Dual-electrode traveling wave optical modulators and methods

• US 6,738,174 B1
• Filed: 02/23/2001
• Issued: 05/18/2004
• Est. Priority Date: 02/23/2001
• Status: Expired due to Term

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Bigband Networks Incorporated (II-VI Incorporated)
• Inventors: Hill, Marc E., King, Jonathan P., Wu, Hui
• Primary Examiner(s): Ben, Loha
• Application Number:
  US09/792,222
• Time in Patent Office: 1,180 Days
• Field of Search: 359/245, 359/246, 359/247, 359/248, 359/251, 359/254, 359/255, 359/237, 359/279, 359/320, 359/295, 385/2, 385/3, 385/4, 385/14, 385/39, 385/40, 385/41, 385/131, 257/431, 257/432, 257/435
• US Class Current: 359/245
• CPC Class Codes: G02F 1/035 in an optical waveguide structure
• CPC Class Codes: G02F 2201/12 electrode

Abstract

The invention discloses phase-shifters, modulators, and method that produces a smaller π by means of a field excitation using multiple electrodes. A negative signal is introduced that travels with the positive signal, which enhances the electric field significantly. The field enhancement is provided by the superposition of the fields accumulated from each electrode. A base or substrate material can be made from any compound having linear electro-optic properties, such as lithium niobate, lithium tantalite, potassium lithium niobate, potassium titanyl phosphate or gallium-arsenide. For lithium niobate, there are two possible orientations of electric field, z-cut orientation or x-cut orientation.

Claims

1. A modulator device employing dual electrodes, comprising:

a first electrode having a first polarity;

a second electrode, spaced apart from the first electrode, having a second polarity that is opposite of the first polarity; and

an optical waveguide placed underneath and in between the first and second electrodes, thereby creating a horizontal electric field.

2. The modulator device of claim 1, further comprising a first ground electrode spaced apart from the first electrode, and a second ground electrode spaced apart from the second electrode, the combination of the first and second electrodes suppressing couplings to parasitic modes at high frequencies.

3. The modulator device of claim 1, further comprising a light input signal comprising a first optical signal and a second optical signal.

4. The modulator device of claim 3, wherein the first optical signal travels through the first electrode.

5. The modulator device of claim 4, wherein the second optical signal travels through the second electrode.

6. The modulator device of claim 5, further comprising a modulated output light by re-combination of the first and second optical signals.

7. The modulator device of claim 1, further comprising a first ground electrode, coupled to the first electrode, and a second ground electrode coupled to the second electrode, the first and second ground electrodes suppressing couplings to parasitic modes at high frequencies.

8. The modulator device of claim 7, further comprising a buffer layer extending from the first ground electrode, the first electrode, the second electrode, and the second ground electrode, and placed above the optical waveguide.

9. The modulator device of claim 1, further comprising a buffer layer extending from the first electrode and the second electrode.

10. The modulator device of claim 1, wherein the first polarity comprises a positive polarity, and the second polarity comprises a negative polarity.

11. The modulator device of claim 1, wherein the first polarity comprises a negative polarity, and the second polarity comprises a positive polarity.

12. A method for modulating a signal, comprising:

placing a first electrode spaced a distance d1 from a second electrode, the first electrode having a polarity opposite that of the second electrode; and

generating a first traveling electrical wave by superposition of an electric field induced between the first and second electrodes, the amount of the electric field being determined by the distance d1.