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Self-Aligned Optical Fiber/Laser Structure

IP.com Disclosure Number: IPCOM000042284D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+3]

Abstract

A single lithography fabrication process may be used to integrate the fabrication of a semiconductor laser and a V-groove alignment structure supporting the laser. The step of aligning the laser with a V-groove substrate (which is used to align other optical elements with the laser) is thus avoided. A standard mounting technique for coupling laser diodes to optical fibers uses a silicon substrate patterned with V-grooves to precisely define the position of the fibers. A laser diode is then attached to the substrate, p-side down, and back contact is made via wire bonding or soldering [1]. This technique still requires that the laser diode be aligned on the silicon substrate. We propose to utilize the unique etching properties of III-V compounds in order to form the fiber-aligning V-grooves in a III-V compound instead of silicon.

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Self-Aligned Optical Fiber/Laser Structure

A single lithography fabrication process may be used to integrate the fabrication of a semiconductor laser and a V-groove alignment structure supporting the laser. The step of aligning the laser with a V-groove substrate (which is used to align other optical elements with the laser) is thus avoided. A standard mounting technique for coupling laser diodes to optical fibers uses a silicon substrate patterned with V-grooves to precisely define the position of the fibers. A laser diode is then attached to the substrate, p-side down, and back contact is made via wire bonding or soldering [1]. This technique still requires that the laser diode be aligned on the silicon substrate. We propose to utilize the unique etching properties of III-V compounds in order to form the fiber-aligning V-grooves in a III-V compound instead of silicon. This permits us to form the V-grooves on the same III-V substrate as the active element, thereby allowing integration of the two and elimination of any need for aligning a separate active element with the V- groove structure. The proposed configuration is shown in the figure, which may be constructed using the following process sequence: 1) Epitaxial layer growth for double heterostructure device 2) V-groove formation a) oxide growth b) photolithography c) wet chemical anisotropic~etch 2,3 3) Active stripe formation
a) oxide growth b) photolithography c) p-diffusion 4) Metallization and facet etch
a) photolithography b) metal depositon and lift-off c) oxide etch (metal acting as an etch mask) d) ion etch facets e) contact metallurgy 5) Separate individual devices (saw or cleave) and mount Steps 1, 2, 4, and 5 are common to standard laser diode processing, while step 3 is required for standard silicon optical bench technology. The proposed process requires no additional masking or oxide steps compared with standard techniques and yet eliminates the need for a complicated alignment of the laser with the fiber optics. The fiber and possibly a lens for improved coupling are held in place by the V-grooves. The...