Semiconductor micro-resonator device

• US 5,926,496 A
• Filed: 05/20/1997
• Issued: 07/20/1999
• Est. Priority Date: 05/25/1995
• Status: Expired due to Fees

• Current Assignee: Northwestern University
• Original Assignee: Northwestern University
• Inventors: Rafizadeh, Deana, Ho, Seng-Tiong
• Primary Examiner(s): Bovernick, Rodney
• Assistant Examiner(s): Song, Yisun
• Application Number:
  US08/859,559
• Time in Patent Office: 791 Days
• Field of Search: 372/92, 372/94, 372/67
• US Class Current: 372/92
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/3133 the optical waveguides being made of semiconducting materials
• CPC Class Codes: G02F 2203/055 wavelength filtering
• CPC Class Codes: G02F 2203/15 involving resonance effects, e.g. resonantly enhanced interaction
• CPC Class Codes: H01S 5/026 Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers stabilisation of output H01S5/06
• CPC Class Codes: H01S 5/10 Construction or shape of the optical resonator , e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region H01S5/20 takes precedence
• CPC Class Codes: H01S 5/1032 Coupling to elements comprising an optical axis that is not aligned with the optical axis of the active region
• CPC Class Codes: H01S 5/1075 Disk lasers with special modes, e.g. whispering gallery lasers
• CPC Class Codes: H01S 5/11 Comprising a photonic bandgap structure
• CPC Class Codes: H01S 5/34306 emitting light at a wavelength longer than 1000nm, e.g. InP based 1300 and 1500nm lasers
• CPC Class Codes: H01S 5/3434 with a well layer comprising at least both As and P as V-compounds

Abstract

An optical, semiconductor micro-resonator device includes a microcavity resonator and a pair of adjacent waveguides. The microcavity resonator may be formed as a disk, a ring or closed loop with arbitrarily curved circumference with a diameter of approximately 56000 λ_lg /_res or less where λ_lg is the longest operating wavelength of light and n_res is the propagating refractive index. A portion of each of the waveguides is disposed adjacent to the microcavity resonator wherein the adjacent portion may be either tangential to the microcavity resonator or curve about a respective portion of the microcavity resonator. Light propagating in the first waveguide with a wavelength on resonance with the microcavity resonator is coupled thereto via resonant waveguide coupling and from the microcavity resonator the light is coupled to the second waveguide for output therefrom. Light propagating in the first waveguide with a wavelength that is off resonance with the microcavity resonator is not coupled to the microcavity resonator but continues to propagate in the first waveguide for output therefrom. The microcavity resonator and waveguides are formed of semiconductor materials for on-chip integration with other semiconductor devices.

Claims

1. A semiconductor micro-resonator device having a range of operating wavelengths of light including a longest wavelength λ

_lg of light comprising;

a microcavity resonator capable of propagating light and formed as a semiconductor microcavity ring having an outer diameter less than or approximately equal to 560 λ

_lg /n_res where n_res is the propagating refractive index of light in the microcavity resonator;

an input waveguide for propagating light therein formed of semiconductor materials and having an input port and an output port, a portion of said input waveguide being disposed adjacent to said microcavity resonator;

an output waveguide for propagating light therein formed of semiconductor materials having an output port, a portion of said output waveguide being disposed adjacent to said microcavity resonator wherein light propagating in said input waveguide with a wavelength off resonance with said microcavity resonator is output from said output port of said input waveguide and light propagating in said input waveguide with a wavelength on resonance with said microcavity resonator is coupled to said microcavity resonator and from said microcavity resonator to said output waveguide for output from the output port of said output waveguide wherein each of said input and output waveguides is separated from the resonator by a gap having a propagating refractive index of light therein of n_gap and wherein the gaps between the waveguides and the microcavity resonator are each less than ##EQU2##

2. A semiconductor micro-resonator device having a range of operating wavelengths of light including a longest wavelength λ

_lg of light comprising;

a microcavity resonator capable of propagating light and formed of semiconductor materials with a diameter of approximately 56000 λ

_lg /n_res or less where n_res is the propagating refractive index of light in the microcavity resonator;

an input waveguide for propagating light therein formed of semiconductor materials and having an input port and an output port, a portion of said input waveguide being disposed adjacent to said microcavity resonator;

an output waveguide for propagating light therein formed of semiconductor materials having an output port, a portion of said output waveguide being disposed adjacent to said microcavity resonator wherein light propagating in said input waveguide with a wavelength off resonance with said microcavity resonator is output from said output port of said input waveguide and light propagating in said input waveguide with a wavelength on resonance with said microcavity resonator is coupled to said microcavity resonator and from said microcavity resonator to said output waveguide for output from the output port of said output waveguide wherein said portion of the input and/or output waveguide adjacent to said microcavity resonator is curved partially about said microcavity resonator and said curved portion of the waveguide is curved only over a limited arc angle so as to limit phase mismatch between the light in the waveguide and microcavity resonator to less than π

/2.

3. A semiconductor micro-resonator device having a range of operating wavelengths of light including a longest wavelength λ

_lg of light comprising;

a microcavity resonator capable of propagating light and formed of semiconductor materials with a diameter of approximately 560 λ

_lg /n_res or less where n_res is the propagating refractive index of light in the microcavity resonator;

an input waveguide for propagating light therein formed of semiconductor materials and having an input port and an output port, a portion of said input waveguide being disposed adjacent to said microcavity resonator but separated therefrom by a gap formed with an associated refractive index that is less than ##EQU3## where n_gap is the propagating refractive index of the gap;

an output waveguide for propagating light therein formed of semiconductor materials having an output port, a portion of said output waveguide being disposed adjacent to said microcavity resonator but separated therefrom by a gap that is less than ##EQU4## where n_gap is the refractive index of the gap and wherein light propagating in said input waveguide with a wavelength off resonance with said microcavity resonator is output from said output port of said input waveguide and light propagating in said input waveguide with a wavelength on resonance with said microcavity resonator is coupled to said microcavity resonator and from said microcavity resonator to said output waveguide for output from the output port of said output waveguide.

4. A semiconductor micro-resonator device as recited in claim 3 wherein said microcavity resonator is a semiconductor microcavity ring.

5. A semiconductor micro-resonator device as recited in claim 3 wherein said microcavity resonator is a semiconductor microcavity disk.

6. A semiconductor micro-resonator device as recited in claim 3 wherein said microcavity resonator is a semiconductor closed loop resonator with arbitrary curved circumference.

7. A semiconductor micro-resonator device as recited in claim 3 wherein said microcavity resonator and said waveguides are formed of multilayer semiconductors including a substrate, a first cladding layer disposed on top of said substrate, a guiding layer disposed on top of said first cladding layer and a second cladding layer disposed on top of said guiding layer where said guiding layer has a refractive index higher than the respective refractive index of each of the first and second cladding layers.

8. A semiconductor micro-resonator device as recited in claim 7 wherein said microcavity resonator and waveguides are formed by etching said top cladding layer either fully or partially in a pattern defining the outer walls of said microcavity resonator and waveguides.

9. A semiconductor micro-resonator device as recited in claim 7 wherein said microcavity resonator and waveguides are formed from a wafer of said multilayer semiconductor and the outer sidewalls of said microcavity resonator and waveguides are formed by etching said cladding layer and said guiding layer of said wafer in a desired geometry.

10. A semiconductor micro-resonator device as recited in claim 9 wherein said etching extends into said first cladding layer.

11. A semiconductor micro-resonator device as recited in claim 3 wherein said microcavity resonator and said waveguides are formed of multilayer semiconductors including a substrate, a cladding layer disposed on the substrate and a guiding layer disposed on the cladding layer wherein the guiding layer has a refractive index higher than the refractive index of the cladding layer.

12. A semiconductor micro-resonator device as recited in claim 11 wherein said microcavity resonator and waveguides are formed by etching the guiding layer either fully or partially in a pattern defining the outer walls of the microcavity resonator and waveguides.

13. A semiconductor micro-resonator device as recited in claim 7 wherein said substrate is formed of GaAs.

14. A semiconductor micro-resonator device as recited in claim 7 wherein said substrate is formed of InP.

15. A semiconductor resonator device as recited in claim 7 wherein said first cladding layer is formed of Al_x Ga_1-x As where 0≦

x≦

1.

16. A semiconductor resonator device as recited in claim 7 wherein said first cladding layer is formed of In_x Ga_1-x-y As_y P where 0≦

x≦

1 and 0≦

y≦

1.

17. A semiconductor micro-resonator device as recited in claim 7 wherein said guiding layer is formed of Al_x Ga_1-x As where 0≦

x≦

1.

18. A semiconductor micro-resonator device as recited in claim 7 wherein said guiding layer is formed of In_x Ga_1-x-y As_y P where 0≦

x≦

1 and 0≦

y≦

1.

19. A semiconductor micro-resonator device as recited in claim 7 wherein said second cladding layer is formed of Al_x Ga_1-x As where 0≦

x≦

1.

20. A semiconductor micro-resonator device as recited in claim 7 wherein said second cladding layer is formed of In_x Ga_1-x-y As_y P where 0≦

x>

1 and 0≦

y≦

1.

21. A semiconductor micro-resonator device as recited in claim 3 wherein said portion of the input and/or output waveguide adjacent to said microcavity resonator is generally straight and tangential to said microcavity resonator.

22. A semiconductor micro-resonator device as recited in claim 3 wherein said portion of the input and/or output waveguide adjacent to said microcavity resonator is curved partially about said microcavity resonator.

23. A semiconductor micro-resonator device as recited in claim 22 wherein said curved portion of the waveguide is curved only over a limited arc angle so as to limit any phase mismatch between the light in the waveguide and microcavity resonator to less than π

/2.

24. A semiconductor micro-resonator device comprising:

a microcavity resonator capable of propagating light and formed of semiconductor materials, said microcavity resonator being electrically tunable to vary the resonance thereof;

an input waveguide for propagating light therein formed of semiconductor materials and having an input port and an output port, a portion of said input waveguide being disposed adjacent to said microcavity resonator;

an output waveguide for propagating light therein formed of semiconductor materials having an output port, a portion of said output waveguide being disposed adjacent to said microcavity resonator wherein light propagating in said input waveguide with a wavelength off resonance with said microcavity resonator is output from said output port of said input waveguide and light propagating in said input waveguide with a wavelength on resonance with said microcavity resonator is coupled to said microcavity resonator and from said microcavity resonator to said output waveguide for output from the output port of said output waveguide wherein said device has a range of operating wavelengths of light including a longest wavelength λ

_lg of light and wherein said microcavity resonator is a semiconductor microcavity ring having an outer diameter less than or approximately equal to 560 λ

_lg /n_res where n_res is the propagating refractive index of light in the microcavity resonator and each of said input and output waveguides is separated from the resonator by a gap having a refractive index n_gap and wherein the gaps between the waveguides and the microcavity resonator is less than ##EQU5##

25. A semiconductor micro-resonator device comprising:

a microcavity resonator capable of propagating light and formed of semiconductor materials, said microcavity resonator being electrically tunable to vary the resonance thereof;

an input waveguide for propagating light therein formed of semiconductor materials and having an input port and an output port, a portion of said input waveguide being disposed adjacent to said microcavity resonator;

an output waveguide for propagating light therein formed of semiconductor materials having an output port, a portion of said output waveguide being disposed adjacent to said microcavity resonator wherein light propagating in said input waveguide with a wavelength off resonance with said microcavity resonator is output from said output port of said input waveguide and light propagating in said input waveguide with a wavelength on resonance with said microcavity resonator is coupled to said microcavity resonator and from said microcavity resonator to said output waveguide for output from the output port of said output waveguide wherein said portion of the input and/or output waveguide adjacent to said microcavity resonator is curved partially about said microcavity resonator and wherein said curved portion of the waveguide is curved only over a limited arc angle so as to limit any phase mismatch between the light in the waveguide and microcavity resonator to less than π

/2.