JP2005189374A - Oxide glass material for optical device material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide glass material having low absorption and producing a heterogeneous phase having sufficiently high absorption by condensed irradiation of short pulse laser light, for manufacturing an optical device such as a waveguide by forming an inner structure in the glass material, and to provide a method for manufacturing the material. <P>SOLUTION: The glass material contains a light absorbing substance having intrinsic absorption in a wavelength region shorter than 600 nm and no intrinsic absorption in the wavelength region from 600 nm to less than 2,000 nm, for example, either germanium oxide or tin oxide or an oxide containing the combination of these having a group IV element having higher ionization tendency added to the above oxide. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an amorphous material mainly composed of an oxide whose optical characteristics change only at the focused irradiation portion by a short pulse laser, a manufacturing method thereof, and a short pulse for inducing a change in optical characteristics. The present invention relates to a laser irradiation method. Such an oxide-based glass material can be used as a material for an optical element or the like used in the optical communication field.

A glass material made of an amorphous oxide or the like is widely used as an optical material in the field of optical communication because of its excellent transparency and homogeneity. For example, an optical fiber or a planar waveguide (hereinafter referred to as PLC) is also a high-purity silica. It is formed by spinning (SiO ₂ ) glass or the like and forming a film.

Furthermore, a structure in which portions having different characteristics are formed inside the glass material (hereinafter referred to as an internal structure), for example, by imparting a periodic refractive index change, has been made to express functionality. For example, fiber gratings and multilayer filters that function as wavelength filters have been commercialized. In addition, research and development on photonic crystals having highly controlled internal structures are now underway.

As a method of forming the internal structure in the glass material, for example, a method of forming a multilayer film by alternately stacking different materials by a vacuum film forming method, and forming a buried waveguide structure by combining patterning and film formation by photolithography etc. , A method of precipitating fine crystals of noble metal fine particles or oxides in glass by irradiating photosensitive glass containing noble metal etc. with ultraviolet rays and further heat treatment, germanium oxide (GeO ₂ ) An optical fiber or PLC made of SiO ₂ -based glass added with UV light is irradiated with ultraviolet rays to cause a periodic refractive index change, partially by irradiating an electron beam or laser light onto a glass material, etc. Methods for generating defects, melt crystallization, and the like are known.

In recent years, a region with high energy density in the glass due to the focused irradiation of a short pulse laser has caused the density of the glass material to increase and the precipitation of fine particles such as noble metals in the focused region. (Referred to as “heterogeneous phase”), a method for forming an internal structure in glass has been developed.

For example, a method of generating a light-induced refractive index change by condensing and scanning a laser with a high peak output value to form an optical waveguide inside a glass material (for example, Patent Document 1) or exhibits a nonlinear optical effect. A method of forming an optical waveguide that becomes a part of an optical Kerr shutter type switch or the like inside a material by condensing and irradiating laser light inside oxide glass or the like (for example, Patent Document 2, Patent Document) 3) is known. Further, as an example of precious metal fine particle precipitation, a method of selectively forming an altered region inside a glass material by photoreducing metal ions such as precious metal by focused irradiation of pulsed laser light (for example, Patent Document 4) or a similar method There is known a method (for example, Patent Document 5) in which fine nuclei are crystallized by subsequent heat treatment after micronucleation is performed.

As an example of applying the internal structure formation by short pulse laser irradiation to a device, a method for obtaining an optical waveguide with a grating (for example, Patent Document 6) and a method for obtaining an optical waveguide array (for example, Patent Document 7) are known. .

In addition, depending on the characteristics of the precipitate phase and altered phase formed by short pulse laser irradiation, and how different from the characteristics of the non-irradiated part that is the matrix, the functions attributable to the internal structure formed Different. For example, the smaller the refractive index change, the smaller the grating can be realized. From such a viewpoint, it has been researched and developed to generate precipitated or altered phases consisting of various materials such as noble metals, compound semiconductors, and ferroelectrics in glass materials, and in parallel with the development of materials suitable for them. Has been done. For example, the ionic value of an example in which a glass material containing Al ₂ O ₃ is studied as a composition suitable for forming an excellent optical waveguide with little propagation loss (for example, Patent Document 8) or glass containing rare earth ions or the like. Number change occurs (for example, Patent Document 9) and a display material (for example, Patent Document 10) using the same, and glass material for inducing precipitation of non-metallic particles such as Si (for example, Patent Document 11) For example.

For glass materials other than glass materials produced by methods other than the melt solidification process, a short pulse laser is applied to a thin film or multilayer film mainly made of amorphous oxide by a vacuum film-forming method such as sputtering. Thus, research and development of methods and materials for forming fine particles and the like have been conducted. Examples of thin films and multilayer films that are subjected to short pulse laser irradiation include a method of forming Ag fine particles in a multilayer film made of Ag and a metal oxide (for example, Patent Document 12), a structure of a thin film such as indium oxide, There are examples (for example, Patent Document 13 and Patent Document 14) in which a change in etching characteristics is caused.

Further, advanced laser irradiation methods such as irradiation with different laser beams for assist during short pulse laser irradiation have been studied, and polychromatic display materials and the like are known. (For example, Patent Document 15)

The method of forming the internal structure on the glass material by irradiating the short pulse laser beam as described above can simultaneously form the internal structure and synthesize the material, and can form an almost arbitrary shape with high accuracy. Since it is easy, it is considered useful as a processing method for optical elements such as PLC and photonic crystal.

Japanese Patent Laid-Open No. 9-311237 “Optical Waveguide and Method for Producing the Same” Japanese Patent Laid-Open No. 10-288799 “Optical Waveguide Circuit and Nonlinear Optical Device” Japanese Patent Laid-Open No. 11-167036 “Optical Waveguide Circuit and Nonlinear Optical Device” Japanese Patent Laid-Open No. 11-60271 “Metal Fine Particle Dispersed Glass and Method for Producing the Same” Japanese Patent Laid-Open No. 11-71139 “Microcrystalline Dispersed Glass and Manufacturing Method Thereof” JP 2000-249859 “Manufacturing method of optical waveguide with grating” Japanese Patent Laid-Open No. 11-231151 “Optical Waveguide Array and Manufacturing Method Thereof” Japanese Patent Laid-Open No. 2001-228344 “Optical Waveguide” JP 2000-33263 “Selective reforming method inside solid material and solid material whose interior is selectively modified” Japanese Patent Application Laid-Open No. 2002-154845 “Method for producing display material by laser light irradiation” JP 2001-235609 “Non-metallic particle precipitated glass and method for producing the same Japanese Patent Application Laid-Open No. 2003-12345 “Coloring method of heat ray shielding glass” Japanese Patent Application Laid-Open No. 2003-178625 “Transparent Conductive Film Having Optical Element Function and Manufacturing Method Thereof” Japanese Patent Application Laid-Open No. 2003-171783 “Selective Etching Process for Metal Oxide Film and Metal Oxide Film, Optical Element, and Conductive Film selectively Etched by the Method” JP 2003-19863 A "Transparent inorganic material capable of forming a heterogeneous portion having an arbitrary shape that exhibits a behavior different from that of surroundings when irradiated with ultraviolet rays and a method for producing the same"

When optical waveguides and photonic crystals are produced by forming an internal structure in a glass material to exhibit optical functionality, it may be preferable that the characteristics such as the refractive index of each phase constituting the internal structure differ greatly. is there. For example, the larger the relative refractive index difference, the smaller the size of the waveguide, and the higher the diffraction efficiency of the diffraction grating. Considering the case where an internal structure such as a waveguide is formed in a glass material by irradiating with a short pulse laser beam, a state of high energy density is locally generated by irradiating the short pulse laser locally. The refractive index of the portion where the characteristics have changed (hereinafter referred to as the heterogeneous phase) is significantly different from the portion where the laser light is not irradiated and no change in state such as particulate precipitation occurs (hereinafter referred to as the unirradiated region). It will be preferable.

In the case where a material different from a glass material such as a noble metal is deposited in the glass material, the glass material must contain the element such as the noble metal, and in order to increase the refractive index of the foreign phase, the foreign phase It is necessary to increase the volume fraction of the fine particles precipitated inside.

  That is, in order to greatly change the characteristics of the heterogeneous phase, a substance constituting the fine particles to be deposited must be present in a certain amount in advance as a substance constituting the glass material in the glass material. As a result, the refractive index of the glass material in the unirradiated region may be increased, and the difference from that of the heterogeneous phase may be decreased.

  In addition, in order to form a transparent and homogeneous glass material, there is a composition limitation depending on the composition range that can be vitrified in the glass material system, so a large amount of a noble metal element having a small solid solubility limit in oxide glass is used. Even if it is added, crystallization such as precipitation and aggregation of fine particles in the melt-solidification process may occur, and a transparent and homogeneous glass material may not be obtained.

As described above, when an element is fabricated using a method for producing a waveguide, a photonic crystal, etc. by forming an internal structure in a glass material and exhibiting optical functionality, a predetermined function is exhibited. There is a problem that there are cases where it is difficult to select or produce the glass material.

The present invention has been devised to solve such problems, and it is possible to form a heterogeneous phase that has small absorption and the like and that has sufficiently large absorption and the like by condensing and irradiating a short pulse laser beam. An object of the present invention is to provide an oxide-based glass material and a method for producing the same.

In order to achieve the object, the oxide-based glass material of the present invention has a matrix containing an absorbing substance that has intrinsic absorption in a wavelength range shorter than 600 nm and does not have intrinsic absorption in a wavelength range of 600 nm to less than 2000 nm. The intrinsic absorption can be induced in the wavelength range from 600 nm to less than 2000 nm by the focused irradiation of the pulsed laser light with the focusing point adjusted inside the glass material. Examples of the absorbing material include those obtained by adding a group IV element of the periodic table having a higher ionization tendency to an oxide made of any one of germanium oxide and tin oxide or a combination thereof. Moreover, it is preferable that at least a part of the periodic table group IV element added to the absorbing material is present as a non-oxide or a non-stoichiometric oxide. The absorbing substance is coated with a material that does not exhibit intrinsic absorption in the wavelength range of 400 nm or more and less than 2000 nm and that does not induce intrinsic absorption in the wavelength range of 400 nm or more and less than 2000 nm even when irradiated with pulsed laser light. It is preferable.

Further, in the absorbing material, the periodic table group IV element is silicon and the oxide is germanium oxide, or the periodic table group IV element is silicon or germanium and the oxide is tin oxide. preferable.

The material covering the absorbing substance is preferably an amorphous oxide.

Hereinafter, the present invention will be described in more detail. The basic idea of the present invention is that a non-oxide phase such as a semiconductor or an original oxide is constituted by using a photoreduction reaction or the like by short pulse laser irradiation from an oxide phase having a small absorption preferable as a light medium. The formation of a heterogeneous phase accompanied by a large change in characteristics is achieved by generating a phase composed of an oxide or the like having a greatly reduced cation valence.

As for the wavelength dependence of the optical properties to be satisfied by the absorbing material, it is preferable that the absorption is large at the wavelength corresponding to the two-photon absorption process in order to effectively cause local change due to the focused irradiation of the short pulse laser. On the other hand, in order to be able to freely set the condensing position, it is necessary that the absorption is small outside the condensing region. That is, it is important that the absorption is small at the wavelength of the short pulse laser light, but the absorption is large at the half wavelength. For example, when an Al ₂ O ₃ : Ti laser is used, the wavelength of the laser beam is 800 nm, and the wavelength corresponding to the two-photon absorption process is 400 nm, which is a half of the wavelength. And in the wavelength used when using the oxide-based glass material according to the present invention as an element, the portion other than the heterogeneous phase has a small refractive index and absorption, and the heterogeneous phase portion has a large refractive index and absorption. Is preferred. In addition, the wavelength bands of light used in the optical communication field are mainly 1.3 μm band and 1.5 μm band, and the upper limit of the wavelength used for information transmission is considered to be about 2000 nm.

For the reasons described above, the inventors of the present invention collect and irradiate pulsed laser light that is an absorbing substance having no intrinsic absorption in a wavelength range of 600 nm or more and less than 2000 nm and whose focusing point is adjusted inside the glass material. Thus, an attempt was made to find an absorbing material capable of inducing intrinsic absorption in a wavelength range from 600 nm to less than 2000 nm. Here, intrinsic absorption refers to light absorption specific to a substance caused by inner electrons of electrons constituting the substance, an electron system, elementary excitation of a Hall system, lattice vibration, or the like. In addition, the portion constituting the oxide glass material other than the absorbing substance has no intrinsic absorption in the wavelength range of 400 nm to less than 2000 nm, and the intrinsic absorption in the wavelength range of 400 nm to less than 2000 nm even when irradiated with pulsed laser light. It is preferable from the viewpoint of the function after forming the internal structure and forming the device, that it is made of a material that does not induce (hereinafter referred to as a non-absorbing material). The absorbing material must be capable of inducing intrinsic absorption in the wavelength range of 600 nm or more and less than 2000 nm by condensing and irradiating a short pulse laser beam because the oxide glass material according to the present invention is used. This is because the refractive index and the absorption coefficient are increased in the wavelength range of use of the element using the element.

Through the above considerations, the inventors of the present invention search for a material from the viewpoint of a stable oxide having a relatively narrow band gap and no intrinsic absorption in the above optical wavelength range or sufficiently small. As a result, attention has been focused on group IV elements such as Ge and Sn. Then, as a method for easily obtaining a glass material containing a large amount of oxygen defects in order to promote the photoreduction reaction, it was conceived that a vacuum film-forming method such as a sputtering method was used, and an oxide was further used to act as a reducing agent. An attempt was made to add an element that is easier to oxidize than the cation constituting the phase. Usually, when a glass material is produced by such a combination, an element that is more easily oxidized is preferentially oxidized, and thus it is difficult to obtain a glass material containing a reducing agent as described above. For example, a glass in which a Ge phase is present in the SiO ₂ phase can be produced and can be easily conceived, but it is difficult to envisage producing a glass in which the Si phase or the SiO phase is present in the GeO ₂ phase. A glass material having a structure in which a metal phase is generated in the SiO ₂ phase is well known from research examples such as glass melting in a reducing atmosphere and fine particle-dispersed thin films by a co-sputtering method.

However, when the inventors tried a simultaneous sputtering method of GeO ₂ and Si and compared the optical characteristics of the obtained thin film with an oxide thin film made of only GeO ₂ , the thin film maintained an amorphous structure and was ultraviolet. As a result, the absorption edge shifted due to the intrinsic absorption in the visible short wavelength region, but no increase in absorption was observed in the longer wavelength range. Based on this finding, the inventors have further searched for materials and found an absorbent material disclosed in the present invention. In addition, since such an absorbing material exhibits remarkable two-photon absorption, if the focusing position is set at a shallow position so as to form a heterogeneous phase in the vicinity of the surface, abrasion easily occurs and the surface is destroyed. In order to prevent this, it has also been found that coating with a non-absorbing material such as SiO ₂ or Al ₂ O ₃ is effective. The present invention has been completed based on these research results.

By using the oxide-based glass material according to the present invention, it is possible to form a heterogeneous phase having greatly different optical characteristics in a portion where the short pulse laser beam is condensed and irradiated. Conventionally, only a small amount of added component precipitates and the volume fraction of precipitated fine particles in the heterogeneous phase is about 1% or less. However, in the oxide-based glass material of the present invention, the absorbing substance in the heterogeneous phase portion. Is altered by reaction such as reduction as it is, so that the volume fraction can be changed from several percent to several tens of percent. In addition, in the portion not irradiated with the short pulse laser beam, extremely low absorption or the like is shown, and as a result, an internal structure having a large difference in characteristics from the heterogeneous phase portion can be obtained.

In the following, the best mode for carrying out the present invention by the inventors will be described. As an oxide-based glass material that is capable of forming a heterogeneous phase with a sufficiently large light absorption, etc. by utilizing a phenomenon such as a photoreduction reaction by condensing and irradiating a short pulse laser beam with a small absorption, etc. Wavelength range of 600 nm or more and less than 2000 nm by condensing and irradiating a pulsed laser beam with a condensing point adjusted inside the glass material, which is an absorbing substance having no intrinsic absorption at a wavelength of 600 nm or more and less than 2000 nm. Oxide-based glass material consisting only of an absorbing substance capable of inducing intrinsic absorption in the above, or no absorption in the wavelength range of the absorbing substance and the wavelength of 400 nm or more and less than 2000 nm, and a wavelength of 400 nm or more and 2000 nm even when irradiated with pulsed laser light Materials that do not induce intrinsic absorption in the wavelength range below It is preferable that consists referred to hereafter as the non-absorbing materials) and.

In addition, a non-absorbing material that may be combined with an absorbing substance needs to absorb as little as possible short-wave laser light and light in a wavelength range used as an element, and has intrinsic absorption in a wavelength range from 400 nm to less than 2000 nm. In addition, it is necessary that intrinsic absorption is not induced in a wavelength range of 400 nm or more and less than 2000 nm even by focused irradiation of a short pulse laser beam. As such a material, for example, there is SiO ₂ free of H 2 impurities and OH defects.

Further, as an absorbing material satisfying such a condition, an oxide made of any one of germanium oxide (GeO ₂ ) and tin oxide (SnO ₂ ) or a combination thereof is added to the periodic table IV group having a higher ionization tendency. Some have added elements. These oxides have a very small absorption coefficient, and transmit light well in a wavelength range of 400 nm or more and less than 2000 nm. Then, for example, by adding a periodic group IV element to the oxide such as GeO ₂ and Si, the oxide can have intrinsic absorption caused by oxygen defects such as Si—Ge bonds and 600 nm or more. An absorbing material that does not cause intrinsic absorption of light having a wavelength can be used. Furthermore, in order to make the intrinsic absorption due to oxygen defects stronger, and to promote the photoreduction reaction by short pulse laser irradiation and the like to generate a phase composed of Ge or Sn from the oxide phase of GeO ₂ or SnO ₂ In addition, it is preferable that at least a part of the group IV element of the periodic table exists as a non-oxide or non-stoichiometric oxide capable of acting as a reducing agent for the oxide. The minimum band gaps of indirect transitions of Si and Ge are 1.12 eV and 0.66 eV (300 ° K), respectively, and the wavelengths are about 1.1 μm and 1.9 μm, respectively. Since it does not show intrinsic absorption, optical properties such as refractive index and absorption coefficient can be compared with those in the oxide state in the wavelength range from 600 nm to less than 2000 nm if a phase composed of these semiconductors can be generated. Can be greatly changed. In addition, when focused irradiation is performed to form a heterogeneous phase in the vicinity of the surface of the absorbing material phase, the surface may be evaporated or destroyed by laser ablation, so that the absorbing material may be made of SiO ₂ or the like for the purpose of preventing abrasion. The non-absorbing material is preferably coated, and the non-absorbing material is preferably an oxide from the viewpoint of stability and durability.

The method for synthesizing an oxide according to the present invention and the method for adding a group IV element to the oxide are not limited to a specific method, but are generally easy to add group IV elements and have a non-stoichiometric composition. As a method for easily synthesizing the oxide phase, a known vacuum film forming method such as a sputtering method can be used. For example, a method in which a Si chip is placed on the surface of a sputtering target obtained by sintering GeO ₂ oxide powder and simultaneously sputtered in a discharge gas such as argon, or GeO ₂ and Si are used as independent targets and discharged simultaneously. And a method of forming a multilayer film by alternately forming GeO ₂ and Si.

Regarding the focused irradiation of the short pulse laser according to the present invention, the wavelength of the laser beam and the method of the focused irradiation are not limited to a specific wavelength or method, but are caused by the composition of the target oxide glass. It is possible to select a suitable method from known methods according to the absorption spectrum to be absorbed, the thickness of the coating with the non-absorbing material, the condensing position inside the glass material to be formed, the size and shape of the heterogeneous phase to be formed by condensing irradiation, etc. it can.

Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples.

In this example, a heterogeneous phase was formed by irradiating a two-layer film in which a silicon oxide thin film was overcoated with a thin film of a germanium oxide-based absorbing material to form a heterogeneous phase, and its characteristics were evaluated. The outline of the present embodiment is as follows.

By using a high frequency sputtering apparatus and placing four Si chips on the surface of a germanium oxide (GeO ₂ ) target and performing simultaneous sputtering, an Si-added GeO ₂ thin film as an absorbing material is formed on the surface of a silica glass substrate (thickness 1 mm). Filmed. Further, a silicon oxide (SiO ₂ ) overcoat for preventing abrasion during laser irradiation was formed on the surface to prepare a two-layer film sample. With respect to laser light irradiation, the optical system was adjusted so as to pass through the layer 3 made of a non-absorbing material and form the light-collecting region 7 inside the layer 2 made of the absorbing material as shown in FIG. In order to form a planar heterogeneous phase, the two-layer film sample is fixed to a two stage that can be driven horizontally, and the stage is moved to perform focused irradiation of short pulse laser light while scanning the irradiation position, Overlaid straight lines. The sample was evaluated for changes in optical properties by spectral transmittance measurement, and X-ray diffraction measurement was performed for the purpose of identifying a heterogeneous phase.

Below, manufacturing conditions and evaluation conditions are demonstrated more concretely. As a film forming apparatus, a high-frequency sputtering apparatus (SPF-320H manufactured by Anelva) using a high-frequency power source with a transmission frequency of 13.56 MHz and a rated power of 500 W was used. The film forming procedure is as follows. Argon (Ar) gas (purity 99.999%) was used as the discharge gas, and the vacuum exhaust rate was adjusted so that the pressure in the film formation chamber was 1 Pa at a flow rate of 20 SCCM (20 mL per minute in the standard state). A glow discharge was performed by applying a discharge power of 200 W by adjusting a high-frequency power source, and a GeO ₂ film added with Si was formed to a thickness of 25 μm on the surface of a silica glass substrate placed facing a position 40 mm directly above the target. Thereafter, the substrate was moved immediately above the SiO ₂ target, and a SiO ₂ film having a thickness of 20 μm was formed under the same conditions to obtain a two-layer film sample. The substrate holder was water-cooled (water temperature about 25 ° C.), and the substrate temperature during film formation was kept at 150 ° C. or lower.

The short pulse laser irradiation uses a titanium sapphire (Al ₂ O ₃ : Ti) laser, a wavelength of 800 nm, a pulse repetition frequency of 250 kHz, a pulse width of about 260 fs (femtosecond), an irradiation energy of 300 mW, and a 40 × objective lens. The sample was condensed and irradiated through a condensing system using an optical microscope.

The XY stage on which the sample is fixed was provided with a motor-driven XY direction moving mechanism and a piezoelectric element Z-direction driving mechanism with the incident direction of laser light as the Z direction. The condensing position in the sample was adjusted by driving in the Z direction so that the condensing point was located at a position on the side in contact with the SiO ₂ overcoat film in the Si-added GeO ₂ film.

  A linear drawing process was performed by irradiating the sample with a short pulse laser beam while scanning the sample in the X direction at a scanning speed of the XY stage of 1 mm / s. After drawing a straight line once, the XY stage is moved 10 μm in the Y direction, and the XY stage is scanned in the X direction while condensing and irradiating a short pulse laser beam, and the surface scan by overwriting is performed. It was.

  FIG. 2 shows the results of spectral transmittance measurement and X-ray diffraction measurement at the position irradiated with laser light (irradiated portion) and the position not irradiated (unirradiated portion). In the unirradiated portion, strong intrinsic absorption was observed at a wavelength of about 500 nm or less, but it was confirmed that there was no intrinsic absorption in the wavelength range of 600 nm to 2000 nm. Absorption at a wavelength of 500 nm or less was estimated to be due to oxygen defects. It was confirmed that the irradiated portion was dark brown by visual observation, and that a large absorption was observed by spectral transmittance measurement.

  The result of the X-ray diffraction measurement for the same sample is shown in FIG. Measurement was performed by a goniometer method driven by θ-2θ using Cu—Kα rays (wavelength 0.15406 nm). A reflection peak due to the crystal phase was not observed in the unirradiated portion, but a reflection peak due to the crystal phase was observed in the irradiated portion, and it was found that some crystal phase was precipitated by short pulse laser irradiation.

  The absorption edge due to the indirect transition between the Si phase and the Ge phase is about 1.1 μm and about 1.9 μm, respectively. As a result of measuring the spectral transmittance of the heterogeneous phase portion, there is an absorption edge near the wavelength of 2 μm. From the two points that it is presumed that a solid solution phase of Si and Ge or a mixed phase of SiO and Ge was generated in the heterogeneous phase from the peak position, the heterogeneous phase part generated by the focused irradiation of short pulse laser light is mainly It was concluded that it consisted of a phase consisting of photoreduced Ge.

Under the same conditions and method as in Example 1, an overcoat film made of an Si-added SnO ₂ thin film and silicon oxide (SiO ₂ ) as an absorbing material was formed on the surface of a silica glass substrate to prepare a two-layer film sample. Then, a heterogeneous phase was formed in the Si-added SnO ₂ layer, which is an absorbing substance, by performing focused irradiation with a short pulse laser beam.

  As a result of measuring the spectral transmittance in the same manner as in Example 1, it was confirmed that in the non-irradiated portion, strong intrinsic absorption was observed at a wavelength of about 500 nm or less, but there was no intrinsic absorption in the wavelength range of 600 nm to 2000 nm. It was. It was confirmed that the irradiated portion was blackish brown by visual observation, and it was confirmed by spectral transmittance measurement that the absorption was large in the wavelength range of 600 nm to 2000 nm. The minimum band gap of the indirect transition of the Sn phase is 0.08 eVd, and the wavelength of the corresponding intrinsic absorption is about 15.5 μm, which is consistent with the fact that absorption occurs in the wavelength range below that wavelength. It was concluded that this resulted in the formation of Sn phase.

The pulse according to the present invention has a matrix containing an absorbing substance that has intrinsic absorption in a wavelength range shorter than 600 nm and has no intrinsic absorption in a wavelength range of 600 nm to less than 2000 nm, and has a condensing point adjusted inside a glass material. Oxide glass materials that can induce intrinsic absorption in the wavelength range from 600 nm to less than 2000 nm by condensing and irradiating laser light are used to irradiate optical elements, photonic crystals, etc. in the field of optical communication with short pulse lasers. In addition to being able to be used as a material for the formation of oxides, it can also be used as a display material for laser printing inside oxide-based solids, and as a material for forming diffraction gratings and photomasks by short pulse laser irradiation. It is considered possible.

It is explanatory drawing of the condensing irradiation position in the case of a two-layer film sample. It is a spectral transmittance measurement result of a short pulse laser irradiation part and an unirradiated part. It is an X-ray-diffraction measurement result of a short pulse laser irradiation part and an unirradiated part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate glass 2 Layer made of absorbing material 3 Layer made of non-absorbing material 4 Condensing lens 5 Parallel laser beam 6 Condensed laser beam 7 Focal-induced heterogeneous phase 11 Spectral transmittance curve 12 of silica substrate Spectral transmittance curve 13 Spectral transmittance curve 21 of irradiated portion X-ray diffraction profile 22 of non-irradiated portion X-ray diffraction profile 23 of irradiated portion Reflection peak due to crystal phase

Claims (8)

A pulsed laser beam having a matrix containing an absorbing material that has intrinsic absorption in a wavelength range shorter than 600 nm and no intrinsic absorption in a wavelength range of 600 nm to less than 2000 nm, and that has a condensing point adjusted inside the glass material. An oxide-based glass material capable of inducing intrinsic absorption in a wavelength range of 600 nm to less than 2000 nm by light irradiation. 2. The oxidation according to claim 1, wherein the absorbing material is a group IV element of a periodic table having a higher ionization tendency added to an oxide composed of any one of germanium oxide and tin oxide or a combination thereof. Physical glass material. The oxide-based glass material according to claim 2, wherein at least part of the periodic table group IV element added to the absorbing substance is present as a non-oxide or an oxide having a non-stoichiometric composition. The absorbing material is coated with a material that has no intrinsic absorption in the wavelength range of 400 nm or more and less than 2000 nm and that does not induce intrinsic absorption in the wavelength range of 400 nm or more and less than 2000 nm even when irradiated with pulsed laser light. The oxide-based glass material according to claim 3. 5. The oxide-based glass material according to claim 4, wherein the absorbing substance is a group IV element of the periodic table of silicon and an oxide of germanium oxide. 5. The oxide-based glass material according to claim 4, wherein the absorbing substance is a group IV element of the periodic table of silicon or germanium and the oxide of tin oxide. The oxide-based glass material according to claim 4, 5 or 6, wherein the material covering the absorbing substance is an amorphous oxide. An optical element using at least one of the oxide-based glass materials according to claim 1.

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