Claims
- 1. In filters fabricated on a birefringent electrooptic substrate, a tunable electrooptic add-drop filter apparatus, the apparatus comprising:(a) two input single mode waveguides; (b) a first beam splitter connected to said waveguides; (c) a polarization converter connected to each of said waveguides after said first beam splitter wherein each said polarization converter includes more than one set of spaced apart, spatially periodic, strain-inducing pads wherein the length of said polarization converter is given by: Ltot32 NcL1+(Nc−1)L2 where: Nc=an integral number of polarization coupling regions of length L1 and L2=longer regions between said polarization coupling regions in which polarization coupling does not occur; (d) electrodes in proximity to each said polarization converter; (e) a second beam splitter connected to said waveguides after said polarization converter; and (f) two output single mode waveguides connected to said second beam splitter.
- 2. The apparatus of claim 1 further comprising a plurality of individual strain-inducing pads wherein the spacing between any two such strain-inducing pads is equal to an integer times a particular minimum spacing between adjacent strain-inducing pads.
- 3. The apparatus of claim 2 wherein widths of the strain-inducing pads are varied.
- 4. The apparatus of claim 3 wherein said polarization converter has a center and edges and wherein the width of said strain-inducing pads is greater at the center of said polarization converter and tapers monotonically towards said edges.
- 5. The apparatus of claim 1 further comprising polarization maintaining fibers connected to each input and output single mode waveguide.
- 6. The apparatus of claim 1 further comprising a plurality of said tunable electrooptic add-drop filters in series.
- 7. The apparatus of claim 6 wherein said plurality of tunable electrooptic add-drop filters have different values of Nc where Nc is an integral number of polarization coupling regions.
- 8. The apparatus of claim 1 further comprising a voltage tuner connected to said electrodes.
- 9. In filters fabricated on a birefringent electrooptic substrate, a tunable electrooptic add-drop filter apparatus, the apparatus comprising:(a) two input/output single mode waveguides; (b) a beam splitter connected to the waveguides; (c) a polarization converter connected to each of said waveguides wherein the polarization converter includes more than one set of spaced apart spatially periodic, strain-inducing pads; (d) electrodes on the substrate in proximity to each polarization converter; and (e) a reflector connected to the waveguides after the polarization converter.
- 10. The apparatus of claim 9 wherein the length of the polarization converter is given by:Ltot=NcL1+(Nc−1)L2where:Nc=an integral number of polarization coupling regions of length L1 and L2=longer regions between said polarization coupling regions in which polarization coupling does not occur.
- 11. The apparatus of claim 10 further comprising a multiplicity of individual strain-inducing pads wherein the spacing between any two such strain-inducing pads is equal to an integer times a particular minimum spacing between adjacent strain-inducing pads.
- 12. The apparatus of claim 11 wherein widths of the strain-inducing pads are varied.
- 13. The apparatus of claim 12 wherein said polarization converter has a center and edges and wherein the width of said strain-inducing pads is greater at the center of said polarization converter and tapers monotonically towards said edges.
- 14. The apparatus of claim 9 further comprising a voltage tuner connected to the electrode.
- 15. The apparatus of claim 9 further comprising polarization maintaining fibers connected to each input/output single mode waveguide.
- 16. The apparatus of claim 9 further comprising an optical circulator connected to each said input/output waveguide.
- 17. In filters fabricated on a birefringent electrooptic substrate, a tunable electrooptic add-drop filter method, the method comprising the steps of:(a) providing two input single mode waveguides on said substrate; (b) connecting a first beam splitter to said waveguides; (c) connecting a polarization converter to said waveguides after said first beam splitter wherein said polarization converter is conformed to include more than one set of spaced apart, spatially periodic, strain-inducing pads wherein the length of said polarization converter is given by: Ltot=NcL1+(Nc−1)L2 where: Nc=an integral number of polarization coupling regions of length L1 and L2=longer regions between said polarization coupling regions in which polarization coupling does not occur; (d) connecting electrodes to said polarization converter; (e) connecting a second beam splitter to said waveguides after said polarization converter; (f) connecting two output single mode waveguides to said second beam splitter; (g) connecting to voltage tuner to said electrodes; and (h) applying a voltage to said electrodes through said voltage tuner.
- 18. The method of claim 17 further comprising the step of connecting a plurality of said tunable electrooptic add-drop filters in series.
- 19. The method of claim 17 further comprising the step of replacing step e with the step of adding a reflector to said waveguides after said polarization converter.
RELATED APPLICATIONS
The applicants claim the benefit of the provisional patent application filed on Jan. 17, 2001, application Ser. No. 60/262,356.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
5748810 |
Schmid |
May 1998 |
A |
Non-Patent Literature Citations (1)
Entry |
Z. Tang, O. Eknoyan, and H. F. Taylor, “Polarisation-Independent Electro-Optically Tunable Wavelength Filter in LiTaO3,” Electron. Lett. 30, 1758-1759 (1994). |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/262356 |
Jan 2001 |
US |