DE102012101058B3 - Method for manufacturing cohesive connection between optical glass fiber and glass brick, involves approaching glass fiber to glass brick, where approximate glass fiber and glass block are irradiated with laser light - Google Patents

Abstract

The method for manufacturing a cohesive connection between an optical glass fiber and a glass brick, involves approaching a glass fiber (1) to a glass brick (2). The approximate glass fiber and the glass block are irradiated with laser light. The material is vaporized outside of an optical splice position (6). The vaporized material is deposited due to temperature gradients. The optical fiber is fused with the glass brick by heating.

Description

The invention relates to a method for connecting a glass fiber with a glass brick.

By virtue of the "thermal splicing" described in the prior art, both single-mode and multimode glass fibers as well as glass fiber bundles can be connected to one another in a material-locking, low-damping and durable manner. Since splicing, as a frequently performed operation, has a considerable impact on the costs of laying and assembling an optical fiber cable, handy devices have been developed which can also be used under difficult conditions on site. These devices perform all the steps required to weld the optical fibers fully automatically. The attenuation of the splice connection produced with such a device depends, inter alia, on the exact alignment of the light-conducting fiber cores, the quality of the fiber end faces (roughness, break angle) and the welding parameters selected by the operator or specified by the respective program (welding time, welding current). For example, a too high or too low fiber temperature during welding can lead to a splice connection whose attenuation is above the desired limit of, for example, D <0.02 dB.

Fiber optic cables can also be spliced using a special arc splicer, with installation cables connected at their ends to respective "pigtails" - short single fibers with connectors at one end. The splicer precisely adjusts the light-guiding cores of the two ends of the glass fibers to be spliced. Adjustment is done fully automatically in devices described in the prior art, manually in older models by means of micrometer screws and microscope.

It is described in the prior art that fibers can be bonded to a glass block under the action of laser energy. The splicing of glass fibers leads to a deformation of the fiber due to the thermal action of heat, in particular laser action. Furthermore, a problem of "under-melting" of the fiber edges for larger fiber diameter, since z. B. there is a gap between the fiber and the glass brick.

The object of the invention is therefore to provide a method which does not have the disadvantages and shortcomings described.

The object is achieved by the claim 1. Advantageous embodiments will become apparent from the dependent claims.

• a. Annähern der Glasfaser an den Glasstein,
• b. Bestrahlen der angenäherten Glasfaser und des Glassteins mit Laserlicht,
• c. Verdampfen von Material außerhalb der Spleißstelle,
• d. Deposition des verdampften Materials aufgrund von Temperaturgradienten und
• e. Verschmelzung der Faser mit dem Stein durch Erwärmen.

Thus, there is provided a method of making a material bond between an optical fiber and a glass block by performing the following steps:

• a. Approximating the glass fiber to the glass stone,
• b. Irradiating the approximated glass fiber and the glass block with laser light,
• c. Vaporizing material outside the splice site,
• d. Deposition of the vaporized material due to temperature gradients and
• e. Fusion of the fiber with the stone by heating.

A glass fiber is brought to a glass block, preferably by means of an automatic device. The glass fiber, that is to say the area of the fiber facing the glass brick and the glass brick, are heated by the irradiation with laser light.

The generation of splices with existing devices with previous process control leads to the fact that the load and deformation of the fiber is too high due to the thermal effect of the laser power. In addition, undershoot of the fiber edges occurs for larger fiber diameters due to remaining gaps between fiber and glass brick.

The deformation of the fibers by the thermal action of the laser power can be reduced by shifting the power maximum from the splice inward or outward. When moving outward, the fiber is loaded the least. When splicing fibers with a larger diameter, the connection no longer succeeds in a conventional manner reliably, since the edges of the fiber ends tend to round and thus no connection between the fiber and the glass brick is made at the edge.

• – Für kurze Prozesszeiten sieht man die Deposition von Glasstaub bzw. Glaspartikeln an der Faser. Diese stammen von dem Glasstein verdampften Material und finden sich sowohl innerhalb und auch außerhalb des Fokusbereichs.
• – Bei längeren Prozesszeiten erwärmt der Randbereich des Fokus die Faser mit den darauf befindlichen Partikeln. Diese verbinden sich mit der Faser und dem Glasstein und bilden eine Art Füllmaterial.
• – Die resultierenden Spleiße zeigen im bereich von einigen 100 μm eine leichte Verdickung der Faser durch das aufgetragene Material und eine Verrundung nach außen am Bereich des Überganges von der Faser zum Glasstein.
• – Eine identische Form ist auch für kleinere Faserdurchmesser nachweisbar, so dass man von identischen Abläufen ausgehen kann, diese aber zeitlich schneller ablaufen.

By extrapolating the results for smaller fiber diameters results in a larger diameter of the laser ring, as used in the previous experiments. Tests with corresponding larger diameters show the following changes:

• - For short process times you can see the deposition of glass dust or glass particles on the fiber. These come from the material vaporized from the glass brick and are found both inside and outside the focus area.
• - For longer process times, the edge area of the focus heats the fiber with the particles on it. These combine with the fiber and the glass stone and form a kind of filling material.
• The resulting splices show a slight thickening in the range of a few 100 .mu.m Fiber through the applied material and a rounding outward at the area of the transition from the fiber to the glass brick.
• - An identical shape is also detectable for smaller fiber diameter, so that one can assume identical processes, but these run faster in time.

Thus, an alternative form of fiber-stone splicing can be performed, which also does not have the disadvantages of the prior art.

The innovation of the invention compared. In the prior art, material is vaporized outside the splice (from the stone and from the fiber). This leads to a deposition of the vaporized material due to the temperature gradient. The fiber fuses with the stone by heating the bonding partners. The advantages over In the prior art, gaps between fiber and stone can be bridged, which leads to avoiding underfelting of the fiber edges. In addition, the thermal stress at the splice is lower.

The glass fiber and glass block are thus heated at the splice site by the laser beam envelope and material from the glass brick and fiber is evaporated outside the splice site. Deposition of the vaporized material occurs due to the temperature gradients between the splice site and the heated site, which in turn results in fusion of the fiber with the glass brick.

For the purposes of the invention, a glass fiber refers to a long thin fiber made of glass. Glass fibers can be used as fiber optic cable for data transmission and flexible light transport of z. As laser radiation, used as a roving or as a textile fabric for thermal and acoustic insulation, and for glass fiber reinforced plastics. The glass fibers are aging and weather resistant, chemically resistant and non-flammable.

By means of the method according to the invention, optimization of the splices for small diameters (in particular smaller than 720 μm) can advantageously be achieved by shifting the size of the ring diameter of the laser inwards or outwards. It can also be extrapolated to larger fiber diameter, whereby the duration of the splicing process extended accordingly.

The method preferably uses two process zones, so that the glass fiber and the glass block are irradiated on both sides by laser light, wherein preferably both laser focussing points lie on the glass block. As a result, a uniform and bilateral fusion of the fiber with the glass block can be achieved.

Furthermore, it is preferred that the distances of the focusing points relative to one another and to the splice point are freely selectable. In this way, the temperature distribution and development of the compound can be controlled in the welding point, which means that a submergence of the connection partners, namely the glass fiber and the glass block is prevented.

In this regard, it may also be preferred that the intensities of the individual laser focusing points are freely selectable. The temperature of the glass fiber and the glass block can be determined by measuring instruments. The gauges can also determine the temperature at the splice site. Because the intensities of the individual laser focusing points can be set independently of one another, it is possible to react quickly to temperature variations, so that an optimal fusion is ensured.

It is preferred that the focussing points be generated by a single laser beam, where the laser beam is split into two focussing points. However, it may also be preferred that the focussing points be generated by separate lasers. Depending on the splicing device, it may also be advantageous if not one laser but two lasers with corresponding two laser focusing points act on the glass fiber or the glass block.

In the following, the prior art and the invention will be explained with reference to drawings. Show it:

1 Bonding a glass fiber to a glass block of the prior art;

2 Connecting a glass fiber with a glass block according to the invention.

1 shows the preparation of a connection between a glass fiber and a glass block according to the prior art. The laser beam beam axis 3 lies on the splice point 6 , so that there is a high temperature here. There is a direct connection between fiber 1 and stone 2 by melting the connection partner by laser energy, in particular a laser beam 3 . 4 , Here are the connection partners by heat at a splice 6 compressed, so that a cohesive and permanent connection is formed. The disadvantage here is that when heating the splice 1 . 2 (ie, the bonding partner) the outer edge of the fiber end is heated and thereby rounded, which in turn leads to underfelting between fiber 1 and glass stone 2 in the evaporation zone 5 leads.

2 shows the preparation of a connection between glass fiber and glass block according to the invention. The laser beam beam axis 3 is not on the splice point 6 but especially on the glass brick 2 , where the splice site 6 preferably within the laser beam envelope 4 where preferably lower temperatures than in the beam axis 3 consist. The material of the fiber 1 and the glass stone 2 will be outside the splice site 6 evaporated (evaporation zone 5 ), so that there is a deposition of the evaporated material (deposition area 7 ) comes through a temperature gradient. As a result, contamination in the melting point (splice 6 ) be prevented. The gap between fiber 1 and glass stone 2 is bridgeable and sublimations of the fiber edges are omitted. In addition, a small thermal load of the splice occurs 6 on.

LIST OF REFERENCE NUMBERS

1

 glass fiber

2

 glass stone

3

 Laser-beam axis

4

 Laser beam envelope

5

 Abdampfungsbereich

6

 splice

7

 deposition area

Claims (5)

Method for producing a material connection between an optical glass fiber ( 1 ) and a glass brick ( 2 ) by performing the following steps: a. Approaching the fiberglass ( 1 ) to the glass stone ( 2 b. Irradiating the approximated fiberglass ( 1 ) and the glass stone ( 2 ) with laser light, c. Evaporation of material outside the splice site ( 6 ), d. Deposition of the vaporized material due to temperature gradients and e. Fusion of the glass fiber ( 1 ) with the glass brick ( 2 ) by heating. Method according to claim 1, wherein the glass fiber ( 1 ) and the glass stone ( 2 ) are irradiated on both sides by laser light. Method according to claim 1 or 2, wherein both laser focussing points on the glass brick ( 2 ) lie. Method according to one or more of the preceding claims, wherein the distances of the laser focussing points relative to each other and to the splice point ( 6 ) are freely selectable. Method according to one or more of the preceding claims, wherein the intensities of the individual laser focusing points are freely selectable.

Images