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Laser Diode Receptacle for Single-Mode Fiber

IP.com Disclosure Number: IPCOM000119607D
Original Publication Date: 1991-Feb-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 3 page(s) / 102K

Publishing Venue

IBM

Related People

Block, TR: AUTHOR [+3]

Abstract

Three techniques are commonly used today for optical fiber-to-laser diode coupling. The first of these is the pigtail approach whereby the fiber endface is butt coupled to the front facet emitting area of the laser diode chip. This requires hermetic sealing of the laser into a package with the fiber extending out of that package for later termination into a connector. This technique minimizes the flexibility of the next-level package design.

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Laser Diode Receptacle for Single-Mode Fiber

      Three techniques are commonly used today for optical
fiber-to-laser diode coupling.  The first of these is the pigtail
approach whereby the fiber endface is butt coupled to the front facet
emitting area of the laser diode chip. This requires hermetic sealing
of the laser into a package with the fiber extending out of that
package for later termination into a connector.  This technique
minimizes the flexibility of the next-level package design.

      Another approach is to use two lenses between the laser and
fiber in what is referred to as a confocal configuration.  The laser
energy is roughly collimated in the space between the two lenses.
One lens becomes a part of the laser diode receptacle, the other a
part of the mating fiber connector.  A collimated laser beam, as
emitted here from the laser diode receptacle, presents a potential
safety hazard to the human eye (especially if one chooses to transmit
at an 800 nm wavelength).  This is not acceptable in the local loop
and computer interconnect environment.

      The third and very popular technique could be termed a standard
receptacle design.  This has been previously described by the authors
and others.  This technique is fairly simple; a laser diode package
is coupled to a fiber with a single lens element.  It may be used for
either multi-mode or single-mode fiber systems, but the component
tolerances required for single mode are very stringent.  The
advantage of this concept is simplicity, but it suffers from feedback
noise and laser safety concerns.

      The laser diode receptacle described herein features a true
source/fiber connectable interface for maximum packaging flexibility,
provides a solution to the laser safety issue raised above, minimizes
the reflections back into the laser device, and works on either
single- or multi-mode optical fiber.

      The receptacle is shown in the figure.  The source ferrule 1 of
the receptacle takes on the shape of a standard connector ferrule
with appropriate dimensions to allow it to mate with another
connector ferrule 8 using a standard connector adapter 10.  This
connection may be of the physical contact (PC) type, which provides
low loss and minimal reflections.  The laser chip 2 is packaged in an
industry-standard 5.6 mm CD style packa...