Optical waveguides – With optical coupler – With alignment device
Reexamination Certificate
2000-10-25
2001-08-28
Ullah, Akm E. (Department: 2874)
Optical waveguides
With optical coupler
With alignment device
Reexamination Certificate
active
06282346
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns an optical and/or electro-optical connection of two optical and/or electro-optical components.
RELATED TECHNOLOGY
Traditional optoelectric connections have several disadvantages. The mounting elements had a complicated structure and were bulky and expensive. In most cases, each electro-optical component had to be mounted separately on an auxiliary carrier. This necessitated additional mounting methods, e.g., soldering the laser or gluing the fibers in an assembly tube (adhesive can shrink and become brittle with age). These auxiliary carriers then had to be mounted on the main carrier. Due to the fact that now assembly errors were added (e.g., differences in thickness of the solder between the semiconductor laser and the auxiliary carrier), these arrangements were mechanically inaccurate and bulky but still sensitive to temperature and expensive because of the long assembly times.
A first attempt to improve optical and/or electro-optical connections of the type in question is disclosed in unexamined German Patent (Offenlegungsschrift) 4,140,283. However, the connection described in that publication still requires a complicated carrier structure and nothing is said about how the other components are mounted.
Fibers spliced together with thermal energy such as an electric arc as done in the past had to be protected from breakage after splicing by a mechanical device.
In arrangements where one component is soldered, the melting point of solder (120-250° C.) precludes high-temperature applications, e.g., for sensors.
With lasers, modulators, and other electro-optical components, the wire for the electric connection, such as the pump lead-in wire, in previous arrangements has been bonded. This required an extra tool (a bonding machine).
SUMMARY OF THE INVENTION
The present invention concerns an optical and/or electro-optical connection of two optical and/or electro-optical components, each comprising structures with optical waveguides arranged in parallel or essentially parallel to the substrate surface on a carrier board in the area of the connection.
The wavelength range of 0.6 to 1.6 &mgr;m is advantageous for transmission of information for such applications as optical communications technology or for sensors because of the low attenuation and low dispersion of glass fibers. Connecting the optical and electro-optical components required for this transmission in the past has been very cost-intensive, especially when the waveguides of the components to be linked to form a system are monomode waveguides. Joining tolerances in the micrometer and submicrometer range must often be maintained for decades despite great temperature fluctuations. A component of such a system is an arrangement for coupling the light from a semiconductor laser transmitter into a monomode fiber because then two beams with spot widths smaller than 1 &mgr;m must be aligned so they overlap. Since the fiber has a 5-&mgr;m spot, it is advantageous to match the spot widths of the laser and the fiber to each other in a coupling arrangement. This can be accomplished by using a lens between the laser and the fiber, by a lens attached to the end of the fiber or by a spot width taper integrated into the laser chip. Arrangements of components with similarly small spot widths such as semiconductor laser amplifiers or transceivers may also be used.
The components may be connected having spot widths adapted to a glass fiber, such as splitters, modulators, switches, wavelength multiplexers and demultiplexers, because here again the 5-&mgr;m-spot widths and thus the joining tolerances are small. The same thing is also true of arrangements for coupling two fibers such as splices or plugs.
An object of the present invention is to create an optical and electric connection of electro-optical components that can be implemented inexpensively, with long-term stability and thermal stability to make it possible to couple information-transmitting from one or more waveguides of one component into one or more waveguides of the other component in an economically feasible manner.
With regard to the process engineering part of the present invention, an inexpensive technology for aligning and mounting components to yield long-term and thermal stability is to be made available.
According to the present invention, a connection of the type described above is created in which two components are mounted directly on just one single joint carrier board by welding with electromagnetic radiation in the wavelength range of about 1 &mgr;m without using auxiliary carriers.
The present invention provides a process for producing a connection as discussed above where at least one of the components (
10
,
13
) to be mounted is made of a transparent material. The electromagnetic radiation (
19
,
20
,
40
) is selected and matched with the material of the components (
10
,
13
) to be mounted on the carrier board (
15
) so that it penetrates the components (
10
,
13
) on its path to the weld (
18
) without altering their function. A process for producing a connection as discussed above where the components (
10
,
13
) to be joined are made of a non-transparent material is also provided. The electromagnetic radiation (
19
,
20
,
40
) is selected and matched with the material of the components (
10
,
13
) to be mounted on the carrier board (
15
) so that it penetrates through the components (
10
,
13
) on its path to the weld (
17
), forming holes (
21
) without altering the function of the components (FIG.
6
).
Electro-optical components in the sense of the present invention are understood to be structures with optical waveguides aligned essentially parallel to the respective contact surface of the carrier board in the area of the coupling site. Examples include:
Cubic integrated optical or integrated electro-optical chips made of InP, GaAs, PbS, tantalate, glass, germanium, or silicon, e.g., semiconductor lasers, semiconductor detectors, splitters, directional couplers, switches, modulators, multiplexers and demultiplexers, flat spectrographs.
Cylindrical structures such as glass fibers.
With regard to the electromagnetic radiation to be used according to the present invention, radiation from Nd-glass lasers or Nd-YAG lasers with an output wavelength in the range of &lgr;=1 &mgr;m, for example, can be used. Other sources having similar radiation properties in the wavelength range of &lgr;=0.2 &mgr;m to &lgr;=2.0 &mgr;m are also possible.
An advantage of the present invention includes the fact that only a single mounting element with a simple structure is used, namely the carrier board on which all the electro-optical components plus the optional imaging arrangement, e.g., a spherical lens are mounted directly, i.e., without an intermediate carrier or an extra carrier, by a single method, namely welding with electromagnetic radiation.
Various embodiments of the present invention with regard to the object part of the present invention include that the carrier board (
15
) has a contact face (
38
), and the optical and/or electro-optical components (
10
,
13
) are arranged on the flat contact face (
38
) and mounted there (
FIGS. 1
,
2
,
5
and
7
). The carrier board (
15
) also may have two parallel stepped contact surfaces (
29
,
30
) with one of the two components (
10
,
13
) arranged and mounted on each surface (FIG.
3
). A semiconductor on which the carrier board (
15
) is mounted by angled input of the electromagnetic radiation (
23
,
24
) may serve as one (
10
) of the two components (
10
,
13
) (
FIG. 5
) and one (
10
) of the two components (
10
,
13
) may be an electro-optical component having a current lead-in wire (
39
) connected by electromagnetic radiation (
40
) (FIG.
7
). One (
13
) of the two components (
10
,
13
) also may be a fiber (
13
) that is connected to the carrier board (
15
) by utilizing its cylindrical lens effect on the electromagnetic radiation (
20
) (FIGS.
1
and
3
). Moreover, both of the electro-optical components (
10
,
13
)
Becker Manfred
Richter Hartwig
Deutsche Telekom AG
Kenyon & Kenyon
Ullah Akm E.
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