Optical frequency channel selection filter with electronically-controlled grating structures

• US 5,581,642 A
• Filed: 09/09/1994
• Issued: 12/03/1996
• Est. Priority Date: 09/09/1994
• Status: Expired due to Term

• Current Assignee: Gemfire Corp. (Medtronic Plc)
• Original Assignee: Deacon Research
• Inventors: Bischel, William K., Field, Simon J., Brinkman, Michael J., Deacon, David A. G.
• Primary Examiner(s): Lee, John D.
• Application Number:
  US08/303,854
• Time in Patent Office: 816 Days
• Field of Search: 385/8-10, 385/15, 385/31, 385/37, 385/39-42, 385/50, 359/566, 359/569, 359/573
• US Class Current: 385/15
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 2006/12109 Filter
• CPC Class Codes: G02B 2006/12164 Multiplexing; Demultiplexing
• CPC Class Codes: G02F 1/313 in an optical waveguide structure
• CPC Class Codes: G02F 1/3132 of directional coupler type
• CPC Class Codes: G02F 1/3137 with intersecting or branching waveguides, e.g. X-switches and Y-junctions
• CPC Class Codes: G02F 1/3558 Poled materials, e.g. with periodic poling; Fabrication of domain inverted structures, e.g. for quasi-phase-matching [QPM]
• CPC Class Codes: G02F 2201/30 grating
• CPC Class Codes: G02F 2201/307 Reflective grating, i.e. Bragg grating
• CPC Class Codes: G02F 2203/055 wavelength filtering

Abstract

Optical energy transfer devices and energy guiding devices use an electric field to control energy propagation using a class of poled structures in solid material in a channel dropping filter and splitter applications. The poled structures, which may form gratings in thin film or bulk configurations, may be combined with waveguide structures. Electric fields applied to the poled structures control routing of optical energy. In a particular embodiment, an electrode confronts a solid material and bridges at least two elements of a grating disposed transverse of two waveguide segments and overlaps evanescent fields of optical energy in one of the waveguide segments. A switchable grating which consists of a poled material with an alternating domain structure of specific period. In a further embodiment there may be an optically active cladding between a grating and a waveguide. Additional electrodes may be provided for independent tuning of the cladding and the grating structure. When an electric field is applied across the periodic structure, a Bragg grating is formed by the electro-optic effect, reflecting optical radiation with a certain bandwidth around a center wavelength. The grating may be used by itself, or in combination with other gratings to form integrated structures.

Claims

1. A device for selecting optical energy at different wavelengths comprising:

a solid material for passing optical energy along an optical axis;

a first waveguide segment traversing said solid material;

a second waveguide segment traversing said solid material in close proximity and substantially parallel to said first waveguide segment to permit optical coupling between said first waveguide segment and said second waveguide segment;

electrically controllable grating means disposed in said solid material transverse of said optical axis for coupling optical energy selectively between said first waveguide segment and said second waveguide segment; and

at least a first electrically-conductive material forming a first electrode, said first electrode confronting said solid material and bridging at least two elements of said grating means, said at least two elements being disposed transverse of said first waveguide segment and said second waveguide segment and overlapping at least evanescent fields of optical energy in at least one of said first waveguide segment and said second waveguide segment for applying an electric field through said grating means.

2. The device according to claim 1 further including a second grating disposed along one of said first and second waveguide segments transverse to and overlapping at least evanescent fields of optical energy of said one of said waveguide segments.

3. A device for separating optical energy at different wavelengths comprising:

a solid material for passing optical energy along an optical axis;

a first waveguide segment traversing said solid material;

at least a second waveguide segment traversing said solid material and being disposed in close proximity and substantially parallel to said first waveguide segment at least a first location and at a second location along the length of said first waveguide segment to permit optical coupling between said first waveguide segment and said second waveguide segment;

at least two elements defining at least a first grating of a first period and a second grating of a second period, said first grating being disposed transverse of said first waveguide segment and said second waveguide segment and overlapping at least evanescent fields of optical energy in at least one of said first waveguide segment and said second waveguide segment at said first location, said second grating being disposed transverse of said first waveguide segment and said second waveguide segment and overlapping at least evanescent fields of optical energy in at least one of said first waveguide segment and said second waveguide segment at said second location;

an electric field creating means comprising a first electrode means for controlling said optical coupling between said first waveguide segment and said second waveguide segment at said first location and a second electrode means for controlling said optical coupling between said first waveguide segment and said second waveguide segment at said second location; and

control means for controlling selective application of electric fields through said first electrode means and said second electrode means.

4. A device for selecting optical energy at different wavelengths comprising:

a solid material for passing optical energy along an optical axis;

a first waveguide segment traversing said solid material;

a second waveguide segment traversing said solid material and intersecting with said first waveguide segment at an intersection with electrically controllable grating means, said electrically controllable grating means being disposed transverse of said first waveguide segment and said second waveguide segment;

electrically controllable grating means disposed in said solid material for coupling optical energy selectively between said first waveguide segment and said second waveguide segment; and

at least a first electrically-conductive material forming a first electrode, said first electrode confronting said solid material and bridging at least two elements of said grating means for applying an electric field through said grating means.

5. The device according to claim 4 wherein said grating means is disposed at an angle to said first waveguide segment to reflect optical energy from said first waveguide segment into said second waveguide segment, and further including:

a first tapered segment in said first waveguide segment forming an adiabatic expansion in an input path to said grating means; and

p1 a second tapered segment in said second waveguide segment forming an adiabatic contraction in an output path from said grating means.

6. A device for selecting optical energy at different wavelengths comprising:

a solid material for passing optical energy along an optical axis;

a first waveguide segment along said optical axis;

a second waveguide segment disposed adjacent said first waveguide segment in sufficiently close proximity to permit coupling between said first waveguide segment and said second waveguide segment;

a first grating being disposed adjacent to and transverse of said first waveguide segment;

an electrode being disposed adjacent said first grating;

a second grating being disposed adjacent to and transverse of said first waveguide segment; and

electrode means opposing said electrode operative to establish controlled electric fields through said first grating;

said first grating having at least a first period along said optical axis substantially equal to a second period of said second grating;

said first grating and said second grating being separated by a predetermined optical distance.

7. A device for selecting optical energy at different wavelengths comprising:

a solid material for passing optical energy along an optical axis;

a first waveguide segment along an optical axis;

a second waveguide segment disposed adjacent said first waveguide segment in sufficiently close proximity to permit coupling between said first waveguide segment and said second waveguide segment, said second waveguide segment forming a closed path for recirculating field energy;

a grating being disposed adjacent to and transverse of said first waveguide segment; and

an electrode being disposed adjacent said grating.

8. A device for selecting optical energy at different wavelengths comprising:

a solid material for passing optical energy along an optical axis;

a first waveguide segment along an optical axis;

a second waveguide segment disposed adjacent said first waveguide segment in sufficiently close proximity to permit coupling between said first waveguide segment and said second waveguide segment, said second waveguide segment forming a closed path for recirculating field energy;

a grating being disposed adjacent to and transverse of said second waveguide segment; and

an electrode being disposed adjacent said grating.

9. A device for selecting optical energy at different wavelengths comprising:

a solid material for passing optical energy along an optical axis;

a first grating;

a second grating;

a first waveguide segment along said optical axis;

a second waveguide segment disposed adjacent said first waveguide segment in sufficiently close proximity to permit coupling between said first waveguide segment and said second waveguide segment;

said first grating being disposed adjacent to and transverse of said first waveguide segment;

first electrode disposed adjacent said first grating;

said second grating being disposed adjacent to and transverse of said second waveguide segment;

a second electrode disposed adjacent said second grating; and

electrode means opposing said first electrode and said second electrode for establishing control electric fields through said first grating and said second grating;

wherein

said first grating has at least a first period along said optical axis substantially equal to a second period of said second grating;

wherein

said first grating and said second grating are separated by a predetermined optical distance; and

wherein

said control electric fields are applied through said first grating and said second grating.

10. A device for selecting optical energy at different wavelengths comprising:

a solid material for passing optical energy;

means defining a first optical beam propagation axis traversing said solid material;

means defining a second optical beam propagation axis traversing said solid material in close proximity to said first optical beam propagation axis to permit optical coupling between optical beams propagating along said first optical beam propagation axis and said second optical beam propagation axis;

electrically controllable grating means disposed in said solid material transverse of one of said first and second optical axes for coupling optical energy selectively between optical beams propagating along said first optical beam propagation axis and said second optical beam propagation axis; and

at least a first electrically-conductive material forming a first electrode, said first electrode confronting said solid material and bridging at least two elements of said grating means, said at least two elements being disposed transverse of said first optical beam propagation axis and said second optical beam propagation axis and overlapping at least evanescent fields of optical energy in at least one of said first optical beam propagation axis and said second optical beam propagation axis for applying an electric field through said grating means.