Method and system for preventing low order optical transmission modes in multimode optical fiber computer network using annulus laser
AssigneeEnterasys Networks, Inc.
InventorsRobert Simcoe, Bruce A. Schofield, Jerry D. Hutchison, Richard L. Kirk
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Abstract
A method for improving modal bandwidth in computer networks using multimode optical fiber and laser sources is disclosed in which an annular beam is generate by the laser source, thus preventing center fiber transmission modes from reaching the detector. This prevents or lessens a pulse-splitting effect at the detector. The annular beam is generated preferably by configuring a vertical cavity surface emitting laser to have a center totally-reflecting block of 5-7 microns to generate a substantially dark-centered beam.
Claims38
A system for improving modal bandwidth in a network using a multimode optical fiber transmission media, comprising:
- a laser device, comprising an exit aperture, wherein the exit aperture forms one end of a resonant cavity enclosing the laser device, the exit aperture comprising a center block adapted for blocking emission of a portion of a generated laser beam, wherein the center block causes the beam to have a substantially annularly cross-sectioned profile with a substantially dark center region;
- and
- a multimode optical fiber of the network for transmitting the beam.
A method for improving modal bandwidth in a network having a multimode optical fiber transmission media, comprising:
- generating a laser beam with a laser source, said laser source comprising an exit aperture that forms one end of a resonant cavity enclosing the laser device;
- blocking emission of a portion of the generated laser beam with the exit aperture comprising a center block, centered substantially at a center of the exit aperture causing the laser beam to have a substantially annularly cross-sectioned profile and a substantially dark center region;
- and
- coupling the laser beam into the multimode optical fiber of the network for transmission to a detector such that the dark center region of the laser beam covers a portion of the fiber's cross-sectional area, including a central optical axis of the fiber.
A laser device, comprising:
- a laser source that provides a laser beam;
- an exit aperture of the laser source, through which the laser beam is provided externally to the laser source to provide a laser output signal;
- and
- a multimode optical fiber that receives the output signal;
- wherein the exit aperture includes an annularly-shaped non-blocking portion through which laser light may pass, and a blocking center portion within said annularly-shaped non-blocking portion of the exit aperture, said blocking portion being substantially centered at a center of said exit aperture, such that the laser device output signal has an annular pattern and a dark center region within the annular pattern.
Dependencies are inferred from the claim text.