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Beveled Waveguides for Flip Chip Opto-Electronic Receivers

IP.com Disclosure Number: IPCOM000102615D
Original Publication Date: 1990-Dec-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 3 page(s) / 93K

Publishing Venue

IBM

Related People

Flint, EB: AUTHOR [+5]

Abstract

Disclosed is a bevel geometry which may be processed on the end of a waveguide and which results in the incoming optical signal being deflected upwards onto a flipped detector.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Beveled Waveguides for Flip Chip Opto-Electronic Receivers

       Disclosed is a bevel geometry which may be processed on
the end of a waveguide and which results in the incoming optical
signal being deflected upwards onto a flipped detector.

      The use of flipped opto-electronic surface (as opposed to
back-or edge-illuminated) detectors requires that the optical signal
be guided between the chip and the package and then deflected upwards
at the detector site.  A standard approach is to use an optical
waveguide, either a fiber or planar guide, and to bevel the end so
that the light is totally internally reflected (1).   The difficulty
for flipped optoelectronic devices is that this approach requires
that an undercut bevel be etched, a geometry difficult to form with
planar-processed optical waveguides in practice.

      This article describes a bevel geometry (see Fig. 1) which can
be fabricated with standard etching techniques and results in the
optical signal being deflected upwards.

      Fig. 1 shows the proposed geometry.  The waveguide is beveled
at its end so the light propagating in the core of the guide is
deflected, through total internal reflection, down towards the
package substrate.  A mirror at the package/waveguide interface
reflects the light upwards and the light escapes from the guide and
impinges on the detector.

      There are several requirements the technique must meet in order
to minimize the total waveguide/detector coupling loss.
    The light must be totally internally reflected at the first
incidence on the beveled end and transmitted on the second incidence
(see Fig. 1).
    The spot size at the photodetector surface must not be larger
than the sensitive area.
    The reflection loss as the beam traverses the waveguide must be
sufficiently low.
    The beam must be roug...