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Browse Prior Art Database

Electrically Insulated Monolithic Laser Opto-coupler

IP.com Disclosure Number: IPCOM000110591D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Gfeller, F: AUTHOR [+4]

Abstract

Disclosed is an opto-coupler consisting of a laser diode, serving as transmitter, and a photodiode as receiver, both being monolithically integrated on a semi-insulating substrate. In contrast to conventional opto-couplers based on light-emitting diodes, the disclosed structure offers higher speed and a better current transfer ratio.

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Electrically Insulated Monolithic Laser Opto-coupler

       Disclosed is an opto-coupler consisting of a laser diode,
serving as transmitter, and a photodiode as receiver, both being
monolithically integrated on a semi-insulating substrate.  In
contrast to conventional opto-couplers based on light-emitting
diodes, the disclosed structure offers higher speed and a better
current transfer ratio.

      The structure (see the figure) is epitaxially grown on a
semi-insulating GaAs substrate 1, with n+-GaAs contact layer 2,
n-AlGaAs cladding 3, active region 4, p-AlGaAs cladding 5, and
contact electrodes 6.  Lateral confinement of the light emitted by
the laser diode is achieved with a waveguide ridge 7.  To
electrically insulate the laser diode from the photo diode, an
isolation trench 8 is etched to a depth below the n+-GaAs contact
layer 2, surrounding both devices.  The etched mirror trench 9 serves
to access the n+ contact layer and also provides etched laser
mirrors.  In order to achieve a breakdown-voltage of >2000 V, the
laser and photo diodes are separated by an isolation trench width
>200 mm.  To reduce optical coupling losses between laser and photo
diodes, the emitted laser light is guided to the photo diode with a
dielectric ridge waveguide [*] consisting of SiO2 buffer layers 10
and a Si3Ni4 waveguide core 11.

      Reference
[*]  European Patent Application 91810742.