EFFICIENT TERAHERTZ SOURCES BASED ON DIFFERENCE-FREQUENCY GENERATION IN TRIPLY-RESONANT PHOTONIC RESONATORS

• US 20120194901A1
• Filed: 07/12/2010
• Published: 08/02/2012
• Est. Priority Date: 07/10/2009
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation), Massachusetts Institute of Technology
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Joannopoulos, John D., Johnson, Steven G., Loncar, Marko, Rodriguez, Alejandro W., Soljacic, Marin, Zhang, Yinan, Bravo-Abad, Jorge, Burgess, Ian B., McCutcheon, Murray W.
• Granted Patent: US 8,285,091 B2
• Time in Patent Office: Days
• US Class Current: 359/330
• CPC Class Codes: G02F 1/3534 Three-wave interaction, e.g. sum-difference frequency generation G02F1/3532 takes precedence
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 13/00 Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
• CPC Class Codes: H01Q 15/0033 used for beam splitting or combining, e.g. acting as a quasi-optical multiplexer H01Q19/191 and H01Q19/195 take precedence
• CPC Class Codes: H01Q 5/22 RF wavebands combined with non-RF wavebands, e.g. infrared or optical

Abstract

A system for efficient generation of THz radiation is provided that includes a triply-resonant nonlinear photonic resonator coupled to at least one near-infrared (NIR) or optical waveguide and to at least one THz waveguide. The energy traveling through the at least one near-infrared (NIR) or optical waveguide is converted to THz radiation inside the triply-resonant photonic resonator via a nonlinear difference frequency generation (DFG) process.

Claims

1. A system for efficient generation of THz radiation comprising:

a triply-resonant nonlinear photonic resonator coupled to at least one near-infrared (NIR) or optical waveguide and to at least one THz waveguide, wherein energy traveling through the at least one near-infrared (NIR) or optical waveguide is converted to THz radiation inside the triply-resonant photonic resonator via a nonlinear difference frequency generation (DFG) process.

2. The system of claim 1, wherein the triply-resonant photonic resonator comprises a nonlinear photonic resonator for NIR or optical frequencies embedded in or placed in the proximity of a photonic resonator for THz frequencies, in such a way that if the NIR cavity is removed a THz cavity mode would be significantly modified.

3. The system of claim 2, wherein the nonlinear photonic resonator for NIR or optical frequencies comprises a doubly-resonant photonic resonator, the doubly-resonant photonic resonator comprises two resonant wavelengths λ

₁ and λ

₂ in air that support two resonant modes characterized by quality factors Q₁ and Q₂, respectively, and by modal volumes V₁ and V₂, respectively;

with 400 nm<

λ

₁<

20 μ

m and 400 nm<

λ

₂<

20 μ

m.

4. The system of claim 2, wherein the photonic resonator for THz frequencies comprises a resonant wavelength in air λ

_T, a quality factor Q, and a modal volume V_T;

with 30 μ

m<

λ

_T<

3000 μ

m.

5. The system of claim 4, wherein Q₁>

100, V₁<

1000λ

₁³, Q₂>

100, V₂<

1000λ

₂³, Q_T>

100, and, V_T<

1000λ

₁³.

6. The system of claim 3, wherein the doubly-resonant photonic resonator comprises a photonic crystal cavity or a longitudinally perturbed ridge waveguide or undercut ridge waveguide.

7. The system of claim 2, wherein the photonic resonator comprises a longitudinally perturbed ridge waveguide or undercut ridge waveguide or photonic crystal cavity.

8. The system of claim 3, wherein the resonant modes comprise whispering gallery modes.

9. The system of claim 1, wherein the at least one near-infrared (NIR) or optical waveguide comprises a dielectric waveguide or a photonic crystal waveguide.

10. The system of claim 1, wherein the at least one THz waveguide comprises a dielectric waveguide or a photonic crystal waveguide.

11. The system of claim 3, wherein the nonlinear photonic resonator for NIR or optical frequencies comprises a III/V semiconductor.

12. A method for generating efficient THz radiation comprising:

providing a triply-resonant nonlinear photonic resonator coupled to at least one near-infrared (NIR) or optical waveguide and to at least one THz waveguide; and

converting the THz radiation inside the triply-resonant photonic resonator via a nonlinear difference frequency generation (DFG) process.

13. The method of claim 12, wherein the triply-resonant photonic resonator comprises a nonlinear photonic resonator for NIR or optical frequencies embedded in or placed in the proximity of a photonic resonator for THz frequencies, in such a way that if the NIR cavity is removed a THz cavity mode would be significantly modified.

14. The method of claim 12, wherein the nonlinear photonic resonator for NIR or optical frequencies comprises a doubly-resonant photonic resonator, the doubly-resonant photonic resonator comprises two resonant wavelengths λ

₁ and λ

₂ in air that support two resonant modes characterized by quality factors Q₁ and Q₂, respectively, and by modal volumes V₁ and V₂, respectively;

with 400 nm<

λ

<sub>1<

20</sub> μ

m and 400 nm<

λ

₂<

20 μ

m.

15. The method of claim 13, wherein the photonic resonator for THz frequencies comprises a resonant wavelength in air λ

_T, a quality factor Q, and a modal volume V_T;

with 30 μ

m<

λ

_T<

3000 μ

m.

16. The method of claim 15, wherein Q₁>

100, V₁<

1000λ

₁³, Q₂>

100, V₂<

1000λ

₂³, Q_T>

100, and, V_T<

1000λ

₁³.

17. The method of claim 14, wherein the doubly-resonant photonic resonator comprises a photonic crystal cavity or a longitudinally perturbed ridge waveguide or undercut ridge waveguide.

18. The method of claim 13, wherein the photonic resonator comprises a longitudinally perturbed ridge waveguide or undercut ridge waveguide or photonic crystal cavity.

19. The method of claim 14, wherein the resonant modes comprise whispering gallery modes.

20. The method of claim 12, wherein the at least one near-infrared (NIR) or optical waveguide comprises a dielectric waveguide or a photonic crystal waveguide.

21. The method of claim 12, wherein the at least one THz waveguide comprises a dielectric waveguide or a photonic crystal waveguide.

22. The system of claim 14, wherein the nonlinear photonic resonator for NIR or optical frequencies comprises a III/V semiconductor.