Bias control system for electrooptic devices

• US 6,222,965 B1
• Filed: 07/08/1999
• Issued: 04/24/2001
• Est. Priority Date: 07/08/1999
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Smith, Robert W.
• Primary Examiner(s): SIKDER, MOHAMMAD YUNUS
• Application Number:
  US09/349,736
• Time in Patent Office: 656 Days
• Field of Search: 385/40, 385/41, 385/42, 385/44, 385/46, 385/47, 385/48, 385/49
• US Class Current: 385/40
• CPC Class Codes: G02F 1/0123 Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops
• CPC Class Codes: G02F 1/0147 based on thermo-optic effects G02F1/132 takes precedence
• CPC Class Codes: G02F 2203/20 Intrinsic phase difference, i.e. optical bias, of an optical modulator; Methods for the pre-set thereof

Abstract

An optical device includes a substrate formed of an electrooptic material, a waveguide formed in the substrate, an electrically conductive film formed over at least a portion of the waveguide and a source of DC voltage electrically connected to the film for thermally inducing a change in the optical refractive index of the substrate of the optical device.

Claims

1. An optical device, comprising:

a substrate formed of an electrooptic material;

a waveguide formed in the substrate;

an electrically conductive film formed over at least a portion of the waveguide; and

a source of DC bias voltage electrically connected to the film for thermally and electro-optically inducing a change in the optical refractive index of the substrate of the optical device.

2. The device according to claim 1, wherein the electrically conductive film is an electrode.

3. The device according to claim 2, the electrode is selected from the group consisting of a coplanar electrode, a stripe line electrode and an asymmetric electrode.

4. The device according to claim 2, comprising a resistor and wherein the electrode is terminated at the resistor.

5. The optic device according to claim 1, comprising:

a bias tee electrically connected to the film and an electrical data signal and the source of DC voltage and the electrical data signal are electrically connected to the bias tee, the bias tee combining the source of DC voltage and the electrical data signal.

6. The optic device according to claim 1, wherein the device is a Mach-Zehnder interferometric modulator.

7. The optic device according to claim 1, wherein the device is a directional coupler.

8. The optic device according to claim 1, wherein the substrate comprises LiNbO₃.

9. The optic device according to claim 8, wherein the substrate is z-cut LiNbO₃.

10. The device according to claim 1, wherein the electrically conductive film consists essentially of a material selected from the group consisting of gold and aluminum.