WO2019149899A1

WO2019149899A1 - Method and device for direct structuring by means of laser radiation

Info

Publication number: WO2019149899A1
Application number: PCT/EP2019/052522
Authority: WO
Inventors: Alexandre Mermillod-Blondin; Federico Juan Antonio FURCH; Arkadi Rosenfeld
Original assignee: Forschungsverbund Berlin E.V.
Priority date: 2018-02-02
Filing date: 2019-02-01
Publication date: 2019-08-08
Also published as: EP3746255A1; DE102018201596A1

Abstract

The invention relates to a method and a device for direct structuring by means of laser radiation. The invention specifically relates to a method for producing laser-induced optical near-surface structuring in the material of a body, said method comprising the following steps: generating pulsed laser radiation; focussing the pulsed laser radiation (1300) by means of a focussing optical element (1400) for generating focussed laser radiation (1310); and irradiating the pulsed focussed laser radiation (1310) towards the body; beams of the pulsed focussed laser radiation (1310), which, when irradiated towards the material (1100) of the body (1101), are oriented towards a surface (1150) of the material (1100) of the body (1101), forming an angle (β) with the surface (1150) at the incidence point, which is smaller than or the same as the maximum opening angle (α_max) of the focussing optical element. The invention also relates to a device (1000) for producing such near-surface structurings.

Description

Method and device for direct structuring by means of laser radiation

The invention relates to a method and apparatus for patterning materials using laser radiation to form optical structures.

It is known from the prior art to perform micro-structuring by means of individual short laser pulses or laser pulse sequences with defined energy input into the material. Here, the structuring is made so that only

Phase changes, d. H. Refractive index changes in which material occurs. These refractive index changes can be made on the surface or just below the surface of the material. It is also possible to produce material changes laser-induced in volume.

In the previously known in the prior art method, the laser beam is focused perpendicular to the material surface in the material. In one variant, the material is moved transversely relative to the beam direction of the laser radiation to the corresponding

Make structuring in the interior of the volume of the material. In another variant, the material is moved longitudinally with respect to the irradiation direction of the laser radiation or its focus in order to carry out the structuring in the interior of the material. Examples of the generation of laser-induced structures by means of the longitudinal and transverse techniques are described, for example, in an article by Rod Taylor et al. in Laser & Photon. Rev. 2, no. 1-2, pages 26-46 (2008).

With the transversal techniques, it is not possible to produce optical structurings which are comparable to monomode fiber structures since, due to the focussing in the material, one obtains structural distortions, for example in the form of undesired extensions.

In the longitudinal technique, this problem does not occur, but one is characterized by the focusing by the material along the writing or structuring direction by the opening angle of the focusing optics, hereinafter referred to as focusing optics, and the material edges of the object, the material to be structured exists, limited in terms of structuring options. Examples of structurings according to the longitudinal technique can also be found, for example, in G. Cheng et al., Opt Lett. 38 (2013) pp. 1924-1926, and K Mishchik et al. Opt. Express 18 (2010) 24809.

The interaction with a material depends on the one hand on the pulse duration of the laser radiation and on the other hand on the pulse energy. Overall, ultrashort laser pulses, in usually used with pulse durations between 100 femtoseconds to 1000 femtoseconds.

Altogether, three regimes are distinguished in the state of the art in which

Modifications in the material result.

FIG. 1 graphically plots the pulse energy on the ordinate 80 with respect to the pulse duration on the abscissa 90. Overall, there are three areas 100, 200, 300, which are assigned to the three different modification regimes 1, 2, 3.

In each of the areas, a plug-in image 1 1, 12, 13 of a modified structuring is shown, wherein the refractive index changes of the material are indicated by hatching. Oblique hatching indicates a refractive index increase, whereas perpendicular hatching indicates a refractive index depression. Crossed hatches indicate material damage. A hatch density of the simple hatching indicates a size of refractive index change.

The three modification modes 1, 2, 3 are separated from each other by threshold functions 10, 20, 30, which indicate the threshold pulse energy as a function of the pulse duration, at which the transition from one modification regime to another modification regime takes place for individual pulses.

At a certain threshold pulse energy, which is represented by the first threshold value function 10, a material modification in the modification regime 1100 occurs for short laser pulses with a pulse duration of up to approximately 200 femtoseconds, hereinafter abbreviated as fs. In this regime, direct laser writing results in the formation of smooth, uniform optical structures that exhibit a small refractive index change over the unmodified material. By way of example, such structuring is 1 10 im

Insertion image 11 shown. The modification regime 1 100 thus occurs at low

Pulse energies and short pulse durations.

The structures can be examined by phase contrast microscopy. The above-mentioned insertion diagrams schematically represent such images produced by means of phase contrast microscopy. The hatch density of the simple hatching indicates the

Refractive index difference to the starting material. The higher the coating density, the greater the refractive index increase. An irradiation direction 115 of the laser radiation during the generation of the structuring is indicated by means of an arrow. FIG. 2 shows, by way of example, a schematic phase-contrast microscope image 410 for structuring 110 in the first modification regime. An irradiation direction 115 of the pulsed laser radiation is indicated by an arrow. The pulse energy for generating the structuring 1 10 was 80 nanojoules (nJ), the pulse length 100 fs. Evident is a uniform homogeneous structuring 10 with an average increase in the refractive index relative to the refractive index of the starting material, for example quartz glass.

In addition, a scale 1 16 is shown for estimating a size of the structuring 1 10 with a length of 10 pm. A light pipe can take place in the structuring 110 parallel to the direction of irradiation 1 15, along which the structuring 110 was formed.

If the short pulse durations a second energy threshold, by the second

Threshold function 20 is shown in Fig. 1, exceeded, then occur

Material modifications in the regime 2 200 on. The size of the second energy threshold increases to shorter laser pulse durations. For pulses with pulse durations greater than about 200 fs, only the second energy threshold exists. For these pulse durations greater than about 200 fs, there are no material modifications of the first modification regime.

In regime 2 200, the refractive index changes of structuring 120 produced are larger and negative, but material damage 122 and / or due to

Structuring generated stresses 123 in the material at which positive

Refractive index changes are observable. By way of example, this is shown in the second insertion image 12 as well as in somewhat more detail in FIG. The irradiation direction 115 is drawn again.

FIG. 3 shows a further schematic phase-contrast microscope image 420 of a structuring 120 which is produced under conditions of the second modification regime 2 (cf. FIG. 1). The structuring 120 was produced with a pulse energy of 200 nanojoules at a pulse duration of 100 fs. The structuring is compared to one

Structuring in the modification regime 1 larger and has a larger refractive index difference, a greater increase in the refractive index, over the

Refractive index of the starting material. However, material damage 122, which is indicated by a crossed hatching, as well as stresses 123 in the material, which lead to positive refractive index changes. In this area, a light pipe is possible perpendicular to the plane of the drawing. In order to produce optical fibers, the material is moved vertically relative to the laser radiation, ie out of the plane of the drawing or into the plane of the drawing. An optical fiber thus becomes according to the transverse technique created. The light pipe is thus also perpendicular to the plane of the drawing in the range of generated voltages 123.

From a third pulse of pulse energy of about 400 nanojoules, hereinafter abbreviated as nJ, modifications occur in the so-called third regime 3 300 for pulse durations above about 200 fs. The third pulse energy threshold is by means of the third

Threshold function 30 indicated. The structuring 130 shows large

Refractive index changes, however, with strong material damage 132 and

Voltages 133 are linked. By way of example, this is indicated in the third insertion image 13.

The values shown in FIG. 1 are to be understood by way of example and are to be understood by the same

structuring material as well as the actually used optical focusing conditions, etc. dependent. The structurings produced, which are shown in FIGS. 1 and 2 and 3, are likewise to be regarded as exemplary and schematic only.

Furthermore, it may be in the structuring of materials on the surface or

come close to the surface to ablation, which are also very undesirable and interfere with the refractive index-related structuring or impossible.

For the methods known from the prior art for direct laser-induced structuring of material, there are therefore considerable limitations in the production of structuring, in particular surface-near structuring, which can be used, for example, as optical components, for example for optical sensors.

The invention is therefore based on the object to provide a method and an apparatus for forming laser-induced surface structuring or near-surface structuring, which eliminate or minimize the above limitation. In particular, it is desirable to be able to produce monomode-like waveguide structures as structurings.

The object is achieved by a method with the features of

Patent claim 1 and a device for generating the structuring according to the patent claim 1 1 solved.

As a near-surface patterning, a structuring of the material is considered, which is formed near the surface of the material, wherein a distance from the Surface is smaller than an extent of structuring. Surface structuring is considered to be a structuring which extends as far as the surface, ie which is bounded on one side by the surface itself.

The method for producing laser-induced near-surface optical structuring or surface structuring in the material of a body comprises the method steps: generating pulsed laser radiation;

Focusing the pulsed laser radiation by means of a focusing optics;

Irradiating the pulsed laser radiation on a surface of the material of the body; in which

Rays of focused pulsed laser radiation, which when irradiated on material of

On which one surface of the material of the body is directed, enclose with the surface at the point of impact an angle which is less than or equal to the whole

Opening angle of the focusing optics is. The whole or maximum opening angle a _max of

Focusing optics is directly linked to the numerical aperture NA of the focusing optics, which is given by:

NA = n - sin ^ 2,

where n is the refractive index of the medium in which the radiation propagates.

It has surprisingly been found that in this case on the surface or just below the surface in the interior of the material to be structured body homogeneous structures with a significantly larger refractive index difference than in the known from the prior art modification regime 1 can be generated without disturbing material damage occur. The invention thus makes it possible to combine the advantages of the prior art modification regimes 1 and 2 and to produce microstructures which are homogeneous, show a high refractive index change from the starting material and none by means of short laser pulses having only a few electric field oscillations cause undesirable material damage. There are thus uniformity and freedom of material damage achievable, as they are known for optical structures according to the modification regime 1 of the prior art, as well as the properties of the modification regime 2, namely on the one hand the ability to create large structurings and on the other structuring with high To produce refractive index changes over the starting material.

With the method according to the invention, it is possible to produce structures on the surface or in a region immediately below the surface, which in its optical

Properties of commercial single-mode optical fibers almost correspond. This makes it possible to create almost any optical structures such as optical fibers, splitters, couplers, interferometers and photonic structures near the substrate surface of the body. These structures can be produced flexibly and inexpensively

Particularly preferably, the structuring is formed so that the generated

Structuring to which one surface of the material reaches. This means that the structuring with the changed, in particular increased, refractive index relative to the refractive index of the starting material of the body at the surface is limited by the surface itself.

Preferably, the focus is set to the surface of the body or to a position in an area inside the body below the surface, wherein the distance of the focus from the surface is less than a diameter, more preferably less than a radius, of the laser radiation in the focus of the material is. This can be optimal

Achieve structuring results. The radius here is the distance from the center of the radiation having a rotationally symmetrical beam profile in the focus perpendicular to the direction of propagation, at which the intensity of the radiation has dropped to 1 / e ² . e is the Euler number.

The structuring is preferably carried out with a laser radiation which has a focus diameter of less than 10 μm in air, preferably between 0.5 μm and 7 μm and most preferably between 1 and 3 μm. With these diameters, it is possible to produce well-homogeneous structurings extending parallel to the surface, whose

Extents parallel to the surface larger than the diameter of the focus of the

Load radiation are.

To be particularly advantageous, it has been found to perform the focusing of the laser radiation by means of a specular optics as focusing optics. This makes it possible to ensure that the beam properties, in particular a pulse duration and a chromatic aberration, are affected as little as possible by the focusing. This is important because the interaction with the material takes place in the non-linear region and thus the properties of the laser radiation have a decisive influence on the interaction with the material.

In an advantageous embodiment, the pulsed laser radiation has a pulse duration of less than 40 fs. Very short laser pulses with pulse widths as short as possible, preferably of 10 fs or less, are preferred. As a result, the energy range in which the pulse energies can lie in order to obtain a homogeneous and non-destructive structuring is significantly increased. Thus, laser pulses are preferably used, the few

Have vibration cycles of the electric field. In English, such pulses are also referred to as few-cycle laser pulses.

For a given pulse duration, the required pulse energy for generating the desired structuring is thus less than the pulse energy which is necessary for the same pulse duration, according to the prior art, a modification according to the second

Modification regime to execute.

In one embodiment, it is therefore provided that a pulse energy of the individual pulses of the pulsed focused laser radiation or of the pulsed focused laser radiation on the one surface is less than a threshold pulse energy, from the case of a perpendicular irradiation on the one surface, a modification according to the second modification regime occurs.

The required pulse energy of individual pulses to generate the near-surface

Structuring or surface structuring at the indicated shallow angles relative to the surface of the material to be patterned is smaller than the pulse energy for surface ablation when irradiated perpendicularly to the surface. In a preferred embodiment, all of the pulse energies, in each case based on the respective pulse duration, are below a pulse energy threshold value for laser ablation in the case of perpendicular irradiation.

In a particularly preferred embodiment, however, all pulse energies, in each case based on the respective pulse duration, are above the corresponding threshold energy for the first modification regime.

The energy thresholds for the modification regimes can be determined for a material to be structured by examining the modifications for perpendicular laser pulse radiation.

Since, with a very flat irradiation of the laser radiation on the one surface, a part of the light emerging from the focusing optics does not impinge on this one surface of the surface In a preferred embodiment, a portion of the laser radiation is blocked so that the unblocked portion of the pulsed laser radiation impinges on only one surface.

In a preferred embodiment, a portion of the laser radiation is blocked before impinging on the focusing optics. This blocking is preferably carried out near the

Inlet opening of the focusing optics. In other embodiments, blocking of a portion of the laser radiation in the focusing optics or after the focusing optics, i. H. executed between the focusing optics and the body to be structured.

The blocking can be done, for example, by "mirroring" a part of the laser radiation. In this way, the energy associated with the blocked part of the radiation can be absorbed at a location remote from the focusing optics and the body to be structured and / or converted to another form of energy. Other embodiments provide that the blocking takes place in an absorber.

In one embodiment, in order to create extensive near surface structuring or surface structuring parallel to the surface of the body, the body to be patterned and the focused laser radiation are moved relative to one another in a plane parallel to the surface of the body, i. to

structuring bodies and the focus of the laser radiation are moved relative to each other.

The movement speed is selected depending on the material to be structured, the pulse duration used and the pulse energy and a focus size and focus position.

In order to connect the inventively formed laser-induced surface structures or near-surface structures with other structuring in volume, is provided in a development that the body is additionally tilted relative to the focused laser radiation, so that the angle of incidence of the focused laser radiation is greater than the opening angle of the focusing optics and the focus is moved into the volume of the body such that laser-induced volume laser-induced structures are generated in the volume, which are applied to the extended laser-induced

Surface structuring adjacent. As a result, however, no further

Surface structuring created, but a structuring made in the interior of the volume of the material of the body. These are preferably carried out according to the longitudinal technique in the first modification regime. Alternatively or additionally, the body can be moved perpendicular to the original orientation of the one surface. The laser light then penetrates optionally via another surface of the body into the material. Since the focus length of the focusing optics is dependent on the refractive index of the matter or the space between the focusing optics and the focus position, the focal length in air or vacuum is different from the focal length in the interior of the material of the body. In order to form connection structures on a surface structuring or a near-surface structuring in the interior of the body, therefore, a further relative movement parallel to the original orientation of the one surface of the body is usually necessary in addition.

For the production of such a near-surface structuring or a

Surface structuring is proposed an apparatus for producing laser-induced optical near-surface structuring in a material of a body, comprising: a laser for generating pulsed laser radiation; a focusing optics for focusing the pulsed laser radiation and produce pulsed focused

Laser radiation; wherein the focusing optic is positioned relative to the material so as to radiate the pulsed focused laser radiation onto the material of the body, the focusing optic being positioned relative to the material such that focused pulsed laser radiation is impinged upon the body when irradiated onto the body Surface of the material of the body are directed, with the surface at the point of impact an angle (ß) include, which is less than or equal to the entire opening angle (a _max ) of the

Focusing optics is.

The invention will be explained in more detail with reference to a drawing. Hereby show:

FIG. 1 is a graph plotting the pulse energy versus pulse duration to illustrate different modification regimes according to the prior art (prior art); FIG.

FIG. 2 shows an exemplary laser-induced structuring according to the prior art according to the modification regime 1 (prior art); FIG.

FIG. 3 shows an exemplary prior art laser-induced patterning according to the modification regime 2 (prior art); FIG. 4 shows a schematic structure of a device for laser-induced structuring of materials;

Fig. 5 shows a further schematic structure of a device for laser-induced

Structuring of materials;

FIG. 6 is an exemplary phase contrast micrograph of a structured. FIG

material; and

Fig. 7 is a schematic cross-sectional view through a body with a

Surface structuring.

FIG. 4 schematically shows a structure of a device 1000 for producing surface-near structuring or surface structuring 11 10 in a material 1100 of a body 1 101. The apparatus 1000 comprises a laser system 1200, which provides short laser pulses with pulse durations in the femtosecond range and high energy. The laser system 1200 may include a so-called seed laser 1210 and a

Amplifier 1220, and optionally pulse shaping 1230 include. The individual components of the laser system 1200 are given only by way of example and by way of example.

The laser radiation 1300 generated by the laser system 1200 is guided on a focusing optics 1400. The focusing optics 1400 is preferably designed as a specular focusing optics. In this way it can be ensured that the pulse properties, in particular their pulse duration, are not or only minimally changed. A so-called Schwarzschild design is preferred.

The focusing optics 1400, which is generally similar to a reflective microscope objective, has a so-called maximum opening angle a _max for the out of the focusing optics

1400 emergent focused laser radiation 1310. This is the maximum angle at which rays 1311, 1312, 1313, 1314 of the focused laser radiation 1310 intersect. Illustratively, this is the angle between enveloping jets 131 1, 1312. The numerical aperture NA of focusing optics 1400 can be determined by refractive index n of the material, typically air or vacuum, between focusing optics 1400 and 1400

Material 1 100 of the body to be structured 1101 and this maximum opening angle

Express O _max according to the following formula:

NA = n - sin ^ 2. The focused laser radiation 1310 is irradiated onto a surface 150 of the material 1100 or of the body 10110. This is done so that a maximum angle ß _max between incident beams 131 1 -1314 and the one surface 1 150, measured against the surface 150 1, smaller than the maximum aperture angle a _{max of} the focusing optics 1400 or equal to the maximum aperture angle c of the focusing optics 1400 is.

The focus is in this case arranged on the surface 1 150 or in the interior of the material 1 100 immediately below the surface 150 1. A maximum distance of the focus from the surface 150 is preferably smaller than a diameter of the laser radiation in focus, more preferably smaller than a radius of the laser radiation in focus. A focus diameter of the focused laser radiation 1310 is in the order of preferably less than 10 pm, preferably in the range between 1 pm and 7 pm and particularly preferably in the range of 1, 5 pm to 3 pm, these values in each case to a

Focus size, which in air or vacuum, d. H. in the absence of too

structuring material results.

In the illustrated embodiment, the body 1 101 having the material 1 100 to be structured is connected to a mechanical movement unit 1500 which is designed to make the body 1 101 and thus the material 1 100 to be structured parallel to the surface 150 of the material 1 100 to be structured to move. This makes it possible to produce extensive near-surface structuring or surface structuring 1 1 10 in the material 1 100. These combine the advantages that

Material modifications according to the prior art in the Modification Regimes 1 and 2 have. Thus, it is possible to achieve large refractive index differences of the structurings 1100 relative to the surrounding material 1100. Furthermore, the

Structuring 1 1 10 expanded and generated homogeneously. As a result, structures 1 1 10 can also be created which are comparable in their properties to monomode fibers.

The material selected is preferably quartz glass, which is referred to in English as "fused silica". This is non-crystalline quartz glass, ie usually amorphous silicon dioxide, S1O2. However, it is also possible to structure other materials with the described method or the device described. The wavelength of the laser radiation used can be adapted to the respective material. The material should be transparent to the laser radiation used for structuring, ie have sufficient transmission, so that no significant absorption of the light of the laser radiation occurs. The structuring of the material then takes place via nonlinear effects due to the high pulse energy with the laser pulses, which comprise only a few oscillation cycles of the electric field.

To form an extensive near-surface structuring or

Surface structuring, it is only necessary that the focus of the laser radiation relative to the material to be structured, is moved. This can be done as in the embodiment described above via a mechanical movement of the material or the corresponding body parallel to the surface of the material to be structured by means of a movement unit. Alternatively or additionally, however, it is also possible to move the laser radiation, which usually has a mechanical

Movement of the focusing optics relative to the body or the material to be structured can take place. Again, the relative movement is such that the maximum angle ß _max between incident on the surface of the material to be structured rays and the surface itself is less than the maximum opening angle a _{max of} the focusing optics. Thus, the movement of the focusing optics and the body takes place parallel to the

Surface of the material to be structured.

FIG. 5 diagrammatically shows a further embodiment of a device 1000 for

Forming near-surface laser-induced structuring or

Surface structuring 11 10 shown in a material 1100 of a body 1 101. The same technical features of Figures 4 and 5 are marked with the same reference numerals and only described in detail once.

In this alternative, the irradiation of the focused laser radiation 1310 is so flat on the surface 1 150, that a portion of the beams 1312, 1314, if they are not blocked, not on the surface 150 1 of the material 1 100, but on a side edge 1 180th of the material 1 100 or the body 1101 meet. These rays 1312, 1314 of the focused laser radiation 1310 entering via the side edge 1180 of the material 1100 cause prolonged, generally undesired, aberrations, due to aberrations,

Structuring 1190.

The rays 1312, 1314 are shown partially in dashed lines, since these are to the

be prevented by means of a blocking device 1600 blocked. This blocking device 1600 may be formed as an absorber 1601. It would also be possible to emit the portion of the radiation to be blocked from the beam path of the focused laser radiation 1310. Blocking this proportion of Laser radiation does not have to take place between the focusing optics 1400 and the material 1100 or body 1101 to be structured, but can also take place in the focusing optics 1400 or even before the focusing optics 1400. Since laser radiation 1300 which is generally flared onto the focusing optics 1400 is directed, the blocking of a part of the laser radiation 1300 can already take place prior to entry into the focusing optics 1400. As a result, the advantage is achieved that the space between the focusing optics 1400 and the material to be structured 1100 is not limited.

Also in this embodiment, it is provided, a relative movement between the part of the focused laser radiation 1310, which is applied to the surface 1150 of

structuring material 1100, and to perform the structuring of the material. For this purpose, the movement unit 1500 is provided again.

The propagation direction of the focused laser radiation 1310 is at this

Embodiment preferably aligned parallel to the surface 1 150 of the body 1101. The direction of propagation is the direction along which the laser radiation propagates in space without the presence of the body.

FIG. 6 shows schematically a phase-contrast micrograph 2440 of a sample which is structured with a device similar to that according to FIG. 5, with the beams 1312, 1314 entering via the side edge 1180 of the material 1100 for the purpose of illustrating the effects that occur were not blocked

(See Fig. 5).

On the left, the structuring according to the invention 11 10 can be seen, the high

Has refractive index difference from the refractive index of the starting material. On the right, by aberration, elongated unwanted patterns 1190 are seen caused by the unblocked portion of the beams 1312, 1314 of the focused laser beam 1310 that have entered over a side edge 180 of the material. Their focus position at which they have carried out the unwanted structuring 1 190, is significantly removed from the focus position, the incident on the surface 1 150 rays 1311, 1313th

In order to be able to connect the structures close to the surface or surface structuring, which can achieve monomode-fiber-like optical properties, to structures formed in the volume, it is provided in a further development of the invention that the movement device comprises the material to be structured or the Body with the material to be structured and / or the imaging optics pivoted relative to each other so that an irradiation can be made at angles which are significantly greater than the maximum aperture angle of the focusing optics. In this way, for example, a structuring according to the longitudinal technique can be carried out around the near-surface structures according to the invention or

To provide surface structuring with formed in the volume connection structures and / or connect.

Alternatively, a lateral movement parallel to the surface of the body coupled with a movement perpendicular thereto can be used to control the

Forming connection structures in the interior of the material of the body. This can be done, for example, by the penetrating over the side edge laser beams that have produced in Fig. 6, the unwanted structuring, via a suitable

Relative movement of body 1001 and focusing optics 1400 in volume of the material of the body, the terminal structure or the connection structures 1 120, 1 121 (see Fig. 7) form. This can be done analogously to the longitudinal technique of the prior art.

The irradiation of the laser radiation for forming the connection structures does not have to take place via the one surface, but can also take place via the side edges 1180, 1 181 of the body 1 101 (cf. FIG. 7).

FIG. 7 schematically shows a cross section through a body 1 101 made of a material 1100, on the one surface 150 of which a surface structuring 11 10 according to the method described here is formed. The surface structuring 1 110 is limited to the upper side 1 150 of the body 1101 by this surface 1 150. This means that the surface structuring 11 10 with the increased refractive index over the refractive index of the material 1100 inside the body 1 101 extends to the surface 1150 of the body 1101. Parallel to the surface 1150 is the

Surface structuring 1 110 formed homogeneous and extended. At ends 1 115,

1 116 of the surface structuring 1 110 connecting structures 1 121, 1122 are formed. These connection structures extend from the surface structuring 11 10 into the interior of the material 1 100 respectively to the opposite side edges 1180, 1 181. This makes it possible light over one of the side edges 1180, 1 181 in one of

Coupling connection structures 1121, 1 122, which then the light to the

Surface structuring 1 1 10 passes. The light can then be removed from the body 1101 via the corresponding other of the connection patterns 1121, 1 122 be led out. On the surface 1150 substances located or with the surface 1 150 in contact sample (both not shown), the light conduction in the surface structuring 1 110 influence. These

Changes in the light pipe can be detected and evaluated. Thus, a surface pattern 11 10 may be used as an optical sensor.

The terminal structures 1121, 1 122, as modifications in the first

Modification regime, for example, be carried out according to the longitudinal technique.

Other embodiments provide that the surface structuring 1 110 in the body 1 101 extends to the side edges 1 180, 1181 or to a side edge 1180, so that without the use of terminal structures light in the

Surface structuring via one of the side edges of the body of the material can be coupled. This embodiment is indicated by a dashed line 1110-a, which represents a delineation of the continued structuring 1 110 to the rest of the material 1100. In this embodiment, then missing

Terminal structures 1120, 1 121.

It should be noted that structuring according to the invention, for example of quartz glass, is possible under very flat angles of incidence at pulse energies below the

Pulse energies are, however, which are for inducing a modification in the modification regime 2 but above the threshold energy for material modifications in the modification regime 1. The shorter the pulse duration of the short laser pulses used for the generation, the greater the pulse energy margin, between the threshold energy for the

Material modifications in the modification regime 1 and the threshold energy for

Material modifications in the modification regime 2. Therefore, to form the

Surface structuring preferably pulse durations in the range of 10 foreign seconds and less used.

LIST OF REFERENCE NUMBERS

1 first modification regime

2 second modification regime

3 third modification regime

10 first threshold function

1 1 slot-in picture

12 insertion picture

13 insertion picture

20 second threshold function

30 third threshold function

80 ordinates

90 abscissa

100 range of the first modification regime

1 10 structuring

115 direction of irradiation

116 scale

120 structuring

122 material damage

123 voltages

126 scale

130 structuring

132 material damage

200 range of the second modification regime

300 area of the third modification regime

410 phase contrast micrograph

420 phase contrast micrograph

1000 device

1 100 material

1 101 body

1 110 structuring

1 110-a Line to indicate continuation of structuring 1 115, 1 116 End of structuring

1 120.1 121 connection structures

1 150 surface

1 180, 1 181 (opposite) side edges 1 190 prolonged, unwanted structuring

1200 laser system

1210 seed lasers

1220 amplifier device

1230 pulse shaping devices

1300 laser radiation

1310 focused laser radiation

131 1 rays

1400 focusing optics

1500 movement unit

1600 blocking device

1601 absorber

2440 phase-contrast micrograph

Gmax maximum opening angle of the focusing optics

ßmax maximum angle between incident rays and surface

Claims

claims

1. A method of producing laser-induced optical near-surface

Structuring or surface structuring (1 110) in the material (1 100) of a body (1101) comprising

Generating pulsed laser radiation (1300);

Focusing the pulsed laser radiation (1300) by means of focusing optics (1400) to produce pulsed focused laser radiation (1310);

Irradiating the pulsed focused laser radiation (1310) onto the material (1100) of the body (1101);

characterized in that

Rays (131 1-1314) of the pulsed focused laser radiation (1310) directed at a surface (150) of the material (1100) of the body (1101) when irradiated onto the material (1100) of the body (1101) , with the surface (1050) at the point of impact include an angle (ß), which is less than or equal to the maximum opening angle (a _max ) of the focusing optics (1400).

2. The method according to claim 1, characterized in that the focusing is performed with a specular optics as focusing optics (1400).

3. The method according to claim 1 or 2, characterized in that the focus on the surface (1 150) of the material (1100) is adjusted.

4. The method according to any one of claims 1 or 2, characterized in that the focus is formed in the interior of the material (1100) below the one surface (1150), wherein a distance of the focus from the one surface (1150) of the body (1 101) is smaller than the diameter of the focused laser radiation in focus, more preferably smaller than the radius of the focused laser radiation in focus.

5. The method according to any one of claims 1 to 4, characterized in that a part of the pulsed laser radiation (1300) or pulsed focused

Laser radiation (1310) is blocked so that the unblocked portion of the pulsed focused laser radiation (1310) occurs only on the one surface (1150) of the material (1100) of the body (1101) or passes through the one surface (1 150).

6. The method according to any one of claims 1 to 5, characterized in that the one surface (1150) of the body (1101) parallel to the one surface (1150) of the material (1100) of the body (1101) relative to the focused laser radiation

(1310) is moved to form an extended patterning (1110).

7. The method according to any one of the preceding claims, characterized in that in addition the body (1 101) and the pulsed focused laser radiation

(1310) are pivoted relative to each other, so that an angle of incidence of the focused laser radiation (1310) greater than the opening angle of

Focusing optics (1400) is and the focus in the volume of the material (1 100) of the body (1101) is moved so that in addition laser-induced volume structures are generated in the volume, which adjoin the near-surface generated laser-induced structures (11 10).

8. The method according to any one of the preceding claims, characterized in that the numerical aperture (NA) of the focusing optics (1400) is chosen to be less than or equal to 0.5.

9. The method according to any one of the preceding claims, characterized in that the on the one surface (1 150) of the material (1 100) incident rays (131 1, 1313) of the pulsed focused laser radiation (1310) at most an angle with the one surface (1150) which is smaller than half the full aperture angle (a _max ) of the focusing optics (1400).

10. The method according to any one of the preceding claims, characterized in that a pulse energy of the individual pulses of the pulsed focused

Laser radiation (1310) or of the surface on a striking part of the pulsed focused laser radiation (1310) less than one

Threshold pulse energy is above which a modification according to the second modification regime (2) occurs in a perpendicular irradiation on the one surface (1150).

1 1. Apparatus for generating laser-induced optical near-surface

Structuring or surface structuring (11 10) in a material (1100) of a body (1 101) comprising:

a laser (1200) for generating pulsed laser radiation (1300);

a focusing optics for focusing the pulsed laser radiation and generating pulsed focused laser radiation;

wherein the focusing optics (1400) is arranged relative to the material (1100) such that the pulsed focused laser radiation (1310) is irradiated onto the material (1100) of the body (1101),

characterized in that

the focusing optic (1400) is arranged relative to the material such that the beams (1311 - 1314) of the focused pulsed laser radiation (1310) that are incident upon the

Irradiating the body (1101) onto a surface (1150) of the material (1400) of the body (10110), with the surface (1150) at the point of impact forming an angle (β) which is less than or equal to the full aperture angle (11). Q _max ) of the focusing optics (1400).