US 5,332,690 AGranted

Method of making an integrated optical package for coupling optical fibers to devices with asymmetric light beams

AssigneeAT&T Bell Laboratories

InventorsAlfred Y. Cho, Deborah L. Sivco, Daryoosh Vakhshoori

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Abstract

This invention embodies an integrated optical package including an optical component having an asymmetric modal output, and a lens integrated with the component for coupling to another optical component having a large modal area. The coupling is achieved by the use of a Polymeric Elongated Waveguide Emulating (PEWE) lens. In the exemplary embodiment the first optical component is a modulator, and the other optical component is an optical fiber. A facet of the modulator is etched by reactive ion etching (REE) which allows integration of the PEWE lens on a common substrate. The lens is manufactured using a polymer film on a dielectric cladding layer. The fabrication relies on the remelt and reflow properties of polymer films to provide a smooth adiabatic mode contraction from a circular (optical fiber) mode (.apprxeq.6 .mu.m in diameter) to a semiconductor mode (.apprxeq.1 .mu.m) over a length of 250 .mu.m. The PEWE lens permits coupling with an insertion loss of 0.5 dB and 80 percent-coupling efficiency, even though the lens is butt-coupled to a fiber without any external lens. The PEWE lens allows the realization of better than 80 percent direct fiber butt-coupling efficiencies to semiconductor lasers, photodetectors, optical modulators, switches and amplifiers with a simultaneous order of magnitude relaxation of the alignment tolerances typically needed for the coupling of semiconductor devices with single-mode fibers.

Claims5

Dependent claims

A method of fabricating an integrated optical package,

said package comprising an optical device with an asymmetric modal area and an elongated lens for coupling the device to an optical component having large modal area relative to said asymmetric modal area, which comprises:
beginning with a substrate having a compound semiconductor structure thereon comprising an active layer and a bottom and a top cladding layers,
etching a trench in said structure so as to expose a facet of a device on each side of the trench, said etching removing a modal thickness of the lower cladding layer and all of the other layers of the structure above said lower cladding layer while refilling those portions of said structure which are intended to be used as the optical device,
forming in said trench centrally between two facets a diamond-shaped elevated form the length of which is equal to a half of the width of the trench between the facets, the thickness of the diamond shaped form being equivalent to at least the diameter of the core of a fiber to be optically coupled to the device,
coating the whole of the structure with a thin layer of a polymeric material in a thickness equivalent to the height of the active layer in said device,
converting the profile of the combined polymeric material to a profile with a gentle slope between said center portion and said facet-adjoining portion, and
removing an excess of thickness of said polymeric material adjacent each facet so as to reduce this thickness to that corresponding to the height of the active layer in said device.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/107,541Filed 17 Aug 1993 · division
Priority: 8 May 1992
Granted: 26 Jul 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G02B 6/42
Coupling light guides: coupling light guides with opto-electronic elements
G02B 6/4206
The coupling comprising intermediate optical elements, e.g. lenses, holograms: optical features
G02B 19/0028
Characterised by the optical means employed: refractive and reflective surfaces, e.g. non-imaging catadioptric systems
G02B 19/0052
For use with a light source: the light source comprising a laser diode