JP3023048B2 - Optical fiber probe and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber probe and a method of manufacturing the same, for example, an optical fiber probe used in a photon scanning microscope for measuring the shape of an object by detecting evanescent light localized on the surface of the object. About.

[0002]

2. Description of the Related Art A photon scanning microscope, which measures the shape of an object by detecting evanescent light localized in a region smaller than the wavelength of light on the surface of the object, has an ultra-high resolution with a resolution exceeding the diffraction limit of a conventional optical microscope. Known as a high-resolution optical microscope.

More specifically, as shown in FIG. 6, for example, when the sample surface is irradiated from the back surface of the sample 50 under the condition of total reflection, an evanescent field is generated on the sample surface according to the surface shape. In a photon scanning microscope, a resolution exceeding the diffraction limit of a conventional optical microscope is obtained by measuring the intensity of this evanescent field with an optical probe 52 having a detection end 51 having an opening smaller than the wavelength of evanescent light. be able to.

The resolution of a photon scanning microscope is as follows:
It is determined by the effective aperture diameter of the optical probe. On the other hand, since the intensity of the evanescent field decreases exponentially with the distance from the sample surface, the optical probe
The opening diameter can be equivalently reduced by simply sharpening the tip. Therefore, in order to improve the resolution of the photon scanning microscope, it is important to sharpen the tip of the optical probe.

For this reason, various methods for producing an optical probe having a sharp tip have been attempted. For example, a method of sharpening one end of an optical fiber composed of a core and a clad doped with germanium oxide by etching (H. Pagnia,
J. Radojewski and N. Sotnik: Optik 86 (1990) 87)) and the like.

[0006]

However, the conventional optical fiber probe 52 has a cladding diameter D (90 μm).
m) is much larger than the length L (about 2 to 6 μm) of the detection end 51, so that the peripheral end 53 of the clad is
There is a possibility that the sample and / or the probe itself may be damaged by colliding with zero.

Further, since the output of the evanescent light is extremely small, it is necessary for the optical fiber probe for detecting the evanescent light (power) to avoid the influence of the scattered light and to increase the detection efficiency.

In order to solve this problem, the applicant of the present invention, for example, as shown in FIG. 7, attaches one end of an optical fiber 61 comprising a core 64 and a clad 62 to a base end 63 in which the thickness of the clad 62 is reduced. An optical fiber probe 60 having a detection end 65 with a sharpened core 64 and a method of manufacturing the same have been proposed and filed as Japanese Patent Application No. 5-291829.

This optical fiber has, for example, a cladding 62 diameter of 125 μm, a proximal end 63 diameter d2 of 24 μm and a length L
2, the diameter of the core 64 is 3.4 μm, the tip angle θ of the detection end 65 is 14 degrees, and the length L1 of the detection end 65 is 5 μm.

The optical fiber probe 60 is
Chromium and gold were deposited on the surface to form coating layers 66A and 66B, and a minute opening 67 was formed at the tip of the detection end 65. Further, in order to form a more uniform coating layer, the coating layers 66A and 66B rotate the optical fiber probe 60 around its central axis, for example, and supply vapor such as gold from a direction perpendicular to the central axis. It was created by forming a vapor deposition film on the surface of the optical fiber probe 60.

However, when this vapor deposition method is employed, the upper surface of the base end portion 63 is parallel to the direction in which the vapor is supplied, and it is difficult to form a vapor-deposited film.

The present invention has been made in view of the above-mentioned problems, and an optical fiber probe which has a high detection efficiency and is easy to manufacture without causing the peripheral edge of the clad to collide with the sample surface. The purpose is to provide.

It is another object of the present invention to provide a method for manufacturing an optical fiber probe having a high detection efficiency without causing the clad portion to collide with the sample surface.

[0014]

In order to solve the above-mentioned problems, an optical fiber probe according to the present invention is provided such that one end of an optical fiber comprising a core and a clad is sharpened conically from the outer periphery of the clad to the center of the core. And a detection end portion.

In the optical fiber probe according to the present invention, the core is made of quartz doped with germanium oxide,
The clad is made of quartz.

Further, the optical fiber probe according to the present invention is characterized in that a light-shielding coating layer is provided at the detection end, and a minute opening smaller than the wavelength of the detection light is provided at the tip of the detection end. I do.

The optical fiber probe according to the present invention is characterized in that the light-shielding coating layer is made of gold.

Further, in the method of manufacturing an optical fiber probe according to the present invention, one end of an optical fiber composed of a quartz core and a quartz clad doped with germanium oxide at a high concentration is made of hydrofluoric acid or an aqueous solution of ammonium fluoride, hydrofluoric acid and water. A first etching step of forming a tapered portion in the clad by etching at an interface between an etching solution and a fluid having a lower specific gravity than the etching solution, and etching the tapered portion with hydrofluoric acid to form a core at the tip of the tapered portion of the clad. A second etching step of forming a recessed recess, and a flat portion in which the tapered portion is etched with an etching solution composed of an aqueous solution of ammonium fluoride, hydrofluoric acid and water to make the tip of the core flush with the tip of the tapered portion. A third etching step for forming a film, and forming the tapered portion from an aqueous solution of ammonium fluoride, hydrofluoric acid and water. By etching with an etching solution, characterized in that a fourth etching step of forming a detecting end which is sharpened conically toward the center of the core from the outer periphery of the cladding.

In the method of manufacturing an optical fiber probe according to the present invention, the etching solution has a volume ratio of an aqueous solution of ammonium fluoride having a concentration of 40% by weight, a hydrofluoric acid having a concentration of 50% by weight, and water having a volume ratio of X: 1: Y. (Y = arbitrary), and in the fourth etching step, etching is performed with an etchant satisfying X ₄ > 1.7.

Further, the method of manufacturing an optical fiber probe according to the present invention comprises a coating step of coating a detection end with gold and then providing a fine opening smaller than the wavelength of the detection light at the tip of the detection end. Features.

In the method of manufacturing an optical fiber probe according to the present invention, in the coating step, the optical fiber probe is rotated about its central axis, and gold vapor is supplied from the side of the detection end or obliquely below. The detection end is coated with gold, and the tip of the detection end is formed as a minute opening.

Further, in the method of manufacturing an optical fiber probe according to the present invention, one end of an optical fiber comprising a quartz core and a quartz clad doped with germanium oxide at a low concentration is made of hydrofluoric acid or an aqueous solution of ammonium fluoride, hydrofluoric acid and water. A first etching step of forming a tapered portion on the clad by etching at an interface between an etching solution and a fluid having a lower specific gravity than the etching solution, and etching the tapered portion with an etching solution comprising an aqueous solution of ammonium fluoride, hydrofluoric acid and water And a second etching step of forming a conical sharpened detection end from the outer periphery of the clad to the center of the core.

Further, in the method of manufacturing an optical fiber probe according to the present invention, one end of an optical fiber comprising a quartz core and a quartz clad doped with germanium oxide at a high concentration is made of hydrofluoric acid or an aqueous solution of ammonium fluoride, hydrofluoric acid and water. Etching at the interface between the resulting etchant and a fluid having a lower specific gravity than the etchant to form a base end with a reduced clad diameter at one end of the optical fiber and a taper at the base end of the base end. A first etching step to be formed, a base end portion being cut off at the base end, a break-off step, and a taper portion being etched with an etching solution composed of an aqueous solution of ammonium fluoride, hydrofluoric acid and water to form a core from the outer periphery of the clad. A fourth etching step of forming a detection end portion which is sharpened conically toward the center.

[0024]

In the optical fiber probe according to the present invention, one end of the optical fiber comprising the core and the clad has a detection end which is sharpened conically from the outer periphery of the cladding to the center of the core. Function as a detection unit for detecting

Further, in the optical fiber probe according to the present invention, the light-shielding coating layer provided on the surface of the detection end functions as a light-shielding portion for blocking light. The detection light having a wavelength close to the size of the light is selectively taken in.

In the method of manufacturing an optical fiber probe according to the present invention, in the first etching step, one end of an optical fiber composed of a quartz core and a quartz clad doped with germanium oxide at a high concentration is connected to an aqueous solution of hydrofluoric acid or ammonium fluoride. A taper portion is formed in the clad by etching at an interface between an etching solution composed of hydrofluoric acid and water and a fluid having a lower specific gravity than the etching solution. In the second etching step, the taper portion is etched with hydrofluoric acid to form a core. In the third etching step, the tapered portion is etched with an etching solution composed of an aqueous solution of ammonium fluoride, hydrofluoric acid, and water to form a concave portion depressed with respect to the tip of the clad of the tapered portion. Form a flat part with the tip flush, and in the fourth etching step, taper Part of the aqueous solution of ammonium fluoride, to form a detectable end which is sharpened conically toward the center of the core from the outer periphery of the cladding is etched with an etching solution composed of hydrofluoric acid and water.

In the method for manufacturing an optical fiber probe according to the present invention, in the coating step, the optical fiber probe is rotated about its central axis,
Gold vapor is supplied from the side surface of the detection end or obliquely downward to coat gold on the side surface of the detection end to form a coating layer, and the tip of the detection end is made a minute opening.

In the method for manufacturing an optical fiber probe according to the present invention, in the first etching step, one end of an optical fiber composed of a quartz core and a quartz clad doped with germanium oxide at a low concentration is connected to an aqueous solution of hydrofluoric acid or ammonium fluoride. , cladding to form a tapered portion by etching at the interface between the specific gravity lighter fluid from the etching solution and the etching solution composed of hydrofluoric acid and water, in the second etching step <br/>, aqueous ammonium fluoride a tapered portion Then, a conical sharpened detection end is formed from the outer periphery of the clad to the center of the core by etching with an etching solution comprising hydrofluoric acid and water.

In the method for manufacturing an optical fiber probe according to the present invention, in the first etching step, one end of an optical fiber composed of a quartz core and a quartz clad doped with germanium oxide at a high concentration is connected to an aqueous solution of hydrofluoric acid or ammonium fluoride. Etching at the interface between an etchant comprising hydrofluoric acid and water and a fluid having a lower specific gravity than the etchant to form a base end with a reduced cladding diameter at one end of the optical fiber, and A taper portion is formed at an end, and in a folding step, a first etching step and a base end portion are cut off at the base end. In a fourth etching step, the taper portion is made of an aqueous solution of ammonium fluoride, hydrofluoric acid, and water. Etching is performed with an etchant to form a conically sharpened detection end from the outer periphery of the clad to the center of the core.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an optical fiber probe and a method of manufacturing the same according to the present invention will be described below in detail with reference to the drawings.

The optical fiber probe according to the present invention is, for example,
For example, as shown in FIG. _c The cladding diameter is
d₀ From one end of the cladding 3 to one end of the optical fiber 1
The tip angle which is sharpened conically toward the center of 2 is θ
It has a detection end 4. Specifically, for example, core 2 diameter
d_c Is 3.4 μm and the cladding diameter d₀ Is 125 μm
And the tip angle θ of the detection end 4 is 25 degrees,
The radius of curvature at the end is 10 nm or less. Also, optical fiber
1 is made of germanium oxide GeO._Two Stone with added
English SiO_Two And the cladding 3 is made of quartz SiO_Two From
Become.

Optical fiber probe 10 having such a structure
In the embodiment, the detection end 4 functions as a detection unit that detects evanescent light. As a result, an optical fiber probe with high detection efficiency is obtained without the peripheral end of the clad colliding with the sample surface.

Here, a method of manufacturing the optical fiber probe according to the present invention will be described. Germanium oxide GeO
_A core 2 made of quartz SiO ₂ added with
The end face of the cladding 3 made of O ₂ is added to a buffered hydrofluoric acid solution having a volume ratio of X: 1: Y (Y = arbitrary) composed of an aqueous solution of ammonium fluoride having a concentration of 40% by weight, hydrofluoric acid having a concentration of 50% by weight, and water. When placed in contact _{with, SiO 2: SiO 2 + 6HF} → H 2 SiF 6 + 2H 2 O H 2 SiF 6 + 2NH 3 → (NH 4) 2 SiF 6 GeO 2: GeO 2 + 6HF → H 2 GeF 6 + 2H 2 The cladding 3 and the core 2 are etched by a chemical reaction of OH ₂ GeF ₆ + 2NH ₃ → (NH ₄ ) ₂ GeF ₆ .

The core 2 made of quartz to which germanium oxide GeO ₂ is added and the clad 3 made of quartz have a difference in the dissolution rate in the buffered hydrofluoric acid solution. The difference between the dissolution rates of the core 2 and the clad 3 has a strong correlation with the volume ratio X of ammonium fluoride, and although there is some variation depending on the temperature of the solution, X = about 1.5 to 1.7, The dissolution rate of the clad 3 is substantially equal, and when X <1.5 (or X <1.7), the dissolution rate of the core 2 is relatively high, and X>
At 1.5 (or X> 1.7), the dissolution rate of the cladding 3 is relatively high. Therefore, by using this buffered hydrofluoric acid solution as an etchant, the core 2 and the clad 3 can be selectively etched.

In the following, the clad diameter d ₀ is 125 μm, the core diameter d _c is 3.4 μm, and the germanium oxide GeO in the core is
_The case of using an optical fiber having a relatively high addition rate of 25% by mole is described.

That is, in this method of manufacturing an optical fiber probe, in the first etching step, one end 20 of the optical fiber 1 shown in FIG. 2A is made of hydrofluoric acid and a liquid having a lower specific gravity than hydrofluoric acid, for example, spindle oil, silicon oil or the like. At the interface of, for example, etching is performed for about 25 to 30 minutes to form a tapered portion 21 in the clad 3 as shown in FIG. 2B, for example.

In the second etching step, the tapered portion 21 is etched with hydrofluoric acid, for example, for about 2 to 3 minutes, so that, for example, as shown in FIG. A concave portion 22 is formed.

Further, in the third etching step, the taper portion 21 is made to have a volume ratio X of ammonium fluoride NH ₄ F.
Is 1.5 to 1.7 and the volume ratio Y of water is 1 (or
An etching solution composed of a buffered hydrofluoric acid solution having a volume ratio of 5: 1: 10, for example, for about 30 minutes to 50 minutes (in the case of a volume ratio of the etching solution of 5: 1: 10, for example, 60 minutes)
2D to about 90 minutes) to form a flat portion 23 in which the tip of the core 2 and the tip of the tapered portion 21 are flat as shown in FIG. 2D, for example.

In the fourth etching step, the tapered portion 21 is etched with, for example, a buffered hydrofluoric acid solution having a volume ratio X of ammonium fluoride NH ₄ F of 5 for about 60 to 90 minutes, for example. For example, as shown in FIG. 2E, a detection end 4 which is sharpened conically from the outer periphery of the clad 3 to the center of the core 2 is formed.

Here, the first etching step will be described in detail. Near the interface between hydrofluoric acid and spindle oil or silicon oil, the concentration of hydrofluoric acid changes continuously, and the concentration gradient changes the etching rate. That is, the concentration of hydrofluoric acid is almost 0 near the interface, and the concentration of hydrofluoric acid increases toward hydrofluoric acid. Therefore, the etching rate near the interface is almost 0, and the etching rate increases toward hydrofluoric acid.

At such an interface of hydrofluoric acid, the optical fiber 1
Is etched, at a position where the concentration of hydrofluoric acid is at a normal level, the diameter of the clad 3 is reduced while the optical fiber 1 keeps the cylindrical shape, but the concentration of hydrofluoric acid is almost 0 near the interface. Therefore, the etching rate becomes almost 0, and the diameter of the clad 3 does not decrease. When the etching is performed until the columnar portion is completely melted, the conical tapered portion 21 is formed at one end of the optical fiber 1 as described above.

Generally, near the interface of hydrofluoric acid, the concentration of hydrofluoric acid is continuously changing, so that the above-mentioned first etching step can be performed. Exists, and the optical fiber 1 is etched by the vapor. Therefore, in this embodiment, the etching in the first etching step is performed at the interface between hydrofluoric acid and spindle oil or silicon oil.

[0043] Further, the optical fiber 1 has a high addition rate of oxidation in the core 2 Germanium GeO ₂ (25 mol%), the etching rate of the core 2 in a hydrofluoric acid, the etching rate of the cladding 3 Very fast.

In the first etching step, since the etching was performed at the interface between hydrofluoric acid and spindle oil or silicon oil, the tapered portion 21 was formed as described above, and the clad 3 ahead of the tapered portion 21 was completely etched. After that, the core 2 before the tapered portion 21 was etched. However, in the second etching step,
The tapered portion 21 was etched in hydrofluoric acid.
Is etched first to form a recess 22 in which the core 2 is recessed with respect to the tip of the clad 3 of the tapered portion 21 as described above.

In the third etching step, the flat portion 2 flush with the recess 22 is formed at the tip of the clad 3 of the tapered portion 21.
In order to form the cladding 3, it is necessary to selectively etch the cladding 3.
Ammonium Fluoride N Higher Etching Rate
When the volume ratio X of H ₄ F is 1.5 to 1.7 and the volume ratio Y of water is Y
The etching is performed using an etching solution having a value of 1.

When etching is performed in this third etching step using an etching solution having a volume ratio of 5: 1: 10, the cladding 3 is relatively slow in the third etching step because the etching rate of the cladding 3 is relatively low. Can be reduced.

Further, since the etching rate of the core 2 depends on the distribution (amount) of germanium oxide GeO ₂ , in the etching solution of X = 5 in the fourth etching step, the germanium oxide GeO ₂ near the center of the core 2 is removed. The etching rate is high because the amount is large, and the etching rate is low near the periphery of the core 2 because the amount of germanium oxide GeO ₂ is small. As a result, in the fourth etching step, a conical sharpened detection end portion 4 is formed from the outer periphery of the clad 3 to the center of the core 2.

The tip angle θ of the detection end 4 formed in the fourth etching step depends on the distribution of germanium oxide GeO _{2 in} the core 2 and the ammonium fluoride N in the etching solution.
It depends on the volume ratio X of H ₄ F. For this reason, in the fourth etching step, etching is performed using an etching solution having a volume ratio X of ammonium fluoride NH ₄ F of 5 to set the tip angle θ to 25 degrees, for example.

Thus, for example, the optical fiber probe 10 having the structure shown in FIG. 1 is formed. As a result, in this method of manufacturing an optical fiber probe, the shape of the detection end 4 is determined depending on the distribution of germanium oxide GeO ₂ , so that a conical shape with high reproducibility and good symmetry can be formed. it can.

Then, this optical fiber probe 10 is
For example, when used as an optical probe for detecting evanescent light in a photon scanning microscope, the peripheral end of the clad does not collide with the sample surface, and functions as an optical probe with high detection efficiency.

In the above-described embodiment, in the first etching step, etching was performed at the interface between hydrofluoric acid and spindle oil or silicon oil. Even if etching is performed at the interface with the spindle oil or the silicon oil, the tapered portion 21 can be formed similarly.

[0052] In this case, the temperature of the etchant from 6 0 degrees to 90 degrees, for example, for 20 minutes to about 4 0 min etching, etching effect comparable when using hydrofluoric acid. That is, an etching rate similar to that in the case of using hydrofluoric acid can be obtained, and the etching is not hindered by impurities of silicon oil and the like, and the surface of the formed tapered portion 21 becomes smooth.

In an optical fiber probe for detecting evanescent light in a photon scanning microscope, a light-shielding coating layer is provided other than at the end of the detection end in order to reduce the influence of scattered light and improve detection efficiency. Is desirable. Gold is known to have high light-blocking properties and to be hardly oxidized. Furthermore, gold is a promising coating layer because it can effectively control thermal radiation and reduce the effects of temperature fluctuations. However, it hardly adheres to quartz glass, and even if it is directly coated on the tip of an optical fiber, it has a thickness of 10 nm. It is difficult to coat uniformly with the above thickness, and it is conceivable that it will fall off easily.

Therefore, in the optical fiber probe according to the present invention, as shown in FIG. 3, for example, a first coating layer 5A made of chromium and a second coating layer 5B made of gold are provided on the detection end 4 and the detection is performed. A minute opening 6 smaller than the wavelength of the detection light is provided at the end of the end 4. By providing the first coating layer 5A made of chromium, the second coating layer 5B made of gold is formed uniformly and stably.

In the above embodiment, the second coating layer 5
Although gold was used as B, the second coating layer 5B may be, for example, aluminum, silver, or the like as long as it is a light-shielding material.
In the above-described embodiment, chromium is used as the first coating layer 5A. However, the first coating layer 5A easily adheres or adheres to quartz glass, and the material used for the second coating layer 5B adheres. Alternatively, any material that can be easily adsorbed may be used.

Further, for example, between the first etching step and the second etching step, etching for adjusting the angle of the tip of the tapered portion 21 and the variation in shape may be performed. As a result, even if the tapered portion 21 formed in the first etching step has a variation in shape, an optical fiber probe having a uniform shape can be finally formed.

Further, for example, in the above-described first etching step, the etching is terminated before the core 2 and the clad 3 at the tip of the tapered portion 21 are completely melted, and the diameter of the clad is reduced at the tip of the tapered portion 21. After the formed base end (not shown) is left, the base end is cut off as a cut-off step instead of the above-described second and third etching steps, and then the etching in the fourth etching step is performed. Is performed, a conical detection end 4 can be formed in the same manner as described above.

In the optical fiber probe 15 having the structure shown in FIG. 3, the coating layer 5 on the surface of the detection end 4 is provided.
Functions as a light-shielding portion that blocks light, and can selectively take in detection light having a wavelength close to the size of the minute opening from the minute opening 6 at the tip of the detection end portion 4.

In this case, in the method of manufacturing an optical fiber probe according to the present invention, as shown in FIG. 4, for example, the optical fiber probe 15 is rotated about a central axis thereof in a vacuum using a vacuum evaporation apparatus, and Chromium or gold vapor 30 from the direction perpendicular to the axis or obliquely below the detection end 4
Is supplied and vapor-deposited, so that the coating layer 5
A and 5B are formed. In addition, since the shape of the optical fiber probe is conical, chromium or gold vapor is easily deposited on the surface of the detection end portion 4, and the coating layers 5A and 5B can be formed in a short time. No covering layer is formed at the tip of the detection end 4, and a minute opening 6 is formed.

As a result, for example, an optical fiber probe having the structure shown in FIG. 3 described above is formed, and a coating layer is easily formed on the side surface of the detection end 4 and a minute opening 6 is formed at the tip of the detection end 4. can do. In the optical fiber probe manufactured in this manner, the detection light is taken in only from the minute aperture 6 provided at the tip of the detection end portion 4, so that the effect of the scattered light can be reduced and the detection efficiency can be increased, and the power can be increased. Extremely small evanescent light can be reliably detected.

On the other hand, after the optical fiber 1 is etched to form the detection end 4 by the above-described optical fiber probe manufacturing method shown in FIG. 2, the volume ratio is further increased to 10: 1: 1.
60 minutes to 12 minutes with an etching solution consisting of buffered hydrofluoric acid solution
By performing the etching for about 0 minutes, for example, as shown in FIG. 5, an optical fiber probe 40 having a sharpened portion 4A in which the tip of the core 2 of the detection end portion 4 is sharpened can be produced. That is, according to this method, the optical fiber probe 40 having a high aspect ratio (the tip angle θ is small) can be formed, and the resolution can be improved.

In this method, since the sharp portion 4A is formed at the tip of the core 2 by etching for a relatively long time of about 60 to 120 minutes, the shape of the optical fiber 1 before etching may vary. The effect can be reduced.

In addition, the first etching step of the etching method shown in FIG.
Of the optical fiber probe having the volume ratio of 10: 1:
By etching for 1 hour and 30 minutes with an etching solution composed of the buffered hydrofluoric acid solution, the optical fiber probe 40 having a thin sharpened portion 4A in which the tip of the core 2 of the detection end portion 4 is sharpened in the same manner as described above. Can be created. However, in this case, there are problems that the sharp portion 4A is broken during etching, the radius of curvature at the tip becomes large, and the reproducibility is poor.

[0064] Further, although in the above description it has been described a case where the addition rate of the germanium oxide GeO ₂ in the core 2 with 25 mol% of the optical fiber, the addition rate of the germanium oxide GeO ₂ in the core 2 is 3. Even if an optical fiber having a relatively low addition rate of 6 mol% is used, the optical fiber probe having the conical detection end portion 4 shown in FIG. 1 can be manufactured.

In this case, since the dissolution rates of the core 2 and the clad 3 in the buffered hydrofluoric acid solution are close to each other, the etching cannot be selectively performed by the four-step etching shown in FIG.

That is, in this method of manufacturing an optical fiber probe, in the first etching step, the above-described FIG.
Is etched at the interface between hydrofluoric acid and a liquid having a lower specific gravity than hydrofluoric acid, for example, silicon oil, to form a tapered portion 21 in the cladding 3 as shown in FIG. 2B, for example.

In the second etching step, the optical fiber having the tapered portion 21 formed at the tip is etched with an etching solution having a buffer hydrofluoric acid solution volume ratio of 1.5 to 1.7: 1: 1.

As a result of the experiment, as in the case of the optical fiber probe shown in FIG. 1 described above, the detection end was sharpened in a conical shape from the outer periphery of the clad 3 to the center of the core 2 by etching for one hour in the second etching step. The part 4 can be formed.

The optical fiber probe according to the present invention is not limited to the optical probe in the above-described photon scanning microscope, and, for example, a light from an optical fiber is incident on an optical waveguide or the like, so that the optical coupling efficiency is high. It can also be used as a coupling device.

[0070]

As is apparent from the above description, according to the present invention, one end of the optical fiber composed of the core and the clad has a conical sharpened detection end from the outer periphery of the clad to the center of the core. Since the detection end functions as a detection unit for detecting evanescent light, an optical fiber probe that can be easily manufactured can be provided without the peripheral end of the clad colliding with the sample surface.

Further, in the present invention, the light-shielding coating layer provided on the surface of the detection end functions as a light-shielding part for blocking light, and the light-shielding coating layer provided at the tip of the detection end has a small aperture smaller than the wavelength of the detection light. By selectively capturing detection light having a wavelength close to the size of the minute aperture, an optical fiber probe with high detection efficiency can be provided.

In the present invention, since the light-shielding coating layer is made of gold, it is possible to provide an optical fiber probe in which the coating layer is hardly oxidized.

In the method of manufacturing an optical fiber probe according to the present invention, in the first etching step, one end of an optical fiber composed of a quartz core and a quartz clad doped with germanium oxide at a high concentration is connected to an aqueous solution of hydrofluoric acid or ammonium fluoride. A taper portion is formed in the clad by etching at an interface between an etching solution composed of hydrofluoric acid and water and a fluid having a lower specific gravity than the etching solution. In the second etching step, the taper portion is etched with hydrofluoric acid to form a core. In the third etching step, the tapered portion is etched with an etching solution composed of an aqueous solution of ammonium fluoride, hydrofluoric acid, and water to form a concave portion depressed with respect to the tip of the clad of the tapered portion. Form a flat part with the tip flush, and in the fourth etching step, taper The part is etched with an etching solution consisting of an aqueous solution of ammonium fluoride, hydrofluoric acid, and water to form a conical sharpened detection end from the outer periphery of the clad to the center of the core. An optical fiber probe having high detection efficiency can be easily manufactured without colliding with the optical fiber probe.

In the method of manufacturing an optical fiber probe according to the present invention, in the coating step, the optical fiber probe is rotated around its central axis,
By supplying gold vapor from the side of the detection end or obliquely below and coating the side of the detection end with gold to form a coating layer, and by making the tip of the detection end a minute opening,
A uniform coating layer can be formed, and minute openings can be easily formed.

In the method for manufacturing an optical fiber probe according to the present invention, in the first etching step, one end of an optical fiber composed of a quartz core and a quartz clad doped with germanium oxide at a low concentration is connected to an aqueous solution of hydrofluoric acid or ammonium fluoride. , cladding to form a tapered portion by etching at the interface between the specific gravity lighter fluid from the etching solution and the etching solution composed of hydrofluoric acid and water, in the second etching step <br/>, aqueous ammonium fluoride a tapered portion Using an optical fiber doped with germanium oxide at a low concentration in the core, by etching with an etchant consisting of hydrofluoric acid and water to form a conical sharpened detection end from the outer periphery of the clad to the center of the core The edge of the cladding does not collide with the sample surface and the optical fiber The chromatography Bed can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of an optical fiber probe to which the present invention is applied.

FIG. 2 is a diagram for explaining a method of manufacturing an optical fiber probe according to the present invention.

FIG. 3 is a diagram showing a structure of another optical fiber probe to which the present invention is applied.

FIG. 4 is a diagram for explaining a specific coating process.

FIG. 5 is a diagram showing a structure of another optical fiber probe to which the present invention is applied.

FIG. 6 is a diagram schematically illustrating the principle of a photon scanning microscope.

FIG. 7 is a diagram showing a structure of a conventional optical fiber probe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Core 3 Cladding 4 Detecting end 4A Sharp part 5A First coating layer 5B Second coating layer 6 Micro opening 10, 15, 40 Optical fiber probe 20 One end 21 Tapered part 22 Concave part 23 Flat part 30 Metal particles (steam)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G02B 6/00 301 G02B 6/44 396 6/10 21/00 6/44 396 C03C 25/06 21/00 G02B 6/00 B (58) Field surveyed (Int. Cl. ⁷ , DB name) G01B 11/00-11/30 G01N 37/00

Claims (10)

(57) [Claims] 1. An optical fiber probe comprising: an end of an optical fiber comprising a core and a clad; and a detection end which is sharpened conically from the outer periphery of the clad to the center of the core. 2. The optical fiber probe according to claim 1, wherein said core is made of quartz to which germanium oxide is added, and said cladding is made of quartz. 3. The optical fiber according to claim 1, wherein a light-shielding coating layer is provided on the detection end, and a minute aperture smaller than the wavelength of the detection light is provided at a tip of the detection end. probe. 4. The optical fiber probe according to claim 3, wherein said light-shielding coating layer is made of gold. 5. An etching solution comprising an aqueous solution of hydrofluoric acid or ammonium fluoride, an aqueous solution of hydrofluoric acid and water, and a fluid having a specific gravity lower than that of said etching solution. A first etching step of forming a tapered portion in the clad by etching at an interface with the substrate, and a second etching of etching the tapered portion with hydrofluoric acid to form a recess in which the core is recessed with respect to the tip of the clad in the tapered portion. A third etching step of etching the tapered portion with an etchant comprising an aqueous solution of ammonium fluoride, hydrofluoric acid, and water to form a flat portion in which the tip of the core and the tip of the tapered portion are flush with each other; The tapered part is etched with an etching solution consisting of an aqueous solution of ammonium fluoride, hydrofluoric acid, and water to And a fourth etching step of forming a conically sharpened detection end from the outer periphery of the core to the center of the core. 6. The etching solution according to claim 1, wherein the etching solution comprises an aqueous solution of ammonium fluoride having a concentration of 40% by weight, hydrofluoric acid having a concentration of 50% by weight and water having a volume ratio of X: 1: Y (Y = arbitrary). manufacturing method of the fourth optical fiber probe according to claim 5, wherein in the etching step and performing etching with an etching solution of X _4> 1.7. 7. The optical fiber probe according to claim 5, further comprising a coating step of coating the detection end with gold and then providing a fine aperture smaller than the wavelength of the detection light at the tip of the detection end. Manufacturing method. 8. The coating step includes rotating the optical fiber probe about its central axis and supplying gold vapor from the side surface or obliquely below the detection end to coat the detection end with gold. 8. The method for manufacturing an optical fiber probe according to claim 7, wherein the tip of the detection end is a minute opening. 9. An etching solution comprising hydrofluoric acid or ammonium fluoride aqueous solution, hydrofluoric acid and water, and a fluid having a specific gravity lower than the etching solution, wherein one end of an optical fiber comprising a quartz core and a quartz cladding doped with germanium oxide at a low concentration is added. A first etching step of forming a tapered portion in the clad by etching at an interface with the substrate, and etching the tapered portion with an etching solution comprising an aqueous solution of ammonium fluoride, hydrofluoric acid and water to form a cone from the outer periphery of the clad to the center of the core A second etching step of forming a sharpened detection end. 10. An optical fiber comprising a quartz core and a quartz clad doped with germanium oxide at a high concentration, and one end of an optical fiber comprising an aqueous solution of hydrofluoric acid or ammonium fluoride, hydrofluoric acid and water, and a fluid having a specific gravity lower than that of the etching solution. A first etching step of forming a base end with a reduced cladding diameter at one end of the optical fiber and forming a tapered portion at the base end of the base end by etching at an interface with the base end; The taper portion is etched with an etchant comprising an aqueous solution of ammonium fluoride, hydrofluoric acid and water, and the detection end is sharpened conically from the outer periphery of the clad to the center of the core. And a fourth etching step of forming a portion.