Optical waveguides – Planar optical waveguide
Reexamination Certificate
1998-09-29
2001-05-29
Ullah, Akm E. (Department: 2874)
Optical waveguides
Planar optical waveguide
Reexamination Certificate
active
06240232
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to a process for the production of a waveguide beam converter according to the preamble of claim The process according to the invention is used, in particular, for the production of a waveguide beam converter for increasing the radiation density of a laser beam collection emitted by a linear array of laser diodes.
Individual semiconductor laser diodes are known to represent radiation sources with high radiation density. For physical reasons, however, substantial limitations are found for semiconductor-laser radiation sources with high radiation power. This is because laser diodes output individual laser beams in the form of stripes, so that in order to produce a compact laser beam collection with high radiation power, the striped individual laser beams need to be arranged above one another. However, the high power loss from semiconductor laser diodes places a limitation on the packing density of individual laser diodes. It is therefore necessary for the individual laser beams emitted by a plurality of individual laser diodes to be concentrated, for example using a waveguide beam converter.
A waveguide beam converter of this type is, for example, disclosed by international patent application WO 94/152 34. This document describes a fiber-optic arrangement made up of a plurality of curved rectangular optical fibers, by means of which an input laser beam collection which is emitted by a linear array of laser diodes and consists of individual laser beams arranged next to one another, is converted into an output laser beam connection made up of striped individual laser beams arranged above one another. At their input, the optical fibers are arranged next to one another in a line, so that each individual laser beam of the input laser beam collection is injected into a separate optical fiber. At their output, the optical fibers are arranged above one another in the form of a stack, so that an output laser beam collection of rectangular cross section is emitted from the end faces of the optical fibers. This output laser beam collection is subsequently injected through a spherical lens into a fiber laser of circular cross section.
At their input, the optical fibers are fastened in precision grooves in an alignment block, these being designed in such a way that the arrangement and spacing of the optical fibers with respect to one another corresponds to the arrangement and spacing of the individual laser beams injected. The optical fibers are made of silicate glasses containing alkali metals or alkaline earth metals (soft glass), for example BAK 5 for the fiber core and BAK 2 for the fiber cladding, which is in turn enclosed by a supporting clad made, for example, of LAKN 12. The fiber-optic bundle is produced by the following steps:
Firstly, the fiber core with the fiber cladding is produced. Subsequently, the fiber cladding is covered with the material of the support clad, which has a significantly higher etching rate than the material of the fiber cladding. Before the material of the support clad is subsequently etched off down to a thin support clad layer, the above-described composite made up of the fiber core, fiber cladding and support clad layer is drawn in such a way that, after drawing, the cross section of the fiber core is still somewhat greater than the intended final size.
A number of optical fibers produced in this way are then stacked on one another and connected to one another. The stack is then once more provided with a jacket and then again drawn until the stack has the desired geometry. The optical fibers in the stack are subsequently separated at one end of the stack by etching, fastened next to one another in the precision grooves of the alignment block and formed in such a way that individual laser beams emitted from the linear array of laser diodes can be injected into the ends of the fibers.
As can be seen from the description above, the production of a waveguide beam converter of the type mentioned in the introduction is currently elaborate and complicated, and therefore very cost-intensive.
SUMMARY OF THE INVENTION
The object of the invention is to provide a process for the production of a waveguide beam converter which is simple to carry out and makes it possible, in a straightforward way, to produce a plurality of waveguide beam converters at the same time.
This object is achieved by a process of the type mentioned in the introduction, having the features of claim
1
.
The advantage of this process according to the invention consists, in particular, in that the production of the waveguide beam converter requires only a small number of process steps, known from planar technology, which are straightforward to carry out.
Further, in the process according to the invention, it is advantageously possible to produce glasses of high optical quality on a substrate in accordance with requirements. The glass compositions may be tailored to the specific purpose. Radiation losses in the waveguide beam converter can in this way be kept as small as possible.
Further, it is possible with the process according to the invention, in a straightforward way, to tailor the glass properties to the constraints pertaining to the system as a whole, by varying the glass compositions.
A particular advantage of this production process consists in that the laser diode array, for example a linear array of laser diodes or a plurality of individual laser diode chips, can be fitted on the same substrate as the waveguide beam converter. Likewise, coupling lenses for injecting the input laser beam collection into the waveguide beam converter and/or coupling lenses for injecting the output laser beam collection into an individual optical fiber, a further laser or a different device, may also be arranged on this substrate. The result achieved by this is that both the laser diode array and coupling lenses, which may be necessary, can be mounted in a straightforward way so as to be precisely aligned with the waveguide beam converter. To this end, for example, positioning holes or edges may be produced in or on the substrate.
It is further advantageous that the waveguides can be made from an SiO
2
glass which contains more than 50 cation % of SiO
2
. Glasses of this type have high optical quality. The radiation losses in the waveguide beam converter, that is to say both in the light-carrying waveguide core and at the interface between the waveguide core and the waveguide cladding, can consequently be kept low. An essential advantage of the aforementioned SiO
2
glasses is that they can be produced by vapor deposition, which substantially facilitates the production of glass layers on a substrate. Individual glass layers can be produced without great difficulty free of bubbles and free of cords so that they are placed precisely above one another, which produces interfaces which are free of defects and therefore of high optical quality. A further advantage is that these glasses can be removed again by vapor-phase etching methods.
An advantageous process for the production of a waveguide on a substrate, the waveguide being detached from the substrate at least over a first part of its length and being connected to the substrate over a second part of its length, and an advantageous embodiment of the process according to the invention are given in claim
4
and claim
5
, respectively. An advantage in this case is that use is exclusively made of process steps known from planar technology, which can be carried out in conventional semiconductor technology fabrication lines.
It is also advantageously possible with the process according to the invention, in a straightforward way, to produce a waveguide beam converter in which the waveguides are arranged in such a way that a plurality of output laser beam collections can be extracted from them. As a result, it is advantageously possible for the input laser beam collection emitted by a laser diode array to be shaped into a plurality of rectangular output laser beam collections, which can th
Groetsch Stefan
Schneider Hartmut
Spaeth Werner
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
Ullah Akm E.
LandOfFree
Process for the production of a waveguide beam converter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the production of a waveguide beam converter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the production of a waveguide beam converter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2531743