Traveling wave, linearized reflection modulator

• US 6,535,320 B1
• Filed: 09/15/2000
• Issued: 03/18/2003
• Est. Priority Date: 09/15/2000
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Burns, William K.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): HINDI, OMAR Z
• Application Number:
  US09/663,135
• Time in Patent Office: 914 Days
• Field of Search: 385/14, 385/2, 385/3, 385/4, 385/40, 385/1, 385/16, 385/12, 359/188, 359/173, 359/245, 359/251, 359/254, 359/238, 356/481, 356/477
• US Class Current: 359/245
• CPC Class Codes: G02F 1/2255 controlled by a high-frequency electromagnetic component in an electric waveguide structure

Abstract

A traveling wave, linearized, modulator device includes: an optical waveguide disposed on a substrate and consisting of an input-output portion, a terminal portion and a plurality of arms disposed between and connected to the other portions. A first arm has an optical characteristic that varies responsive to supplying of an electric field thereto. A reflector (e.g., mirror) located at the distal end of the terminal portion of the optical waveguide causes light entering the input-output portion and propagating through the waveguide to be reflected back through the waveguide so as to exit through the input-output portion. A traveling wave electrode structure disposed on the substrate terminates in an open circuit substantially at the distal end of the terminal portion of the waveguide. The electrode structure includes an electrode disposed on the first arm so as to supply an electric field to that arm responsive to an electrical voltage being supplied to the electrode. A radio frequency signal and a direct current bias are supplied to the first electrode such that the radio frequency signal is biased at a non-quadrature, preferably 104.5 degree, bias point providing minimum third-order distortion, thereby providing substantially linearized modulator operation.

Claims

1. A traveling wave, linearized, modulator device comprising:

an electro-optical modulator comprising a substrate;

an optical waveguide disposed on said substrate and comprising an input-output portion, a terminal portion having a distal end and a plurality of arms disposed between and connected to said input-output portion and said terminal portion, said arms being offset with respect to said input-output portion and said terminal portion and extending parallel to each other, and at least a first one of said arms having an optical characteristic that varies responsive to supplying of an electric field thereto;

a reflective means located at the distal end of said terminal portion of said optical waveguide for causing light entering said input-output portion and propagating through said optical waveguide to be reflected back through the optical waveguide so as to exit through said input-output portion; and

a traveling wave electrode structure disposed on said substrate and terminating in an open circuit substantially at the distal end of said terminal portion of the optical waveguide, said electrode structure including an electrode disposed on said first arm of said plurality of optical waveguide arms so as to supply an electric field to said first arm responsive to an electrical voltage being supplied to said electrode, said open circuit and said electrode structure matching velocities of an electrical and an optical waveform both as said light enters said waveguide and as said light is reflected back out of said waveguide; and

means for supplying a radio frequency signal and a direct current bias to said first electrode such that the radio frequency signal is biased at a non-quadrature bias point providing minimum third-order distortion, thereby providing substantially linearized modulator operation.

2. A device according to claim 1 wherein said bias point is set between 100°

and 110°

.

3. A device according to claim 2 wherein said bias point is set at 104.5°

.

4. A device according to claim 3 wherein said electrode structure further includes a second electrode disposed on a second arm of said plurality of arms.

5. A device according to claim 4 wherein said electrode structure further include a third electrode disposed in an area of said substrate spaced from said plurality of arms.

6. A device according to claim 5 wherein said second and third electrodes are connected to ground.

7. A device according to claim 6 wherein said reflective means comprises a reflective coating disposed at the distal end of said terminal portion of said optical waveguide.