Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making named article
Reexamination Certificate
1999-03-05
2001-12-18
Angebranndt, Martin (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making named article
C430S945000, C219S121690, C219S121680, C385S040000, C385S048000, C385S052000
Reexamination Certificate
active
06331382
ABSTRACT:
The present invention relates to methods of fabricating mirrors in polymer waveguides.
BACKGROUND
Telecommunication systems using light propagating in different waveguides expand more and more today. There is a large interest in extending the optical networks even up to private homes and local business estates, the so called local access network which is also called “Fibre To (In/From) the Home”, “Fibre To (In/from) the Customer (Business)”, etc. Also, there is a large interest in extending the use of optical networks in LANs, i.e. local area networks, used for interconnecting computers in a business estate and furthermore for communication inside computer equipment and for communication between computers and peripheral devices such as printers etc. In order to achieve this expansion, the costs of the components of the optical networks of course have to be reduced as much as possible. Very important costs are related to producing the optical transmitter and receiver modules including lasers, LEDs, etc. and other active or passive is devices.
In optical transmitter and receiver modules and other optical products which have integrated waveguides for light there is a need for mirrors which can reflect light or generally make a abrupt change of the direction of light propagated in the optical waveguides such as to deflect the light out of a waveguide to some receiver. Mirrors which can generally be formed by end surfaces of optical waveguides can be produced using different methods. Mirrors in the waveguide plane achieving a reflection at a surface to air has been disclosed by Honeywell, for example for creating sharp 90° bends in a waveguide, and mirrors for deflecting light out of a waveguide plane have been disclosed by Dupont and IBM, see for example Lawrence A. Hornack, editor “Polymers for lightwave in integrated optics”, Marcel Decker K. K., New York, 1992, Chapter 9 by B. Booth, Dupont. In the company Ericsson, he department MIRC has in cooperation with the Institute for Optical Research disclosed mirrors in waveguides for defecting out of a waveguide plane produced by means of an UV-excimer laser, see Gunnar Boström, “Waveguide grating couplers”, graduate report at the Royal Institute of Technology, Stockholm, Trita. Phys. 2138, Sep. 15, 1994.
In U.S. Pat. No. 5,327,415 a method of producing a reflector for a laser in a semiconductor material is described, see FIGS. 2
a
-2
c
. A metal mask having 28, 34 defines the opening of the reflector at the surface of the material.
SUMMARY
It is an object of the invention to provide a method providing an accurate positioning of an optoelectrical device or chip to be correctly coupled to a channel-type waveguide formed in the surface layer of a substrate.
It is a further object of the invention to provide a method for positioning an optoelectrical device in relation to a reflector formed in the surface layer of a substrate.
It is a firer object of the invention to provide a method for making a reflector in an optical waveguide allowing a simulation of reflecting surfaces.
Thus the position of an oblique mirror structure inside a polymer waveguide is accurately defined by using an integrated mask of metal, which is defined using photolithography, on top of the waveguide structure. The metal mask only lets the laser light through where material is to be removed, i.e. ablated, in order to manufacture or several mirrors. The need for a high accuracy of the position in space of the laser radiation beam can be reduced since in the lithographic may which defines the metal mask intended for producing the reflector also a pattern can be included defining the contact pads intended for flip-chip mounting of lasers and photodiodes. Self-aliging flip-chip mounting comprising soldering isles allows a very accurate positioning of the optocomponents which will then have a correct location in relation to the mirror obtained. The edge inside the integrated metal mask, which defines the position of the reflecting surface can be a straight line or be curved, for example having a parabolic profile, in it order that more light which diverges from e.g. a laser diode will be collected in the waveguide structure or that light from the waveguide will be better focused on for example the input surface of a photodiode.
Another metal layer can be applied directly under the undercladding or even at a suitable place under the waveguide core in order to use this for metallizing the mirror surface. Then the metaling of the surfaces which will form the mirrors is made in the same process and directly after the cavity being made, when the radiation beam reaches this metal surface. The laser beam will then also affect this inner metal layer but at a substantially lower velocity than the polymer material. Metal will then be removed in a very finely divided form having a high velocity of the particles therein. They will then deposit on available surfaces, and thus on the mirror surface owing to that it is located very close to the surface of the inner metal region. The surface of the inner metallization should advantageously be diffusely reflecting in order to minimize ablation due to reflections of the laser beam.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the methods, processes, instrumentalities and combinations particularly pointed out in the appended claims.
REFERENCES:
patent: 5327415 (1994-07-01), Vettiger et al.
patent: 5367585 (1994-11-01), Ghezzo et al.
patent: 5393371 (1995-02-01), Chang et al.
patent: 5544268 (1996-08-01), Bischel et al.
patent: 5909524 (1999-06-01), Tabuchi
patent: 6049641 (2000-04-01), Deacon et al.
patent: 2100876 (1983-01-01), None
Hornak, Lawrence, “Polymers for Lightwave and Integrated Optics”, Marcell Dekker, Inc. New York, 1992, Chapter 9.
Boström, Gunnar, “Wave grating couplers”, Royal Institute of Technology, Stockholm, Trita, Phys 2138, Sep. 15, 1994.
Robertsson, et al., “New Patternable Dielectric and Optical Materials for MCM-L/D-ad o/e-MCM-packaging”, First IEEE Int. Symp. On Polymeric Electronics packaging, Oct. 26-30, 1997, Norrköping, Sweden.
Angebranndt Martin
Burns Doane Swecker & Mathis L.L.P.
Telefonaktiebolaget LM Ericsson (publ)
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