EP4751111A1 - New optical device for using the synergistic effect of photonic nanojet and plasmons for signal and resolution enhancement in spectroscopy - Google Patents

Abstract

An optical device called NMS (nano-engineered microsphere) is developed, which consists of an optical microsphere with a built in nanoelement. By illuminating the microsphere, a photonic nanojet is created that illuminates the nanoelement at the tip of which plasmons are excited. The nanoelement can be, for example, a metal nanocone whose base is built in a microsphere, and plasmons are excited at the tip, or a nanowire with a metal tip. The microsphere can contain a cavity that offers additional protection for the nanoelement and can cause higher enhancement. When used, for example, in Raman spectroscopy, which we call NMERS (nano-engineered microsphere enhanced Raman spectroscopy), the joint action of the photonic nanojet and plasmon leads to a combined enhancement of Raman scattering, and if the sample is mapped, the resolution of the mapping is also improved. NMERS offers some improvements over the best enhancement methods so far such as SERS and TERS, and NMS can be used in a variety of other microscopic and spectroscopic applications.

Description

Hew optical device for using the synergistic effect of photonic nanojet and plasmons for signal and resolution enhancement in spectroscopy

The present invention relates to an optical device based on a mechanically fixed microsphere, which, through nano-engineering, obtained the properties of exploiting the synergistic effect of a photonic nano jet and plasmons, which leads to significant signal and resolution enhancement in spectroscopy and microscopy. Properties and possibilities of the invention are presented on the example of Raman spectroscopy.

Raman spectroscopy is a widely used and popular spectroscopic method that provides information on the identity, type, properties and changes of the substance being studied in a wide range of scientific and technical fields . Due to its inelastic nature, Raman scattering has only a small share in the total scattering of light on matter, which is why the obtained signal is also weak. For this reason, various Raman signal enhancement techniques have been developed. One of the popular and well- established methods is surface-enhanced Raman scattering (SERS) , which exploits plasmon enhancement of the electric field with the help of metallic nanoparticles (e . g. silver or gold) to enhance Raman scattering. The advantage of this method is extremely high signal enhancement, but the negative side is poor reproducibility and complicated and expensive preparation of nanoparticles . A partial improvement of this method is TERS (tip enhanced Raman spectroscopy) , which uses a metallic tip to obtain plasmon enhancement identical to that of SERS . In addition to the extremely high enhancement, TERS is characterized by better reproducibility compared to SERS and the possibility of Raman mapping, which is also of significantly better resolution compared to ordinary Raman mapping. The disadvantages of the TERS method are the high cost of application (an additional AFM (atomic force microscopy) or STM (scanning probe microscopy) system with a Raman device is required) and complicated usage . Moreover, TERS systems are often designed in a way that the incident light comes at an angle from the side, which leads to additional problems with sample excitation and signal collection. In such designs the incident light also requires an additional microscope objective .

On the other hand, one of the new and promising method of enhancement is based on a photonic nano jet - a narrow and intense beam of light that is created from the shadow side of a microlens (most often a microsphere) under suitable conditions when illuminated with light . Raman enhancement is obtained due to the high intensity of the photonic nanojet, which is generated by illuminating a microsphere located on the sample being studied. Although the photonic nano jet enhancement levels are much lower than the enhancement levels of SERS or TERS method, photonic nano jet is gaining more and more popularity as it shows to be a reproducible, simple and inexpensive enhancement method. Also, this method can be used during Raman mapping if the microsphere is fixed and controlled mechanically or optically.

Our innovation enables a new approach to Raman enhancement, It brings the advantages of the previously mentioned methods, and eliminates their individual disadvantages . The innovation is called NMS (nano-engineered microsphere) and is based on a mechanically attached and controlled dielectric microsphere into which a nanoelement has been incorporated by nano-engineering. NMS enables the formation of a photonic nano jet and an improved ability to collect scattered light, while the nanoelement creates plasmonic enhancement. In this way, a synergistic combination of enhancement using the photonic nano jet and plasmons occurs . Such new method of Raman spectroscopy enhancement we will call NMERS (nano-engineered microsphere enhanced Raman spectroscopy) . The microsphere plays a triple role here - it creates a photonic nanojet, improves the collection of scattered light from the sample, and serves as a nanoelement holder for plasmon enhancement . This elegant design offers significant improvements over TERS, SERS, or the photonic nano jet method. The plasmonic part of NMERS enables extremely high levels of enhancement of the incident electric field, like those of TERS or SERS . However, due to the synergistic effect with the photonic nanojet, an even greater enhancement occurs for two reasons : a) Photonic nanojet of high light density (diameter below 300 nm) can be produced with microscopic lenses of relatively low magnification (20-50 times) , which is more than an order of magnitude higher laser light density (laser light power per unit area) compared to standard TERS techniques . That light is proportionally enhanced at plasmonic element, while the intensity of the scattered Raman light, which is enhanced once more at the plasmonic element, increases by the power of two; b) The enhancement is further increased due to the improved ability to collect scattered light by the microsphere, due to its antenna effect, which can be more than 10 times . In total, all three contributions allow extremely high enhancement, up to three orders of magnitude higher than either SERS or TERS methods . Moreover, a high reproducibility similar to that of the TERS method is obtained due to the fact that the nanoelement is attached to the microsphere . In NMERS, the microsphere is mechanically fixed and its movements are controlled with nanometer resolution. This enables mapping with nanometer resolution. The mapping resolution is at the level of the TERS method due to its nanoelement and highly localized plasmon enhancement . However, the price of the device with the NMERS method is significantly lower, and the application is simpler compared to TERS . This is because NMERS does not require another system like AFM or STM. The plasmonic part is contained in the microsphere itself . Also, the incident light arrives perpendicular to the sample through the same lens that collects the signal, unlike many TERS systems where an additional lens is required for incident light coming at an angle from the side . The stated features of NMERS place this method at the very top of Raman enhancement methods . However, NMS is not only designed for the field of Raman spectroscopy. NMS can be used in any area where plasmon enhancement can be used, such as surface enhanced infrared absorption (SEIRA) , plasmon-enhanced fluorescence spectroscopy (PEFS) or enhancement of Rayleigh scattering in optical microscopy. NMS can also be useful even when there is no need for plasmon enhancement; for example in optical microscopy, where the microsphere provides improved resolution due to the photonic nano jet and its light-collecting improvement .

The NMS innovation is developed in four variants, depending on the design of the microsphere and nanoelements . The ways of controlling the microsphere are also variable . The listed designs are examples of innovation. However, the innovation also includes those examples that are not explicitly listed here, but consist of a microsphere with a nanoelement where plasmons on the nanoelement are excited using a photonic nanojet . We identify the microsphere with a nanocone in the cavity as variant I, the microsphere without a cavity with a nanocone on the edge as variant II, the microsphere with a nanowire in the cavity as variant III, and the microsphere without a cavity with a nanowire as variant IV. The microsphere control can be performed either using one or more thin optical fibers, an AFM cantilever, or an objective adapter. We can assign a vertical z axis to the microsphere through its center, which is also its axis of symmetry. The vertical z-axis is directed upwards, while the direction of propagation of the incident light is downwards, i . e . in the negative direction of the z-axis . Accordingly, we can refer to the upper and lower (shadow) side of the microsphere . The incident light hits the upper part of the microsphere, while a photonic nano jet is created on the lower (shadow) side .

The attached figures show the design of the NMS, the enhancement mechanism and the principle of the NMERS method, where : Figure la is a schematic of the cross-section of the front side of variant I - microsphere (1) with a nanocone (3) in the cavity (2) , with the z axis marked;

Figure lb is a schematic of the front side of variant I - microsphere (1) with a nanocone (3) in a cavity (2) ;

Figure 1c is a schematic of the floor plan of variant I - microsphere (1) with a nanocone (3) in a cavity (2) ;

Figure 2a is a schematic of the front side of variant II - microsphere (4 ) with nanocone (3) , with z axis marked;

Figure 2b is a schematic of the floor plan of variant II - microsphere (4) with nanocone (3) ;

Figure 3a is a schematic of the cross-section of the front side of variant III - microsphere ( 1) with a nanowire (5) with a metal tip (6) in the cavity (2) , with the z axis marked;

Figure 3b is a schematic of the front side of variant III - microsphere (1) with a nanowire (5) with a metal tip ( 6) in a cavity (2 ) ;

Fig . 3c is a schematic of the floor plan of variant III - microsphere (1) with a nanowire (5) with a metal tip (6) in the cavity (2) ;

Figure 4a is a schematic of the front side of variant IV - microsphere (4 ) with a nanowire (5) with a metal tip ( 6) , with the z axis marked;

Figure 4b is a schematic of the floor plan of variant IV - microsphere (4) with a nanowire (5) with a metal tip (6) ;

Figure 5a is a schematic of the excitation part of the enhancement mechanism, which is divided into photonic nanojet (8 ) and plasmon ( 9) ; Figure 5b is a schematic of the collection part of the enhancement mechanism due to the antenna effect of the microsphere;

Figure 6 is a schematic of NMS control using one tapered optical fiber (13) ;

Figure 7 is a schematic of NMS control using two tapered optical fibers (13, 18 ) ;

Figure 8 is a schematic of NMS control using the AFM cantilever (22) ;

Figure 9 is a schematic of NMS control using the adapter (23) for the objective (24 ) ;

Figure 10 is a schematic of the use of NMS for the enhancement of Raman spectroscopy.

NMS variant I (Figure 1) consists of a microsphere (1) with a cavity (2) on the lower side, in which there is a nanocone (3) . The base of the nanocone (3) is built in the microsphere (1) , and the tip is directed towards the edge of the microsphere and placed on the vertical ( z) axis, so that the longer axis of the nanocone (3) forms an angle with the z-axis . The base of the cone (3) is built in the cavity (2 ) at the side, outside the light propagation axis, in order to free up space for a better passage of light . The tip of the nanocone (3) is located on the light propagation axis ( z-axis) in order to produce plasmonic excitation at the tip under the influence of the photonic nanojet .

NMS variant II (Figure 2) consists of a microsphere (4 ) without a cavity, on the underside of which there is a nanocone (3) whose base is built in the microsphere ( 4 ) . The base of the cone (3) is built in on the side, outside the axis of light propagation (z-axis) , in order to free up space for a better passage of light . The tip of the nanocone (3) is located on the light propagation axis (z-axis) in order to produce plasmon excitation at the tip under the influence of the photonic nanojet . The longer axis of the nanocone (3) forms an angle with the z-axis .

NMS variant III (Figure 3) consists of a microsphere (1) with a cavity (2) on the lower side, in which there is a nanowire (5) . One end of the nanowire (5) is built in the microsphere (1) , and the other end with a metal nanosphere ( 6) on top is directed towards the edge of the microsphere (1) and placed on the vertical ( z) axis, so that the longer axis of the nanowire (5) forms an angle with the z axis . The nanowire (5) is built in the cavity (2) at the side, outside the light propagation axis (z- axis) , in order to free up space for a better passage of light . The tip with the metal nanosphere ( 6) is located on the light propagation axis ( z-axis ) in order to produce plasmon excitation at the tip under the influence of the photonic nano j et .

NMS variant IV (Figure 4 ) consists of a microsphere without a cavity (4) , on the underside of which there is a nanowire (5) , one end of which is built in the microsphere (4 ) . The nanowire (5) is built in on the side, outside the axis of light propagation (z-axis) , in order to free up space for a better passage of light. The tip with a metal nanoball ( 6) is located on the axis of light propagation (z-axis) in order to produce plasmonic excitation at the tip under the influence of the photonic nanojet . The longer axis of the nanowire (3) forms an angle with the z-axis .

In all variants, the microsphere (1, 4 ) can be of any size and material that enables the creation of a photonic nanojet. The tip of the nanoelement (3, 5) should be of a suitable size that enables the excitation of plasmons . The tip of the nanoelement (3, 5) should be metallic and should correspond to the wavelength of the excitation light (for example, silver for green light or gold for red) . In the variant with a cavity (2) , the diameter of the cavity (2) of the microsphere (1) should be such that the nanoelement (3, 5) fits inside the cavity (2 ) and that the light is well focused on the nanoelement (3, 5) , i . e . to be able to form suitable photonic nanojet . For example, for a microsphere (1) with a diameter of 5 pm, a nanocone (3) whose angle is 80° and the radius of curvature of the tip is 5 nm, the cavity (2) can be 900 nm in diameter .

The enhancement mechanism in NMERS can be divided into excitation (Figure 5a) and collection contribution (Figure 5b) . During excitation, the incident light beam (7 ) comes to the upper side of the microsphere (1) , passes through the microsphere (1) , where on the other side (the lower side) a photonic nano jet (8) is formed, which excites plasmons ( 9) on the nanoelement (3) and at the same time it illuminates the sample (10) . The synergistic joint contribution of the photonic nano jet (8) and plasmons ( 9) results in an extremely high enhancement of the Raman scattering (11) on the sample (10) . Scattered light (11) is synergistically enhanced again by plasmons ( 9) and collected by the same microsphere (1) , which, due to its antenna effect, enables better light collection. The microsphere enables the collection of scattered light from almost the entire solid half-angle above the sample ( 10) and collimates the collected light so that the beam of return light (12) above the microsphere (1) is almost completely covered by the microscope objective .

The NMS production consists of the production or procurement of microspheres and the production of the nanoelement . Microspheres can be made by one of the standard methods, for example by exposing the material powder to a flame, or they can be obtained as a powder or in suspension. If the microspheres are not suspended, this should be done as a first step. The suspended microspheres are then dropped onto a glass slide where they are allowed to air dry. Under the microscope, the microsphere is touched with a tapered optical fiber . The tip of the fiber is previously dipped in optical glue . This way the microsphere attaches on the tip of the fiber. UV light cures the glue . In variants where a microsphere with a cavity is required, a fiber with a microsphere is attached to a device for precise removal of material, for example a device with a focused ion beam, where a cavity of the desired geometry is hollowed out. In variants with or without a cavity, the fiber with the microsphere is then installed in a sputtering device where a thin layer of the desired material is sputtered onto the lower part of the microsphere or into the cavity. Then, in a device for precise removal of material, the desired nanoelement is formed from a layer of sputtered material .

In the case when the nanoelement is a nanowire, instead of a thin layer, localized nanoparticles of the desired material are sputtered, which serve as seeds for the growth of nanowires using one of the standard deposition methods, for example LPVCD (low pressure chemical vapor deposition) . Then, the excess nanowires are removed in a device for precise removal of material .

The NMS can be controlled in a number of ways, either mechanically or by using an optical trap. Mechanically, for example, this can be done by means of a thin optical fiber (13) attached to a micropositioner or a piezo stage (14) (Figure 6) . The microsphere (1) is attached to the optical fiber (13) using optical glue (15) or by some other way. The optical fiber (13) is attached to the microscope slide (16) , which is attached to the micropositioner (14 ) . The fiber (13) should form a small angle (17 ) with the horizontal plane so that the microsphere (1) comes into contact with the substrate . Additional strength is provided by the second vertically glued tapered optical fiber (18 ) to the first fiber (13) (Figure 7 ) . The connection of two fibers (13, 18 ) can be achieved with optical glue (19) or in some other way. Two fibers (13, 18 ) are attached to a microscope slide with a rectangular cut-out (20) which is attached to the micropositioner (14 ) . The second fiber ( 18) should also form a small angle (21) with the horizontal plane . The NMS can also be installed in a tipless AFM cantilever (22) with a hole (Figure 8) , or in an adapter (23) for a microscope objective (24) (Figure 9) .

Installing NMS on existing experimental devices is simple. The NMS (1, 3) on optical fibers ( 13, 18) is attached to the micropositioner or piezo stage (14 ) which is located next to the device microscope (25) . By moving the stage (14) , the NMS (1, 3) is brought to the desired position under the microscope (25) and any usual measurement can begin. The NMS (1, 3) on the AFM cantilever (22) is attached to the AFM unit of the device where the NMS (1, 3) is positioned under the microscope (25) by controlling the AFM unit . The NMS (1, 3) in the adapter (23) is attached to the existing microscope objective (24 ) and by the motors inside the adapter (23) NMS is positioned (1, 3) to the desired position.

The scheme of NMS usage for Raman spectroscopy is shown in Figure 10. Using the micropositioner (14 ) the NMS (1, 3) is positioned under the incident laser beam (7) coming from the microscope objective (24) of the Raman microscope (25) . The focus of the incident beam (7 ) is regulated by the z motor (26) , and the position of the sample by the x-y microscope stage (27 ) . The laser beam comes from the laser source (28 ) , and the collected Raman scattering (11) is directed to the monochromator (29) . The data is processed on the computer (30) , which also controls the microscope (25) .

List of reference signs

(1) A microsphere with properties that enable the formation of a photonic nano jet (8) ; common diameters are a few micrometers or several tens of micrometers, and the common material is quartz, polystyrene, BaTiOa and the like . (2) Spherical cavity on the underside of the microsphere (1) ; the size of the cavity is small enough not to disrupt the creation of a photonic nano jet (8 ) , and large enough to fit a nanoelement (3, 5) .

(3) A nanocone where plasmon excitation ( 9) is created on the tip due to light illumination; the nanocone is made of metal material and its tip is of dimension that enables the creation of plasmons .

(4) A microsphere without a cavity that enables the formation of a photonic nano jet (8) ; common diameters are a few micrometers or several tens of micrometers, and the common material is quartz, polystyrene, BaTiOs and the like.

(5) A nanowire on whose metal tip ( 6) a plasmon excitation (9) is created due to light illumination; it can be made of silicon or other suitable materials .

(6) A metallic nanospherical tip on which plasmon excitation ( 9) is generated due to light illumination; it is of dimensions that enable the creation of plasmons; it is located on the nanowire (5) .

(7) An incident laser beam that illuminates the microsphere (1) .

(8 ) Photonic nano jet that is formed on the shadow side of the microsphere (1) due to light illumination (7 ) .

( 9) Plasmon excitation on the metal tip of the nanoelement (3, 5, 6) that occurs due to light illumination.

(10) The sample of interest that is being studied.

(11) Raman scattering that occurs when a sample is illuminated with light .

(12) Collected light that has small divergence due to antenna effect of the microsphere (1) .

(13) The first partially tapered optical fiber produced by stretching a standard telecom fiber, where the thicker end has a diameter of 125 pm, and the tapered tip is about 60% of the diameter of the microsphere (1) that is attached to it .

(14 ) A micropositioner or piezo stage used to control the NMS.

(15) Optical glue used to attach the microsphere (1) to the tapered optical fiber (13) .

(16) A piece of the microscope slide to which the fiber (13) is attached; the microscope slide is attached to the micropositioner ( 14 ) .

(17) Small angle of inclination of the first optical fiber (13) .

(18) Second partially tapered optical fiber produced by stretching a standard telecom fiber, where the thicker end has a diameter of 125 pm, and the tapered tip is about 60% of the diameter of the microsphere (1) . (19) Optical glue that fixes the connection of two optical fibers (13,18) .

(20) A piece of microscope slide with a rectangular cut-out to which two optical fibers (13,18) are attached.

(21) A small angle of inclination of the second optical fiber (18) .

(22) Tipless AFM cantilever with a hole in which the microsphere is attached (1) .

(23) Lens adapter (24) that houses the NMS.

(24) Microscopic objective.

(25) Raman microscope.

(26) Z motor of the microscope.

(27) X-Y microscope stage for moving the sample (10) .

(28) Laser source.

(29) Raman spectrometer.

(30) Computer for controlling the Z motor (26) of the microscope (25) and the X-Y microscope stage (27) .

Claims

Patent claims

1. An optical device for work in multiple applications, which includes : a microsphere (1) and a nanoelement (3, 5) wherein the microsphere ( 1) on the lower side contains a cavity (2) inside which the nanoelement (3, 5) is placed, and the longer axis of the nanoelement (3, 5) forms an angle with the vertical (z) microsphere axis (1) ; by illuminating the microsphere (1) , a photonic nano jet (8 ) is created at the shadow side of the microsphere (1) , which excites plasmons ( 9) on the nanoelement (3, 5) .

2. An optical device for work in multiple applications, which includes : a microsphere (4 ) and a nanoelement (3, 5) wherein by illuminating the microsphere (4 ) a photonic nano jet (8 ) is created at the shadow side of the microsphere (4 ) which excites plasmons ( 9) on the nanoelement (3, 5) which is located on the lower side of the microsphere (4) , and the longer axis of the nanoelement (3, 5) forms an angle with the vertical (z) axis of the microsphere (4 ) .

3. The optical device of claim 1 wherein the nanoelement is a nanocone (3) whose base is built in inside the cavity (2) of the microsphere (1) on the side, and the tip of the nanocone (3) is placed on the vertical (z) axis of the microsphere ( 1) .

4 . The optical device of claim 2 wherein the nanoelement is a nanocone (3) whose base is built in the surface of the microsphere (4 ) on the side, and the tip of the nanocone (3) is placed on the vertical ( z) axis of the microsphere (4) .

5. The optical device of claim 1 wherein the nanoelement is a nanowire (5) whose one end is built in inside the cavity (2) of the microsphere (1) on the side, and the tip of the nanowire (6) is placed on the vertical (z) axis of the microsphere (1) .

6. The optical device of claim 2 wherein the nanoelement is a nanowire (5) whose one end is built in the surface of the microsphere (4 ) on the side, and the tip of the nanowire ( 6) is placed on the vertical (z) axis of the microsphere (4) .

7. The optical device of claims 1 or 2 wherein the photonic nano jet (8) and plasmons ( 9) enable the enhancement of the signal obtained from the excited sample (10) , the improvement of the mapping resolution of the sample (10) which reaches nanometer resolution, and the microsphere (1, 4 ) enables Improved light collection from the sample (10) using the antenna effect .

8. The optical device of claims 1 or 2 wherein the microsphere (1, 4 ) which contains the nanoelement (3, 5) is attached to the partially tapered optical fiber (13) by means of an optical gluee (15) or in some other way; the fiber ( 13) is attached to the microscope slide (16) , which is attached to a micropositioner, piezo stage or some other stage ( 14 ) , which serves to control the device .

9. The optical device of claim 1 or 2 wherein the microsphere (1, 4 ) which contains the nanoelement (3, 5) is attached to the partially tapered optical fiber (13) by means of an optical glue (15) or in some other way; the second partially tapered optical fiber (18) is attached perpendicularly to the first (13) by means of an optical glue (19) or in some other way; the fibers (13, 18) are attached to a microscope slide with a rectangular cutout (20) which is attached to a micropositioner, piezo stage or some other stage (14 ) , which serves to control the device.

10. The optical device of claim 1 or 2 wherein the microsphere (1, 4) which contains the nanoelement (3, 5) is attached to a tipless AFM cantilever (22) with a hole attached to a micropositioner, piezo stage or some other stage (14 ) or to the AFM controller which serves to control the device .

11. The optical device of claim 1 or 2 wherein the microsphere (1, 4) which contains the nanoelement (3, 5) is attached to a adapter (23) for the microscope objective (24 ) which serves to control the device .

12. The optical device of claims 1 and 8 or 1 and 9 or 2 and 8 or 2 and 9 wherein the diameter of the microsphere (1, 4 ) is larger than the diameter of the tip of the fiber (13) , and small enough that the microsphere (1) would not be too heavy for the fiber (13) .

13. The optical device of claims 1 and 8 or 1 and 9 or 2 and 8 or 2 and 9 wherein during use it is slightly tilted (17, 21) so that the microsphere (1, 4 ) and/or nanoelement (3, 5) touch the sample (10) , but the fibers ( 13, 18 ) do not touch the sample (10) .

14. The optical device of claims 1 and 8 or 1 and 9 or 2 and 8 or 2 and 9 wherein upon contact of the microsphere (1, 4 ) and/or nanoelement (3, 5) with the sample ( 10) due to the flexibility of the fibers (13, 18 ) , the microsphere (1, 4 ) and/or nanoelement (3, 5) maintain contact with the sample (10) and follow the relief of the sample ( 10) .

15. The optical device of claim 1 wherein the position of the tip of the nanoelement (3, 6) is close enough to the sample (10) that there is an interaction of plasmons ( 9) with the sample (10) , and is sufficiently protected by the cavity (2 ) .

16. The optical device of claim 1 or 2 wherein the nanoelement (3, 5) is partially flexible so that its tip follows the relief of the sample ( 10) .

17. The production process wherein under a microscope the tip of the partially tapered optical fiber (13) is immersed in a drop of optical glue that has previously been placed on a microscope slide; a drop of the microspheres suspension is placed on the microscope slide and placed under the microscope; the tip of the fiber (13) is brought to the microsphere (4 ) and touches the microsphere (4 ) which is located on the microscope slide, whereby the microsphere (4 ) is caught on the fiber (13) ; the connection of the microsphere (4 ) and the fiber (13) is illuminated with UV light to cure the glue ( 15) ; the microsphere (4 ) on the fiber (13) is installed in a sputtering device where a thin layer of the material is sputtered to the bottom of the microsphere (4) ; the microsphere (4 ) on the fiber (13) is installed in a device for precise removal of particles where the nanoelement (3, 5) is formed by a focused ion beam or in some other way from the sputtered thin layer of material .

18. The production process wherein under a microscope the tip of the partially tapered optical fiber ( 13) is immersed in a drop of optical glue that has previously been placed on a microscope slide; a drop of the microspheres suspension is placed on the microscope slide and placed under the microscope; the tip of the fiber (13) is brought to the microsphere (1) and touches the microsphere (1) which is located on the microscope slide, whereby the microsphere (1) is caught on the fiber (13) ; the connection of the microsphere (1) and the fiber (13) is illuminated with UV light to cure the glue ( 15) ; the microsphere (1) on the fiber (13) is installed in a device for precise removal of particles where a cavity (2 ) is hollowed out from the lower side of the microsphere (1) with a focused ion beam or in some other way; the microsphere (1) with the cavity (2) on the fiber (13) is installed in a sputtering device where a thin layer of the material is sputtered into the cavity (2) ; the microsphere (1) with the cavity (2 ) on the fiber ( 13) is installed in the device for precise removal of particles where the nanoelement (3, 5) is formed by a focused ion beam or in some other way from the sputtered thin layer of material .