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Synchronized Output Laser Array

IP.com Disclosure Number: IPCOM000089189D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Comerford, LD: AUTHOR [+2]

Abstract

Lower skewing is achieved between channels in a multichannel GaAs laser optical data link by injecting light from the clock fiber back into the other lasers via lightguide coupling. Light propagating in the cladding of the clock fiber leaks to an optical coupling slab, which is so oriented and metallized that internally reflected light in the slab leaks into the other fibers and becomes injected back into the other lasers. Optical injection controls the time delay between current and light pulses for better synchronization of the laser array.

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Synchronized Output Laser Array

Lower skewing is achieved between channels in a multichannel GaAs laser optical data link by injecting light from the clock fiber back into the other lasers via lightguide coupling. Light propagating in the cladding of the clock fiber leaks to an optical coupling slab, which is so oriented and metallized that internally reflected light in the slab leaks into the other fibers and becomes injected back into the other lasers. Optical injection controls the time delay between current and light pulses for better synchronization of the laser array.

The figure illustrates an array of four lasers and four lightguides, but ordinarily many more lasers and lightguides would be used in practice. The laser array is bonded to a silicon substrate which also has etched alignment grooves for a cylinder lens (for laser collimation) and the lightguides. A flat slab is used to hold the fibers against the groove walls during bonding and often becomes part of the package. The slab is here used also to couple light from the clocking fiber back into the other fibers for injection back into the other lasers.

Optical coupling is achieved by matching the index of refraction of the slab to the index of refraction of the fiber cladding so that light propagating in the cladding leaks to the slab.

If the cladding light leaks into the slab in a highly directional beam, it may be reflected back and forth in the slab in alignment with the fibers. The width of the s...