Method and apparatus for channel selective control of light propagation in an optical waveguide

• US 7,006,733 B2
• Filed: 01/21/2004
• Issued: 02/28/2006
• Est. Priority Date: 09/10/2002
• Status: Expired due to Fees

• Current Assignee: Universite Laval
• Original Assignee: Photintech Inc.
• Inventors: Tork, Amir, Birabassov, Rouslan, Zohrabyan, Armen, Galstian, Tigran, Dumont, Dany
• Primary Examiner(s): CONNELLY CUSHWA, MICHELLE R
• Application Number:
  US10/760,398
• Publication Number:
  US 20040151434A1
• Time in Patent Office: 769 Days
• Field of Search: 385/10, 385 27- 30, 385/37
• US Class Current: 385/37
• CPC Class Codes: G02B 2006/12107 Grating
• CPC Class Codes: G02B 6/02061 Grating external to the fibre and in contact with the fibre, e.g. evanescently coupled, gratings applied to the fibre end mechanically induced in the fibre G02B6/02071, surface relief on the fibre G02B6/02066
• CPC Class Codes: G02B 6/02066 Gratings having a surface relief structure, e.g. repetitive variation in diameter of core or cladding
• CPC Class Codes: G02B 6/02085 characterised by the grating profile, e.g. chirped, apodised, tilted, helical
• CPC Class Codes: G02B 6/02195 characterised by means for tuning the grating
• CPC Class Codes: G02B 6/266 the optical element being an attenuator
• CPC Class Codes: G02B 6/2826 using mechanical machining means for shaping of the couplers, e.g. grinding or polishing grinding, polishing in general B24
• CPC Class Codes: G02B 6/29334 Grating-assisted evanescent light guide couplers, i.e. comprising grating at or functionally associated with the coupling region between the light guides, e.g. with a grating positioned where light fields overlap in the coupler
• CPC Class Codes: G02B 6/29391 Power equalisation of different channels, e.g. power flattening
• CPC Class Codes: G02F 1/011 in optical waveguides, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/1326 Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
• CPC Class Codes: G02F 2201/307 Reflective grating, i.e. Bragg grating
• CPC Class Codes: G02F 2203/055 wavelength filtering

Abstract

A variable optical device for selectively controlling propagation of light within an optical waveguide. The optical device comprises: a relief modulation defining a grating disposed proximal the waveguide and having a respective grating index of refraction n_G; a matrix surrounding at least the relief modulation, the matrix having an index of refraction n_EO that is controllable, in response to a selected stimulus between a first value that is substantially equal to the grating index of refraction n_G, and a second value that is different from n_G; and at least one electrode for supplying the selected stimulus to the matrix-grating system.

Claims

1. A variable optical device for selectively controlling propagation of light within an optical waveguide, the optical device comprising:

a hidden relief modulation (HRM) cell disposed proximal the optical waveguide, the HRM cell comprising;

a relief modulation defining a grating disposed on a surface of the HRM cell opposite the waveguide and having a respective grating index of refraction n_G; and

at least one electrode disposed on the surface of the HRM cell adjacent the relief modulation; and

a matrix disposed between the HRM cell and the optical waveguide, the matrix being in electrical contact with the at least one electrode and surrounding at least the relief modulation, the matrix having an index of refraction n_EO that is controllable, in response to a selected stimulus between a first value that is substantially equal to the grating index of refraction n_G, and a second value.

2. An optical device as claimed in claim 1, wherein the relief modulation is disposed relative to the waveguide so as to interact with any one or more of:

core modes of light propagating within the waveguide;

an evanescent field of light propagating within the waveguide; and

cladding modes of light propagating within the waveguide.

3. An optical device as claimed in claim 1, wherein the relief modulation comprises any one or more of:

chirped;

apodized and blazed relief modulations.

4. An optical device as claimed in claim 1, wherein the grating index of refraction n_G is substantially fixed.

5. An optical device as claimed in claim 4, wherein the grating index of refraction n_G is substantially equal to a cladding index of refraction n_CLAD of a cladding layer of the waveguide.

6. An optical device as claimed in claim 1, wherein the grating index of refraction n_G is variable in response to a predetermined stimulus.

7. An optical device as claimed in claim 6, wherein a sign of change of the grating refractive index n_G in response to the stimulus is opposite the sign of change of the matrix refractive index n_EO in response to the stimulus.

8. An optical device as claimed in claim 7, wherein an average refractive index of the grating and the matrix is substantially constant.

9. An optical device as claimed in claim 1, wherein the at least one electrode comprises an array of electrodes adapted to generate an arbitrary electric field in the vicinity of the grating.

10. An optical device as claimed in claim 9, wherein the electrodes are positioned out of contact with an evanescent field of light propagating in the waveguide core.

11. An optical device as claimed in claim 1, further comprising two or more relief modulations defining respective gratings, each grating being associated with at least one respective electrode.

12. An optical device as claimed in claim 11, wherein at least one grating is oriented relative to the waveguide differently from at least one other grating.

13. An optical device as claimed in claim 1, further comprising:

a first mode converter disposed upstream of the relief modulation for converting core modes into cladding modes; and

a second mode converter disposed downstream of the relief modulation for converting cladding modes into core modes.

14. An optical device as claimed in claim 1, wherein the relief modulation is oriented at an angle relative to a core of the waveguide, such that light reflected by the relief modulation is at least partially out-coupled from the core.

15. An optical device as claimed in claim 14, further comprising a photodetector disposed to receive at least a portion of the out-coupled light.