Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
2003-06-27
2004-12-21
Ullah, Akm Enayet (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S147000
Reexamination Certificate
active
06832861
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The communications industry's conversion from electrical to optical communications engineering has accelerated the demand for and the requirements of optical transceiver modules in all fields of data transmission. Both high-rate optical transmission technology on long-distance lines via glass fibers, as well as optical transmission technology with comparatively lower data rates via relatively “thick” polymer fibers or hybrid glass/polymer fibers (so-called HCS fibers), are increasingly used. In the former case, hundreds of kilometers are typical, whereas only some 10 to 100 m are transmitted at data rates of a maximum of some 100 MB/s in the latter case. Systems of this second type are used within mobile means (motor vehicles, railway, airplanes) or for the so-called in-house linkage, i.e., within a building, such as for the data connection of all multi-media devices existing in a house (TV, internet, video recorder, audio devices, PCs, etc.). For cost reasons these networks do often not operate with laser diodes but instead are operated using simple surface light emitting light diodes (LEDs). For coupling such an LED to a relatively thick optical waveguide, a very inexpensive structure may be used, although significant precision is still required. An electro-optical module that contains the coupling point from the LED transmitter to the waveguide or from the photo diode receiver to the optical waveguide, is called optical transceiver.
2. Technical Background of the Invention
For a coupling of a surface-emitting LED and a relatively thick polymer fiber optical waveguide, generally two constructions exist, namely constructions without beam formation and constructions with beam formation. It is noted by way of non-limiting example that typical dimensions may be 250×250 &mgr;m
2
for the LED and 1000 &mgr;m diameter for the polymer fibers. Beam formation means that some or all of the light rays emitted by the LED are changed in their propagation through lenses or curved mirrors so that a higher light portion can be coupled into the optical waveguide compared to a case where such measures are not taken. In any case, the alignment of the optical waveguide to the LED requires a high precision in view of the relevant dimensions, such as those given by example above.
One approach for this type of coupling is presented by the MicroMID technology which has recently become known. An example of this technology is described in DE 198 51 265 A1. Here, a micro-structured plastic support is used, the shape of the support being capable of being designed very flexibly. The manufacture of a reflector for the LED while simultaneously manufacturing an electronic circuit on the substrate is possible. An adjustment of the optical waveguide is implemented by means of a three-dimensional structure formed on the substrate. However, the high equipment costs of this technology are disadvantageous so that only the manufacture of large numbers of pieces justifies their use. Finally, since in the MicroMID technology the electronic circuit of the transceiver must be imaged in conformity with the injection molding tool, the technology is cumbersome in attempting to adapt to client-specific variants of the circuit. An adjustment is implemented between LED and optical waveguide in a structure ordered from LED to micro-structured printed circuit board to fiber plate to optical waveguide. Publications with respect to the MicroMID process can be found in Kragl, H. et. al.: “MICROMID: A low cost fabrication technology for polymer fiber transceiver modules”, POF Conference 2000, Boston, and in Kragl, H. et. al.: “Microstructured three-dimensional printed circuit boards: a novel fabrication technology for optical transceiver modules”, Proc. MicroTec 2000 Conference, Hannover.
For coupling an optical fiber and an LED, a coupling device where the LED optically opposes the end face of the fiber is known from DE 38 34 395 C2. The LED is fixedly connected to a support and is electrically connected by a bond wire to a conductor formed on the support. A coupling element is connected to the support and receives the end portion of the optical fiber. The LED is directly arranged on a planar electrode, namely a so-called lead frame. The coupling element receives the end of an optical fiber, the optical fiber having a free end face to be opposed to the LED, the coupling element having a type of a column which comprises sections matching with the conductors of the lead frame, so that these conductors are received in the sections. The LED is attached on the one conductor, whereas the other conductor is connected to the LED through a bond wire. In order to attach the LED on the lead frame in a highly precise manner, an optical pattern detection process is required, which proceeds so slowly that a use in mass production must be ruled out. If, however, the placing of the semiconductor element is left to a mass die bonder, a tolerance in the range of 50 &mgr;m to 70 &mgr;m must be accepted. When attaching the coupling element to the lead frame, there is some likelihood that the lead frame will be damaged, and the bond wire can be damaged even more easily. If this is to be avoided, additional tolerances must be taken into consideration so that, in the case of mass production, an overall tolerance of 200 &mgr;m must be taken into consideration.
A coupling arrangement for coupling an optical waveguide to an opto-electronic device, e.g. a light emitting diode or a photo diode, is known from EP 0 611 975 A1. This coupling arrangement uses a cuboid base member made of a silicon monocrystal and a cuboid cover member also made of a silicon monocrystal, the cover member planarly lying thereon. A V-shaped groove for receiving the uncovered end of an optical waveguide is formed in the base member, the groove ending in a reflecting, oblique surface inclined by 45°. On the end of the groove opposite to the oblique surface, this groove opens into a V-shaped groove of a larger cross section, which provides for the accommodation of the covered section of the optical waveguide and which extends up to an edge of the base member. In the area over the oblique surface, the opto-electronic device is attached on the base member. The cover member comprises on its side facing the base member a V-shaped groove whose cross section corresponds to the larger cross section of the V-shaped groove in the base member. In the area in which the semiconductor component is located, the cover member has a recess, which offers space for the accommodation of the opto-electronic device. The orientation of the base member and the cover member on each other is carried out by means of two spheres, which are received in matching pyramid-shaped recesses formed in the base member and in the cover member. The cover member has two openings through which a casting compound can be filled into the area of the electro-optical device and the covered optical waveguide. This publication does not provide any clue regarding how the opto-electronic device is aligned on the reflecting oblique surface to obtain the desired accuracy that is defined by +/−1 &mgr;m.
A laser-glass fiber coupling and a method of establishing such a coupling connection is known from DE 33 39 189 A1. In this coupling arrangement, the coupling point is encapsuled with a curing resin mass to obtain optically favorable relations and to obtain a device for coupling a semiconductor and a fiber optical waveguide that is insensitive against environmental influences.
An optical coupling between an optical semiconductor and a fiber optical waveguide is known from U.S. Pat. No. 6,004,046. This arrangement uses a paraboloid mirror, not only bundling the light rays emitted by the optical semiconductor, but also at the same time deflecting them by 90°.
SUMMARY OF THE INVENTION
An object of the invention is to provide a coupling arrangement for optically coupling an end of an optical waveguide with at least one electro-optical or opto-electrical element an
DieMount GmbH
Jansson & Shupe & Munger Ltd.
Ullah Akm Enayet
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