Low loss optical switch with inducible refractive index boundary and spaced output target

• US 5,911,018 A
• Filed: 11/18/1997
• Issued: 06/08/1999
• Est. Priority Date: 09/09/1994
• Status: Expired due to Term

• Current Assignee: Gemfire Corp. (Medtronic Plc)
• Original Assignee: Gemfire Corp. (Medtronic Plc)
• Inventors: Bischel, William K., Field, Simon J., Deacon, David A.G., Dyer, Mark J., Brinkman, Michael J., DeWath, Edward J.
• Primary Examiner(s): Healy, Brian
• Application Number:
  US08/972,673
• Time in Patent Office: 567 Days
• Field of Search: 385/1, 385/2, 385/3, 385/4, 385/8, 385/9, 385/11, 385/14, 385/15, 385/16, 385/18, 385/23, 385/24, 385/31, 385/39, 385/40, 385/45, 385/129, 385/130, 385/131, 385/132
• US Class Current: 385/16
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• 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 1/377 in an optical waveguide structure
• CPC Class Codes: G02F 2201/30 grating
• CPC Class Codes: G02F 2201/305 diffraction grating
• CPC Class Codes: G02F 2201/307 Reflective grating, i.e. Bragg grating
• CPC Class Codes: G09F 9/305 being the ends of optical fibres G09F9/302 takes precedence

Abstract

An extremely low-loss optical switch element includes a first waveguide segment having first and second regions longitudinally-adjacent with each other and having an index of refraction difference which is greater when the switch element is in an "on" state than when it is in an "off" state. The two regions have a common boundary which is oriented at an angle in the first waveguide so as to redirect optical energy through total internal reflection when the switch element is in the "on" state. The switch element further includes a second waveguide segment spaced from the first waveguide segment and disposed and oriented to guide optical energy redirected from the first waveguide segment when the switch element is in the "on" state.

Claims

1. An optical switch element disposed along a first waveguide segment and having first and second states, comprising:

first and second regions longitudinally-adjacent with each other in said first waveguide segment, said first and second regions defining a common boundary therebetween, said first and second regions having an index of refraction difference which is greater when said switch element is in said first state than when said switch element is in said second state, and wherein said boundary is oriented at such an angle to said first waveguide segment as to redirect optical energy through total internal reflection when said switch element is in said first state; and

a first optical index structure spaced from said first waveguide segment and disposed and oriented to guide optical energy redirected from said first waveguide segment when said switch element is in said first state.

2. An element according to claim 1, wherein said first optical index structure comprises an optical redirecting structure.

3. An element according to claim 2, wherein said optical redirecting structure comprises a second waveguide segment.

4. An element according to claim 2, for use in switching optical energy having a first optical mode;

wherein the index transition across said boundary when said switch element is in said first state is sufficient to redirect said first optical mode through total internal reflection;

and wherein said optical redirecting structure is capable of guiding an optical mode both when said switch element in said first state and when said switch element is in said second state.

5. An element according to claim 2, for use with a control signal;

wherein one of said first and second regions is poled in a first poling direction and the other of said first and second regions is a member of the group consisting of an unpoled region and a region poled in a second poling direction different from said first poling direction;

further comprising an applicator disposed to apply said control signal to said switch element such that said first and second regions have an index of refraction difference which varies in response to said control signal.

6. An element according to claim 5, wherein at least one of said first and second regions are electro-optic, and wherein said applicator comprises an electrode.

7. An element according to claim 5, wherein both said first and second regions are poled.

8. An element according to claim 2, wherein at least one of said first and second regions are thermo-optic.

9. An element according to claim 2, for use in switching optical energy having a first optical mode;

further comprising a connector region in which a first index of refraction boundary is induced when said switch element is in said first state but not when said switch element is in said second state, said first index of refraction boundary being capable of, and being disposed to, further direct optical energy redirected out of said first waveguide segment, said first index of refraction boundary including at least a portion which is disposed outside of said first waveguide segment and closer than said optical redirecting structure to said first waveguide segment.

10. An element according to claim 9, further comprising a second optical index structure in said connector region which is present at least when said switch element is in said second state, said second optical index structure being incapable of guiding optical modes when said switch element is in said second state.

11. An element according to claim 9, wherein a second index of refraction boundary is induced in said connector region when said switch element is in said first state but not when said switch element is in said second state, said first and second index of refraction boundaries defining a connector waveguide segment.

12. An element according to claim 11, wherein said connector waveguide segment when induced is butt coupled to said optical redirecting structure.

13. An element according to claim 11, wherein said connector waveguide segment when induced is in contact with said first waveguide segment.

14. An element according to claim 9, further comprising a fixed mirror disposed to further redirect optical energy directed by said first index of refraction boundary.

15. An element according to claim 9, for use with a control signal;

wherein said connector region includes a material having first and second regions having a common boundary, at least said first region being poled so as to define a poling transition across said common boundary;

said poling in at least said first region being such that said material exhibits an index of refraction difference across said boundary, which difference varies in response to said control signal;

said first and second regions being disposed such that said common boundary at least in part defines said first index of refraction boundary when said switch element is in said first state.

16. An element according to claim 15, wherein said control signal has a first condition in response to which said switch element is in said first state, and a second condition in response to which said switch element is in said second state;

further comprising an applicator applying said control signal to said first region;

wherein said first region is poled so as to exhibit a lower index of refraction when said control signal applied to said first region is in said first condition than when said control signal applied to said first region is in said second condition.

17. An element according to claim 16, wherein said poling in at least said first region is such that said material exhibits substantially no index of refraction difference across said common boundary when said control signal is in said second state.