Optical waveguide including singlemode waveguide channels coupled to a multimode fiber

• US 5,712,937 A
• Filed: 12/01/1994
• Issued: 01/27/1998
• Est. Priority Date: 12/01/1994
• Status: Expired due to Fees

• Current Assignee: Charles K. Asawa, Jane K. Asawa, Michi Asawa, Mike H. Asawa
• Original Assignee: Charles K. Asawa, Jane K. Asawa, Michi Asawa, Mike H. Asawa
• Inventors: Asawa, Mike H., Asawa, Jane K., Asawa, Charles K., Asawa, Michi
• Primary Examiner(s): Bovernick, Rodney B.
• Assistant Examiner(s): SANGHAVI, HEMANG
• Application Number:
  US08/347,947
• Time in Patent Office: 1,153 Days
• Field of Search: 359/112, 359/116, 359/110, 359/111, 385/12, 385/44, 385/13, 385/45, 385/46, 385/50, 385/129, 385/51, 385/52, 385/49, 385/48, 385/39, 385/42, 385/28, 385/29, 385/31, 385/124, 385/132, 340/541
• US Class Current: 385/49
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/125 Bends, branchings or intersections
• CPC Class Codes: G02B 6/14 Mode converters
• CPC Class Codes: G02B 6/30 for use between fibre and thin-film device
• CPC Class Codes: H04B 10/2581 Multimode transmission

Abstract

An intrusion-alarmed optical fiber communication system, where light from two or more sources are launched with a planar channel waveguide launcher into two or more modes of a multimode graded-index transmission fiber, is disclosed. Input fibers containing the source light waves and the output fibers are in direct contact with the waveguide channels. Waveguide channels redistribute the light from input channels to output channels by rerouting, crossing, merging, or splitting channels. Waveguide launcher precisely launches data light into the fundamental mode and intrusion monitor light into high order modes of a multimode graded-index fiber. Fiber intrusion attenuates light in high order modes, but much less of the data in the fundamental mode, thereby forming a basis for the intrusion-alarmed system. Waveguide launcher permits light from a plurality of sources to be launched selectively into several types of fibers: singlemode fibers, multimode fibers, multicore fibers, multimode fibers having high refractive-index ring profile within the fiber core boundary. Waveguide channel configuration permit other versatile functions to be performed; these include optical time domain reflectometry, channel feedback stabilization of the diodes, launching light from more than one light source into the fundamental mode of a multimode graded-index fiber, and other functions. Means for launching and propagating the fundamental mode in multimode graded-index fiber in order to increase bandwidth capacity of said fiber are disclosed. Optical-electronic intrusion-alarmed systems with synchronous phase sensitive detection of intrusion are described, including reference recovery means. In order to decrease false alarm rates, information on transmitter light source variations are transmitted to the receiver via digital bit stream. A precise fiber optic sensor system based on the waveguide launcher is disclosed.

Claims

1. A planar optical waveguide device for launching a plurality of optical beams into a plurality of sets of predetermined propagation modes of a multimode fiber, comprising:

a plurality of optical singlemode waveguide channels on said planar optical waveguide,

a plurality of optical sources for providing said plurality of optical beams,

each of said optical singlemode waveguide channel propagating one of said optical beam from one of said optical source,

each of said plurality of optical singlemode waveguide channels laterally positioned and angularly aligned with respect to each other in a predetermined arrangement for coupling with said multimode fiber,

channel-to-fiber coupling means for connecting said plurality of optical singlemode waveguide channels to said multimode fiber so as to launch said optical beams into said sets of predetermined propagation modes of said multimode fiber,

whereby each of said optical beam of said plurality of optical beams, propagating in said optical singlemode waveguide channel of said plurality of optical singlemode waveguide channels, is launched into said set of predetermined propagation modes of said multimode fiber.

2. The planar optical waveguide device of claim 1, wherein:

said multimode fiber is a multimode graded-index fiber with a cylindrical core,

said channel-to-fiber coupling means couples in contact a preselected first optical singlemode waveguide channel selected from said plurality of optical singlemode waveguide channels to said multimode graded-index fiber, and aligns axis of said preselected first optical singlemode waveguide channel collinearly to axis of said multimode graded-index fiber,

whereby said optical beam in said preselected first optical singlemode waveguide channel is launched into a fundamental propagation mode of said multimode graded-index fiber.

3. The planar optical waveguide device of claim 2, wherein:

said channel-to-fiber coupling means couples in contact a preselected second optical singlemode waveguide channel selected from said plurality of optical singlemode waveguide channels to said multimode graded-index fiber,

axis of said preselected second optical singlemode waveguide channel angularly aligned to said axis of preselected first optical singlemode waveguide channel and to said axis of multimode graded-index fiber,

said preselected second optical singlemode waveguide channel laterally positioned within said cylindrical core of said multimode graded-index fiber,

whereby said optical beam in said second optical singlemode waveguide channel is launched into substantially high order modes of said multimode graded-index fiber.

4. The planar optical waveguide device of claim 3, wherein:

said axis of said preselected second optical singlemode waveguide channel aligns at zero angle, and parallel, with respect to said axis of first optical singlemode waveguide channel,

said preselected second optical singlemode waveguide channel positioned laterally within said cylindrical core and touching boundary of said cylindrical core of said multimode graded-index fiber,

whereby said optical beam propagating in said preselected second optical singlemode waveguide channel is launched into substantially highest order propagation modes of said multimode graded-index fiber.

5. The planar optical waveguide device of claim 3, wherein:

said channel-to-fiber coupling means couples in contact a preselected third optical singlemode waveguide channel selected from said plurality of optical singlemode waveguide channels to said multimode graded-index fiber,

axis of said preselected third optical singlemode waveguide channel aligned angularly with said axis of said preselected first optical singlemode waveguide channel and with said axis of said multimode graded-index fiber,

said preselected third optical singlemode waveguide channel laterally positioned within said core boundary of said multimode graded-index fiber,

whereby said optical beam in said preselected third optical singlemode waveguide channel is launched into substantially high order propagation modes of said multimode graded-index fiber.

6. The planar optical waveguide device of claim 2, further comprising:

a plurality of additional optical singlemode waveguide channels,

a plurality of additional optical sources for providing a plurality of additional optical beams,

each said additional optical singlemode waveguide channel propagating one additional optical beam from one additional optical source,

each of said plurality of additional input optical singlemode waveguide channels forming an input junction with said first optical singlemode waveguide channel,

whereby said plurality of additional optical beams are propagated into said first optical singlemode waveguide channel,

whereby said optical beam plus said plurality of additional optical beams are propagated into a fundamental propagation mode of said multimode fiber.

7. The planar optical waveguide device of claim 1, wherein:

said multimode fiber is a multimode graded-index fiber with a cylindrical core,

said channel-to-fiber coupling means couples in contact a preselected said optical singlemode waveguide channel selected from said plurality of optical singlemode waveguide channels to said multimode graded-index fiber,

said preselected optical singlemode waveguide channel laterally positioned within said cylindrical core of said multimode graded-index fiber,

whereby said optical beam propagating in said preselected optical singlemode waveguide channel is launched into substantially high order propagation modes of said multimode graded-index fiber.

8. The planar optical waveguide device of claim 1, further comprising;

a plurality of feedback singlemode waveguide channels,

each of said feedback singlemode waveguide channel forming a junction with one of said optical singlemode waveguide channels, wherein said junction splits a predetermined fraction of said optical beam propagating in said optical singlemode waveguide channel into said feedback waveguide channel,

whereby each of said feedback singlemode waveguide channel propagates fraction of said optical beam propagating in said optical singlemode waveguide channel.

9. The planar optical waveguide device of claim 8, further comprising:

a plurality of detectors for detecting said fraction of said optical beam propagating in each of said feedback singlemode waveguide channel,

whereby detected voltage of each of said detector is used for feedback controlling power output level of each corresponding said optical source emitting said optical beam into said optical singlemode waveguide channel,

whereby said power output levels of said plurality of optical sources, and said optical beam power levels propagating In corresponding said optical waveguide channels, are feedback controlled in power.

10. The planar optical waveguide device of claim 1, further comprising:

a plurality of auxiliary optical singlemode waveguide channels,

a plurality of auxiliary optical sources for providing a plurality of auxiliary optical beams,

each of said auxiliary optical singlemode waveguide channel propagating one of said auxiliary optical beam from one of said auxiliary optical source,

each of said plurality of auxiliary optical singlemode waveguide channels forming an input junction with one of said plurality of optical singlemode waveguide channels in a predetermined manner,

each said auxiliary optical beam propagating in said auxiliary optical singlemode waveguide channel propagated into said optical singlemode waveguide channel,

whereby both optical beams, said optical beam and said auxiliary optical beam, propagating in said optical singlemode waveguide channel are launched into predetermined propagation modes of said multimode fiber.

11. A method for launching a plurality of optical beams into e plurality of sets of redetermined propagation modes of a multimode fiber, comprising:

providing said plurality of optical beams from a plurality of optical sources,

providing a plurality of optical singlemode waveguide channels on a planar waveguide,

providing each said optical singlemode waveguide channel propagating one said optical beam from one said optical source,

providing said multimode fiber,

angularly aligning and laterally positioning each of said plurality of optical singlemode waveguide channel with respect to each other for coupling to said multimode fiber,

aligning and coupling in contact said plurality of optical singlemode waveguide channels to said multimode fiber,

whereby each said optical beam of said plurality of optical beams is launched into said set of predetermined propagation modes of said multimode fiber.

12. The method of claim 11, wherein:

providing a preselected first optical singlemode waveguide channel selected from said plurality of optical singlemode waveguide channels,

providing a multimode graded-index fiber with a cylindrical core,

coupling in contact said preselected first optical singlemode waveguide channel to said multimode graded-index fiber,

collinearly aligning axis of said preselected first optical singlemode waveguide channel to axis of said multimode graded-index fiber,

whereby said optical beam propagating is said preselected first optical singlemode waveguide channel is launched into a fundamental propagation mode of said multimode graded-index fiber.

13. The method of claim 12, wherein:

providing a preselected second optical singlemode waveguide channel selected from said plurality of optical singlemode waveguide channels,

aligning axis of said preselected second optical singlemode waveguide channel at an angle with said axis of said preselected first optical singlemode waveguide channel,

laterally positioning said preselected second optical singlemode waveguide channel within said core boundary at coupling in contact interface,

whereby said optical beam propagating in said preselected second optical singlemode waveguide channel is launched into substantially high order propagation modes of said multimode graded-index fiber.