Browse Prior Art Database

Photoformed Optical Deflector

IP.com Disclosure Number: IPCOM000110744D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 3 page(s) / 107K

Publishing Venue

IBM

Related People

Goodman, D: AUTHOR [+4]

Abstract

Miniature optical deflection structures which are compatible with integrated circuit technology as well as optical fiber technology are needed to realize the potential of future optoelectronic packages. Here techniques for fabricating optical deflection structures, testing them, as well as several structures for using them, are disclosed.

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Photoformed Optical Deflector

       Miniature optical deflection structures which are
compatible with integrated circuit technology as well as optical
fiber technology are needed to realize the potential of future
optoelectronic packages.  Here techniques for fabricating optical
deflection structures, testing them, as well as several structures
for using them, are disclosed.

      Optical deflection structures (total internal mirrors) have
been micromachined in planar optical waveguides using excimer lasers
with the intent for interfacing to an optical detector (receiver)
(1,2).  The technique is limited to substrates which are not readily
damaged by exposure to excimer laser radiation.  Here, a technique
and structure are described which make it possible to fabricate a
section of planar optical waveguide containing a total internal
reflection mirror (i.e., optical deflection structure) which can be
fabricted on standard electronic packaging substrates (ceramic, glass
epoxy, etc.) or even on delicate optoelectronic chips (GaAs, InP, Si,
etc.).

      The technique for forming an optical deflection structure
involves the use of a novel exposure tool/technique that is readily
implemented using conventional lithographic light sources, optics,
and photomasks.  The key element is the introduction of a prism to
optical path in order to create the appropriate incident angle of
light for exposing the waveguide material to create a bevel.

      Two photoexposures are used to create the optical deflector.
The first exposure is a contact print and creates an optical
waveguide section.  The second exposure is used to fabricate the
Total Internal Reflection (TIR) mirror.  The sample is exposed at
non-normal incidence and the shadowing effect from the mask creates
the TIR mirror [1].  Because light is refracted at the air-glass
interface, exposing the sample at an angle, d, is not sufficient to
create a TIR mirror (a>45o) as proposed in (1).  This is accomplished
by exposing the sample through a prism which minimizes this
refraction by reducing the angle of incidence of the light on the
quartz.  Oil or alcohol is included between the various interfaces to
insure physical contact.

      In a typical process, a negative photoresist is coated on a
substrate.  The substrate is coated with is...