JP2003020258A - Method and device for processing fine cavity in transparent dielectric material by use of light - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for processing a fine cavity by the use of light, by which a long hole having a diameter of from several tens of micron to submicron can be formed in a transparent dielectric material. SOLUTION: In the device for processing the fine cavity in the transparent dielectric material by the use of light, the transparent dielectric material 5, a liquid 6 being brought into contact with an end face of the transparent dielectric material 5, an ultrashort light pulse irradiation means 1 capable of irradiating from an interface between the end face of the transparent dielectric material 5 and the liquid 6 to the other end face of the transparent dielectric material 5 while scooching, and an imaging means 9 for imaging the processed conditions of the fine cavity formed by the ultrashort light pulse irradiation are provided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a transparent dielectric material such as glass, which has a diameter of several tens of microns (μ) by using an ultrashort optical pulse.
m) to a microcavity processing method and apparatus for manufacturing a long hole with a submicron diameter, and more particularly to a method for manufacturing a hole having an aspect ratio of the depth and the diameter of more than 10, a nonlinear optical waveguide or a photonic device. It is used for the production of crystals, microfluidics (microfluidics control) and the like.

[0002]

2. Description of the Related Art At present, a technique for making a hole of 100 μm or less in a metal or a dielectric by using a high intensity femtosecond laser processing technique is used for various purposes. Since this technique is based on laser ablation, the edge portion of the hole can be machined cleanly. However, the depth and diameter aspect ratios of the holes are up to 5, and deep holes cannot be processed.

The following are examples of such conventional techniques. (1) "Applied Physics Vol. 67, No. 9, pp1051-
1055 (1998) ”, there is reported a technique for forming a hole in molten glass by using a laser. (2) "Varel et al. Applied Physi
cs A65 pp367-373 (1997) ”, long holes are formed by a femtosecond laser beam in a vacuum or a nitrogen atmosphere. Its purpose is to make microchanneling. However, since this method is drilling by laser ablation, many cracks occur and the formation of holes is not smooth. In addition, the hole shape is basically conical.

Further, in the following document, a solution is attached to the back surface, laser light is irradiated through glass, and holes are formed. It is a large hole drilling by converting light energy into heat. (3) “Ikeno et al., Journal of Japan Society for Precision Machining 55/2/1989”
In order to fabricate a three-dimensional optical waveguide or a three-dimensional photonic crystal, thin film formation, lithography,
A method is described in which a two-dimensional structure is formed by etching, and the two-dimensional structure is repeatedly laminated to form a three-dimensional structure. However, this method is time-consuming and costly because an expensive semiconductor process is used.

As described above, according to the conventional method for producing a three-dimensional optical waveguide or a three-dimensional photonic crystal, a two-dimensional structure is produced by forming a thin film for each layer, lithography, etching, etc., and repeating the lamination. This is a complicated process.
In addition, there are surface modification and drilling of the transparent dielectric with a high-intensity femtosecond laser, but it is not possible to drill holes with a small diameter. The present inventors have proposed a method for producing a waveguide by changing the induced refractive index with a femtosecond laser, and obtained the present invention as a result of further research.

[0006] Other proposals in this field include JP-A-2000-314817 and JP-A-2001-83347.

[0007]

As described above, according to the conventional technique, a long hole having a diameter of several tens of microns to a submicron is manufactured in a transparent dielectric such as glass by using an ultrashort laser beam. A method for processing fine cavities has not been proposed, and in particular, a method for manufacturing a hole having an aspect ratio of depth and diameter of more than 10 has not been developed.

In view of such a situation, the present invention provides a method for processing a fine cavity in a transparent dielectric object using light capable of forming a long hole with a diameter of several tens of microns to a submicron, and The purpose is to provide the device.

[0009]

In order to achieve the above object, the present invention provides: [1] In a method of processing a fine cavity in a transparent dielectric object using light, liquid is applied to an end surface of the transparent dielectric object. It is characterized in that they are brought into contact with each other, and an ultrashort light pulse is focused and irradiated from the opposite end face from the transparent dielectric object to the end face to perform fine cavity processing.

[2] In the method for processing a minute cavity in a transparent dielectric object using light as described in [1] above, the entire length of the cavity is determined by applying an ultrashort optical pulse to the tip of the formed cavity again. It is characterized in that the light is focused and irradiated, and it is repeated a plurality of times.

[3] In the method for processing a fine cavity in a transparent dielectric object using light as described in [1] above, the cavity is
The diameter is 0.1 μm to several tens of μm, and the length is several tens μm to several mm.

[4] In the method for processing fine cavities in a transparent dielectric body using light as described in [1] above, the transparent dielectric body is silica glass.

[5] In the method for processing fine cavities in a transparent dielectric object using light as described in [1] above, the liquid is water.

[6] In the method for processing a fine cavity in a transparent dielectric body using light as described in [1] above, the ultrashort optical pulse is a titanium sapphire laser and has a wavelength of 800 nm.

[7] In a microcavity processing apparatus for a transparent dielectric object using light, a transparent dielectric object, a liquid that contacts an end surface of the transparent dielectric object, and the end surface of the transparent dielectric object. And an image for imaging the processing state of the microcavity formed by the irradiation of the ultrashort light pulse, starting from the boundary surface of the liquid and the liquid, and irradiating the end surface opposite to the end surface by shifting the irradiation. And a conversion means.

According to the present invention, as described above, a liquid is brought into contact with the end surface of the transparent dielectric body, and an ultrashort light pulse is focused and irradiated from this transparent dielectric body to the end surface from the opposite end surface. Is from 0.1 μm to several tens of μm, and length is several tens of μ
A cavity of m to several mm is formed. The ablated debris pops out due to the liquid. The entire length is again focused by irradiating the other end of the formed cavity with an ultrashort light pulse,
Achieve multiple times.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view of an apparatus for processing a fine cavity in a transparent dielectric object using light, showing an embodiment of the present invention.

In this figure, 1 is a titanium sapphire laser, 2 is a shutter, 3 is a density filter, 4 is a first objective lens, 5 is quartz glass (sample), 6 is water (distilled water), and 7 is illumination light. Is a halogen lamp, 8 is a second objective lens, and 9 is a CCD camera.

Here, the laser pulse of 120 fs, 800 nm, 1 kHz emitted from the titanium sapphire laser 1 propagates along the optical axis (+ z direction). The quartz glass 5 has a thickness of 1 mm, and its end face is in contact with the water 6. Both surfaces of the quartz glass 5 were optically polished for in-situ observation. Then, the optical image of the hole was observed using a semi-transmission optical microscope.

First, an ultrashort light pulse is focused on the end face of the quartz glass 5 (the first shot is the boundary face between the water 6 and the quartz glass 5) by the objective lens 4 of the microscope having a numerical aperture of 0.55. . Next, the quartz glass 5 was displaced in the + z direction to slowly move the condensing point toward the end face opposite to the end face.

The exposure time of the shutter 2 was set to 1/63 seconds. Since the shutter 2 was opened 3 times at one focal point,
The total number of pulses is 3 x (1/63) x 1000-48. Since the occurrence of ablation was limited to the region near the converging point, the quartz glass 5 was gradually displaced to form a long hole. Further, the focal point was moved to the next focal point by 1 μm every 49 pulses.

[Experimental Results] There is water on the end surface of the quartz glass,
Drilling was done both without water. As the intensity of pulse energy increased, the hole depth increased and the diameter increased.

FIG. 2 shows three holes having a diameter of 4 μm formed in the end surface of quartz glass without water. The pulse energy was about 1 μJ. From this figure, it can be observed that the holes stop near a depth of 12 μm. It is thought that the main cause is that it is difficult for the debris to be completely discharged from the small hole in the air, so that the ablated debris is redeposited on the wall of the hole. The processing condition after that point was similar to the movement of voids in the quartz glass.

Water is used in the present invention in order to minimize the influence of redeposition as described above. This caused most of the debris to disperse in the water, greatly reducing redeposition,
The hole depth has increased. As shown in FIG. 3, water can be observed to flow into the holes and mix with the ablation debris while the holes extend toward the front surface. At the same time, the quality of the holes has improved.

However, as the depth of the hole became longer, the amount of water decreased, the amount of debris at the tip of the hole increased, and redeposition was clearly observed. As a result, as shown in FIG.
At around μm, the holes stopped. However, stronger energy can be used to create deeper, larger diameter holes.

FIG. 5 shows a 21 μm diameter, 750 μm long hole opened using a pulse of about 3 μJ.

As described above, in order to reduce the dust caused by ablation, a highly accurate hole was made from the end face of the quartz glass by a femtosecond infrared laser pulse using water. The long holes with the smallest diameter formed using the present invention had well-defined walls and no clear conical shape was seen at the hole tips.

As described above, according to the present invention, a liquid is brought into contact with the end surface of the transparent dielectric body, and the end surface of the transparent dielectric body is focused and irradiated with an ultrashort light pulse.
This is a method of forming a cavity having a size of μm and a length of several tens of μm to several mm. More specifically, water droplets are attached to the end surface of the quartz glass, and a titanium sapphire laser with a wavelength of 800 is applied from the opposite side.
Concentrated irradiation at nm, 120 fs, 0.2 to 0.4 mW causes the ablated glass debris to jump out into the water, reducing redeposition of debris and forming highly accurate holes. Further, by irradiating the other end of the hole with a laser, the hole can be lengthened.

In this manner, a hole having a hole diameter of 21 μm and a length of 750 μm was formed with an energy of 3 μJ. Without water, the length is up to 20 μm. Furthermore, it is also possible to bend in the lateral direction from the middle.

According to the present invention, an optical waveguide, a photonic crystal, or a micro electric circuit made of a conductive substance can be formed by encapsulating substances having different refractive indexes in the holes. further,
In recent years, attempts have been made to create a micro-integrated chemistry laboratory that is 1 / 10,000,000 of the human scale in a glass chip of several centimeters square, but it can be applied to the microfluidics here.

The present invention can be applied as follows.

(1) An optical waveguide can be constructed by filling a substance (liquid) having an appropriate refractive index inside.

(2) A non-linear optical waveguide can be constructed by filling the inside with a substance (liquid) having an appropriate non-linear refractive index.

(3) A conductive path can be formed by filling the inside with a conductive substance.

(4) A photonic crystal can be formed by arranging them in an array.

(5) As a three-dimensional microchannel,
For example, capillary electrophoresis, icrofluidics (microfluidic control), MEMS (Micro Elec)
Examples include a tro mechanical system) and an integrated flow injection, which can be applied to such a thing.

The present invention is not limited to the above embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0039]

As described above in detail, according to the present invention, the diameter is from several tens of microns to submicron,
Long holes can be formed.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for processing a minute cavity in a transparent dielectric object using light, showing an embodiment of the present invention.

FIG. 2 is a drawing-substituting photograph showing a state of processing a fine cavity in a transparent dielectric object which is opened on the end surface of quartz glass without water.

FIG. 3 is a drawing-substituting photograph showing a state of microcavity processing on a transparent dielectric object having water on the end surface according to the present invention.

FIG. 4 is a drawing-substituting photograph showing a state in which holes are stopped at a length of 200 μm due to redeposition with water by the method of microcavity processing according to the present invention.

FIG. 5 is a drawing-substituting photograph showing holes formed by the method of microcavity processing according to the present invention.

[Explanation of symbols]

1 Titanium sapphire laser 2 shutter 3 Density filter 4 First objective lens 5 Quartz glass (sample) 6 Water (distilled water) 7 Halogen lamp as illumination light 8 Second objective lens 9 CCD camera

Claims (7)

[Claims] 1. A microcavity is formed by bringing a liquid into contact with an end surface of a transparent dielectric object, and irradiating the end surface of the transparent dielectric object with an ultrashort light pulse from the opposite end surface to collect and irradiate the liquid. A method for processing fine cavities in a transparent dielectric object using light. 2. The method for processing a fine cavity in a transparent dielectric object using light according to claim 1, wherein the entire length of the cavity is such that an ultrashort light pulse is focused again at the tip of the formed cavity. A method of processing a fine cavity in a transparent dielectric object using light, which is characterized by irradiating and repeating it several times. 3. The method for processing a fine cavity in a transparent dielectric body using light according to claim 1, wherein the cavity has a diameter of 0.1 μm to several tens of μm and a length of several tens of μm to several m.
A method for processing fine cavities in a transparent dielectric object using light, characterized by being m. 4. A method for processing a fine cavity in a transparent dielectric object using light according to claim 1, wherein the transparent dielectric object is quartz glass. Micro cavity processing method. 5. The method for processing a fine cavity in a transparent dielectric object using light according to claim 1, wherein the liquid is water. Method. 6. The method for processing a fine cavity in a transparent dielectric object using light according to claim 1, wherein the ultrashort light pulse is a titanium sapphire laser and has a wavelength of 800 nm. A method for processing fine cavities in a transparent dielectric object. 7. (a) a transparent dielectric body, (b) a liquid contacting the end face of the transparent dielectric body, and (c) starting from an interface between the end face of the transparent dielectric body and the liquid, Ultrashort light pulse irradiating means for irradiating the end surface opposite to the end surface of the transparent dielectric object with displacement, and (d) imaging for imaging the processing state of the microcavity formed by the irradiation of the ultrashort light pulse. An apparatus for processing fine cavities in a transparent dielectric object using light, comprising: