EP2335104A1

EP2335104A1 - Compact multiplexer/demultiplexer

Info

Publication number: EP2335104A1
Application number: EP09783762A
Authority: EP
Inventors: Ingo Smaglinski; Thomas Petigk; Martin Popp; Samuel Brantzen; Thomas Paatzsch
Original assignee: Cube Optics AG
Current assignee: Huber and Suhner Cube Optics AG
Priority date: 2008-10-09
Filing date: 2009-10-06
Publication date: 2011-06-22
Also published as: WO2010040726A1; US20110222817A1; DE102008042716A1; US8532444B2

Abstract

The present invention relates to a multiplexer/demultiplexer having a connection for injecting and/or outputting an optical signal which has signal components of different wavelengths, a carrier plate (8) with at least one wavelength-sensitive element (11), a focusing member (13) with at least two focusing elements (14, 14'), and a detector or signal generator plate (1) on which at least two detectors (4) or signal generators are arranged. In order to achieve this, the invention proposes that the focusing member (13) has at least one fibre stop, which is preferably formed in one piece with the focusing member and is intended to adjust a waveguide, and is connected to the detector or signal generator plate (1) or to the carrier plate (8) via an elastic connecting element (23).

Description

Compact multiplexer / demultiplexer

The present invention relates to a compact multiplexer / demultiplexer.

The so-called multiplex method is a method for the common transmission of several independent signals (primary signals) over a single transmission medium. In a multiplexer, the various primary signals are combined into a single multiplex signal and transmitted. On the receiving side they are separated again in a demultiplexer. In the so-called frequency multiplexing method, each signal occupies a frequency band of a certain width. By modulating with staggered carrier frequencies, the base bands of several primary signals are shifted to higher frequency positions so that they come to lie next to each other on the frequency scale. This results in a frequency multiplexed signal which is then optionally amplified and transmitted. On the receiver side, the individual signals are usually separated again by means of frequency filters and brought by demodulation in the original frequency position.

For the transmission of signals on optical waveguides, the so-called wavelength division multiplexing method is generally used, which represents an optical frequency division multiplexing method. In the multiplex method, light signals of different frequency are used for the transmission. Each frequency used provides its own transmission channel, on which the actual data to be transmitted can be modulated (amplitude modulation). The data signals modulated in this way are then bundled by means of corresponding optical coupling elements and transmitted simultaneously but independently of one another. At the receiver of this optical multiplex connection in a demultiplexer then the individual optical transmission channels by means of corresponding wavelength-selective elements, for. B. passive optical filters, again separated and converted with corresponding detector elements into electrical signals.

Optical multiplexers and demultiplexers have long been known. In principle, a multiplexer can also be used as a demultiplexer by reversing the beam path and vice versa. In this case, only instead of detectors, which transmitted the received - -

convert optical signals into electrical signals, lasers which generate the corresponding optical signals to be transmitted are used.

In the following, the description explicitly refers to demultiplexers. It is understood, however, that the described features can be used with advantage also in multiplexers, in which case the beam direction is simply reversed.

Demultiplexers generally have an input terminal for coupling an optical signal having signal components of different wavelengths, at least one wavelength-sensitive element and at least two focusing elements, wherein the wavelength-sensitive element and the focusing elements are arranged such that at least a part of a via the input terminal coupled optical signal first on the wavelength-sensitive element and then on a focusing element and another part first on the wavelength-sensitive element and then encounters another focusing element. A wavelength-selective element is understood to be any element which, when placed in the beam path, influences one, several or even all wavelength channels. Influencing is understood as meaning, for example, reflection, absorption, amplification, attenuation, interruption or polarization.

By a focusing element is meant any element capable of concentrating incident parallel beams of light substantially at one point, the so-called focus or focus. As focusing elements, for example, optical lenses or concave mirrors can be used.

In the simplest case, the demultiplexer has only one wavelength-sensitive element and two focusing elements. An input signal consisting of two separate frequency components (frequency channels) is then directed to the wavelength-sensitive element which reflects one frequency component and transmits the other. The focusing elements are now arranged such that one receives the transmitted beam and the other receives the reflected beam and focuses in the respective focal point. If a suitable radiation detector, eg. As a photodiode arranged so the amplitude, ie, the radiation intensity of the frequency signal can be detected electrically. In general, however, a demultiplexer has a plurality of wavelength-sensitive elements, on which the signal is directed one after the other along the beam path, each wavelength-sensitive element having a wavelength channel of - -

the remaining signal is disconnected. The arrangement of several wavelength-sensitive elements is also called the filter cascade.

However, the production of demultiplexers is generally very expensive. This is u. a. at the necessary adjustment. The from a corresponding transmission medium, for. As a glass fiber, combined signal must be directed by means of a precisely adjusted arrangement of filters and mirrors to corresponding detector elements in order to effect an effective splitting of the signal into its individual channel components. In addition, known demultiplexers have comparatively large dimensions.

It is already known from EP 1 004 907 an optical wavelength demultiplexer of an optically transparent structure. The signal emerging from a glass fiber is guided inside the transparent material. In this case, the transparent structure is made in two parts, wherein between the two parts corresponding optical filters are arranged. Although this demultiplexer is already compact, it is only to manufacture under great manufacturing effort and must be adjusted consuming. For this reason, it has already been proposed in DE 10 2005 010 557 to arrange a shaped part having a plurality of focusing elements as well as a carrier plate having a plurality of wavelength-sensitive elements on a mounting plate. As a result, the adjustment effort of the focusing elements has been simplified relative to the carrier plate. In the embodiment described in DE 10 2005 010 557, however, the detectors must be adjusted very expensive.

It is therefore an object of the present invention to provide a demultiplexer or multiplexer having a terminal for coupling and / or decoupling an optical signal having signal components of different wavelengths, a carrier plate having at least one wavelength-sensitive element, a focusing member with at least two focusing elements and a detector or signal generator plate on which at least two detectors or signal generators are arranged to provide, which is easier to adjust and also shows a more compact compared to the prior art construction.

This is achieved according to the invention in that the focusing element has at least one fiber stop, preferably integrally formed with the focusing element, for the adjustment of a waveguide and is connected to the detector or signal generator plate or to the carrier plate via an elastic connecting element. - -

By this measure, the hitherto customary adjustment can be changed and thus simplified. In the first step, the fiber is placed on the fiber stop and fixed. As a result, the fiber is adjusted relative to the focusing.

Next, the carrier plate is placed on and aligned with the detector or signal generator plate. It should be noted that the two steps mentioned above can also be carried out in reverse order.

Only then is the focusing member actively aligned with the carrier plate and the detector and signal generator plate. In this case, a light signal can be coupled via the glass fiber, so that the beam path can be followed. The detectors can be used to detect whether the signal is correctly aligned with the detector surface. As soon as this is the case, the focusing member is connected via an elastic connecting element to the carrier plate or preferably to the detector or signal generator plate.

Although, as already stated, the present invention can equally be used for multiplexers and demultiplexers, in the following the invention will be described by means of a demultiplexer only. It is understood, however, that in principle, a multiplexer could be designed accordingly, with only the signal direction reversed and the detectors by signal generators, such as. As LEDs or VCSEL laser must be replaced.

In a preferred embodiment, the detectors of the detector plate are arranged on the side facing the focusing member of the detector plate, preferably between the focusing and the detector plate, a gap is formed and the detectors are at least partially arranged in the gap. This embodiment has the advantage that the light beam leaving the focussing elements does not have to pass through the detector plate, but can be directed directly at the detector elements. The gap between the focusing member on the one hand and the detector plate on the other hand, for example, can be realized by spacer elements which are arranged between the focusing and detector plate, so that between two spacers forms a gap, in turn, the detectors can be arranged. Of course, the spacer elements may be integrally formed either with the focusing member and / or with the detector plate.

In a further preferred embodiment, the focusing element and the element connected to the focusing element via the connecting element, ie detector plate or carrier plate, are made of different materials, so that at the typical operating temperatures - -

tures, such as Example, at a temperature of 25 ° C, the material from which the focusing member is made, a greater coefficient of expansion than the material from which the element connected via the connecting element with the focusing element is made.

In a preferred embodiment, the focusing member is connected to the detector plate. Therefore, the connection element and its advantages with respect to the connection of the focusing element with the detector plate will be described below. It is understood, however, that the focusing member could instead also be connected to the carrier plate.

Thus, it is possible, for example, to produce the focusing element as a molded part made of plastic, wherein the focusing elements can be integrally formed as curved reflecting surfaces, as described in DE 10 2005 010 557, the content of which is hereby incorporated into this application.

The detector plate may instead be made of a material having a significantly lower coefficient of expansion, such. B. Kovar or a ceramic. By Kovar is meant alloys that have a very low coefficient of thermal expansion, typically less than 10 ppm / K. Since the detector plate receives the detectors, corresponding electrical connections must be passed through the detector plate. In order to achieve a high overall tightness, for example, metal glass feedthroughs can be used. However, these can only be realized with materials having a very low coefficient of expansion. The use of different materials therefore allows the cost-effective and simple production of the focusing element as a molding made of plastic and at the same time vacuum-tight electronic feedthroughs through the detector plate.

Due to the different coefficients of expansion of the detector plate on the one hand and the focusing element on the other hand, however, in extreme temperature situations a de-adjustment of the demultiplexer may occur.

Therefore, in a preferred embodiment, it is provided that the connecting element has two spring elements, each in two mutually perpendicular directions each have at least twice as large spring constants as in the third, perpendicular to the two first spatial directions spatial direction, the so-called elasticity direction, the two Spring elements have elasticity directions that are not parallel to each other. In principle, connecting elements can be used, as they are for example in the - -

DE 10 2005 040 731 are described and shown, the contents of which are hereby incorporated into this application.

By using the connecting elements described it is achieved that at least the angular accuracy remains relatively high for larger temperature changes. In this case, each spring element serves on the one hand to allow the movement of the first component relative to the second component, in particular with a change in temperature in one direction, the so-called elasticity direction to a limited extent, while a corresponding relative movement in the other to this extent possible in approximately perpendicular directions prevented becomes. In this case, in a preferred embodiment, the elasticity direction runs essentially parallel to the surfaces of the focusing element and the detector plate which are to be aligned with one another.

In a further preferred embodiment, the focusing member is formed as a molded part, wherein preferably the focusing elements are formed integrally with the molded part and consist of curved reflecting surfaces. The curved reflecting surfaces may for example be formed as described in DE 100 43 985, which is incorporated herein by reference. The molding can in principle be designed as described in DE 10 2005 010 557, the content of which is hereby incorporated into this application.

In a further preferred embodiment, the fiber stop can be realized, for example, by a flat surface on which the focal point of the curved surface lies. As a result, the glass fiber must be placed only on the flat surface to facilitate an exact adjustment of the glass fiber in one direction. Embodiments in which the stop permits an adjustment at least in two directions or, particularly preferably, even in three directions, are preferred.

In a further preferred embodiment, the carrier plate has two surfaces arranged parallel to one another, wherein a reflective element is arranged on one surface and the at least one wave-modifying element is arranged on the other surface. By using a support plate with two mutually parallel surfaces ensures that reflective element on the one hand and wave-modifying elements on the other hand are arranged exactly to each other. The reflective element may be, for example, a mirror element. - -

In a further preferred embodiment, it is provided that the at least two detectors of the detector plate lie on a line which runs parallel to the parallel surfaces of the carrier plate. This allows a simple adjustment of the carrier plate relative to the detector plate, so that an optical adjustment in such a way that the parallel surfaces and the detector line run parallel, is easy to implement.

In a further preferred embodiment it is provided that the detector plate and / or the support plate has at least one spacer element, wherein the at least one spacer element is arranged such that a gap between the detector plate and carrier plate is formed, preferably arranged electrical terminals of the detectors within the gap are. Of course, the spacer can be integrally attached to the detector plate and / or the carrier plate. The arrangement of the electrical connections in the gap, the multiplexer / demultiplexer element can be made more compact.

The carrier plate may have passage openings which are provided for the signal beam, so that the carrier plate does not insert any material into the beam path. If curved reflective surfaces are used as focusing elements, the entire demultiplexer / multiplexer, apart from the unavoidable bandpass filters, can do without any material in the beam path. As a result, a high signal yield can be achieved.

Further advantages, features and applications of the present invention will become apparent from the following description of a preferred embodiment and the accompanying drawings. Show it:

1 a detector plate,

2 is a perspective view of a carrier plate,

3 is another perspective view of the carrier plate of Fig. 2,

4 is a perspective view of a focusing,

5 shows a perspective view of a focusing element with glass fiber, FIG. 6 shows a perspective view of a connecting element, FIG. 7 shows an exploded view of the demultiplexer,

9 shows a perspective view of the detector plate with attached carrier plate, FIG. 10 shows a perspective view of the detector plate with attached carrier plate and focusing element, FIG.

11 is another perspective view as in Fig. 10, - -

FIG. 12 shows a perspective view with the course of radiation drawn in, and FIG. 13 shows a perspective view similar to the view of FIG. 12.

1 shows a detector plate 1 is shown. The detector plate 1 has a base plate 2 made of nickel-plated Kovar. On the base plate 2, four detectors 4 are arranged with corresponding signal processing elements 3.

The base plate 2 has a series of fused in glass electrical feedthroughs 5, via which the detectors can be contacted electrically from the back of the base plate 2. For ease of illustration, the connecting wires have not been shown.

The detector plate 1 has a series of spacer elements 6, 7, the meaning of which will be described later.

In Fig. 2 and Fig. 3, two perspective views of a support plate 8 are shown. The support plate 8 has two mutually parallel surfaces 9, 9 '. On one surface 9 ', a mirror element 10 is arranged, while on the opposite surface 9 a plurality of wave-modifying elements 1 1 are arranged. As wave-modifying elements, band filters are used, each of which transmits a certain wavelength channel, while all other wavelength channels are reflected. The support plate 8 is made of metal. In order to ensure passage of the light rays from the wave-modifying elements to the reflecting element 10 and back, corresponding holes 12 are made in the support plate 8.

4, a focusing member 13 is shown. The focusing element has a number of focusing elements 14, 14 '. The focusing elements 14, 14 'are curved reflecting surfaces which are curved so as to focus a parallel beam of light at a point, the so-called focal point or focal point. The focusing member 13 is formed as a molded part, d. H. the focusing member and the focusing elements 14, 14 'are integral. Furthermore, two stop surfaces 15, 15 'are provided. To adjust a glass fiber 16 (see Fig. 5), the glass fiber 16 is placed on the two fiber stops 15 and 15 '.

The divergent light beam emerging from the glass fiber end lies in the focal point of the focusing element 14 '. Focusing element 14 'converts the divergent light beam into a parallel beam of light and then becomes more detailed as will be discussed below - -

directed and reflected on the reflection element 10 and then directed to a further focusing element 14. In the light path, a first wavelength-sensitive element 11 is arranged, which ensures that only one wavelength channel strikes the focusing element 14. The focusing element 14 converts the parallel light beam into a focused beam, the detectors 4 being arranged in the focus of the focusing elements 14.

In Fig. 6, a connecting element is shown, which is provided for the connection of the focusing element 13 with the detector plate 1. The connecting element consists of a web 21 and four extending therefrom spring elements 17, 18, 19, 20, each having a contact portion and an adjoining portion with respect to the contact portion of reduced thickness. The web 21 has bends and a shutter bending mechanism, so that the connecting element can be made in one piece.

In Fig. 7 is an exploded view of the demultiplexer is shown. The detector plate 1 is applied to a connection tongue 22, via which the electrical contacting of the detector elements takes place. Evident are also the support plate 8 and the focusing member 13th

FIG. 8 shows a perspective view of the detector plate 1 with the focusing element 13 attached. The focusing element 13 is connected to the detector plate 1 via the connecting element 23. The focusing member 13 is contacted at each of the four peripheral edge surfaces with one of the spring elements of the connecting element 23. The connecting element 23 is in contact with the web 21 on the spacer surfaces 6. By the pads 6, which are integrally formed with the detector plate 1, it is ensured that there is a gap between the focusing elements of the focusing member 13 and the detector plate 1, in which the detectors 4 are arranged. In other words, the detectors 4 are located between the detector plate 1 and the focusing element 13.

In Fig. 9 is a perspective view of a detector plate 1 with attached support plate 8 is shown. In contrast to the previous embodiments, the detector plate 1 on Abstandsflächen 7, which serve for receiving the support plate 8. Instead, the support plate 8 integrally formed spacers 24, with which the support plate 8 is seated on the detector plate 1, so that a gap between the support plate 8 and detector plate 1 forms, can be arranged in the electrical connections, which allows the detector element smaller to design. - -

In Fig. 10, finally, a perspective view is shown in which both the support plate 8 and the focusing member 13 are applied to the detector plate 1. A similar view from another perspective can be seen in FIG. In a particularly preferred embodiment, a cap (not shown) is placed over the carrier plate 8 and the focusing member 13 so that the cap with the detector plate 1 forms a closed space, which is evacuated in a preferred embodiment or filled with a protective gas. Advantageously, therefore, the closed space is sealed vacuum-tight.

FIGS. 12 and 13 show perspective views of a detector plate 1 with an attached focusing element 13, the beam path being shown schematically here. Parallel rays are represented as cylinders, while divergent rays are represented as cones.

It can be seen that light emerges divergently from the glass fiber 10, striking a first curved reflecting surface, which converts the divergent light into a parallel light beam shown as a cylinder. This light beam now passes through the hole made in the carrier plate (the carrier plate is not shown in this drawing) and strikes the mirror element 10, which directs the light beam onto the first wavelength-modifying element. There, only one wavelength channel is transmitted, while all other wavelength channels are reflected back by the mirror element 10. The transmitted wavelength channel now encounters a focusing element and is focused on the detector surface. The element reflected by the wavelength-modifying element is reflected again at the mirror element 10 and then impinges on the second wavelength-modifying element. Again, only one wavelength channel will be able to pass, while all other wavelength channels will be reflected. As a result, in each case one wavelength channel is imaged on a respective detector 4.

The described demultiplexer is extremely compact and can be easily adjusted. In the first step, the support plate 8 is placed with applied mirror element 10 and wave-modifying elements 1 1 on the detector plate 1 and aligned so that the parallel surfaces are parallel to the detector line. The support plate 8 is then fixed on the detector plate 1, z. B. glued.

In the next step, the fiber 10 is fixed to the focusing member 13 by means of the fiber stops and the focusing member 13 is connected to the connecting member in such a way that in each case a wavelength channel is imaged onto a detector surface. - -

LIST OF REFERENCES

1 detector plate

2 base plate

3 signal processing element

4 detector

5 electrical implementation

6, 7 spacer element

8 support plate

9, 9 'mutually parallel surfaces

10 mirror element

1 1 wave-modifying element

12 hole

13 focusing element

14, 14 'focusing elements

15, 15 'stop surfaces

16 fiberglass

17, 18, 19, 20 spring elements

21 footbridge

22 connection tongue

23 connecting element

24 spacer element

Claims

- P atentanspr che

1. Multiplexer / demultiplexer with a connection for the coupling and / or decoupling of an optical signal having signal components of different wavelengths, a support plate (8) with at least one wavelength-sensitive element (11), a focusing element (13) with at least two focusing elements ( 14, 14 ') and a detector or signal generator plate (1) on which at least two detectors (4) or signal generators are arranged, characterized in that the focusing member (13) at least one preferably integrally formed with the focusing fiber stop for the adjustment of a Waveguide and with the detector or

Signal generator plate (1) or with the support plate (8) via an elastic connecting element (23) is connected.

2. multiplexer / demultiplexer according to claim 1, characterized in that the connecting element (23) comprises two spring elements (17, 18, 19, 20), each in two mutually perpendicular directions each at least twice as large spring constants as in the third , Space direction perpendicular to the two first spatial directions, the so-called elasticity direction, wherein the two spring elements have elasticity directions which are not parallel to each other.

3. Multiplexer / demultiplexer according to one of claims 1 to 2, characterized in that the focusing member (13) and connected to the focusing member via the connecting element element, detector or signal generator plate (1) or support plate (8) are made of different materials in that, at a temperature of 25 ° C, the material from which the focusing member (13) is made has a greater coefficient of expansion than the material from which the member connected to the focusing member via the connecting member is made.

4. Multiplexer / demultiplexer according to one of claims 1 to 3, characterized in that the detectors (4) of the detector or signal generator plate (1) on the focusing member (13) facing side of the detector or signal generator plate (1) are arranged, wherein preferably between the focusing member and the detector or signal generator plate, a gap is formed and the detectors are at least partially disposed in the gap. - -

5. Multiplexer / demultiplexer according to one of claims 1 to 4, characterized in that the focusing member (13) is formed as a molded part, wherein preferably the focusing sierende elements are integrally formed with the molding and consist of curved reflective surfaces.

6. multiplexer / demultiplexer according to one of claims 1 to 5, characterized in that the fiber stop is formed such that it is the passive adjustment of the waveguide with respect to the focusing member (13) in two, preferably in three, substantially mutually perpendicular directions allowed.

7. Multiplexer / demultiplexer according to one of claims 1 to 6, characterized in that the focusing member is connected via the connecting element with the detector or signal generator plate.

8. Multiplexer / demultiplexer according to one of claims 1 to 7, characterized in that the carrier plate (8) has two mutually parallel surfaces (9, 9 '), wherein on one surface a reflective element (10) and on the other Surface, the at least one wave-modifying element (1 1) is arranged.

9. Multiplexer / demultiplexer according to claim 8, characterized in that the at least two detectors (4) of the detector or signal generator plate (1) lie on a line which runs parallel to the parallel surfaces of the carrier plate (8).

10. Multiplexer / demultiplexer according to claim 8, characterized in that the at least two detectors (4) of the detector or signal generator plate (1) lie in a line which enclose an angle with the parallel surfaces of the carrier plate (8) is selected such that the signal coupled in via the terminal is aligned by the at least one reflecting element (10) perpendicular to the connecting line of the detectors.

1 1. Multiplexer / demultiplexer according to one of claims 1 to 10, characterized in that the detector or signal generator plate (1) and / or the carrier plate (8) at least one spacer element (6, 7), wherein the at least one spacer element ( 6, 7) is arranged such that a gap between the detector or signal generator plate (1) and support plate (8) is formed, wherein preferably electrical connections of

Detectors are arranged within the gap.