Dynamic Terahertz Switching Device Comprising Sub-wavelength Corrugated Waveguides and Cavity that Utilizes Resonance and Absorption for Attaining On and Off states

• US 20130301983A1
• Filed: 05/08/2012
• Published: 11/14/2013
• Est. Priority Date: 05/08/2012
• Status: Active Grant

• Current Assignee: Pinaki Mazumder
• Original Assignee: Pinaki Mazumder
• Inventors: Mazumder, Pinaki, Song, Kyungjun
• Granted Patent: US 8,842,948 B2
• Time in Patent Office: Days
• US Class Current: 385/16
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/1226 involving surface plasmon interaction
• CPC Class Codes: G02B 6/29322 Diffractive elements of the tunable type G02B6/02195 takes precedence; optical modulation devices based on a change of the optical properties of the medium G02F1/00
• CPC Class Codes: G02B 6/35 having switching means by changing the optical properties of the medium G02F1/00
• CPC Class Codes: G02F 1/3515 All-optical modulation, gating, switching, e.g. control of a light beam by another light beam G02F1/353, G02F1/37, G02F1/39 take precedence
• CPC Class Codes: G02F 2203/10 plasmon
• CPC Class Codes: G02F 2203/13 involving THZ radiation
• CPC Class Codes: G02F 2203/15 involving resonance effects, e.g. resonantly enhanced interaction
• CPC Class Codes: Y10T 29/49016 Antenna or wave energy "plumbing" making

Abstract

A terahertz (THz) switch consisting of perfect conductor metamaterials is discussed in this invention. Specifically, we have built a THz logic block by combining two double-sided corrugated waveguides capable of slowing down the electromagnetic waves in the THz regime with a sub-wavelength cavity, having one or more grooves with shorter height than the grooves of the periodic corrugated waveguide. This new type of THz structure is called as the waveguide-cavity-waveguide (WCW). The new invention is based on our mathematical modeling and experimentation that confirms a strong electromagnetic field accumulation inside the tiny cavity which can confine EM field for a long time within a very small effective volume (V_eff) to provide high quality (Q) factor. Therefore, an efficient THz switch can be designed to achieve ON-OFF switching functionality by modulating the refractive index n or extinction coefficient α inside the switching junction. The dimensions of the periodic structure and cavity can be optimized to apply the invention to slow-EM wave devices working at other frequencies in the EM spectrum including the microwave and outside the THz domain which is generally accepted as from 0.3 THz to 3 THz.

Claims

1. A THz spoof surface plasmon polariton (SSPP) or slow-EM wave switch comprising:

(a) Sub-wavelength cavity placed between two sub-wavelength corrugated waveguides having periodic dielectric grooves of higher heights (grooves can be of equal or variable heights) than the heights of grooves, if any, inside the cavity, such that the optimal switching can be achieved by utilizing the resonance and absorption properties of the structure.

(b) Sub-wavelength waveguides on the two ends provide input of said switch and output of said switch.

2. The THz SSPP switch of claim 1, wherein said sub-wavelength waveguides consist of two wave guide structures comprising dielectric and metallic structures, where the dielectric is corrugated having equal or variable heights.

3. The THz SSPP switch of claim 1, wherein said sub-wavelength cavity comprises of dielectric and metallic gap structures.

4. The THz SSPP switch of claim 1, wherein said sub-wavelength cavity provides resonant modes with resonant frequency ω

_o and quality factor Q, which enables EM waves to pass from the input end to the output end.

5. The THz SSPP switch of claim 1, wherein optimal THz switching can be achieved using resonance modulation of said cavity by changing the refractive index of the materials inside the sub-wavelength cavity.

6. The THz SSPP switch of claim 1, wherein optimal THz switching can be achieved using absorption modulation of said cavity by changing the extinction coefficient of the materials inside the sub-wavelength cavity, thereby preventing EM waves from the input end from going to the output end.

7. The SSPP switch of claim 1, wherein optimal switching can be applied to slow-EM wave devices operating outside the THz domain, which is defined as the EM waves in the spectrum ranging from 300 GHz to 3 THz.

8. The SSPP switch of claim 1, wherein said optimal switching can be applied to biosensing devices.

9. The SSPP switch of claim 1, wherein said optimal switching can be applied to construct multiplexer, demultiplexer/decorder, interferometer and nonlinear switches.

10. A method of forming an optimal THz SSPP switch by:

(a) using the resonant modes of a sub-wavelength metallic cavity in order to characterize the On/Off switching of slow EM waves so that control is provided for propagation of EM waves over the input and the output ends of said switch; and

(b) providing a slow EM wave propagation along waveguide structures comprising dielectric and metallic structures, where the dielectric is corrugated having equal or variable heights.

11. The method of claim 10, wherein said sub-wavelength waveguides consist of two wave guide structures comprising dielectric and metallic structures, where the dielectric is corrugated having equal or variable heights.

12. The method of claim 10, wherein said sub-wavelength cavity provides resonant modes with resonant frequency ω

_o and quality factor Q, which enables EM waves to pass from the input end to the output end.

13. The method of claim 10, wherein optimal THz switching can be achieved using resonance modulation of said cavity by changing the refractive index of the materials inside the sub-wavelength cavity.

14. The method of claim 10, wherein optimal THz switching can be achieved using absorption modulation of said cavity by changing the extinction coefficient of the materials inside the sub-wavelength cavity, thereby preventing EM waves from the input end from going to the output end.

15. The method of claim 10, wherein optimal methods can be applied to slow-EM wave devices working at other frequencies in the EM spectrum including the microwave and outside the THz domain which is defined as the EM waves in the spectrum ranging from 300 GHz to 3 THz.

16. The method of claim 10, wherein optimal switching can be applied to biosensing devices.

17. The method of claim 10, wherein optimal switching can be applied to construct multiplexer, demultiplexer/decorder, interferometer and nonlinear switches