JP5844197B2 - Wavelength conversion member and solid-state laser device - Google Patents

Description

  The present invention relates to a wavelength conversion member and a solid-state laser device for a solid-state laser device that excites a solid-state laser medium with light to cause laser oscillation.

Currently, various laser devices are known. For example, a YAG laser as one of solid-state laser devices includes an optical resonator including a solid-state laser medium doped with trivalent neodymium ions (Nd ³⁺ ), a light source for exciting the solid-state laser medium, and the light source And a reflector (condenser) having a reflecting surface facing the solid laser medium.

  Here, the emission spectrum of a xenon flash lamp used as a light source includes a wide wavelength component of 200 nm to 1200 nm. For this reason, the ultraviolet rays contained in the excitation light do not contribute to the excitation of the laser medium and may cause defects such as a color center (color center) in the laser medium.

  In order to avoid such defects in the laser medium, the reflector is provided with a bandpass filter such as a colored glass filter to absorb the ultraviolet light contained in the excitation light and convert the ultraviolet light to a wavelength suitable for the laser medium. It has been proposed to irradiate.

For example, Patent Document 1 ^discloses a wavelength conversion filter made of a crystal or glass doped with trivalent chromium ions (Cr ³⁺ ) between an excitation light source installed in a reflector and a solid laser medium doped with Nd ^3+. It is described that the wavelength distribution of the pumping light is converted into a distribution suitable for pumping the laser medium by interposing, thereby obtaining a solid laser device with high efficiency and high beam quality. This wavelength conversion filter absorbs excitation light with a wavelength λ of 400 to 650 nm, emits fluorescence with a wavelength λ suitable for excitation of Nd ³⁺ near 810 nm, and does not require wavelength conversion with light having a wavelength λ near 810 nm. Since the light is transmitted as it is, it is expected that the light emission efficiency of the laser is improved by the excitation light including the wavelength-converted fluorescence.

JP 2002-237635 A

  However, in such a conventional configuration, actually, the improvement of the light emission efficiency of the laser by the wavelength conversion is negligible. The concentration of trivalent chromium ions dispersed in the wavelength conversion filter is generally as low as about 1%. In addition, irradiation light from a xenon flash lamp as a light source passes through the wavelength conversion filter through a linear optical path. Therefore, the probability that the irradiation light from the xenon flash lamp collides with trivalent chromium ions dispersed in the wavelength conversion filter while passing through the wavelength conversion filter is extremely low. Therefore, of the irradiation light from the light source, light having a wavelength that is not involved in the excitation of trivalent neodymium ions collides with the trivalent chromium ions and is absorbed, and further, the fluorescence emitted by the trivalent chromium ions is emitted toward the laser medium. The probability of radiation is low.

  An object of the present invention is to provide a wavelength conversion member and a solid-state laser device for a solid-state laser device that can solve such conventional problems and can practically excite a laser medium by wavelength conversion with high efficiency. There is to do.

The present invention is used in the wavelength conversion of light, Ri Na comprise alumina polycrystalline body containing at least one metal element of chromium and titanium, at least one of the content of the chromium and the titanium, the a wavelength conversion member, wherein 0.01 to 1.0% by mass Rukoto in terms of oxide relative to the total amount of the alumina polycrystal.

The present invention is used in the wavelength conversion of light, alumina containing at least one metal element of chromium and titanium - Ri Na comprise zirconia mixed polycrystalline, at least one of the content of the chromium and the titanium but the alumina - which is a wavelength converting member, wherein 0.01 to 1.0% by mass Rukoto in terms of oxide relative to the total amount of the zirconia mixed polycrystals.
The present invention includes an alumina-zirconia mixed polycrystal used for wavelength conversion of light and containing at least one metal element of chromium and titanium. In the alumina-zirconia mixed polycrystal, alumina and zirconia And a mass ratio of 20:80 to 80:20.

  The present invention also provides a light source, any one of the above-described wavelength conversion members, a solid-state laser medium that is optically excited by light converted by the wavelength conversion member, and a solid that reflects light converted by the wavelength conversion member. A solid-state laser device comprising a reflector for focusing on a laser medium.

According to the present invention, the wavelength converting member used for the solid-state laser device, viewed contains an alumina polycrystalline body containing at least one metal element of chromium and titanium, at least one of the content of the chromium and the titanium , And 0.01 to 1.0% by mass in terms of oxide with respect to the total amount of the alumina polycrystal .

  By including an alumina polycrystal as the wavelength conversion member, light transmitted through the wavelength conversion member is scattered, so that the optical path length of transmitted light is longer than that of conventional glass. As the optical path length becomes longer, the chances of contact between the metal elements and the transmitted light increase, so that the amount of excitation light emitted from the solid-state laser medium by fluorescence emission increases.

  Thereby, the laser medium can be practically excited with high efficiency by wavelength conversion.

According to the present invention, the wavelength converting member used for the solid-state laser apparatus, chromium and alumina containing at least one metal element of titanium - see including zirconia mixed polycrystalline, at least one of said chromium and said titanium Is 0.01 to 1.0% by mass in terms of oxide with respect to the total amount of the alumina-zirconia mixed polycrystal . According to the invention, the wavelength conversion member used in the solid-state laser device includes an alumina-zirconia mixed polycrystal containing at least one metal element of chromium and titanium, and in the alumina-zirconia mixed polycrystal, The mass ratio of alumina to zirconia is 20:80 to 80:20.

  By using the alumina-zirconia mixed polycrystal as the wavelength conversion member, the light transmitted through the wavelength conversion member is scattered, so that the optical path length of the transmitted light is longer than that of the conventional glass. As the optical path length becomes longer, the chance of contact between each of the metal elements and the transmitted light increases, so that the amount of excitation light emitted from the solid-state laser medium by fluorescence emission increases.

  Thereby, the laser medium can be practically excited with high efficiency by wavelength conversion.

  In addition, according to the present invention, by using the wavelength conversion member described above, the laser medium can be excited with high efficiency, and a solid-state laser device with high oscillation intensity can be realized.

It is the schematic which shows the structure of the solid-state laser apparatus which is 1st Embodiment. It is a schematic sectional drawing which shows the structure inside the reflector 4. FIG. It is a graph which shows the change of the delay time of the transmitted light when the content of alumina is changed in the alumina-zirconia mixed polycrystal. It is a graph which shows the result of PL measurement and PLE measurement of the alumina polycrystal containing chromium. It is a schematic diagram which shows the structure of the measuring apparatus for measuring the emitted light intensity of a Nd: YAG medium. It is a graph which shows the measurement result of emitted light intensity.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing the configuration of the solid-state laser apparatus according to the first embodiment. FIG. 2 is a schematic cross-sectional view showing a configuration inside the reflector 4.

  The solid-state laser device 100 includes a flash lamp 1 that is a light source, a solid-state laser medium 2 that emits laser light by being excited by light emitted from the flash lamp 1, and light in a specific wavelength region among light emitted from the flash lamp 1. The light is emitted after being converted in wavelength, and the light emitted from the light emitting tube 3 without changing the wavelength is emitted without changing the wavelength, and the light emitted from the light emitting tube 3 is reflected and collected in the laser medium. The light reflector 4 and reflecting mirrors 5 and 6 are provided. In FIG. 1, the arc tube 3 corresponds to the wavelength conversion member of the present invention.

The flash lamp 1 is a cylindrical straight tube lamp, and a lamp in which a wavelength for exciting the solid laser medium 2 in the wavelength range of the emitted light is appropriately selected. For example, when a solid laser medium 2 doped with trivalent neodymium ions (Nd ³⁺ ) is used, a xenon flash lamp that emits light in a wavelength region including a wavelength of 810 nm to excite trivalent neodymium ions. May be used.

Similar to the flash lamp 1, the solid-state laser medium 2 is formed in a cylindrical shape and is doped with an active species that absorbs and excites light in a specific crystal. For example, Nd: YAG medium doped with neodymium as an active species in a YAG (yttrium, aluminum, garnet) crystal, Er: YAG medium doped with erbium as an active species in a YAG crystal, YVO ₄ (yttrium vanadium. Oxide) Nd: YVO ₄ medium doped with neodymium as an active species in the crystal and Nd: GdVO ₄ medium doped with neodymium in the GdVO ₄ (gadolinium vanadium oxide) crystal can be used.

  The arc tube 3 which is a wavelength conversion member is provided in a cylindrical shape so as to surround the outer periphery of the flash lamp 1, and is made of an alumina polycrystal containing at least one metal element of chromium and titanium. In addition, when the alumina polycrystal contains chromium, the chromium is dissolved in the alumina, and when titanium is contained, the titanium is dissolved in the alumina or dispersed at the grain boundaries of the alumina polycrystal. Exists.

  The light emitted from the flash lamp 1 passes through the alumina polycrystalline body of the arc tube 3 and is emitted to the outside of the arc tube 3. At this time, part of the light is absorbed by chromium or titanium, and is emitted as light having a different wavelength by fluorescence emission.

  Here, it is preferable to use an alumina polycrystal having a larger amount of alumina phase than the total amount of phases other than the alumina phase because the conversion efficiency of transmitted light tends to be higher. These abundances are compared, for example, as follows.

  First, the phases constituting the alumina polycrystal are identified by X-ray diffraction or electron diffraction using TEM. Next, the content of each component of the alumina polycrystal is measured using an ICP emission analyzer (manufactured by Shimadzu Corporation: ICPS-8100). And based on the phase which comprises the identified alumina polycrystal, the abundance of an alumina phase and the abundance which totaled phases other than an alumina phase may each be calculated, and the computed abundance may be compared.

  As a simple comparison method, among the phases constituting the alumina polycrystal identified by X-ray diffraction, the maximum peak intensity value of the alumina phase and the maximum peak of each phase constituting the alumina polycrystal If the value of the maximum peak intensity of the alumina phase is greater than 50% with respect to the total value of the maximum peak intensity of each phase constituting the alumina polycrystal, alumina may be compared with the sum of the intensity values. It can be considered that the abundance of the phase is large. The maximum peak intensity indicates the highest peak intensity in each phase among the peak intensity indicating each phase.

  Light emitted from a xenon flash lamp which is an example of the flash lamp 1 includes light in a wide wavelength range of 200 nm to 1200 nm. The ultraviolet light contained in the emitted light does not contribute to the excitation of the solid-state laser medium 2, and instead causes defects such as a color center (color center) in the solid-state laser medium 2. However, when the arc tube 3 of the present embodiment is used, when the light emitted from the xenon flash lamp passes through the arc tube 3, the ultraviolet light that does not contribute to the excitation of the solid-state laser medium 2 is absorbed by chromium or titanium. For example, chromium emits fluorescence having a wavelength of about 696 nm, and titanium emits fluorescence having a wavelength of about 600 to 1000 nm. The light with a wavelength of 696 nm and 600 to 1000 nm becomes excitation light for exciting the solid-state laser medium 2. In this way, the ultraviolet light that does not contribute to the excitation of the solid-state laser medium 2 out of the light emitted from the xenon flash lamp is absorbed by the arc tube 3 and is emitted from the solid-state laser medium 2 by fluorescence emission of chromium and titanium. Since it is converted into light having a long wavelength that contributes to excitation, the light emitted from the light source as a whole can be used effectively for excitation of the solid-state laser medium 2. Note that the metal element to be contained in the arc tube 3 may be appropriately selected according to the excitation wavelength of the solid-state laser medium 2.

  The flash lamp 1 is formed in a columnar shape as described above, and the arc tube 3 is formed in a cylindrical shape whose central axis is coaxial with the flash lamp 1 and is provided so as to surround the outer periphery of the flash lamp 1. The solid laser medium 2 is formed in a cylindrical shape like the flash lamp 1 and is provided inside the reflector 4 so that the central axis of the flash lamp 1 and the central axis of the solid laser medium 2 are parallel to each other. The reflector 4 includes the flash lamp 1, the solid-state laser medium 2, and the arc tube 3, and is formed in an elliptical tube having an elliptical cross section. The flash lamp 1 and the solid-state laser medium 2 are provided in the internal space of the reflector 4 so that the central axis of the flash lamp 1 and the central axis of the solid-state laser medium 2 are located at two elliptical focal points, respectively. .

  At one elliptical focal position, the light emitted from the flash lamp 1 and transmitted through the arc tube 3 is reflected by the inner surface of the reflector 4 and focused on the solid-state laser medium 2 at the other focal position. The solid-state laser medium 2 is excited by the collected light and emits laser light. Laser light emitted from the solid-state laser medium 2 oscillates between the reflecting mirror 5 and the reflecting mirror 6. One of the reflecting mirrors 5 and 6 (in this embodiment, the reflecting mirror 6) is a semi-transmissive mirror, and the oscillated laser light is emitted as laser output light from the semi-transmissive mirror side, that is, the reflecting mirror 6 side. Is done.

  Here, the difference between the wavelength conversion filter in the prior art and the arc tube 3 of the first embodiment will be described.

  A conventional wavelength conversion filter is made of a material in which a metal element such as chromium or titanium is dispersed in a transparent material (for example, glass). When the light emitted from the flash lamp 1 passes through the wavelength conversion filter, light having a short wavelength such as ultraviolet rays is absorbed by chromium or titanium, and the wavelength of 696 nm or 600 to 1000 nm is generated by the excited fluorescent emission of chromium or titanium. Are emitted in all directions. Here, since the concentration of chromium or titanium in the glass doped with chromium or titanium is about 0.01 to 1.0% by mass, it is absorbed by the wavelength conversion filter and is emitted toward the solid laser medium at a wavelength of 696 nm. Alternatively, the light of 600 to 1000 nm is 1% or less of the light emitted from the flash lamp 1 at the maximum.

  In the arc tube 3 of the first embodiment, at least one kind of chromium and titanium is added to the alumina polycrystal having an average crystal grain size of 0.6 to 10.0 μm with respect to the total amount of the alumina polycrystal. Including 01 to 1.0 mass%. Thereby, there exists a tendency which can maintain the translucency of an alumina polycrystal and the conversion efficiency of transmitted light more highly.

  The individual alumina single crystal particles of the alumina polycrystalline body constituting the arc tube 3 are transparent and transmit light. However, the crystal orientation of the alumina single crystal particles contained in the alumina polycrystal is random. Since the crystal grain size of each alumina single crystal particle is about the same as or larger than the wavelength of the transmitted light, the light transmitted through the alumina polycrystal is Mie scattered by the alumina single crystal particles. Forward scatter becomes dominant. Since the light scattered forward is scattered forward one after another by the adjacent alumina single crystal particles, the light is scattered from the inner side to the outer side of the arc tube 3 as a whole, and the complicated path in the arc tube 3 is caused. After tracing, the light is emitted from the outer peripheral surface of the arc tube 3 toward the reflector 4. As described above, the transmitted light is diffusely reflected in the arc tube 3 as a whole. However, instead of simple irregular reflection, the light passes through a complicated path in the arc tube 3 by Mie scattering, and during that time, an alumina polycrystal The chrome or titanium contained in the body is transmitted while being excited.

  As the length of the path passing through the arc tube 3 is longer, the chance of contact with chromium or titanium increases. Therefore, by using an alumina polycrystal, more chromium or titanium than the conventional glass is excited and excited. Fluorescence having a wavelength of 696 nm or 600 to 1000 nm is emitted from the chromium or titanium formed. This fluorescence having a wavelength of 696 nm or 600 to 1000 nm becomes excitation light capable of exciting neodymium contained in the solid-state laser medium 2. Excitation of more chromium or titanium increases the amount of fluorescence emitted from chromium or titanium at a wavelength of 696 nm or 600 to 1000 nm.

  Here, in the alumina polycrystal, the ratio of the maximum peak intensity value of the alumina phase to the total of the maximum peak intensity values of the phases constituting the alumina polycrystal is 0.95 or more, It is preferable because the mechanical strength of the polycrystalline body and the conversion efficiency of transmitted light tend to be higher.

  Of the light emitted from the flash lamp 1, the light that is not absorbed by chromium or titanium follows a complicated path in the arc tube 3, and is emitted as it is to the outside of the arc tube 3 without being converted in wavelength. Therefore, of the light emitted from the flash lamp 1, the excitation light of the solid-state laser medium 2 having a wavelength of 696 nm or 600 to 1000 nm is radiated as it is outside the arc tube 3.

  As described above, the arc tube 3 of the present embodiment is made of alumina polycrystal, so that the light emitted from the flash lamp 1 and transmitted through the arc tube 3 is irregularly reflected by the alumina single crystal particles and dispersed. Since the chance of contact with titanium is increased, the wavelength conversion efficiency of the solid laser medium 2 to the excitation light of chromium or titanium is greatly improved as compared with the conventional wavelength conversion filter.

  The arc tube 3 made of an alumina polycrystal containing at least one metal element of chromium and titanium can be produced by a conventionally known method for producing ceramics.

For example, alumina powder is used as an alumina raw material, and chromium oxide (Cr ₂ O ₃ ) is added in an amount of 0.01 to 1.0 mass% to the alumina raw material to produce a mixed powder. A mixed powder is mixed with a known binder and solvent to prepare a slurry, and the slurry is formed into a tubular shape by a known molding means such as an extrusion molding method or an injection molding method, and then in an oxygen-containing atmosphere for 5 to 10 hours. The arc tube 3 made of an alumina polycrystal containing chromium can be obtained by baking to a certain extent. Here, the particle size, firing temperature, and firing time of the alumina particles as the raw material are reflected in the crystal particle size of the alumina polycrystal. The average crystal grain size of the alumina polycrystal tends to increase as the particle size of the alumina raw material increases, the firing temperature increases, and the firing time increases. Accordingly, by measuring the average crystal grain size of the alumina polycrystal and the grain size, firing temperature and firing time of the alumina raw material in advance, the average of 0.6 to 10.0 μm as described above is obtained. The crystal grain size can be controlled. When adding titanium, titanium oxide (TiO ₂ ) may be used instead of chromium oxide.

  The average crystal grain size of the alumina polycrystal was obtained by taking a SEM photograph of the surface of the polycrystal and using the software Win Roof (trade name, manufactured by Mitani Corporation) for 230 alumina particles. Image processing is performed to obtain a number distribution for each grain size, and an average crystal grain size is calculated. Specifically, the area within the contour of each target alumina particle was determined, the equivalent circle diameter of each alumina crystal particle was calculated, and the arithmetic average of the calculated equivalent circle diameter was defined as the average crystal grain size.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  Since the second embodiment is different from the first embodiment only in the material of the arc tube 3 and the other configurations are the same, only the arc tube 3 will be described below. A description of the configuration is omitted.

  The arc tube 3 of the first embodiment is an alumina polycrystal containing at least one kind of chromium and titanium. The arc tube 3 of the second embodiment is an alumina-zirconia mixed polycrystal. The body contains at least one of chromium and titanium. In the alumina-zirconia mixed polycrystal, when chromium is contained, chromium is dissolved in alumina, and when titanium is contained, titanium is dissolved in alumina or dispersed at the grain boundary of the alumina phase. Exist.

  Here, when the alumina-zirconia mixed polycrystal is used in which the total amount of the alumina phase and the zirconia phase is larger than the total amount of the phases other than the two phases of the alumina phase and the zirconia phase, This is preferable because the conversion efficiency of transmitted light tends to be higher. The comparison of these abundances is performed by calculating the abundance of the alumina phase and the zirconia phase in the same manner as in the case of the above-mentioned alumina polycrystal, and adding a phase other than the two phases of the alumina phase and the zirconia phase. The total abundance may be calculated and compared.

  In the arc tube 3 of the second embodiment, the average crystal grain size of alumina is 0.3 to 5.0 μm, and the average crystal grain size of zirconia is 0.2 to 2.0 μm. In the mixed polycrystal, the mass ratio of alumina to zirconia (alumina: zirconia) is 20:80 to 80:20. In other words, the alumina content is 20 to 80% by mass and the zirconia content is 80 to 20% by mass.

  The alumina-zirconia mixed polycrystal of the arc tube 3 of the second embodiment contains 0.01 to 1.0 mass% of at least one of chromium and titanium with respect to the total amount of the alumina-zirconia mixed polycrystal. . Thereby, it can maintain higher than the conversion efficiency of the transmitted light of an alumina-zirconia mixed polycrystal.

  The individual alumina single crystal particles and zirconia single crystal particles of alumina and zirconia contained in the alumina-zirconia mixed polycrystal constituting the arc tube 3 are transparent and transmit light. However, the crystal orientations of the alumina single crystal particles contained in alumina and the zirconia single crystal particles contained in zirconia are both random. The crystal grain size of each alumina single crystal particle and the crystal grain size of zirconia single crystal particles are about the same as or larger than the wavelength of the transmitted light, so that it passes through the alumina-zirconia mixed polycrystal. The light to be scattered is Mie scattered by the alumina single crystal particles and the zirconia single crystal particles, and the forward scattering is dominant. Since the light scattered forward is scattered forward one after another by the adjacent alumina single crystal particles or zirconia single crystal particles, the light is scattered from the inside to the outside of the arc tube 3 as a whole. After following a complicated path, the light is emitted from the outer peripheral surface of the arc tube 3 toward the reflector 4. As described above, as a whole, the transmitted light is irregularly reflected in the arc tube 3, but instead of simple irregular reflection, it follows a complicated path in the arc tube 3 by Mie scattering, and during that time, alumina-zirconia The chromium or titanium dispersed in the mixed polycrystal is transmitted while being excited.

  The longer the length of the path through the arc tube 3, the greater the chance of contact with chromium or titanium. Therefore, the use of alumina-zirconia mixed polycrystals excites more chromium or titanium than conventional glass. Then, fluorescent light having a wavelength of 696 nm or 600 to 1000 nm is emitted from the excited chromium or titanium. This fluorescence having a wavelength of 696 nm or 600 to 1000 nm becomes excitation light capable of exciting neodymium contained in the solid-state laser medium 2. Excitation of more chromium or titanium increases the amount of fluorescence emitted from chromium or titanium at a wavelength of 696 nm or 600 to 1000 nm. Note that the metal element to be contained in the arc tube 3 may be appropriately selected according to the excitation wavelength of the solid-state laser medium 2.

  Here, in the alumina-zirconia mixed polycrystal, the sum of the maximum peak intensity values of the phases constituting the alumina-zirconia mixed polycrystal is the sum of the maximum peak intensity values of the alumina phase and the zirconia phase. When the ratio is 0.95 or more, the mechanical strength of the alumina-zirconia mixed polycrystal and the conversion efficiency of transmitted light tend to be higher, which is preferable.

  Of the light emitted from the flash lamp 1, the light that is not absorbed by chromium or titanium follows a complicated path in the arc tube 3, and is emitted as it is to the outside of the arc tube 3 without being converted in wavelength. Therefore, of the light emitted from the flash lamp 1, the excitation light of the solid-state laser medium 2 having a wavelength of 696 nm or 600 to 1000 nm is radiated as it is outside the arc tube 3.

  As described above, the arc tube 3 of the second embodiment includes alumina and zirconia, so that the light emitted from the flash lamp 1 and transmitted through the arc tube 3 is irregularly reflected by the alumina single crystal particles and contained chromium. Or, since the chance of contact with titanium increases, the wavelength conversion efficiency of the solid laser medium 2 to the excitation light of chromium or titanium greatly improves as compared with the conventional wavelength conversion filter.

  Further, the alumina-zirconia mixed polycrystal used in the second embodiment has a longer optical path length of transmitted light than the alumina polycrystal used in the first embodiment, that is, the alumina-zirconia mixed polycrystal. The use of C increases the chance of contact with chromium or titanium than the use of alumina polycrystal. When the contact opportunity increases, the amount of fluorescence emitted with a wavelength of 696 nm or 600 to 1000 nm for optically exciting the solid-state laser medium 2 increases, so that the wavelength conversion efficiency is further improved.

  Furthermore, as a result of diligent research by the present inventors, it has been found that the optical path length of light passing through the alumina-zirconia mixed polycrystal varies depending on the content of alumina in the alumina-zirconia mixed polycrystal.

  FIG. 3 is a graph showing changes in the delay time of transmitted light when the alumina content is changed in the alumina-zirconia mixed polycrystal.

  The vertical axis represents the delay time (psec: pico second) of transmitted light that passes through the alumina-zirconia polycrystal. The alumina-zirconia mixed polycrystal is irradiated with a second harmonic wave of a titanium sapphire laser beam, and the transmitted light is photographed with a streak camera. The time from when the laser beam was irradiated onto the alumina-zirconia mixed polycrystal to when the transmitted light was photographed was defined as the delay time.

As can be seen from the graph, when the content of alumina is 20% by mass to 80% by mass, the delay time of transmitted light is longer than the delay time of only alumina (plotted as 100% Al ₂ O _{3 in the} graph). It has become. Furthermore, it was found that the delay time was the longest when the content of alumina was 35% by mass to 50% by mass.

  It is considered that the longer the delay time of transmitted light, the longer the optical path length of light transmitted through the alumina-zirconia mixed polycrystal. The longer the optical path length, the greater the chance that light transmitted through the alumina-zirconia mixed polycrystal will come into contact with the metal element contained in the alumina-zirconia mixed polycrystal such as chromium or titanium. The amount of excitation light emitted from the solid-state laser medium 2 emitted by the fluorescence emission of the metal element increases.

  Therefore, in the second embodiment, the alumina-zirconia mixed polycrystal constituting the arc tube 3 preferably has a mass ratio of alumina to zirconia of 20:80 to 80:20, and 35:65 to 50. : 50 is particularly preferable.

  In the case of using the alumina-zirconia mixed polycrystal of the second embodiment as compared with the case of using only the alumina polycrystal of the first embodiment, the effect of increasing the optical path length of the transmitted light will be described. Since the refractive index of the zirconia single crystal is higher than that of the crystal, the alumina-zirconia mixed polycrystal of the second embodiment has two types of single crystals having different refractive indexes, so that the transmitted light is more complicated. This is thought to be due to irregular reflection and an increase in the optical path length.

  The arc tube 3 made of a mixed polycrystal containing a metal element such as chromium can be produced by a conventionally known method for producing ceramics as in the first embodiment.

For example, an alumina raw material and a zirconia raw material containing a known stabilizer are mixed, and 0.01 to 1.0 mass% of chromium oxide (Cr ₂ O ₃ ) is added thereto to produce a mixed powder. This mixed powder is mixed with a known binder and solvent to prepare a slurry, and the slurry is formed into a tubular shape by a known forming means such as an extrusion molding method or an injection molding method, and then 5 to 10 in an oxygen-containing atmosphere. By firing for about an hour, the arc tube 3 made of an alumina-zirconia mixed polycrystal containing chromium can be obtained. Here, the particle diameter, firing temperature, and firing time of the alumina particles and zirconia particles as raw materials are reflected in the crystal grain diameter of the alumina-zirconia mixed polycrystal. Therefore, by measuring in advance the relationship between the average crystal grain size and the grain size, firing temperature, and firing time of each raw material, the average crystal grain size of alumina as described above is 0.3 to 5.0 μm. Furthermore, zirconia can be controlled to an average crystal grain size of 0.2 to 2.0 μm. When adding titanium, titanium oxide (TiO ₂ ) may be used instead of chromium oxide.

  Moreover, since the content of alumina in the alumina-zirconia mixed polycrystal depends on the input amount of alumina particles and zirconia particles as raw materials, the input amount of the raw materials is 20 to 80% by mass of alumina. Preferably, the content may be 35 to 50% by mass.

  The average crystal grain size of alumina and the average crystal grain size of zirconia can be measured and calculated by the same method as in the first embodiment.

  In Example 1, as in the first embodiment, an alumina polycrystal (sample 1) made of an alumina sintered body containing 0.4% by mass of chromium with respect to the total amount is used as the material of the arc tube 3. Made and used. The average crystal grain size of the alumina single crystal was 0.55 μm.

  Photo Luminescence (PL) and Photo Luminescence Excitation (PLE) of Sample 1 were measured using a fluorimeter FP6600 (manufactured by JASCO Corporation). For PL, the light of wavelength 566 nm was irradiated to excite chromium, and the fluorescence of chromium was measured in the wavelength range of 590 nm to 850 nm. For PLE, fluorescence emission at a wavelength of 696 nm was measured, and an excitation wavelength at which fluorescence became strong in the range of an excitation wavelength of 350 nm to 650 nm was measured.

  FIG. 4 is a graph showing the results of PL measurement and PLE measurement of an alumina polycrystal containing chromium. The vertical axis represents light intensity (arbitrary unit arb. Unit), and the horizontal axis represents wavelength (nm). Graph A shows the result of PL measurement, and graph B shows the result of PLE measurement. As can be seen from graph A, it was found by PL measurement that Sample 1 has a fluorescence emission characteristic having a peak at a wavelength of 696 nm. Further, as can be seen from the graph B, it was found by the PLE measurement that there is excitation absorption near a wavelength of 566 nm. Moreover, it turned out that it has excitation absorption also near wavelength 420nm.

  Moreover, when the alumina polycrystal body (sample 2) which contains 0.4 mass% of titanium with respect to the total amount was produced as a material of the arc_tube | light_emitting_tube 3, and PL measurement and PLE measurement were performed, the sample 2 was determined by PL measurement. It was found that it has a fluorescence emission characteristic having a peak at a wavelength of 830 nm. Moreover, it turned out that it has excitation absorption by wavelength 360nm vicinity by PLE measurement.

  From these results, when sample 1 or 2 is used as the arc tube material, short-wavelength light including ultraviolet light that causes defects in the Nd: YAG medium out of the light emitted from the light source is sample 1 or 2. The other light having a wavelength necessary for excitation of neodymium is transmitted through the arc tube. The light absorbed by the sample 1 or 2 is emitted as fluorescence having a peak at a wavelength of 696 nm or 830 nm. Since the light of this wavelength contributes to the neodymium excitation of the Nd: YAG medium, the Nd: YAG medium can be excited more efficiently by this fluorescence.

  In Example 2, as in the second embodiment, the material of the arc tube 3 is an alumina-zirconia mixed polycrystalline body made of an alumina-zirconia sintered body containing 0.4% by mass of chromium with respect to the total amount ( Sample 3) was prepared and used.

  The change in the emission intensity of the Nd: YAG medium when the content of the polycrystalline alumina in Sample 3 was changed was measured. The average crystal grain size of the alumina single crystal was 0.55 μm, and the average crystal grain size of the zirconia single crystal was 0.27 μm.

  FIG. 5 is a schematic diagram showing a configuration of a measuring apparatus for measuring the emission intensity of the Nd: YAG medium. In order to measure the emission intensity, the second harmonic (532 nm) of the YAG laser is irradiated onto the sample 3 (FIG. 5, number 11), and the scattered light is collected by the lens 12 and applied to the Nd: YAG medium 13. Irradiated. Light emission from the Nd: YAG medium 13 was measured with a PIN photodiode 15. An IR85 filter 14 is disposed between the Nd: YAG medium 13 and the PIN photodiode 15, and a light shielding block 16 is disposed in the vicinity of the PIN photodiode 15 so as to reduce the influence of noise.

  FIG. 6 is a graph showing the measurement results of the emission intensity. The horizontal axis represents the content (mass%) of alumina in the alumina-zirconia mixed polycrystal, and the vertical axis represents 1.06 nm emission intensity (-). As can be seen from the graph, it was found that the emission intensity was high when the alumina content was in the range of 35 to 65% by mass, and that the emission intensity was particularly high at 35 to 50% by mass.

  This result corresponds to the result of the delay time of the transmitted light shown in FIG. That is, the longer the delay time, the greater the chance of contact with chromium contained in the alumina-zirconia mixed polycrystal, and the greater the amount of excitation light emitted to excite the Nd: YAG medium. As a result, as shown in FIG. This is thought to have led to a significant increase in emission intensity.

As the arc tube of the first embodiment, an arc tube made of only alumina polycrystal and containing 0.4% by mass of chromium was produced, and the oscillation intensity was measured by causing laser oscillation in a solid-state laser device. Furthermore, as the arc tube of the second embodiment, an arc tube made of an alumina-zirconia mixed polycrystal having an alumina content of 50% by mass and containing 0.4% by mass of chromium was manufactured. Furthermore, as a comparative example, an arc tube containing 0.4% chromium in glass was prepared, and the oscillation intensity was measured by causing laser oscillation in a solid-state laser device. The glass containing chromium of the comparative example, the _Al 2 _{O 3} 20.5 mol%, 60 mol% of CaO, MgO and 7 mol%, 1 mol% of BeO, the SiO ₂ 9.5% mol, the glass raw material by mixing TiO ₂ to be 2% moles, and the _Cr 2 _{O 3} with respect to the glass raw material by adding 0.4 mass% was prepared by a known method.

  Assuming that the oscillation intensity of the solid state laser device of the comparative example is 100%, the oscillation intensity of the solid state laser device of the first embodiment is improved to about 105%. Furthermore, assuming that the oscillation intensity of the solid state laser device of the first embodiment is 100%, the oscillation intensity of the solid state laser device of the second embodiment is improved to about 110%.

  Further, as the arc tube of the first embodiment, arc tubes containing 0.4% by mass of titanium were respectively produced in the same manner as the above experiment, and the oscillation intensity was measured by causing laser oscillation in the solid-state laser device. . Further, as the arc tube of the second embodiment, an arc tube comprising an alumina-zirconia mixed polycrystal having an alumina content of 50% by mass and containing 0.4% by mass of titanium is the same as the above experiment. It was prepared. Furthermore, as a comparative example, arc tubes containing 0.4% by mass of titanium in the same glass as in the comparative example using chromium described above were prepared in the same manner as in the above experiment, and laser oscillation was performed using the solid state laser device. The oscillation intensity was measured.

  In the arc tube containing titanium, the oscillation intensity of the solid-state laser device of the first embodiment was improved to about 107% when the oscillation intensity of the solid-state laser device of the comparative example was 100%. Furthermore, assuming that the oscillation intensity of the solid state laser device of the first embodiment is 100%, the oscillation intensity of the solid state laser device of the second embodiment is improved to about 114%.

DESCRIPTION OF SYMBOLS 1 Flash lamp 2 Solid-state laser medium 3 Light emission tube 4 Reflector 5,6 Reflecting mirror 100 Solid-state laser apparatus

Claims (6)

Used in the wavelength conversion of light, Ri Na comprise alumina polycrystalline body containing at least one metal element of chromium and titanium, at least one of the content of the chromium and the titanium, the alumina polycrystal wavelength conversion member, wherein 0.01 to 1.0% by mass Rukoto in terms of oxide relative to the total amount.   2. The wavelength conversion member according to claim 1, wherein in the alumina polycrystal, an average crystal grain size of the alumina crystal is 0.6 to 10.0 μm. Used in the wavelength conversion of light, alumina containing at least one metal element of chromium and titanium - Ri Na comprise zirconia mixed polycrystalline, at least one of the content of the chromium and the titanium, the alumina - wavelength conversion member, wherein 0.01 to 1.0% by mass Rukoto in terms of oxide relative to the total amount of the zirconia mixed polycrystals. An alumina-zirconia mixed polycrystal used for wavelength conversion of light and containing at least one metal element of chromium and titanium, and in the alumina-zirconia mixed polycrystal, a mass ratio of alumina and zirconia There 20: 80 to 80: wavelength conversion member you being a 20. In the alumina-zirconia mixed polycrystal, the average crystal grain size of alumina crystals is 0.3 to 5.0 μm, and the average crystal grain size of zirconia crystals is 0.2 to 2.0 μm. The wavelength conversion member according to claim 3 or 4 . A light source;
The wavelength conversion member according to any one of claims 1 to 5 ,
A solid-state laser medium optically pumped by light converted by the wavelength conversion member;
A solid-state laser device comprising: a reflector that reflects the light converted by the wavelength conversion member and focuses the light on a solid-state laser medium.

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