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Efficient Fiber Coupler using an Ellipsoidal Reflector

IP.com Disclosure Number: IPCOM000107598D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Lean, EG: AUTHOR

Abstract

In this article an ellipsoidal reflector is used to provide very efficient coupling from a GaAs laser output into a single-mode fiber with a small numerical aperture (NA). The concept of this fiber coupler is shown in Fig. 1 where a beam of large NA from a GaAs laser located at the left focal point is coupled into a fiber located in the other focal point as a beam with a smaller NA. The extent of the reduction of the NA depends on the ellipticity of the ellipsoidal reflector and the orientation of the laser. Typically, the GaAs laser has an output beam divergency having an NA of 0.3 to 0.4 in the plane normal to the junction. The single-mode fiber will have an NA of 0.1. A reduction of 3 to 4 in NA is needed for efficient coupling by the ellipsoidal reflector.

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Efficient Fiber Coupler using an Ellipsoidal Reflector

       In this article an ellipsoidal reflector is used to
provide very efficient coupling from a GaAs laser output into a
single-mode fiber with a small numerical aperture (NA).  The concept
of this fiber coupler is shown in  Fig. 1 where a beam of large NA
from a GaAs laser located at the left focal point is coupled into a
fiber located in the other focal point as a beam with a smaller NA.
The extent of the reduction of the NA depends on the ellipticity of
the ellipsoidal reflector and the orientation of the laser.
Typically, the GaAs laser has an output beam divergency having an NA
of 0.3 to 0.4 in the plane normal to the junction.  The single-mode
fiber will have an NA of 0.1.  A reduction of 3 to 4 in NA
is needed for efficient coupling by the ellipsoidal reflector.

      The coupler may provide simpler alignment for the laser and
fiber.  The laser can easily be butted against the base of the
reflector at the focus point.  The fiber can be put inside the hole
with a spherical tip having the proper orientation.  The fiber can be
cemented in with a transparent epoxy.