EP4147084A1

EP4147084A1 - Apparatus for coupling light into an optical fiber

Info

Publication number: EP4147084A1
Application number: EP21723099.4A
Authority: EP
Inventors: Simone Luca PORTALUPI; Peter Michler; Michael Jetter; Norbert WITZ; Andrea Cusano; Antonello Cutolo; Alberto MICCO; Armando RICCIARDI
Original assignee: Universitaet Stuttgart; Universita Degli Studi Del Sannio Di Benevento
Current assignee: Universitaet Stuttgart; Universita Degli Studi Del Sannio Di Benevento
Priority date: 2020-05-08
Filing date: 2021-05-10
Publication date: 2023-03-15
Also published as: WO2021224504A1; IT202000010336A1

Abstract

The present invention is directed to arrangement for coupling and/or receiving light into/from an optical fiber core and to method of manufacturing said arrangement. The arrangement comprises an optical fiber having at least one optical fiber core, an optical fiber coating (22) at one end of the optical fiber partially and/or completely overlapping the fiber end and having a central opening at its end facet exposing the fiber core, the optical fiber coating (22) consisting of an electrically conductive material or is covered with an electrically conductive material, and an opto-electronic device (20) at the facet of the optical fiber coating (22) for coupling and/or receiving light into/from the fiber core and the opto-electronic device (20) being coupled to the optical fiber coating (22) and covers the central opening of the optical fiber coating. According to the invention the opto-electronic device (20) is directly and electrically coupled to the end facet of the optical fiber coating (22).

Description

APPARATUS FOR COUPLING LIGHT INTO AN OPTICAL FIBER

Field of the Invention

The present invention concerns an arrangement comprising an optical fiber having at least one fiber core, an optical fiber coating at one end of the optical fiber partially and/or completely overlapping the fiber end and having a central opening at its end facet exposing the fiber core, the optical fiber coating (22) consisting of an electrically conductive material or is covered with an electrically conductive material, an opto electronic device at the facet of the optical fiber coating for coupling and/or receiving light into/from the fiber core, the opto-electronic device (20) being coupled to the optical fiber coating (22) and covers the central opening of the optical fiber coating.

Background

Opto-electronic devices as presently defined are devices for emitting light and/or for receiving light. The opto-electronic devices for emitting light comprise light sources as for instance, without being limited thereto, light emitting diodes (LED), resonant cavity LED (RCLED), vertical cavity surface emitting lasers (VCSEL), compact electrically driven laser diodes, VCSEL arrays and light emitting arrays. Opto electronic devices for receiving light comprise, without being limited thereto, light detectors as for instance photodiodes, single photon detectors, avalanche photo diodes (APD) or single photon counting modules (SPCM). Other devices, that can emit light and receive light, can combine such technologies or comprise devices based on quantum-physical systems.

These opto-electronic devices allow to connect an electronic or electrical device, as for instance a semiconductor component to an optical fiber girded at its ends by an optical fiber coating such as a ferrule having a central opening for passing light into or out from the optical fiber and / or such as the layers around the core and cladding of the optical fiber, which can have different functions as for example increased mechanical stability or chemical or mechanical protection of the optical fiber. Numerous applications in the field of optical data transmission and optical sensor technology require an efficient coupling and/or receiving of light into and/or from optical fibers, including hollow core fibers and fiber bundles. Due to the small diameter of the standard single mode optical fiber core (around 8 pm for single mode SM fibers and > 100 pm for multi-mode MM fibers), the precise alignment and optical coupling of opto-electronic devices and optical fibers poses a technical challenge. In particular, compact and robust solutions, where the opto-electronic devices are integrated directly on the fiber ends, offer the decisive advantage that they can be used outside a laboratory in harsh environmental conditions. Also, the compact and reliable electrical connection of the electro-optical device poses a technical challenge.

Numerous applications in the field of optical data transmission and optical sensor technology require the efficient coupling of light into optical fibers or the efficient coupling out of light from optical fibers. Due to the small diameter of the standard optical fiber core (around 8 pm for SM fibers and > 100 pm for MM fibers), the precise alignment of light source (such as diode lasers or LEDs) or light detector and optical fiber is a technical challenge.

Prior art arrangement comprising an opto-electronic device for coupling light into an optical fiber and depicted in Fig. 1-4 are hereafter explained. Two miniaturized versions of a prior art arrangement comprising an optical fiber opto-electronic device for coupling light into the optical fiber are shown in Figs. 1 and 2 as well as in Figs. 3 and 4. Fig. 1 shows the first version of the arrangement in the form of a pigtailed butterfly package including a component tray 8 covered by a lid.

Fig. 2 shows the device of Fig. 1 with the lid removed from the component tray 8. As shown in Fig. 2 the component tray 8 is taking up a laser chip 1 on a chip carrier, a monitor photodiode 2, a thermistor 3, a thermoelectric cooler 5, a lens 6, an optical isolator 7, a light output window 9, a fiber pigtail 10 and electrical leads 11.

In this design the light source is adjacent to one end of the optical fiber providing a distance there between. The total size of the arrangement of Fig. 1 and 2 can be limited to a few centimeters due to its butterfly package. Due to its relative complexity, this arrangement however is not sufficiently robust and relatively complex to manufacture. The arrangement of Fig. 3 and 4, realized in the form of the TO Can Package (Transistor Outline Can Package), comprises an opto-electronic device for coupling light into an optical fiber. This TO-can package is intended for datacom applications and comprises a VCSEL 12, a sub-mount 13, a flat window cap 14, a plastic barrel 15, a (plastic) lens 16, barrel for connection to a fiber ferrule 17 and electrical feedthroughs 18.

Due to the TO Can Package having a diameter of only 5.1 mm at the widest point of the case of a TO-46 housing, this arrangement takes up considerably less space than the Butterfly Package version described above. However, even this type of packaging is not compact enough to ensure the scalability of the light source-fiber pairs. Due to the simple plug-in connection, the coupling efficiencies of this system are relatively small.

The biggest disadvantage of the above two known arrangements shown in Figs. 1 to 4 including an electro-optical device for coupling light into an optical fiber, however, is their high sensitivity to temperature fluctuations and vibrations and the associated reduction in coupling efficiency. This prevents the use of these arrangements under adverse external conditions, such as in the engine compartment of motor vehicles or sensors in industrial plants or in application of optical fiber sensors used in the life science field. 3D printed connectors used in research offer very high coupling efficiency due to the precise alignment of fiber and light emitter, but are very complicated to manufacture and not very stable. Above all, however, both prior art arrangements are hardly if not at all suitable for use as the active element of a robust, portable sensor, which can be used for measuring the smallest quantities of substances, for example for detecting chemical and biological compounds under harsh outdoor conditions.

The US 6263 002 B1 discloses an arrangement of the kind defined by the precharacterizing clause of claim 1. Fig. 1A-1E of this document shows a coupling of the opto-electronic device to the optical fiber coating embodied as an electrically conductive ferrule which coupling is of indirect nature via a mirror on the facet of the optical fiber, which mirror is disposed between said device and the ferrule. The US 2011/194820 A1 discloses an arrangement comprising an optical fiber having at least one fiber core, an optical fiber coating at one end of the optical fiber embodied as electrically isolating ferrule, and an opto-electronic device at the facet of ferrule for coupling and/or receiving light into/from the fiber core.

Summary

An object of the invention is therefore to provide an arrangement of the kind defined by the pre-characterizing features of claim 1 that is not affected by the above- mentioned disadvantages of the prior art and, above all, is insensitive to changes in environmental conditions and has the smallest possible footprint.

A further object of the invention is to provide an arrangement of the kind defined by the pre-characterizing features of claim 1 that suitable for use as the active element of a robust, portable sensor, which can be used for measuring the smallest quantities of substances, for example for detecting chemical and biological compounds under harsh outdoor conditions.

A still further object of the invention is to provide a cost-effective method for manufacturing an arrangement of the invention.

These objects are solved with regard to the arrangements by the features of claim 1 and with regard to the method by the features of claim 8. Advantageous developments of the invention are defined by in the respective sub claims.

The invention thus provides an arrangement of the kind defined by the precharacterizing clause of claim 1 , characterized in that the opto-electronic device is directly and electrically coupled to the end facet of the optical fiber coating.

The optical fiber core is the region that runs along the fiber's length in which the light is guided. The fiber core is typically made of glass or plastic but it can be also made of liquid or air in the case of specialty fibers such as the micro-structured fibers.

Since the opto-electronic device is coupled to the optical fiber coating for coupling light into and/or receiving light from the fiber core via the central opening of the fiber coating the arrangement of the invention is not affected by the above-mentioned disadvantages of the prior art and, above all, is insensitive to changes in environmental conditions and has the smallest possible footprint. Further, the electrical connections are realizable in a very compact and robust manner. Further, the coupling of the opto-electronic device to the optical fiber coating providing for a direct stable arrangement or at least a very close arrangement with respect to one another in a stable manner, for instance gluing or another bonding technology, in accordance with the invention allows the arrangement of the invention to be suitable for use as the active element of a robust, portable sensor, which can be used for measuring the smallest quantities of substances, for example for detecting pollutants under harsh outdoor conditions.

For facilitating the mounting of the opto-electronic device to the optical fiber coating and to make the mounting as precise as possible, advantageously one or more alignment markers are provided to the end facet of the optical fiber coating as orientation guide for the attachment of the opto-electronic device. Doing so it is advantageous to make one of the markings corresponding to the outline of the opto electronic device.

In order to provide for a stable and relatively easy to realize connection of the opto electronic device to the optical fiber coating, the opto-electronic device advantageously is coupled to the end facet of the optical fiber coating by means of an electrically conductive adhesive. The electrically conductive adhesive preferably is a transparent, refractive index-adapted adhesive.

To enhance the light transfer from the fiber to the opto-electronic device, the opto electronic device (20) advantageously is coupled to the fiber core by means of a refractive index-adapted material.

Advantageously the opto-electronic device is integrally coupled with the facet of the optical fiber coating, as for instance an electrically conductive coating (22) and / or the metallized layers around the core and cladding of the optical fiber, preferably monolithically.

The monolithic integration of the opto-electronic device with the optical fiber coating and the resulting stability of the connection allows to use the device to couple light between an optical fiber and the opto-electronic device, also under harsh conditions. Furthermore, the compact design resulting from this connection allows reliably coupling of arrays consisting of several optical fibers or opto-electronic devices.

The optical fiber coating, which consists either of an electrically conductive material or of an electrically insulating or poorly conducting material covered with an electrically conductive layer so that the optical fiber coating is in direct electric contact with the opto-electronic device. The opto-electronic device is connected to some kind of power supply and electronics or electrics, which is in contact with the optical fiber coating to close the electrical circuit.

The opto-electronic devices have beam angles that do not necessarily match the radiation angle (numerical aperture) of the optical fiber. In this case, additional optical components, as for example lenses, are required in front of the opto-electronic device. In the inventive concept, these components must either be integrated into the tip of the optical fiber in front of the opto-electronic device or integrated into the structure of the opto-electronic device.

Additionally, between the opto-electronic device and the optical fiber it is possible to put metallic and/or dielectric nanostructures such as metalenses, dielectric stacks such as distributed Bragg reflectors, and/or optical cavities such as Fabry-Perot cavities.

Furthermore, the invention provides for a method of manufacturing the arrangement of the invention as defined above, comprising the steps: a) positioning the opto-electronic device at the optical fiber coating in front of the opening of the optical fiber coating, and b) fixing the positioned opto-electronic device on the optical fiber coating by means of an electrically conductive adhesive, preferably with a conductive epoxy, or fixing it with any other method, that is enabling an electrical contact, preferably by gold bonding, Indium bonding, or silver conductive paste or soldering or sintering, c) attaching the optical fiber coating to the fiber end before step a) or after step b). Advantageously the method comprises the following preparatory steps before step a): d) in the case of isolating or poorly conductive optical fiber coating, depositing a conductive layer to the optical fiber coating, possibly also covering its opening e) in case of covering its opening removing the layer from the opening of the optical fiber coating.

It is further of advantage to conduct the following preparatory steps before step a): f) depositing a thin adhesion promoting film on the non-conducting or the poorly conductive optical fiber coating, , possibly also covering its opening, g) depositing a conductive layer on the adhesion promoting film on the optical fiber coating, possibly also covering its opening, h) in case of covering its opening, removing the conductive layer and/or the adhesion promoting film from the opening of the optical fiber coating.

According to a preferred embodiment, the thin adhesion promoting layer consists of a titanium layer deposited using an electron beam evaporator (EBPVD) and the electrically conducting layer consists of a gold layer; more preferably the non conducting optical fiber coating is made of ceramic material such as a ferrule, the titanium layer is about 10 nm thick and the gold layer is about 150 nm thick.

To promote the mounting of the optoelectronic device to the optical fiber coating i) the one or more alignment markers (23) are written to the end face of the optical fiber coating (22) as orientation guide for the attachment of the opto-electronic device (20), in particular a marking (23) corresponding to the outline of the opto-electronic device (20) before step a), or before step a) and d), or before step a) and after step d), or before step a) and after step e).

Alternatively, i) one or more alignment markers (23) are written to the end facet of the optical fiber coating (22) as orientation guide for the attachment of the opto-electronic device (20), in particular a marking (23) corresponding to the outline of the opto-electronic device

(20) before step a), or before step a) and f), or before step a) and after step f), or before step a) and after step g), or before step a) and after step h).

The laser used for realizing the alignment markers preferably is a pulsed UV dye laser, more preferably the laser is a KrF laser, and even more preferably with a laser light wavelength of 248 nm.

In a particularly advantageous embodiment of the method according to the invention the following preparatory step before step a) is provided: k) putting onto the fibre core and/or into the opening of the optical fiber coating a transparent material, adapted with respect to the refractive index of the optical fiber core material and the refractive index of the opto-electronic device material such that the refractive index of the transparent material lies between the refractive index of the optical fiber core material and the refractive index of the opto-electronic device material, this transparent refractive index matching material can be the electrically conductive adhesive.

Alternatively, the following preparatory step after depositing the conductive layer and in case of covering its opening, successive removing the layer and/or film is provided: k) putting onto the fiber core and/or into the opening of the optical fiber coating a transparent material, adapted with respect to the refractive index of the optical fiber core material and the refractive index of the opto-electronic device material such that the refractive index of the transparent material lies between the refractive index of the optical fiber core material and the refractive index of the opto-electronic device material, this transparent refractive index matching material can be the electrically conductive adhesive.

The method of the invention, further advantageously comprises the following preparatory steps before step a) and d) and f): a photoresist layer is put onto the facet of the optical fiber coating and the optical fiber core and optical fiber cladding, preferably by spin coating, in the area of the optical fiber core and cladding, and in addition also in other areas, the photoresist will be cured by exposing it to light, in the next step developer is applied to remove the not exposed photoresist, In step e) or h) the removing is made by a lift off process.

Brief Description of the Drawings

Further details and advantages of the invention will now be explained in more detail by means of an example shown in the drawings. Fig. 1 shows a schematic view of a first version of a prior art arrangement comprising an opto-electronic device for coupling light into an optical fiber,

Fig. 2 shows a view of the inside structure of the arrangement of Fig. 1 ,

Fig. 3 shows a schematic view of a second version of a prior art arrangement comprising an opto-electronic device for coupling light into an optical fiber, Fig. 4 shows a view of the inside structure of the arrangement of Fig.3,

Fig. 5a-c show in the form of top view, three steps to prepare the inventive method for preparing the inventive device for coupling light into an optical fiber or into an opto-electronic device,

Fig. 6b/6c show schematically a variant of the second and third steps of Fig. 5a-c.

Fig. 1-4 are explained at the introduction with respect to the prior art.

In contrast to the prior art devices described in the introduction, the inventive arrangement comprising the opto-electronic device for coupling light into an optical fiber or from the optical fiber into a opto-electronic device does not provide for any unwanted distance between the opto-electronic device and the core of the fiber, at least not more than a distance between the opto-electronic-device and the thickness of the optical fiber coating adjacent of the opening of the optical fiber coating plus the coupling means, as for instance a glue for coupling the opto-electronic device to the optical fiber coating, as shown in Fig. 5c and Fig. 6c.

Fig. 5c and Fig. 6c each show the end 21 of an optical fiber coating 22 embedding and surrounding, respectively one end of a not-shown optical fiber (having a cladding and a core) and equipped with an opto-electronic device 20. The conductive or metalized optical fiber coating 22 serves as one of the electrical connections of the opto-electronic device 20. The second electrical connection of the opto-electronic device can be of any kind, preferably the opto-electronic device is connected via the second electrical connection to a printed circuit board (PCB) not shown in Fig. 5 and 6. The opto-electronic device 20 of the Figs. 5c and 6c versions of the device as found has a general shape. The optical fiber coating 22 has a cylindrical body surrounding the fiber and having a central opening exposing at least the core and cladding of the fiber. In Fig. 5 and Fig. 6 the optical fiber coating is chamfered at the rim of its circular cover.

In order to produce the device for coupling light into an optical fiber, the opto electronic device 20 is first positioned in front of the facet of the optical fiber coating in the area of its opening above the fiber core as shown in Fig. 6b according to a manual production variant. To ensure a correct positioning of the opto-electronic device 20, the facet of the optical fiber coating 22 may be provided in advance with alignment markers 23. In Fig. 6b, these markers 23 are precisely overlapped to the outline of the connecting side of the opto-electronic device 20. In Fig. 5b, the corners of the connecting side of the opto-electronic device are marked on the facet of the optical fiber coating. To fix the opto-electronic device on the marked area of the facet of the optical fiber coating end 21 , a transparent material is used whose refractive index is adapted to that of the fiber core or to the opto-electronic device material or in between both materials, and/or is used a conductive glue or bonding method.

In addition to such manual assembly of the opto-electronic device using a marker, industrial production can also be considered, for example using a pick & place machine that does not require markers to support assembly also the opto-electronic device could be positioned by a video-controlled process or any other suitable method.

On the basis of Fig. 5a-c, a variant of the manually guided manufacturing process is now explained in more detail, in which an electrically insulating optical fiber coating (for instance a ceramic ferrule) is used, which is made electrically conductive before the actual assembly of the opto-electronic device takes place. The optoelectronic device 20 preferably is integrated onto the facet of the optical fiber coating 22 in three manufacturing steps. First, an electron beam evaporator (EBPVD) is used to deposit a thin film as an adhesion-promoting agent, preferably consisting of a preferably 10 nm thick titanium layer, and an electrically conducting layer, preferably 150 nm thick gold layer, on the non-conducting optical fiber coating 22, preferably made of ceramic material. For this purpose, the fiber optical fiber coating 22 is tilted in an electron beam evaporator by 50° to 70°, preferably by 60° with respect to the evaporation direction in order to deposit both on the facet of the optical fiber coating and on a portion of its outer surface. Subsequently, both layers are removed by means of a laser, preferably a pulsed dye laser, more preferably a KrF laser with a light wavelength of 248 nm, over the fiber core and optionally a multi part alignment markers 23 are written on the facet of the optical fiber coating for later positioning of the opto-electronic device 20 (see Fig. 5a). A special plastic holder is used to fix the position and angle between the lithography writing laser beam and the top of the optical fiber coating. In the next step (Fig. 5b), the opto-electronic device 20 is aligned with a micromanipulator, the alignment markers 23 in the conductive layer being used, and fixed with an electrically conductive adhesive, preferably an electrically conductive, transparent, refractive index-adapted adhesive or fixing it with any other method, that is enabling an electrical contact, preferably by gold bonding, Indium bonding, or silver conductive paste or soldering or sintering, (final state: Fig. 5c). The refractive index-matching material is used to minimize optical losses, while an electrically conductive epoxy/bonding material being used to allow for electric contact. The advantage of the active alignment is that the opto-electronic device is precisely aligned on the optical fiber core simultaneously ensuring that these two elements (refractive index-matching material and conductive epoxy/bonding) are precisely placed and do not mix on the device surface nor on the facet of the optical fiber, obstructing the aperture corresponding to the optical fiber core.

As an alternative to the above manufacturing steps, a photoresist layer is put onto the facet of the optical fiber coating and the optical fiber core and cladding, for example by spin coating, in the area of the optical fiber core and cladding the photoresist will be cured by exposing it to light, this can be done from above the facet or preferably by coupling light to the distant other end of the optical fiber. In the next step developer is applied to remove the not exposed photoresist of the facet of the optical fiber coating. As next step, an adhesion-promoting agent can be deposited on the facet, for example an electron beam evaporator (EBPVD) is used to deposit a thin film as an adhesion-promoting agent, preferably consisting of a preferably 10 nm thick titanium layer, and an electrically conducting layer, preferably 150 nm thick gold layer, on the non-conducting optical fiber coating 22 over the adhesion-promoting agent. When the electrically conductive layer sticks to the coating the step of depositing an adhesive-promoting layer can by omitted. Subsequently the cured photoresist, the electrically conductive layer or the cured photoresist, the electrically conductive layer and the adhesive promoting layer are removed by a lift off process from the area of the optical fiber core.

The optical fiber can be put into the optical fiber coating so that the opening inside the end facet of the optical fiber coating is empty. In this case a transparent material, adapted with respect to the refractive index of the optical fiber core material and the refractive index of the opto-electronic device material such that the refractive index of the transparent material lies between the refractive index of the optical fiber core material and the refractive index of the opto-electronic device material, fills the opening and bridges the small gap between the optical fiber core and an opto electronic device. It is also possible to strip of the jacket of the optical fiber end; in this case the fiber core and cladding will intrude into the opening in the optical fiber coating end face. In this case the refractive index-matching material has not to fill the small opening.

As adhesive techniques can be used for example but not limiting conductive epoxy, gold bonding, soldering such as preform or paste, Indium bonding, Silver conductive paste or sintering. The optical fiber can be a light guiding structure as but not limited to single mode fibers, multimode fibers, multicore fibers, fiber bundles and fiber arrays. These techniques can be applied to one or multiple opto-electronic devices simultaneously on one or more optical fiber coatings. More than one light guiding structure can be placed in one optical fiber coating, which can have multiple openings corresponding to the light guiding structures.

The fiber end can be permanently fixed, reversibly fixed, or loose inside the optical fiber coating. Monolithic integration allows the component to be used in adverse environmental conditions.

List of reference signs

1 laser chip

2 photo diode 3 thermistor

4 chip carrier

5 thermoelectric cooler

6 lens

7 optical isolator 8 component tray

9 light output window

10 fiber pigtail

11 electrical leads

12 VCSEL 13 sub-mount

14 window cap

15 barrel

16 lens

17 barrel for connection to a fiber ferrule 18 electrical feedthroughs

19a Adhesive medium

19b Refractive index matching material

20 opto-electronic device

21 optical fiber coating end facet 22 optical fiber coating

23 alignment markers

Claims

1. An arrangement for coupling and/or receiving light into/from an optical fiber core, the arrangement comprising:

- an optical fiber having at least one optical fiber core,

- an optical fiber coating (22) at one end of the optical fiber partially and/or completely overlapping the fiber end and having a central opening at its end facet exposing the fiber core, the optical fiber coating (22) consisting of an electrically conductive material or is covered with an electrically conductive material, and

- an opto-electronic device (20) at the facet of the optical fiber coating (22) for coupling and/or receiving light into/from the fiber core, the opto-electronic device (20) being coupled to the optical fiber coating (22) and covers the central opening of the optical fiber coating, characterized in that the opto-electronic device (20) is directly and electrically coupled to the end facet of the optical fiber coating (22).

2. The arrangement according to claim 1 , wherein one or more alignment markers (23) are provided to the end facet of the optical fiber coating (22) as orientation guide for the attachment of the opto-electronic device (20).

3. The arrangement according to claim 2, wherein one of the markings (23) corresponds to the outline of the opto-electronic device (20).

4. The arrangement of one of claim 1 to 3, wherein the opto-electronic device (20) is coupled to the end facet of the optical fiber coating (22) by means of an electrically conductive adhesive.

5. The arrangement of one of claim 1 to 4, wherein the opto-electronic device (20) is coupled to the fiber core by means of a refractive index-adapted material.

6. The arrangement of claim 4, wherein the electrically conductive adhesive is a transparent, refractive index-adapted adhesive.

7. The arrangement according to claim 1 to 5, wherein the opto-electronic device (20) is integrally coupled to the optical fiber coating (22), preferably monolithically.

8. A method of manufacturing the arrangement according to any one of claims 1 to 7, comprising the steps: a) positioning the opto-electronic device (20) at the optical fiber coating (22) in front of the opening of the optical fiber coating, and b) fixing the positioned opto-electronic device (20) onto the facet of the optical fiber coating (22) by means of an electrically conductive adhesive, preferably with a conductive epoxy, or fixing it with any other method, that is enabling an electrical contact, preferably by gold bonding, Indium bonding, or silver conductive paste or soldering or sintering, c) attaching the optical fiber coating (22) to the fiber end (21 ) before step a) or after step a) or after step b).

9. The method according to claim 8, comprising the following preparatory steps before step a): d) in the case of isolating or poorly conductive optical fiber coating, depositing a conductive layer to the optical fiber coating (22), possibly also covering its opening e) in case of covering its opening removing the layer from the opening of the optical fiber coating (22).

10. The method according to claim 8, comprising the following preparatory steps before step a): f) depositing a thin adhesion promoting film on the non-conducting or the poorly conductive optical fiber coating (22), possibly also covering its opening, g) depositing a conductive layer to the adhesion promoting film on the optical fiber coating (22), possibly also covering its opening, h) in case of covering its opening removing the conductive layer and/or the adhesion promoting film from the opening of the optical fiber coating (22); preferably the thin adhesion promoting layer consists of a titanium layer deposited using an electron beam evaporator (EBPVD) and the electrically conducting layer consists of a gold layer; more preferably the non-conducting optical fiber coating (22) is made of ceramic material, the titanium layer is about 10 nm thick and the gold layer is about 150 nm thick.

11. The method according to claim 8 and 9, in which: i) the one or more alignment markers (23) are written to the end facet of the optical fiber coating (22) as orientation guide for the attachment of the opto-electronic device (20), in particular a marking (23) corresponding to the outline of the opto-electronic device (20) before step a), or before step a) and d), or before step a) and after step d), or before step a) and after step e).

12. The method according to claim 10, in which: i) the one or more alignment markers (23) are written to the end facet of the optical fiber coating (22) as orientation guide for the attachment of the opto-electronic device

(20), in particular a marking (23) corresponding to the outline of the opto-electronic device (20) before step a), or before step a) and f), or before step a) and after step f), or before step a) and after step g), or before step a) and after step h).

13. The method according to claim 11 and 12, in which the alignment marks (23) are written by a laser, preferably the laser being a pulsed UV dye laser; more preferably a KrF laser, even more preferably a KrF laser with a laser light wavelength of 248 nm.

14. The method according to claim 8, comprising the following preparatory step before step a): k) putting onto the optical fiber core and/or into the opening of the optical fiber coating a transparent material, adapted with respect to the refractive index of the optical fiber core material and the refractive index of the opto-electronic device material such that the refractive index of the transparent material lies between the refractive index of the optical fiber core material and the refractive index of the opto electronic device material, this transparent refractive index matching material can be the electrically conductive adhesive.

15. the method according to claim 9 or 10, comprising the following preparatory step after depositing the conductive layer and in case of covering its opening, successive removing the layer and/or film on the opening: k) putting onto the facet of the optical fiber coating and/or into the opening of the optical fiber coating a transparent material, adapted with respect to the refractive index of the optical fiber core material and the refractive index of the opto-electronic device material such that the refractive index of the transparent material lies between the refractive index of the optical fiber core material and the refractive index of the opto-electronic device material, this transparent refractive index matching material can be the electrically conductive adhesive.

16. The method according to claim 9 or 10 comprising the following preparatory steps before step a) and d) and f): a photoresist layer is put onto the facet of the optical fiber coating (22) and the optical fiber core and optical fiber cladding, preferably by spin coating, in the area of the optical fiber core and cladding, and in addition also in other areas, the photoresist will be cured by exposing it to light, in the next step developer is applied to remove the not exposed photoresist,

In step e) or h) the removing is made by a lift off process.