Source: http://www.google.com/patents/US6815865?dq=5708422
Timestamp: 2014-03-12 20:08:08
Document Index: 480341066

Matched Legal Cases: ['art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 32', 'art 25', 'art 34', 'arts 34', 'arts 7', 'art 152', 'art 152', 'art 152', 'arts 101', 'art 101', 'art 101', 'art 152', 'art 165']

Patent US6815865 - Switching arrangement for a radiation guide - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsThe radiation guide switching arrangement having at least one radiation guide switch is produced from a sandwich wafer. The sandwich wafer has a substrate, a covering layer and an electrically insulating intermediate layer. Each radiation guide switch has a moveable switching part (7) as well as at least...http://www.google.com/patents/US6815865?utm_source=gb-gplus-sharePatent US6815865 - Switching arrangement for a radiation guideAdvanced Patent SearchPublication numberUS6815865 B2Publication typeGrantApplication numberUS 10/182,670PCT numberPCT/CH2001/000072Publication dateNov 9, 2004Filing dateJan 31, 2001Priority dateJan 31, 2000Fee statusPaidAlso published asDE50101190D1, US20030117038, WO2001057578A1Publication number10182670, 182670, PCT/2001/72, PCT/CH/1/000072, PCT/CH/1/00072, PCT/CH/2001/000072, PCT/CH/2001/00072, PCT/CH1/000072, PCT/CH1/00072, PCT/CH1000072, PCT/CH100072, PCT/CH2001/000072, PCT/CH2001/00072, PCT/CH2001000072, PCT/CH200100072, US 6815865 B2, US 6815865B2, US-B2-6815865, US6815865 B2, US6815865B2InventorsCornel MarxerOriginal AssigneeSeralco Microtechnology Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (13), Non-Patent Citations (4), Referenced by (6), Classifications (22), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetSwitching arrangement for a radiation guideUS 6815865 B2Abstract The radiation guide switching arrangement having at least one radiation guide switch is produced from a sandwich wafer. The sandwich wafer has a substrate, a covering layer and an electrically insulating intermediate layer. Each radiation guide switch has a moveable switching part (7) as well as at least two radiation guide ends (6), which come to rest in a plane and are arranged closely adjacent to one another such that radiation which emerges from one radiation guide end (6) can be blocked on its optical path to another guide end (6), or can be reflected into this other guide end, by means of the switching part (7). The intermediate space (5) which accommodates the switching part (7) between the guide ends (6) is filled with an index matching liquid (87) which has a predetermined refractive index, and the radiation-carrying core (8) of each radiation guide (49) is designed to taper such that radiation collimation (14) can be achieved by interaction with the refractive index of the index matching liquid (87) and the free core profile (13) in the space which is filled with liquid.
DESCRIPTION OF THE INVENTION OBJECT OF THE INVENTION The object of the invention is to provide a radiation guide switching arrangement which has low radiation losses, or exactly adjustable radiation losses, with a good switching response.
ACHIEVEMENT OF THE OBJECT The object is achieved by producing a radiation guide arrangement having at least one radiation guide switch from a sandwich wafer with a substrate, a covering layer, and an electrically insulating intermediate layer. Each radiation guide switch has at least one moveable switching part as well as at least two radiation guide ends which come to rest in a plane. The radiation guide ends are arranged closely adjacent to one another such that radiation which emerges from one radiation guide end can be blocked on its optical path to another guide end, or can be reflected into this other guide end, by means of the switching part. The intermediate space which holds the switching part is, according to the invention, filled with an index matching liquid having a predetermined refractive index. Furthermore, the core of each radiation guide, which carries the radiation, is designed to taper such that radiation collimation can be achieved by interaction with the refractive index of the index matching liquid and the free core profile in the space which is filled with liquid.
The radiation guide switching arrangement according to the invention also makes use of radiation guide switches with a mirrored switching part. If a switching part such as this is used, then, on the one hand, it is possible to �pass on radiation� between mutually opposite radiation guide ends when the switching part is withdrawn from the intermediate space, as already indicated above. When the switching part is inserted into the intermediate space, the passing on of radiation is interrupted; however, radiation which emerges from a radiation guide can now be reflected (passed on) into another radiation guide. If passed on �straight�, the collimated beam emerges from the one guide and enters the opposite guide. If not, the collimated beam is deflected by the mirror. In order that this switching operation can operate with minimal radiation losses, the radiation guide ends as well as the mirrored surface must be positioned exactly. To do this, all the radiation guide ends to be switched are located in a plane. The mirror surfaces of the switching part must then be positioned at right angles on this plane. It has now been shown that a mirrored switching part which was produced according to the method described in WO98/12589 had mirror surfaces which are not at right angles, which then led to additional radiation losses between two guide ends.
The expression a good switching response does not just mean that the radiation is transmitted with losses that are as low as possible when the switch is in the �switched-on position�. The switching times must also be reproducible, and it must be possible to carry out the switching operations quickly. However, this also refers to switching processes by means of which a predetermined attenuation can be set. However, the switching times in the case of the radiation guide switch known from WO98/12589 differed; furthermore, high voltages had to be applied to the comb structure of each holder having a switching part, in order that it was possible to overcome the �tearing free effect� from one switching position to the other.
It has been possible to eliminate this �tearing free effect� in the embodiment described below since two identical comb structure engaging in one another have no longer been used, and, instead the tine end region of one of the two comb structures has a region with a broadened cross section. This thus results in a second fixed-position comb structure which matches the first comb structure. The comb tines of the second comb structure are arranged with a gap with respect to the first comb structure. A first and a second electrical voltage can be applied to the two comb structures in order to produce an electrostatic movement. It is now possible to configure the region with a broadened cross section, that is to say to design it with an electrostatic voltage application, such that the switching part can be held in a stable position.
BRIEF DESCRIPTION OF DRAWINGS Examples of the radiation guide switching arrangement according to the invention and of its production will be explained in more detail in the following text, with reference to the figures. Further advantages of the invention will become evidence from the following description text. In the figures:
FIG. 4d showing a comb structure with a row of tines whose tines are analogous to those in FIG. 4c; just with the �arrow-shaped� transition being replaced by a stepped transition, and
FIG. 11 shows a cross section through the matrix-like radiation guide switching arrangement, produced using flip chip technology, along the lines XI�Xl in FIG. 9,
APPROACHES TO IMPLEMENTATION OF THE INVENTION The radiation guide switch 2, according to the invention, of a radiation guide switching arrangement 4 and as illustrated in FIG. 1 has been produced as a sandwich wafer from an SOI wafer 39 (silicon on insulator) by means of a production method as described in the following text. The radiation guide switch 2 has four radiation guide insert channels 1.1 a to 1.1 d, which are arranged at right angles to one another and into which, once the switch has been produced, radiation guides 49 can be inserted which are provided with points and taper toward the fiber end in accordance with the following description. All the radiation guide insert channels 1.1 a to 1.1 d lie in a single plane and run to a central space 5.1 in which a switching part 7.1, whose side surfaces are in this case mirrored, engages such that it can move. When the switching part 7.1 is inserted into the space 5.1, signals can then be transmitted between the radiation guides which are inserted into the insert channels 1.1 a and 11.d, as well as 1.1 b and 1.1 c. When the switching part 7.1 is withdrawn, signals can be transmitted between the radiation guides which are inserted into the insert channels 1.1 a and 1.1 c, as well as 1.1 b and 1.1 d. FIG. 1 shows the switching part 7.1 in an intermediate position, with no voltage applied.
Between the two arrangements�spring elements, supporting bars, comb structure 51 a, 51 b, 21 a, 22 a and 52 a, 52 b, 21 b, 22 b�the slot 18 which accommodates the holder 19.1 has recesses 63 and, offset with respect to them, the holder 19 has studs 64. The recesses 63 and the studs 64 are arranged symmetrically with respect to the holder axis and with respect to the center line of the slot 18.1. The overall width, measured over two studs 64 which are arranged to the left and right of the holder shaft, is less than the width of the slot 18.1 only by a tolerance. The studs 64 and the recesses 63 are arranged with respect to one another, when the switching part 7.1 is in the rest position, such that the larger portion of the length of the studs 64 is located in the part of the gap 18.1 where there is no recess, and only a subregion of the studs, which corresponds to the longitudinal direction of the holder movement in the switching process, is located above the respective recess 63. If an electrical voltage is now applied between the covering layer area 60 and the covering layer area 65, then an electrostatic attraction force is produced, as described above, via the cam structure 22.1 a and 22.1 b as well as via the studs 64 and the �recess structure� on the holder 19.1.
Details of the radiation guide switch 2 are described in FIGS. 3a and 3 b with reference to a radiation guide switch 20. The radiation guide switch 20 is designed analogously to the radiation guide 2. However, it is designed such that it remains electrically on the one hand in an inserted �active� equilibrium position (in which signals are transmitted between radiation guides in the channels 1.2 b and 1.2 a which are analogous to the channels 1.1 a to 1.1 d) when a different voltage is applied and, in a further position, in a pushed-out �active� equilibrium position (in which signals are transmitted between radiation guides in the channels 1.2 a/1.2 c and 1.2 b/1.2 d). The radiation guide switch 20 is shown in a position with respect to the position of the radiation guide 2 and is used together with a further fifteen radiation guide switches in the switch chip 127 described in the following text. Analogous elements of the radiation guide switches 2 and 20 are annotated by the same reference symbols, but distinguished by �0.1� for the radiation guide 2 and with �0.2� for the radiation guide 20.
FIG. 4c shows a tine arrangement according to that which has already been indicated in FIG. 1. The tines 23 a and 23 b, respectively, of the moving tine arrangement are in this case identical to those in FIGS. 4a and 4 b. The fixed-position tines 24 a and 24 b, respectively, are designed analogously to the tines 31 a ; in the free tine end region, the part 32 is designed such that it tapers to a tip 25. The remaining region 37 still has a cuboid cross section. Since the gap between the bars 23 a and 23 b, respectively, which have equal widths, and the web part 25 decreases as they move toward one another, the electrostatic attraction force F3 rises, as shown by the curve region 40. When the tapering regions 25 are pushed in between the tines 23 a and 23 b, respectively, the force F3 is constant (curve region 41), since there is now no change in the gap width. The force decreases (curve region 42) only when the thin �web spike� 26 enters the region in which the free tine ends of the tines 23 a and 23 b are scattered. If the thin web spike 26 has no �edge disturbance� in the intermediate region of the tines 23 a and 23 b, respectively, the electrostatic force F3 is constant once again (curve region 43). This tine arrangement does not require any mechanical stop either, but has the advantage of shorter switching tines than the tine arrangement shown in FIG. 4b. Further refinement options for a tine arrangement are illustrated in the form of an associated electrostatic force/movement diagram in FIG. 4d. This tine arrangement has the same radiation guide switch 20 as that shown in FIGS. 3a and 3 b. In contrast to the tine arrangements in FIGS. 4b and 4 c , the mutually opposite tine arrangements in this case are identical, with in each case one tine part 34 a and 34 b, which has a cuboid cross section on a thin tine foot 36. The force/movement diagram associated with this tine arrangement has an analogous profile, with a few exceptions, to the force/movement diagram in FIG. 4c. However, a difference results that a constant force region A4, as shown in FIGS. 4a and 4 b, starts once again when the tine ends, which are located opposite one another in the gap of the other ones, are at the same level. However, in comparison to the force/movement diagrams shown in FIGS. 4b and 4 c , there is a deeper notch in a second constant force region C4 once the tine parts 34 a and 34 b have moved passed one another, virtually to a force F4→0.
The thin webs 77 then become the filigree parts as illustrated in FIGS. 1 and 3a/b. Since the switching part (mirror) 7.1 or 7.2, respectively, the holder 19.1 or 19.2, respectively, the supporting bars 21.1 a and 21.1 b as well as 21.2 a and 21.2 b, respectively, the sprung lugs 16 and the spring elements 51 a/b and 52 a/b as well as 107 and 109, respectively, together with their webs 57 are merely formed as a filigree structure from elements with thin widths, while these are necessary in accordance with mechanical requirements, they are �etched free�. An analogous situation applies to the comb structures.
Instead of having to design the switching parts 7, 7.1, 7.2 and 101 such that radiation is completely blocked or is completely transmitted between two respective guide ends, only partial blocking can also be provided. An element such as this is then used for defined attenuation of signal radiation. In order to achieve this aim, it would now be possible to think of inserting a mirror only partially into a space 150 carrying radiation between two respective guide ends 151 a and 151 b. However, it has been found that, although this would allow attenuation, such attenuation would, however, be highly dependent on the polarization. This means that the attenuation of the TE (transelectrical) and TM (transmagnetic) waves would differ. In order to reduce the polarization dependency, the switching part 152 is in this case (FIGS. 12 and 13) provided with an attenuating metallic coating. The reflection and attenuation characteristics of such a coating can be calculated, by way of example, in accordance with Born and Wolf, �Principles of Optics�, �An absorbing film on a transparent substrate�, page 628 et seqq, Pergamon Press, 1975.
The polarization dependency between the two wave types�TE and TM waves�is due to the fact that, in the case of a diffraction arrangement, the boundary conditions on the metallized free edge of the switching part 152 may be different. The polarization dependency can now be reduced if the switching part 152 is no longer arranged only slightly away from the vertical with respect to the aligned axis 153 of the two guide ends 151 a and 151 b, but an angle of less than 65�. Very good results have been achieved with an inclination of less than 50�, and preferably at 45�.
Instead of only a single radiation guide switch 2 or 100, a number of radiation guide switches may also be used in one radiation guide switching arrangement. Once such matrix-like arrangement 120 for m �incoming� and n �outgoing� radiation guides 121 a to 121 d and 122 a to 122 d has m�n, in this case sixteen, radiation guide switches 100 aa to 100 dd. The sixteen radiation guide switches 100 aa to 100 dd make it possible to switch the signal flow between the radiation guides 121 a to 121 d and 122 a to 122 d. An arrangement 120 such as this is illustrated in FIGS. 9 and 10, with the switching parts 101 aa-101 dd likewise being mirrored in this case. 2m+n or m+2n, in this case twelve, electrical drive connections 123 a to 123 d, 124 a to 124 d and 125 a to 125 d are provided for driving the radiation guide switches 100 aa to 100 dd, which are arranged like a matrix.
Sixteen radiation guide switches 100 are applied to the switch chip 127, in an analogous manner to those illustrated in FIGS. 3a and 3 b. In order to avoid overloading in FIG. 9, only the contact surfaces 111 to 114 of the individual radiation guide switches 100 a a to 100 dd, as well as the holder 103 with the mirrored switching part 101, are illustrated. Furthermore, the switch chip 127 has in each case four aligning channels 131 for introduction of the �incoming� and �outgoing� radiation guides 121 a to 121 d and 122 a to 122 d. In order to provide the electrical drive for the radiation guide switches 100 aa to 100 dd, the switch chip 127 has, on a face which is free of aligning channels, four bonding pad pairs 123 a/124 a to 123 d/124 d and, on the side which is free of other aligning channels, four bonding pads 125 a to 125 d. Wires are bonded to these pads, and lead to the houding.
In order, by way of example, to introduce the second mirrored switching part 101 a b in the first row in FIG. 10 into the central space 5 in the free space section 135 a b between the waveguide subelements 133 a b and 134 a b, the voltage +V0 is applied to the connection 124 b, and the voltage −V0 is applied to the connection 125 a. There is now a voltage of 2V0 only on the radiation guide switch 100 ab, and this is able to switch the bistable suspension. Only the voltage V0 itself is present on the other radiation guide switches 100 aa, 100 ac and 100 ad in the first row and those switches 100 bb , 100 cb and 100 db in the second column, and this is not sufficient for them to switch. There is thus a �through connection� between the two radiation guides 121 a and 122 b. Furthermore, FIG. 9 also shows through connections for the guides 121 b and 122 c, for the guides 121 c and 122 a, as well as for the guides 121 d and 122 d. Analogously to the matrix-like arrangement of a number of radiation guide switches as described above, a number of attenuating units 160 a to 160 d may also be arranged together. The attenuating units 160 a to 160 d can now also be combined linearly to form a so-called array. Attenuating units 160 a to 160 d may also be arranged together with radiation guide switches on a chip. The production process can likewise be carried out by means of photolithography and an etching technique. The distance between the individual attenuating units should, however, correspond to the standard distance between the radiation guide switches described above.
In the case of fiber ribbons, a number of radiation guides are joined together and are adhesively bonded with a separation of 250 μm. There is thus likewise a distance of 125 μm between the individual fibers, which have a standard separation of 125 μm. This distance is sufficient for an �electrostatic motor� for movement of the switching part 152. This �electrostatic motor� is designed analogously to that of the radiation guide switches, as is illustrated in FIGS. 1, 3 a and 3 b. In order to connect this �electrostatic motor� electrically, appropriate wire bonding must be implemented. To do this, a second printed circuit board is arranged underneath the silicon substrate (for example underneath the silicon substrate 70), with this silicon substrate having bonding surfaces. The arrangement is now chosen such that the bonding wires in this case run in the space between the radiation guides.
The position of the relevant switching part 165 a to 165 d is now chosen such that optimum coupling is achieved for the two �switched� radiation guide ends in the switched state, and a coupling loss of at least 50 dB is achieved for the other radiation guide ends.
p=k�w2/2 u=F2+2F�G(sinθ)+(G2+�)sin2θ where θ is the tilt angle between the two guide ends. Since, however, mirrors 165 a and 165 d are interposed in the arrangement shown in FIG. 15, θ is an angle value without a reflection value (correction by double addition of the reflection angle of the relevant mirror).
2 If typical values are inserted in this formula, then this results in a coupling loss ┌ of more than 55 dB in a wavelength band from 1250 nm to 1630 nm, and with a tilt angle of 12�. This means that the core axis of the radiation guide ends into which radiation is no longer intended to be coupled should preferably be at a tilt angle θ of at least 12�.
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