transmission spectrum of the Fabry-Perot resonance; and
an electronically gated or thermally gated absorber material on a surface of the dielectric slab, the absorber material having an electrically tunable absorption at the qBIC resonant frequency.
2. The resonator of claim 1 , wherein the qBIC resonance has a resonant wavelength in the range from 1 μm to 2 μm.
3. The resonator of claim 1 , wherein the absorber material is electrically gated.
4. The resonator of claim 3 , wherein the absorber material is graphene.
5. The resonator of claim 4 , wherein the graphene is chemical vapor deposited graphene.
6. The resonator of claim 1 , wherein the planar dielectric slab is a silicon nitride slab.
7. The resonator of claim 6 , wherein the waveguide further comprises a silicon electrode adjacent to a surface of the silicon nitride slab opposite the absorber material.
8. The resonator of claim 7 , wherein periodic grating comprises dimerized silicon oxide grating elements.
9. The resonator of claim 8 , wherein the absorber material is graphene.
10. The resonator of claim 1 , wherein the absorber material is selected from indium tin oxide, vanadium dioxide, germanium-antimony-tellurium, indium zinc oxide, and titanium nitride.
11. A method for modulating the intensity of monochromatic radiation using a dielectric resonator comprising:
a waveguide comprising a planar dielectric slab; and
a periodic grating on the planar dielectric slab, wherein the waveguide supports a vertical Fabry-Perot resonance and the periodic grating supports a qBIC resonance, the supported qBIC resonance having a qBIC resonant frequency corresponding to a peak in the transmission spectrum of the Fabry-Perot resonance; and
an electronically gated or thermally gated absorber material on a surface of the dielectric slab, the absorber material having an electrically tunable absorption at the qBIC resonant frequency,
the method comprising:
illuminating the waveguide with free space radiation at normal incidence to excite the vertical Fabry-Perot resonance and a lateral guided mode resonance at the qBIC resonant frequency, wherein the lateral guided mode resonance and the vertical Fabry Perot resonance couple to produce a Fano resonance having a Lorentzian line shape with a minimum transmittance and a maximum reflectance at the qBIC resonant frequency; and
adjusting a gate bias on the electronically gated absorber material or a temperature of the thermally gated absorber material to modulate the intensity of the qBIC resonance.
12. The method of claim 11 , wherein the absorber material is electronically gated.
13. The method of claim 12 , wherein adjusting the gate bias modulates the intensity of transmission at the qBIC resonant frequency from 100% to 0%.
14. The method of claim 11 , wherein the absorber material is thermally gated.