KR20070018070A - Method and structure for non-linear optics - Google Patents

Abstract

The present invention relates to a compound for nonlinear optics for use at 350 nm and below. This compound includes a material for nonlinear optics comprising A _x M _(1-x) Al ₃ B ₄ O ₁₂ . x is greater than or equal to 0 and less than or equal to 0.1, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, and M is Sc, Y, La, Yb, and Lu It is selected from the configured group. This compound is free of molybdenum-containing impurities of 1000 ppm or more.

Nonlinear Optics, Crystals, Polarization, Dopants, Seeds

Description

METHOD AND STRUCTURE FOR NON-LINEAR OPTICS}

[Related App Cross Reference]

This application claims priority to US Provisional Patent Application No. 60 / 562,881, dated April 16, 2004, and US Provisional Patent Application No. 60 / 562,626, dated April 14, 2004, both of which are incorporated into this application. Let's do it.

[Statement of invention rights made under government-funded research or development]

The present invention has been made using funds provided by some National Science Foundation-approved ECS-0114017. The US government may have certain rights in this invention.

[Reference to "sequence listing", table, or computer program listing addendum filed on compact disc]

Not applicable

The present invention relates generally to certain compounds having optical properties. More specifically, the present invention provides, by way of example, certain compounds comprising A _X M _(1-X) Al ₃ B ₄ O ₁₂ at selected wavelengths of electromagnetic radiation. x is greater than or equal to 0 and less than or equal to 0.1, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, and M is selected from the group consisting of Sc, Y, La, Yb, and Lu. By way of example only, the compounds are useful for electromagnetic radiation having wavelengths of 350 nm and below, but it will be appreciated that the present invention has a very wide range of applications.

Nonlinear optical (NLO) materials are special in that they affect the properties of light. A well known example is the polarization of light by a constant material, such as when the material rotates polarization vectors of absorbed light. If the effect of the polarization vector by the absorbed light is linear, then the light emitted by the material has the same frequency as the absorbed light. NLO materials affect the polarization vector of light absorbed in a nonlinear manner. As a result, the frequency of light emitted by the nonlinear optical material is affected.

For example, a beam of coherent light of a given frequency, such as produced by a laser, has an appropriately oriented NLO crystal with a non-zero component of a secondary polarizability tensor. When propagated through, the crystal will generate light at a different frequency, thus extending the useful frequency range of the laser. The generation of this light may be due to processes such as sum-frequency generation (SFG), difference-frequency generation (DFG), and optical parametric amplification (OPA). Devices using NLO crystals include, but are not limited to, up and down frequency converters, optical parametric oscillators, optical rectifiers, and optical switches.

Frequency generation in NLO materials is largely an important effect. For example, two monochromatic electromagnetic waves with frequencies ω ₁ and ω ₂ , which propagate through NLO crystals with appropriate orientations, can result in the generation of light of various frequencies. Mechanisms for defining the frequency of light using these two distinct frequencies are sum frequency generation (SFG) and difference frequency generation (DFG). SFG = light of frequency ω ₃ is the sum of two incident frequencies, ω ₃ = It is a process generated as ω ₁ + ω ₂ . In other words, SFG is useful for converting long wavelengths of light into shorter wavelengths of light (eg, in the vicinity of infrared light, or from visible to ultraviolet light). A special case of sum frequency generation is the second harmonic generation (SHG) when ω ₃ = 2ω ₁ , which is satisfied when the incident frequencies are equal, such as ω ₁ = ω ₂ . DFG is a process in which light of frequency ω ₄ is generated as the difference ω ₄ = ω ₁ -ω ₂ of the incident frequency. DFG is useful for converting light of shorter wavelengths into light of longer wavelengths (eg, visible light to infrared). A special case of DFG is when ω ₁ = ω ₂ and thus ω ₄ = 0, which is known as photorectification. Optical parametric oscillation (OPO) is also a form of DFG and is used to produce light of variable frequency.

The conversion efficiency of an NLO crystal for a particular application depends on, but is not limited to, a number of factors: effective nonlinearity of the crystal (piometer / volt [pm / V]), Birefringence (Δn, where n is the refractive index), phase matching conditions (type I, type II, noncritical, quasi, or critical), angle acceptance angle in radians-cm, temperature acceptance in degrees K-cm, work Walk-off (in radians), temperature dependent change in refractive index (dn / dT), optical transparency range (nm), and optical damage threshold (W / cm ² ). Preferred NLO decisions should have an optimal combination of the above characteristics when limited to a particular application.

Borate crystals form a population of inorganic NLO materials used in various applications, such as in laser-based manufacturing, medicine, hardware and metrology, communications, and research. Beta barium borate (BBO: β-BaB ₂ O ₄ ), lithium triborate (LBO: LiB ₃ O ₅ ), and cesium lithium borate (CLBO: CsLi (B ₃ O ₅ ) ₂ ) are especially NLO in high power applications. It is an example of a recently developed borate-based NLO decision that is widely used as a device. Selected properties suitable for the generation of laser light from the mid-infrared to the ultraviolet for this crystal are listed in Table 1.

BBO has good nonlinearity (substantially 2.2 pm / V), transparency between 190 nm and 3500 nm, significant birefringence (essential for phase matching), and high damage threshold (5 GW / cm ² , 1064 nm, 0.1 ns Pulse width). However, high birefringence produces a relatively small angular acceptability that can limit conversion efficiency and laser beam quality. Crystals are difficult to grow to a relatively large size and are somewhat hygroscopic.

LBO shows optical transparency throughout the visible electromagnetic spectrum, extends to ultraviolet light (absorption edge. Coincidence 160 nm) and has a high damage threshold (10 GW / cm ² , 1064 nm, 0.1 ns pulse width). However, it has an inherent birefringence that is insufficient for phase matching to produce deep UV radiation. Moreover, LBO must be incongruently melted and prepared by flux-assisted crystal growth methods. This results in smaller crystals and higher production costs, thus limiting production efficiency.

CLBO appears to be able to produce UV light due to the combination of high nonlinearity and sufficient birefringence. Crystals can also be produced on a relatively large scale. However, crystals often deteriorate too much moisture and often constantly absorb moisture from the air; Therefore, extreme care should usually be taken in managing the ambient humidity to prevent hydration stress and possible crystal breakage.

In 1981 a crystal called NYAB [Nd _x Y _(1-x) Al ₃ B ₄ O ₁₂ ] was reported in the USSR. 1320 nm to 660 nm of the laser itself, an equivalent frequency (laser self-frequency-doubling) the effect is _{Nd 0 .2 Y 0 .8 Al 3} B 4 O ₁₂ crystal was realized in two in order harmonic determined intrinsic absorption is 1060 nm to It has been found to limit the practicality of laser self frequency equalization of 530 nm.

Years later, several laboratories in China succeeded in improving the crystal growth process and obtained NYAB crystals with good optical quality and reasonable size. Lu et al. Developed a multifunctional crystal Nd _x Y _(1-x) Al ₃ B ₄ O ₁₂ with an effective laser self-frequency equalization conversion. Nd ^{3 +} doped laser gain crystal (Nd ^{3 +} doped laser crystal gain) is, here was a dye laser (pumped), that in itself has a laser radiation of a 1060 nm converted to 530 nm (see Fig. 2 .Lu et al., Chinese Phys . Lett . 3, No. 9 (1986)). NYAB has since been used as a research decision that is often only useful in the visible spectrum. Recent work on Yb-doped YAB as a self-doubling laser gain material has changed slightly in operating laser efficiency and wavelength and follows the same path as NYAB. Laser light is generated in the crystal and self-equivalent to 520 nm of green (see Dekker et al., JOSA B , Vol. 22, No. 2 (2005) 378-384). In addition, an important preparation method in its operation and history limits its use to visible light and infrared light. Therefore, it is highly desirable to improve the technology for this group of compounds that enable optical function with ultraviolet light.

In other words, the optical properties of a nonlinear optical (NLO) material are changed by light passing through the material. Changes in optical properties can be caused by induced electron charge transfer (polarization), which acts as an oscillating dipole. The vibrating dipole can cause the material to emit photons. When the polarization of the material is linear, the emitted photons have the same frequency as the light incident on the material. If the polarization is nonlinear, the frequency of light coming from the material can be any integer multiple of the frequency of incident light. For example, the real effect of frequency doubling is that two photons with frequency ω combine to generate a single photon with a frequency equal to 2ω. Therefore, the wave propagation in synchronization (phase matching) causes the frequency of light to double. Frequency equalization is also referred to as second harmonic generation (SHG). NLO materials were found to be secondary harmonic generation in 1961. Ann . Rev. Mater . Sci . , 16: 203-43 (1986).

Several NLO materials have been recognized in the prior art. For example, the YAl ₃ (BO ₃ ) ₄ NLO crystal can be obtained from Pu Wang ET AL. Growth And Evaluation Of Ytterbium - Doped Yttrium Aluminum Borate as a Potential Self - Doubling Laser Crystal , J. OF THE OPTICAL SOC. OF AM. B, January 1999, 63-69, which is incorporated herein by reference. NLO crystals, such as YAl ₃ (BO ₃ ) ₄ NLO crystals, have been used in a variety of devices. For example, US Pat. No. 5,202,891 describes a neodymium yttrium aluminum borate NLO crystal incorporated into a laser device. US 4,826,283 describes another NLO device made from a single crystal of LiB ₃ O ₅ .

It is known to recrystallize NLO materials to form larger crystals with a homogeneous crystal structure. For example, J.Li et al. Initiate the formation of YAl ₃ (BO ₃ ) ₄ NLO crystals from a flux containing K ₂ MoO ₄ . J.Li ET AL., T he Influenc of Yb ^{3 +} Concentration on Yb : YAl ₃ (BO ₃ ) ₄ , 38 CRYS. RES. TECH. 890-895 (2003), which is incorporated herein by reference. Aluminum-borate NLO crystals grown in the prior art are generally limited to the generation or emission of light of wavelengths longer than 370 nm.

Therefore, it is highly desirable to improve the technology for optical compounds.

[Simple Summary of Invention]

The present invention relates generally to certain compounds having optical properties. More specifically, as an example, the present invention provides certain compounds comprising A _X M _(1-X) Al ₃ B ₄ O ₁₂ at selected wavelengths of electromagnetic radiation. x is 0 or more and 0.1 or less, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, and M is selected from the group consisting of Sc, Y, La, Yb, and Lu. By way of example only, the compounds are useful for electromagnetic radiation having wavelengths of 350 nm and below, but it will be appreciated that the present invention has a very wide range of applications.

According to one embodiment of the invention, there is provided a compound for nonlinear optics used at 350 nm and below. The compound includes a nonlinear optics material comprising YAl ₃ B ₄ O ₁₂ . The compound is free of molybdenum bearing impurity of more than 1000 parts per million.

According to another embodiment of the present invention, the nonlinear optics compound used at 350 nm and below comprising a nonlinear optics material includes Y _(1-x) M _x Al ₃ B ₄ O ₁₂ . x is greater than or equal to 0 and less than or equal to 0.1, and M is selected from the group consisting of Sc, La, Yb, and Lu. The compound is free of more than 1000 ppm molybdenum containing impurities.

According to another embodiment of the invention, the nonlinear optics compound used at 350 nm and below comprising a nonlinear optics material includes Yb _(1-x) M _x Al ₃ B ₄ O ₁₂ . x is 0 or more and 0.1 or less and M is selected from the group consisting of Sc, Y, La, and Lu. The compound is free of more than 1000 ppm molybdenum containing impurities.

According to another embodiment of the invention, the nonlinear optics compound used at 350 nm and below comprising a nonlinear optics material includes Lu _(1-x) M _x Al ₃ B ₄ O ₁₂ . x is 0 or more and 0.1 or less and M is selected from the group consisting of Sc, Y, Yb, and La. The compound is free of more than 1000 ppm molybdenum containing impurities.

According to another embodiment of the invention, the nonlinear optics compound used at 350 nm and below comprising a nonlinear optics material comprises Sc _(1-x) M _x Al ₃ B ₄ O ₁₂ . x is 0 or more and 0.1 or less and M is selected from the group consisting of Y, La, Yb, and Lu. The compound is free of more than 1000 ppm molybdenum containing impurities.

According to another embodiment of the invention, the nonlinear optics compound used at 350 nm and below comprising a nonlinear optics material comprises A _x M _(1-x) Al ₃ B ₄ O ₁₂ . x is greater than or equal to 0 and less than or equal to 0.1, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, and M is selected from the group consisting of Sc, Y, La, Yb, and Lu. The compound is free of more than 1000 ppm molybdenum containing impurities.

According to another embodiment of the present invention, a method of making a compound for nonlinear optics used at 350 nm and below comprises providing a plurality of materials. The plurality of materials include lanthanum containing compounds, which can be decomposed into at least lanthanum oxide upon heating. The method also includes mixing a plurality of materials to form a mixture based on at least information relating to a predetermined ratio, starting a crystallization process in the mixture to form crystals, and crystals comprising lanthanum from the mixture. Removing the step.

According to another embodiment of the present invention, a method of making a compound for nonlinear optics used at 350 nm and below comprises providing a plurality of materials. The plurality of materials include a yttrium containing compound, which may be decomposed into at least yttrium oxide upon heating. The method also includes mixing a plurality of materials to form a mixture based on at least information relating to a predetermined ratio, starting a crystallization process in the mixture to form crystals, and crystals comprising yttrium from the mixture. Removing the step.

The present invention achieves many advantages over the prior art. For example, certain embodiments of the present invention provide a new method of preparation that excludes contaminants that prevent the operation of borate huntites in the ultraviolet spectrum. In addition, preparation methods have been developed to enable rapid formation of crystals by using a creative chemical method. Such a method has enabled the production of large single crystals of the present invention, which have not been achieved so far in the prior art. Formulation methods have also been developed such that when heated to the melting point the volatility of the starting mixture is lower than in the prior art.

According to certain embodiments of the present invention, what is described herein are nonlinear optical (NLO) crystals that reduce the concentration of compounds that adversely affect the optical properties of the crystals in connection with what are known as NLO crystals. This undesirable compound is present in varying degrees in conventional NLO crystals, in particular conventional aluminum-borate NLO crystals. Some of the disclosed crystals are useful for modifying the wavelength of incident light, such as light emitted by a laser. For example, some of the disclosed crystals may convert an input laser beam of a first wavelength into an output laser beam of a second wavelength, where the second wavelength is any integer value of the incident wavelength, substantially 300 nm, typically As substantially 250 nm, more typically substantially less than 175 nm.

Some of the crystals disclosed have a volume of substantially greater than 0.1 mm ³ , typically substantially 1 mm ³ , more typically substantially 5 mm ³ . This crystal includes the initial material and may also include one or more secondary materials different from the initial material. In some embodiments, including secondary materials, any secondary materials that interfere with the generation and / or emission of light of a desired wavelength are present at low concentrations relative to their concentration in conventional NLO crystals. For example, a secondary material that interferes with the generation and / or emission of light of a desired wavelength may be substantially less than 100 ppmw, typically substantially 50 ppmw, more typically substantially less than 10 ppmw. May be present in concentration. In another embodiment, the crystal is substantially free of secondary material that interferes with the generation and / or emission of light of a desired wavelength. For example, a secondary material that interferes with the generation and / or emission of light of a desired wavelength may be a compound comprising transition metal elements and / or lanthanide elements other than yttrium, lanthanum, and lutetium. . However, any of these secondary materials, such as tungsten, are present in the effective solvent and have a limited effect on the generation and / or emission of light of a certain desired wavelength. In some embodiments, the crystals contain, in addition to the tungsten-containing compound, a secondary material that interferes with the generation and / or emission of light of a desired wavelength, substantially 100 ppmv, typically substantially 50 ppmv, more typically substantially Less than 10 ppmv.

Aluminum-borate NLO crystals are yttrium, lutetium, or YAl ₃ (BO ₃ ) ₄ , LuAl ₃ (BO ₃ ) ₄ , and Y _(1-x) Lu _x Al ₃ (BO ₃ ) ₄ , where x is 0 Aluminum-borate NLO crystals having a chemical structure including combinations thereof, such as greater integers). As long as unwanted contaminants that interfere with the generation and / or emission of light of a desired wavelength are substantially reduced or eliminated for known crystals, these materials, when crystallized to a crystal size useful for optical applications, are new compounds. to be.

Also described herein are embodiments of a method of making NLO crystals, particularly aluminum-borate NLO crystals. Certain embodiments provide a precursor material and a solvent, or an initial material and a solvent, wherein the solvent is substantially free of any material that interferes with the generation and / or emission of light of a desired wavelength, and Crystallizing the initial material to form crystals substantially free of any material that interferes with the generation and / or emission of light. For example, the crystal grown from the solvent and the solvent may be substantially free of transition metal elements and lanthanide elements other than yttrium, lanthanum, and lutetium. As another example, the solvent and crystals grown from the solvent may be substantially free of molybdenum.

Embodiments of the method may include mixing a solvent with a precursor material or an initial material to form a mixture, and inserting a seed into the mixture. A seed, such as a crystalline initial material, possibly consisting essentially of the initial material, may be suspended in the mixture. In some embodiments, recrystallizing the initial material includes cooling the mixture and recovering crystals from the mixture. Cooling the mixture may be achieved by cooling the mixture from the melting point of the mixture at or above the first temperature over a growth period that is typically sufficient to grow crystals of the desired size suitable for useful applications, such as growth periods substantially longer than 10 hours. Cooling the mixture to a second temperature below the melting point. For some growth periods substantially longer than 2 hours, the mixture may be cooled with a cooling gradient substantially less than 2 ° C per hour. In some embodiments, the second temperature may be, for example, a temperature between substantially 5 ° C. and substantially 100 ° C. below the melting point of the mixture.

Examples of methods include various NLO crystals, in particular yttrium, lutetium, or YAl ₃ (BO ₃ ) ₄ , LuAl ₃ (BO ₃ ) ₄ , and Y _(1-x) Lu _x Al ₃ (BO ₃ ) ₄ (here X can be used to grow aluminum-borate NLO crystals, such as aluminum-borate NLO crystals having a chemical structure comprising a combination thereof. Suitable solvents include solvents substantially free of transition metal elements and lanthanide elements, and solvents substantially free of molybdenum, other than yttrium, lanthanum, and lutetium, to prevent the generation and / or emission of light of a desired wavelength. Solvents that are substantially free of material. Examples of suitable solvents include one or more of the following compounds: LaB ₃ O ₆ , MgB ₂ O ₄ , and LiF. In some embodiments, the solvent is substantially free of transition metal elements and lanthanide elements other than yttrium, lanthanum, lutetium, and tungsten. An example of a tungsten containing solvent is Li ₂ WO ₄ which can be used with B ₂ O ₃ to grow YAl ₃ (BO ₃ ) ₄ crystals, for example.

The NLO determination described above can be incorporated into a variety of devices, including laser devices. The device can be used, for example, to detect anomaly of the surface of a substrate or to drill holes in the substrate.

Various additional objects, features and advantages of the present invention may be more fully understood with reference to the following detailed description of the invention and the accompanying drawings.

1 is a simplified method of making an optical compound according to an embodiment of the present invention.

2 is a simplified image of an optical compound according to an embodiment of the present invention.

3 is a simplified diagram illustrating the transmission characteristics for an optical compound according to one embodiment of the present invention.

4 is a simplified diagram illustrating frequency conversion by an optical compound according to an embodiment of the present invention.

FIG. 5 shows the percent transmittance of YAl ₃ (BO ₃ ) ₄ crystals (YAB-W) grown with tungsten over a wavelength range from 280 nm to 400 nm, YAl ₃ (BO ₃ ) ₄ crystals containing molybdenum (YAB- Is a line graph showing the percent transmission of Mo) and the percent transmission of YAl ₃ (BO ₃ ) ₄ crystals (YAB-La) substantially free of all transition metal contaminants.

6 is a schematic diagram of a laser device incorporating an NLO crystal.

The present invention relates generally to certain compounds having optical properties. More specifically, the present invention provides, by way of example, certain compounds comprising A _X M _(1-X) Al ₃ B ₄ O ₁₂ at selected wavelengths of electromagnetic radiation. x is greater than or equal to 0 and less than or equal to 0.1, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, and M is selected from the group consisting of Sc, Y, La, Yb, and Lu. By way of example only, the compounds are useful for electromagnetic radiation having wavelengths of 350 nm and below, but it will be appreciated that the present invention has a very wide range of applications.

NYAB was developed as a self-doubling crystal, ie a crystal that is optically excited and generates fundamental wavelengths and second harmonics without the need for separate frequency equalization crystals. However, due to the inherent limitations, the possible applications are strictly limited. First, the fundamental wavelength can often be only 1060 nm and 1300 nm. Second, since crystals are usually only a few millimeters in size, they are often useless in reasonably large crystal sizes that are good for commercial use of the product.

Although NYAB was sometimes available commercially in limited quantities, the pure form of YAB was not produced commercially. Conventional production methods yield small crystals containing significant amounts of nonstoichiometric metal contamination and exhibiting substandard crystal quality. In addition, the fluxing agents used in conventional methods insert significant amounts of contaminants that prevent effective device operation at UV below 350 nm.

According to certain examples of the present invention, various kinds of borate crystals containing one or more kinds of metal ions, such as rare earth metal, have been prepared, and frequency-multiplied Nd: YAG laser (wavelength: 532 nm) is prepared. Experiments on the generation of equal harmonics (wavelength: 266 nm) by performing irradiation over this borate crystal were carried out. For that reason, the ability to experimentally produce NLO materials has been demonstrated to produce harmonic light of 350 nm or less. As a result, a strong generation of second harmonic 266 nm from borate crystals was found to include both Y and Al, and a new NLO crystal in the form of yttrium aluminum borate could transmit and produce ultraviolet radiation below 350 nm. Was achieved.

The present invention produces and utilizes nonlinear optical materials that satisfy Y _(1-x) M _x Al ₃ B ₄ O ₁₂ (where M = Sc, La, Yb, or Lu, and 0 ≦ _x ≦ 0.1). It is the purpose of certain embodiments of to be prepared by a method of removing or significantly reducing contaminants that render the device unavailable in the UV spectrum. More specifically, certain embodiments of the present invention exclude metals, such as Group 6 elements, from those present in the device to be useful in UV below 350 nm.

It is an object of any embodiment of the present invention to provide a method of making a non-linear optical material which satisfies the composition without harmful UV absorption. One embodiment includes a source of substantially 10 to substantially 30 mol% Y, a source of substantially 10 to substantially 40 mol% M, a source of substantially 15 to substantially 40 mol% Al, and substantially 25 to Forming a mixture comprising substantially 50 mol% boron oxide. If M is Sc, then the source of M is generally scandium oxide; If M is La, then the source of M is usually lanthanum oxide; If M is Yb, then the source of M is generally ytterbium oxide; If M is Lu, then the source of M is generally lutetium oxide. The mixture is heated for a temperature and for a time sufficient to form the NLO material. For example, the heating may include heating the mixture to a first temperature of at least 850 K, generally greater than 850 K. Next, the mixture is cooled. After cooling the mixture is ground (grinded to a fine powder, such as ground to mortar and pestle), and then heated to a second temperature of at least 1300 K, generally greater than 1300 K. .

Another method for forming such a crystalline material may be top seeded solution growth, as shown in FIG. 1, but is not limited thereto. The method includes the following processes:

1. High purity oxide powders and chemicals are measured and mixed in appropriate proportions.

2. The mixture is placed in a crucible and placed in a furnace.

3. The mixture is heated and melted into a liquid.

4. After time passes, the melting temperature is near the freezing point.

5. Cold finger material or seed crystals are inserted to initiate crystallization.

6. Melt temperature and device conditions are modified and monitored to promote crystal growth.

7. When appropriate, the system is lowered to room temperature.

8. The decision is removed from the system.

For example, the synthesis of (Y, La) Al ₃ B ₄ O ₁₂ can be performed as follows. Yttrium oxide (Y ₂ O ₃ ) with purity higher than 99.9%, Lanthanum oxide (La ₂ O ₃ ) with purity higher than 99.9%, Aluminum oxide (Al ₂ O ₃ ) with purity higher than 99.9%, and 99.9 Boron oxide (B ₂ O ₃ ) with a purity higher than% was purchased from commercial suppliers such as Aesar and Stanford Material. The mixture was formed comprising substantially 14 wt% yttrium oxide, substantially 30 wt% lanthanum oxide, substantially 19 wt% aluminum oxide, and substantially 37 wt% boron oxide.

As mentioned above, certain embodiments of the present invention relate to nonlinear optical (NLO) devices and electro-optical devices and the ability to employ such devices at 350 nm or less. Certain embodiments of the present invention satisfy the general formula Y _(1-x) M _x Al ₃ B ₄ O ₁₂ (M = Sc, La, or Lu, 0 ≦ _x ≦ 0.1 mol%), It relates to a nonlinear optical material prepared without contaminants that interfere with its use in the ultraviolet (UV) region.

According to some embodiments of the invention, the nonlinear optical material Y _(1-x) M _x Al ₃ B ₄ O ₁₂ (M = Sc, La, or Lu, 0 ≦ _x ≦ 0.1) operates at 350 nm or less Is used for NLO devices. In another example, a nonlinear optical material is used with a laser source for a device that generates optical radiation of 350 nm or less. In another example, the nonlinear optical material is used with a light source for devices that generates optical radiation of 350 nm or less. In another example, the nonlinear optical material is formed in a trigonal crystal class for use at 350 nm or less. In another example, the nonlinear optical material is formed in space group R32 for use at 350 nm or less.

According to certain embodiments of the invention, the non-linear optical material is Yb _(1-x) M _x Al ₃ B ₄ O ₁₂ (M = Sc, La, or Lu, 0 ≦ _x ≦ 0.1) or Lu _{(1- x)} M _x Al ₃ B ₄ O ₁₂ (M = Sc, La, or Lu, and 0 ≦ _x ≦ 0.1) is satisfied. According to some embodiments, the nonlinear optical material Y _(1-x) M _x Al ₃ B ₄ O ₁₂ , Yb _(1-x) M _x Al ₃ B ₄ O ₁₂ , or Lu _(1-x) M _x Al ₃ B ₄ O ₁₂ is doped with Ce and / or Nd. According to certain embodiments, the non-linear optical material is selected from Y _(1-x) M _x Al ₃ B ₄ O ₁₂ or Lu _(1-x) M _x Al ₃ B ₄ O ₁₂ is Ce, Nd, and / or Yb Is doped.

As noted above, NYAB may be useful in limited quantities, but pure forms of YAB have not been produced commercially. Conventional production methods yield small crystals containing large amounts of nonstoichiometric metal contaminants and exhibiting substandard crystal quality. In addition, the solvent used inserts a significant amount of contaminants that interfere with device operation in UV below 350 nm. An overview of the study on huntite borate by Leonyuk & Leonyuk (1995) is a method of producing YAB and its family members, named potassium molybdates K ₂ MoO ₄ and K ₂ Mo ₃ O ₁₀ . The flux system that ultimately remained was described. Unfortunately, these solvent formulas have serious limitations for large-scale crystal growth: a) high flux volatility, b) small crystal yield, and c) Mo atoms contained in the desired borate-huntite structure. Thus, no commercial crystal production of pure YAB occurred, and no NLO crystals were applied to the laser product.

A _x M _(1-x) Al ₃ B ₄ O ₁₂ (where 0 ≦ _x ≦ 0.1, A = (Sc, Y, La, Yb, Lu), M = (Sc, Y, La, Yb, Lu It is an object of certain embodiments of the present invention to produce and utilize nonlinear optical materials that satisfy)), which are produced by methods of removing or significantly reducing contaminants that render the device unavailable in the UV spectrum. More specifically, certain embodiments of the present invention substantially exclude metals, such as Group 6 elements, from those present in the device to be useful in UV below 350 nm. Avoiding the inclusion of Group 6 impurities such as Mo extends the UV transmission of the selected borate hunite. In addition, the absence of inadequate metals in the initial crystal configuration reduces the overall mass absorption of spectral over the entire transparency range, such as 165-2700 nm. With the embodiments described herein, inherent transparency, previously unknown and uncharacterized in the scientific community, can be realized.

As described above, without UV absorption, A _x M _(1-x) Al ₃ B ₄ O ₁₂ (where 0 ≦ _x ≦ 0.1, A = (Sc, Y, La, Yb, Lu), M = ( It is an object of certain embodiments of the present invention to provide a method of making a nonlinear optical material that satisfies Sc, Y, La, Yb, Lu). One embodiment includes a source of substantially 10 to substantially 30 mol% A, a source of substantially 10 to substantially 40 mol% M, a source of substantially 15 to substantially 40 mol% Al, and substantially 25 to Forming a mixture comprising substantially 50 mol% boron oxide. If A or M is Sc, then the source of A or M is generally scandium oxide; If A or M is Y, then the source of A or M is usually yttrium oxide; If A or M is La, then the source of A or M is generally lanthanum oxide; If A or M is Yb, then the source of A or M is usually ytterbium oxide; If A or M is Lu, then the source of A or M is usually lutetium oxide. The mixture is heated for a temperature and for a time sufficient to form the NLO material. For example, the heating may include heating the mixture to a first temperature of at least 850 K, generally greater than 850 K. Next, the mixture is cooled. After cooling the mixture is ground (grinded to a fine powder, such as ground to mortar and pestle), and then heated to a second temperature of at least 1300 K, generally greater than 1300 K. .

As described above, FIG. 1 is a simplified method of making an optical compound according to an embodiment of the present invention. This diagram is merely an example and it should not unduly limit the claims. Those skilled in the art will recognize many variations, alternatives, and modifications. Method 100 includes step 110 for measuring and mixing chemicals, step 120 for moving the mixture to the crucible and furnace, step 130 for melting the mixture, step 140 for optimizing the furnace conditions for crystallization, inserting seeds and starting crystallization. Process 150, and process 160 for cooling the system and extracting the crystals. Although the foregoing has been represented using a selected sequence of processes, there may be many alternatives, modifications, and variations. For example, any of the processes can be expanded and / or combined. Other processes may be inserted in those described above. According to an embodiment, the particular sequence of the process may be replaced with others replaced. For example, process 150 is modified to use spontaneous nucleation or to use a conventional optical crystal growth process that inserts a cold finger into the molten surface. A more detailed description of this process is made here, in particular through the following.

In step 110, certain chemicals are measured and mixed. For example, high purity oxide powders and chemicals are measured and mixed in appropriate proportions. In process 120, the mixture is transferred to a crucible and a furnace. For example, the mixture is placed in a crucible and placed in a furnace. In step 130, the mixture is melted. For example, the mixture is heated and melted into a liquid.

In process 140, the furnace conditions are optimized for crystallization. For example, after a certain time, the melting temperature is near the freezing point. In step 150, seeds are inserted and crystallization begins. For example, seed crystals are inserted to initiate crystallization. In another example, process 150 is modified to use a cold finger material to initiate crystallization. In another example, process 150 is modified to use spontaneous nucleation to initiate crystallization. In addition, the melting temperature and device conditions are modified and monitored to promote crystal growth. In step 160, the system is cooled and crystals are extracted. For example, when appropriate, the system is lowered to room temperature. The decision is removed from the system and ready for testing or further processing.

As an example for method 100, the synthesis of Y _(1-x) La _x Al ₃ B ₄ O ₁₂ (where 0 ≦ _x ≦ 0.1) is carried out as follows:

Yttrium oxide (Y ₂ O ₃ ) with purity higher than 99.9%, lanthanum oxide (La ₂ O ₃ ) with purity higher than 99.9%, aluminum oxide (Al ₂ O ₃ ) with higher purity than 99.9% in process 110 And boron oxide (B ₂ O ₃ ) having a purity higher than 99.9% is obtained. For example, this chemical is obtained from commercial suppliers such as Aesar and Stanford Materials. The mixture is formed comprising substantially 14 wt% Y ₂ O ₃ , substantially 30 wt% La ₂ O ₃ , substantially 19 wt% Al ₂ O ₃ , and substantially 37 wt% B ₂ O ₃ .

In process 120, the mixture is placed in a crucible and a hot furnace in which the air atmosphere is controlled. For example, either ambient or inert air is satisfactory. In process 130, the mixture is heated to another temperature in the range of 1450 to 1575 K from room temperature within 12 hours. The resulting melt is allowed to soak at another temperature for substantially one to three days.

In step 140, the liquid mixture is cooled to a temperature near freezing point at a rate of 20 K / hour. For example, the temperature is substantially in the range 1475-1400 K. At that temperature, the mixture is held for substantially 8 hours. In step 150, by a spontaneous nucleation, or by using a conventional optical crystal growth process to insert crystalline seeds or cold fingers into the molten surface, at a final temperature of 1300 K at a rate of 1-5 K / day While cooling, the product begins to form. In addition, during the growth process, the melting temperature and apparatus conditions are monitored and optionally modified by an automatic control system of the actuator and / or the furnace to promote crystal growth.

In step 160, the system is then cooled to room temperature at a cooling rate of substantially 50 K / hour. Colorless transparent crystals of Y _(1-x) La _x Al ₃ B ₄ O ₁₂ (where 0 ≦ _x ≦ 0.1) are obtained and removed from the furnace.

According to another example for method 100, the synthesis of Lu _(1-x) La _x Al ₃ B ₄ O ₁₂ (where 0 ≦ _x ≦ 0.1) is carried out as follows:

In process 110, lutetium oxide (Lu ₂ O ₃ ) with a purity higher than 99.9%, lanthanum oxide (La ₂ O ₃ ) with a purity higher than 99.9%, aluminum oxide (Al ₂ O ₃ with a purity higher than 99.9% ) And boron oxide (B ₂ O ₃ ) having a purity higher than 99.9%. For example, this chemical is obtained from commercial suppliers such as Aesar and Stanford Materials. The mixture is formed comprising substantially 21 wt% Lu ₂ O ₃ , substantially 30 wt% La ₂ O ₃ , substantially 16 wt% Al ₂ O ₃ , and substantially 34 wt% B ₂ O ₃ .

In process 120, the mixture is placed in a crucible and placed in a high temperature furnace where the air atmosphere of nitrogen is controlled at a partial pressure of oxygen greater than or equal to 3000 ppm. In process 130, the mixture is heated to another temperature in the range of 1450 to 1575 K from room temperature within 12 hours. The resulting melt is allowed to soak at another temperature for substantially one to three days.

In step 140, the liquid mixture is cooled at a rate of 20 K / hour to a temperature near the freezing point. For example, the temperature is substantially in the range 1475-1400 K. At that temperature, the mixture is held for substantially 8 hours. In step 150, by spontaneous nucleation, or by using a conventional optical crystal growth process that inserts crystalline seeds or cold fingers into the molten surface, at a final temperature of 1275 K substantially at a rate of 1-5 K / day. While cooling, the product begins to form. In addition, during the growth process, the melting temperature and apparatus conditions are monitored and optionally modified by an automatic control system of the actuator and / or the furnace to promote crystal growth.

In process 160, the system is then cooled to room temperature at a cooling rate of substantially 50 K / hour. Colorless transparent crystals of Lu _(1-x) La _x Al ₃ B ₄ O ₁₂ (where 0 ≦ _x ≦ 0.1) are obtained and removed from the furnace.

According to another example for method 100, the synthesis of Sc _(1-x) La _x Al ₃ B ₄ O ₁₂ (where 0 ≦ _x ≦ 0.1) is carried out as follows:

In process 110, scandium oxide (Sc ₂ O ₃ ) with a purity higher than 99.9%, lanthanum oxide (La ₂ O ₃ ) with a purity higher than 99.9%, aluminum oxide (Al ₂ O ₃ with a purity higher than 99.9% ) And boron oxide (B ₂ O ₃ ) having a purity higher than 99.9%. For example, this chemical is obtained from commercial suppliers such as Aesar and Stanford Materials. The mixture is formed comprising substantially 8 wt% Sc ₂ O ₃ , substantially 34 wt% La ₂ O ₃ , substantially 18 wt% Al ₂ O ₃ , and substantially 39 wt% B ₂ O ₃ .

In step 120, the mixture is placed in a crucible and placed in a hot furnace in which the air atmosphere is controlled. For example, either atmospheric or nitrogen atmosphere is satisfactory. In process 130, the mixture is heated to another temperature in the range of 1475 to 1600 K from room temperature within 12 hours. The resulting melt is allowed to soak at temperature for substantially 1 to 3 days.

In step 140, the liquid mixture is cooled at a rate of 20 K / hour to a temperature near the freezing point. For example, the temperature is in the range of 1500-1425 K. At that temperature, the mixture is held for substantially 8 hours. In step 150, by a spontaneous nucleation, or by using a conventional optical crystal growth process to insert crystalline seeds or cold fingers into the molten surface, at a final temperature of 1300 K at a rate of 1-5 K / day While cooling, the product begins to form. In addition, during the growth process, the melting temperature and apparatus conditions are monitored and optionally modified by an automatic control system of the actuator and / or the furnace to promote crystal growth.

In process 160, the system is then cooled to room temperature at a cooling rate of substantially 50 K / hour. Colorless transparent crystals of Sc _(1-x) La _x Al ₃ B ₄ O ₁₂ (where 0 ≦ _x ≦ 0.1) are obtained and removed from the furnace.

2 is a simplified image of an optical compound according to an embodiment of the present invention. This diagram is merely an example and should not unduly limit the scope of the claims. Those skilled in the art will recognize many variations, alternatives, and modifications. The optical compound comprises Y _x La _y Al ₃ B ₄ O ₁₂ (where 0 ≦ x, 0 ≦ y, and x + y ≦ 1), made by method 100 as described above. Synthesis begins with yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), and boron oxide (B ₂ O ₃ ). As shown in FIG. 2, the 6 × 6 × 7 mm crystal is large enough and has an optically transparent surface that can function in a laser light crystal device.

3 is a simplified diagram illustrating the transmission characteristics for an optical compound according to one embodiment of the present invention. This diagram is merely an example and should not unduly limit the scope of the claims. Those skilled in the art will recognize many variations, alternatives, and modifications. The optical compound comprises Y _(1-x) La _x Al ₃ B ₄ O ₁₂ , wherein 0 ≦ _x ≦ 0.1, made by method 100 as described above. Synthesis begins with yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), and boron oxide (B ₂ O ₃ ). As shown in FIG. 3, curve 300 shows the percent transmission as a function of wavelength. The transmission percentage remains relatively constant from 350 nm to substantially 175 nm.

4 is a simplified diagram illustrating frequency conversion by an optical compound according to an embodiment of the present invention. This diagram is merely an example and should not unduly limit the scope of the claims. Those skilled in the art will recognize many variations, alternatives, and modifications. The optical compound comprises Y _(1-x) La _x Al ₃ B ₄ O ₁₂ , wherein 0 ≦ _x ≦ 0.1, made by method 100 as described above. Synthesis begins with yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), and boron oxide (B ₂ O ₃ ). For example, the optical compound is a crystal as shown in FIG. 2. During the experiment, a laser pulse having a wavelength of substantially 532 nm is applied to a 6x6x7 mm Y _(1-x) La _x Al ₃ B ₄ O ₁₂ crystal. In response, the crystal outputs a beam of light received by an imaging scintillator card that is sensitive to ultraviolet radiation. As shown in FIG. 4, images were taken using a camera made to cover up to 532 nm with a photographic filter. In that image, blue fluorescence was observed on the imaging scintillator card. Therefore, ultraviolet light was generated by Y _(1-x) La _x Al ₃ B ₄ O ₁₂ crystals through the SHG process and detected by the imaging scintillator card. According to another experiment, a dichronic mirror, in particular optimized for 266-nm light transmission, was placed between the Y _(1-x) La _x Al ₃ B ₄ O ₁₂ crystal and the imaging scintillator card. Blue fluorescence similar to that of FIG. 4 was also observed. Therefore, 266 nm of ultraviolet light was generated by the Y _(1-x) La _x Al ₃ B ₄ O ₁₂ crystal.

As described above, and further emphasized herein, the method may be used to make various forms of optical compounds. According to one embodiment of the present invention, the compound for nonlinear optics used at 350 nm and below is made by method 100. The compound includes a material for nonlinear optics comprising YAl ₃ B ₄ O ₁₂ . The compound is free of molybdenum-containing impurities of at least 1000 ppm. According to another embodiment of the present invention, the compound for nonlinear optics used at 350 nm and below is made by method 100. The compound containing the material for nonlinear optics includes Y _(1-x) M _x Al ₃ B ₄ O ₁₂ . x is greater than or equal to 0 and less than or equal to 0.1 and M is selected from the group consisting of Sc, La, Yb, and Lu. The compound is free of more than 1000 ppm molybdenum containing impurities.

According to another embodiment of the present invention, the compound for nonlinear optics used at 350 nm and below is made by method 100. Compounds containing nonlinear optics include Yb _(1-x) M _x Al ₃ B ₄ O ₁₂ . x is 0 or more and 0.1 or less and M is selected from the group consisting of Sc, Y, La, and Lu. The compound is free of more than 1000 ppm molybdenum containing impurities. According to another embodiment of the present invention, the compound for nonlinear optics used at 350 nm and below is made by method 100. Compounds containing a nonlinear optics material include Lu _(1-x) M _x Al ₃ B ₄ O ₁₂ . x is 0 or more and 0.1 or less and M is selected from the group consisting of Sc, Y, Yb, and La. The compound is free of more than 1000 ppm molybdenum containing impurities. According to another embodiment of the invention, the nonlinear optics compound used at 350 nm and below, including the nonlinear optics material, comprises Sc _(1-x) M _x Al ₃ B ₄ O ₁₂ . x is 0 or more and 0.1 or less and M is selected from the group consisting of Y, La, Yb, and Lu. The compound is free of more than 1000 ppm molybdenum containing impurities.

According to another embodiment of the present invention, the compound for nonlinear optics used at 350 nm and below is made by method 100. The compound containing the nonlinear optics material includes A _x M _(1-x) Al ₃ B ₄ O ₁₂ . x is greater than or equal to 0 and less than or equal to 0.1, A is selected from the group consisting of Sc, Y, Yb, and Lu, and M is selected from the group consisting of Sc, Y, La, Yb, and Lu. The compound is free of more than 1000 ppm molybdenum containing impurities. In one embodiment, M comprises one or more selected from the group consisting of La, Lu, Sc, Y, and Yb. According to another embodiment, A includes one or more selected from the group consisting of Sc, Y, La, Yb, and Lu.

As noted above, according to certain embodiments, each of the various forms of optical compounds made by method 100 is free of molybdenum-containing impurities of at least 1000 ppm. For example, the compound is free of molybdenum-containing impurities of 500 ppm or more. In another example, the compound is free of molybdenum-containing impurities of at least 100 ppm. In yet another embodiment, the compound is free of molybdenum containing impurities of at least 10 ppm. In another example, the compound is free of more than 1 ppm molybdenum containing impurities. In another example, the compound is substantially free of molybdenum containing impurities. According to certain embodiments of the present invention, each of the various forms of optical compounds made by method 100 is free of any impurities greater than 1000 ppm that can prevent the compounds from being used for nonlinear optics of 350 nm and below. For example, the compound is free of any impurities above 500 ppm. In another example, the compound is free of any impurities above 100 ppm. In another example, the compound is free of any impurities above 10 ppm. In another example, the compound is free of any impurities above 1 ppm. In another example, the compound is substantially free of any impurities.

As noted above, according to certain embodiments, each of the various forms of optical compound made by method 100 has a volume substantially greater than 0.001 mm ³ . For example, the compound has a volume substantially greater than 0.01 mm ³ . In another example, the compound has a volume substantially greater than 0.1 mm ³ . In another example, the compound has a volume substantially greater than 1 mm ³ .

According to some embodiments, various forms of optical compounds made by method 100 may be used for nonlinear optics of 350 nm and below. For example, use is associated with wavelengths substantially in the range of 350 nanometers to 160 nm. In another example, the use is associated with a wavelength substantially in the range of 350 nm to 170 nm. According to another example, the use relates to a device generating optical radiation of 350 nanometers or less. In another example, the device comprises a NLO system, a compound associated with a laser system, and / or a compound associated with a light source.

According to certain embodiments, method 100 may be used to make compounds for nonlinear optics that are used at 350 nm and below. For example, the compounds are associated with trigonal systems used at 350 nm or less, and / or with space group R32 used at 350 nm or less. In another example, the compound also includes a dopant comprising one or more selected from the group consisting of Ce, Nd, and Yb. In one embodiment, the nonlinear optical material comprises NYAB. According to another embodiment, the nonlinear optical material comprises Yb: YAB. According to another embodiment, the nonlinear optical material comprises Ce: YAB.

According to another embodiment of the present invention, a method of making a compound for nonlinear optics used at 350 nm and below comprises providing a plurality of materials. The plurality of materials include lanthanum containing compounds, and the lanthanum containing compounds can be decomposed into at least lanthanum oxide upon heating. The method also includes mixing a plurality of materials to form a mixture based on at least information relating to a predetermined ratio, starting a crystallization process in the mixture to form crystals, and lanthanum from the mixture. Removing the crystals. For example, the plurality of materials include lanthanum oxide. In another example, the plurality of materials further comprise boron oxide. In another example, the method further comprises placing the mixture in the furnace. In another example, the method includes heating the mixture to a predetermined first temperature, and cooling the mixture to a predetermined second temperature. In another example, initiating the crystallization process includes inserting a crystalline seed into the molten surface. In another example, the crystal comprises A _x M _(1-x) Al ₃ B ₄ O ₁₂ . x is greater than or equal to 0 and less than or equal to 0.1, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, and M is selected from the group consisting of Sc, Y, La, Yb, and Lu. According to another example, the method is implemented according to method 100.

According to yet another embodiment of the present invention, a method of making a compound for nonlinear optics used at 350 nm and below comprises providing a plurality of materials. The plurality of materials include a yttrium containing compound, which may be decomposed into at least yttrium oxide upon heating. The method also includes mixing a plurality of materials to form a mixture based on at least information relating to a predetermined ratio, starting a crystallization process in the mixture to form crystals, and yttrium from the mixture. Removing the crystals. For example, the plurality of materials include yttrium oxide. In another example, the plurality of materials further comprise boron oxide. In another example, the method further comprises placing the mixture in the furnace. In another example, the method includes heating the mixture to a predetermined first temperature, and cooling the mixture to a predetermined second temperature. In another example, initiating the crystallization process includes inserting a crystalline seed into the molten surface. In another example, the crystal comprises A _x M _(1-x) Al ₃ B ₄ O ₁₂ . x is greater than or equal to 0 and less than or equal to 0.1, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, and M is selected from the group consisting of Sc, Y, La, Yb, and Lu. According to another example, the method is implemented according to method 100.

For the following additional embodiments of the present invention, abbreviations as used are used:

mm : millimeter

NLO : Nonlinear Optics

nm : nanometer

ppm : parts per million

SHG : 2nd harmonic generation

In addition, for the following additional embodiments, the following definitions are provided only to aid the reader in understanding, and are not intended to be narrower than the meaning of the terms understood by one of ordinary skill in the art.

Aluminum- borate NLO Crystals ( Aluminum - Borate NLO Crystal ): NLO crystal having a chemical formula comprising aluminum and borate. Examples of aluminum-borate NLO crystals are yttrium, lutetium, or YAl ₃ (BO ₃ ) ₄ , LuAl ₃ (BO ₃ ) ₄ , and Y _(1-x) Lu _x Al ₃ (BO ₃ ) ₄ (where x Comprises an aluminum-borate NLO crystal having a chemical structure comprising a combination thereof, such as an integer greater than zero).

A laser beam (Laser Beam ): Beam of photons produced by the laser device. The laser beam is, for example, substantially collimated, substantially monochromatic, and substantially coherent.

Molybdenum - Containing Compounds Compound ): A compound having a chemical formula comprising elemental molybdenum or molybdenum such as molybdenum oxide.

Non-linear optical crystal (Nonlinear Optical Crystal ): A crystal exhibiting nonlinear polarization in response to light energy. This crystal includes the initial material and may also include one or more secondary materials.

Primary substance Material ): A crystalline compound having nonlinear optical properties. Initial materials form most of the crystal lattice in NLO crystals. Initial materials, such as initially synthesized or separated, are typically present in powder form. The initial powder material must be recrystallized to form NLO crystals of appropriate size and of appropriate purity for the generation and / or emission of light of the desired wavelength. Instead, the initial material may be formed from the precursor during the recrystallization process.

Precursor materials (Precursor Material ): A material that can be combined with other precursor materials to form an initial material. For example, Y ₂ O ₃ , B ₂ O ₃ , and Al ₂ O ₃ are precursor materials for the formation of YAl ₃ (BO ₃ ) ₄ .

Secondary material Material ): Elements or compounds contained in NLO crystals other than the initial material. Secondary materials may be intentionally incorporated (such as dopants) or unintentionally incorporated (such as contaminants). The secondary material may be a component of the crystal lattice, or may exist outside the crystal lattice.

The transition metal-containing compound (Transition - Metal Containing Compound ): A compound having a chemical formula comprising a transition metal element, or a transition metal such as an oxidized transition metal.

Tungsten-containing compound (Tungsten - Containing Compound ): A compound having a chemical formula comprising tungsten element or tungsten such as tungsten oxide.

The disclosed embodiments relate to nonlinear optical crystals having a reduced amount of constant contaminants associated with known nonlinear optical crystals, such as contaminants that interfere with the nonlinear optical crystals, in particular the optical properties of the nonlinear optical crystals.

Described herein are embodiments of an NLO decision, and examples of how to make and use this decision. The described embodiments are useful for a variety of applications, including but not limited to laser applications.

All NLO crystals include a crystal lattice with at least an initial material. The NLO decision may also include one or more secondary materials. The initial material is doped with various dopants, for example, to change the optical properties of the crystal. Examples of initial materials include, but are not limited to, YAl ₃ (BO ₃ ) _4, LuAl ₃ (BO ₃ ) ₄ , BaB ₂ O ₄ , BaAl ₂ B ₂ O ₇ , K ₂ Al ₂ B ₂ O ₇ , CaAl ₂ B ₂ O ₇ , SrAl ₂ B ₂ O ₇ , TiOPO ₄ , KTiOAsO ₄ , RbTiOPO ₄ , RbTiOAsO ₄ , CsTiOAsO ₄ , LiNbO ₃ , KNbO ₃ , AgGaS ₂ , AgGaSe ₂ , KH ₂ PO ₄ , KD ₂ PO ₄ , NH ₄ PO ₄ , CsH ₂ AsO ₄ , CsD ₂ AsO ₄ , LiIO ₃ , and LiTaO ₃ . These NLO materials can be used alone or in combination.

Among the aluminum-borate NLO crystals, yttrium, lutetium, or YAl ₃ (BO ₃ ) ₄ , LuAl ₃ (BO ₃ ) ₄ , and Y _(1-x) Lu _x Al ₃ (BO ₃ ) ₄ , where x is 0 Aluminum-borate NLO crystals having a chemical structure comprising a combination of these, such as greater integers), in particular, light having a wavelength substantially shorter than 300 nm, typically substantially 250 nm, and more typically substantially 175 nm. It is very suitable for the generation and / or radiation of.

The utilization of NLO crystals, including aluminum-borate NLO crystals, is first derived from their optical properties. In order to achieve the desired optical properties, it is often necessary to grow single crystals with relatively continuous crystal structure and few defects. Moreover, most applications require that the NLO single crystal be of constant size, such as sufficient to make a crystal compatible with an optical device such as a laser, for example. Some useful NLO crystals have a volume substantially greater than 0.1 mm ³ , typically substantially 1 mm ³ , more typically substantially 5 mm ³ .

Before the initial material is recrystallized to form single crystals of appropriate size and purity, the initial material may be present in the form of a powder containing amorphous material or very small crystals. The recrystallization process may begin with the precursor material in the form of powder or may instead be combined with the precursor material to form the initial material. For example, it is possible to combine the solvent and precursor material to form a mixture, and then crystallize the initial material from the mixture. Useful precursor materials include oxides of each element in the chemical structure of the initial material. For example, in forming YAl ₃ (BO ₃ ) ₄ , the precursor material may include: Y ₂ O ₃ , B ₂ O ₃ , and Al ₂ O ₃ . This precursor material is commercially available, for example from Sigma-Aldrich (St. Louis, Missouri).

This disclosure provides methods of growing useful NLO crystals, such as aluminum-borate NLO crystals, from precursor materials, or from initial materials in raw form that are not yet in a form suitable for NLO crystal applications, such as powder form. An Example is described. Some embodiments include mixing a precursor material or initial material with a solvent to form a mixture. This mixture is then cooled and NLO crystals grow as the mixture is cooled. The solvent provides a medium through which the elemental components of the initial material can bind in crystalline form. Without solvents, many initial materials, including YAl ₃ (BO ₃ ) ₄ and LuAl ₃ (BO ₃ ) ₄ , tend to disintegrate unsteadily at high temperatures.

The solvent may be selected to promote the crystallization process by promoting solubility of the precursor material. When the precursor material is acidic, the solubility increases if the solvent is basic. Similarly, when the precursor material is basic, the solubility is high if the solvent is acidic. The pH of the solvent may be adjusted to promote solubility, but strong alkalinity or strong acidity may have a detrimental effect on crystal growth.

In the past, solvents were chosen solely for the effect on the crystallization process. Since the crystals were separated from the solvent during the crystallization process, it was thought that the choice of solvent had little or no effect on the crystals produced by the process. Surprisingly, it has been found that certain elements present in conventional solvents are incorporated into crystals grown from mixtures comprising these solvents. For example, YAl ₃ (BO ₃ ) ₄ crystals grown on K ₂ MoO ₂ contain molybdenum oxide as a secondary material. It has also been found that even if present in small amounts, any of these contaminants can substantially affect the optical properties of crystals grown from mixtures comprising this solvent. For example, this contaminant may interfere with the generation and / or emission of light of a desired wavelength. Conventional YAl ₃ (BO ₃ ) ₄ crystals contain contaminants that prevent the crystals from generating and / or emitting light of wavelengths shorter than 370 nm.

By growing crystals in a mixture free of, or at least substantially free of, certain contaminants, it is possible to produce crystals with improved optical properties. For example, it generates laser light of short wavelengths not obtainable with conventional aluminum-borate crystals, such as wavelengths substantially less than 300 nm, typically substantially 250 nm, and more typically substantially less than 175 nm. And / or it is possible to grow aluminum-borate crystals, such as YAl ₃ (BO ₃ ) ₄ and LuAl ₃ (BO ₃ ) ₄ crystals, which emit.

Certain contaminants are more harmful to the optical properties of NLO crystals than others. For example, certain contaminants interfere with the generation and / or emission of short wavelengths of light, such as wavelengths substantially less than 300 nm, typically substantially 250 nm, and more typically substantially less than 175 nm. . Some contaminants prevent the NLO crystals from absorbing short wavelengths of light, thus inhibiting the frequency mixing process at these short wavelengths. Some of the contaminants incorporated into crystals grown in conventional solvents are compounds containing elements that exhibit charge transfer transitions in the ultraviolet region of the electromagnetic spectrum. This compound interferes with the generation and / or radiation of light of ultraviolet wavelengths. For certain applications, harmful contaminants include compounds containing transition metal elements and / or lanthanide elements other than yttrium, lanthanum, and lutetium. Table 2 shows the concentrations of other elements in the YAl ₃ (BO ₃ ) ₄ crystals grown in a conventional solvent. As shown, YAl ₃ (BO ₃ ) ₄ crystals contain 250 ppmw of molybdenum.

According to any of the disclosed embodiments, special solvents are used in the crystallization process. This solvent can be substantially free of contaminants that can be incorporated into growing crystals and can change the optical properties of these crystals. For example, this solvent may be substantially free of all transition metal elements and lanthanide elements other than yttrium, lanthanum, and lutetium. In some embodiments, the solvent is substantially free of molybdenum containing compounds. In some embodiments, the solvent comprises LaB ₃ O ₆ , MgB ₂ O ₄ , LiF, or a combination thereof. The solvents LaB ₃ O ₆ , MgB ₂ O ₄ , and LiF are particularly useful for forming YAl ₃ (BO ₃ ) ₄ crystals.

Table 3 shows the concentrations of other elements of YAl ₃ (BO ₃ ) ₄ crystals grown in a solvent substantially free of molybdenum. As shown, YAl ₃ (BO ₃ ) ₄ crystals contain 0.15 ppmw of molybdenum.

Several crystal-growth techniques can be used with specially selected solvents to produce NLO crystals with desirable properties. In some embodiments, the mixture formed by mixing the precursor material and solvent, or the raw material and solvent in raw form, is heated to a temperature above the melting point of the mixture. The melting point of the mixture varies depending on the form and amount of the solvent and the form and amount of the precursor material or initial material. In addition, the melting point and other melting properties (such as melt viscosity and melt creeping) can be varied by inserting various additives into the mixture. Some useful additives are alkali metal salts and alkaline earth metal salts. For example, these salts can be oxides, fluorides, or chlorides. The additive is chosen so as not to interfere with one or more, possibly a plurality of, desired optical properties of the crystals formed. For example, additives for the formation of NLO crystals intended to produce second harmonics of short wavelengths are selected so as not to prevent the crystals from absorbing light of this short wavelength.

According to some embodiments of the crystal-growth process, the seeds are inserted into the molten mixture and then slowly cooled from the first temperature to the second temperature. Seeds are typically small crystals of the initial material and often have a homogeneous array of crystal structures. In some embodiments, the seed floats in the molten mixture as the mixture cools from the first temperature to the second temperature. As the mixture cools, the initial material crystallizes. Crystallization can occur around the seed as a single crystal with a homogeneous crystal arrangement that matches the crystal arrangement of the seed.

Most of the crystal growth occurs over the growth period while the mixture is cooled from the first temperature to the second temperature. The first temperature may be at or near the melting point of the mixture. The second temperature may be a temperature lower than the melting point of the mixture, for example, it is substantially 5 ° C. to 100 ° C. lower than the melting point of the mixture. The duration of growth period depends on the size of the initial material, the solvent, and the desired crystals. Typically, the crystals will grow at a rate of substantially 0.2 to substantially 0.3 mm per hour. Suitable growth periods are typically substantially longer than 10 hours. During portions of the growth period, such as portions that are substantially longer than 2 hours, the mixture may be cooled with a cooling gradient that is substantially less than 2 ° C. per hour.

Table 4 lists several examples of mixtures containing different combinations of YAl ₃ (BO ₃ ) ₄ and a solvent (as initial material), along with the main melting properties of the mixture. For each mixture, Table 4 lists examples of melting points, growth temperature ranges (ie, ranges between the first and second temperatures), and appropriate growth periods.

In the mixture represented by Table 4, the crystals formed from mixtures 1-4 exhibited varying degrees of creeping. Crystals grown from mixture 5 showed little creep.

In general, in the growth of NLO crystals intended for SHG at short wavelengths, it is advantageous to select a solvent that does not contain transition metal elements and / or lanthanide elements other than yttrium, lanthanum, and lutetium. However, some solvents containing transition metals are particularly effective at promoting melt homogeneity of the initial material. Therefore, in certain cases, with the beneficial effects of solvents containing harmful elements, it is appropriate to weight the potential disturbances to the optical properties of the crystal caused by the possible incorporation of the harmful elements into the NLO crystals. The use of a solvent containing a transition metal is particularly suitable when the NLO crystals grown from the solvent are not intended to be used for SHG at very short wavelengths. For example, for the growth of NLO crystals used for SHG at wavelengths substantially greater than 300 nm, a solvent comprising tungsten may be used in any embodiment of the crystal-growth process. One tungsten containing solvent that is very suitable for the growth of YAl ₃ (BO ₃ ) ₄ crystals is Li ₂ WO ₄ , which can be used with B ₂ O ₃ . Crystals grown from mixture 6 as described in Table 4, incorporating Li ₂ WO ₄ and B ₂ O ₃ , have particularly high quality.

Table 5 shows the concentrations of other elements of YAl ₃ (BO ₃ ) ₄ crystals grown from the mixture 6 illustrated in Table 4. Tungsten was incorporated at 550 ppmw.

In evaluating the effect of tungsten on the optical properties of NLO crystals grown with tungsten solvent, it is helpful to consider FIG. 5. 5 shows the percent transmission of YAl ₃ (BO ₃ ) ₄ crystals (YAB-W) grown with tungsten, the percent transmission of YAl ₃ (BO ₃ ) ₄ crystals (YAB-Mo) containing molybdenum and all transition metals. Shown relative to the percent transmission of YAl ₃ (BO ₃ ) ₄ crystals (YAB-La) substantially free of contaminants. As shown, YAB-W crystals are longer than the wavelength at which the YAB-La crystals begin to absorb light, but begin to absorb light at wavelengths shorter than the wavelength at which the YAB-Mo crystals begin to absorb light. For many applications, shorter wavelength absorption is desirable. For this application, YAB-W crystals are preferred when compared to YAB-Mo crystals, but are inferior to YAB-La crystals.

After forming the crystals using the disclosed method, the homogeneous crystal structure can be demonstrated by X-ray diffraction. The optical properties of the crystal can be analyzed by placing the crystal in the laser beam. For example, YAl ₃ (BO ₃ ) ₄ crystals can be analyzed in this way to confirm the production of second harmonic light.

NLO crystals formed by the disclosed method interfere with the generation and / or emission of light of a desired wavelength, such as wavelengths substantially less than 300 nm, typically substantially 250 nm, and more typically substantially less than 175 nm. NLO crystals, such as aluminum-borate NLO crystals, which are substantially free of any element and / or contain substantially 100 ppmw, typically substantially 50 ppmw, and more typically substantially less than 10 ppmw. Secondary materials that interfere with the generation and / or emission of light of a desired wavelength can be, for example, transition metal elements and lanthanide elements other than yttrium, lanthanum, and lutetium. Crystals can also be classified by the concentration of molybdenum containing compounds. Certain crystals formed by the disclosed method are substantially free of any molybdenum containing compound and / or contain substantially less than 100 ppmw, typically substantially 50 ppmw, and more typically substantially less than 10 ppmw.

The crystals described in this specification have many useful applications. For example, aluminum-borate NLO crystals, such as aluminum-borate NLO crystals having a chemical structure comprising yttrium, lutetium, or a combination thereof, may be incorporated into a laser device, such as the laser device shown in FIG. 6. . Under certain conditions, this crystal can generate and / or emit a short wavelength laser beam.

The laser beam can be used to detect abnormalities of the substrate surface, including the semiconductor substrate. This is done, for example, by directing a laser beam having a pattern to the entire substrate surface, such as a raster pattern, and measuring the coincidence of the reflected light. If the laser beam encounters an abnormality on the substrate surface, such as particles, the reflected light will scatter. Shorter wavelength laser beams are particularly useful because they can detect smaller anomalies. This is important in the semiconductor industry, as the size decreases, the size of anomalies that may adversely affect device functionality also decreases.

Shorter wavelength laser beams can also be used to drill small diameter holes in the substrate. This laser beam concentrates more energy in a smaller area than the longer wavelength laser beam, and thus can apply more energy to the substrate. The ability to drill small diameter holes in a substrate is useful for forming shapes on printed circuit boards, for example.

For certain embodiments of the present invention, what has been described is low concentrations that adversely affect the optical properties of NLO crystals, such as compounds containing transition metal elements and / or lanthanide elements other than yttrium, lanthanum, and lutetium Non-linear optical (NLO) crystals, including aluminum-borate NLO crystals, with contaminants of. Some NLO crystals with low concentrations of this contaminant can generate very short wavelength second harmonics. Also described is an embodiment of a method of making this NLO decision. Some embodiments include growing NLO single crystals, such as aluminum-borate NLO crystals, from a mixture comprising a solvent substantially free of harmful contaminants. The described NLO determination can be used, for example, in a laser device.

The examples and embodiments described herein are for illustrative purposes only, and various modifications or variations of the light will be suggested to those skilled in the art, which are provided by the contents and provisions of the present application and the patents. It is understood that it will be included within the scope of the claims.

Claims (103)

For nonlinear optics compounds used at 350 nm and below, Non-linear optics material comprising YAl ₃ B ₄ O ₁₂ , Compounds free of molybdenum-containing impurities greater than 1000 parts per million. The method of claim 1, Compound free of more than 500 ppm molybdenum-containing impurities. The method of claim 2, Compound free of molybdenum-containing impurities of 100 ppm or more. The method of claim 3, wherein Compounds free of molybdenum-containing impurities of at least 10 ppm. The method of claim 4, wherein Compounds free of molybdenum-containing impurities of at least 1 ppm. The method of claim 5, Compounds substantially free of molybdenum-containing impurities. The method of claim 1, The use is associated with a wavelength substantially in the range of 350 to 160 nanometers (nm). The method of claim 1, The use relates to a device that generates optical radiation of 350 nm or less. The method of claim 8, The device comprises a NLO system. The method of claim 8, The device comprises a compound associated with a laser system. The method of claim 8, The device comprises a compound associated with a light source. The method of claim 1, Compounds associated with the trigonal crystal class used below 350 nm. The method of claim 1, Compounds associated with space group R32 used below 350 nm. The method of claim 1, A compound further comprising a dopant comprising at least one selected from the group consisting of Ce, Nd, and Yb. The method of claim 14, Compounds comprising NYAB. The method of claim 14, A compound comprising Yb: YAB. The method of claim 14, Compounds comprising Ce: YAB. The method of claim 1, A compound having a volume substantially greater than 0.001 mm ³ . The method of claim 18, A compound having a volume substantially greater than 0.01 mm ³ . The method of claim 19, A compound having a volume substantially greater than 0.1 mm ³ . The method of claim 20, Compound having a volume substantially greater than 1 mm ³ . For nonlinear optics compounds used at 350 nm and below, Non-linear optics material comprising Y _(1-x) M _x Al ₃ B ₄ O ₁₂ , x is equal to or greater than 0, equal to or less than 0.1, M is selected from the group consisting of Sc, La, Yb, and Lu, 1000 ppm or more molybdenum-containing impurities free. For nonlinear optics compounds used at 350 nm and below, Non-linear optics material comprising Yb _(1-x) M _x Al ₃ B ₄ O ₁₂ , x is greater than or equal to 0 and greater than or equal to 0.1, M is selected from the group consisting of Sc, Y, La, and Lu, A compound free of molybdenum-containing impurities of at least 1000 ppm. For nonlinear optics compounds used at 350 nm and below, Non-linear optics materials including Lu _(1-x) M _x Al ₃ B ₄ O ₁₂ , x is equal to or greater than 0, equal to or less than 0.1, M is selected from the group consisting of Sc, Yb, and La, 1000 ppm or more molybdenum-containing impurities free. For nonlinear optics compounds used at 350 nm and below, Non-linear optics materials including Sc _(1-x) M _x Al ₃ B ₄ O ₁₂ , x is equal to or greater than 0, equal to or less than 0.1, M is selected from the group consisting of Y, La, Yb, and Lu, 1000 ppm or more molybdenum-containing impurities free. For nonlinear optics compounds used at 350 nm and below, Non-linear optics material comprising A _x M _(1-x) Al ₃ B ₄ O ₁₂ , x is equal to or greater than 0, equal to or less than 0.1, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, M is selected from the group consisting of Sc, Y, La, Yb, and Lu, 1000 ppm or more molybdenum-containing impurities free. The method of claim 26, M is La. The method of claim 26, M is Lu. A compound. The method of claim 26, M is Sc. The method of claim 26, M is Y; The method of claim 26, M is Yb. The method of claim 26, A is a compound of Sc. The method of claim 26, A is Y. The method of claim 26, A is La; The method of claim 26, A is Yb. The method of claim 26, A is a compound which is Lu. The method of claim 26, Compound free of more than 500 ppm molybdenum-containing impurities. The method of claim 37, Compound free of molybdenum-containing impurities of 100 ppm or more. The method of claim 38, Compounds free of molybdenum-containing impurities of at least 10 ppm. The method of claim 39, Compounds free of molybdenum-containing impurities of at least 1 ppm. The method of claim 40, Compounds substantially free of molybdenum-containing impurities. The method of claim 26, The use is associated with a wavelength substantially in the range of 350 to 160 nanometers (nm). The method of claim 26, The use is related to a device that generates optical radiation of 350 nm or less. The method of claim 43, The device comprises a NLO system. The method of claim 43, The device comprises a compound associated with a laser system. The method of claim 43, The device comprises a compound associated with a light source. The method of claim 26, Compounds associated with trigonal systems used below 350 nm. The method of claim 26, Compounds associated with space group R32 used below 350 nm. The method of claim 26, A compound further comprising a dopant comprising at least one selected from the group consisting of Ce and Nd. The method of claim 26, The use is substantially related to wavelengths in the range from 350 nm to 160 nm. The method of claim 26, A compound having a volume substantially greater than 0.001 mm ³ . The method of claim 51, A compound having a volume substantially greater than 0.01 mm ³ . The method of claim 52, wherein A compound having a volume substantially greater than 0.1 mm ³ . The method of claim 53, Compound having a volume substantially greater than 1 mm ³ . For nonlinear optical crystals having a volume substantially greater than 0.1 mm ³ , A nonlinear optical crystal comprising substantially less than 100 ppmw (ppm by weight) of an element that inhibits the ability of the nonlinear optical crystal to generate and / or emit light having a wavelength substantially shorter than 300 nm. The method of claim 55, Nonlinear optical crystals that are aluminum-borate nonlinear optical crystals. The method of claim 55, A nonlinear optical crystal, which is an aluminum-borate nonlinear optical crystal comprising yttrium and / or lutetium. For aluminum-borate nonlinear optical crystals having a volume substantially greater than 0.1 mm ³ , An aluminum-borate nonlinear optical crystal comprising substantially less than 100 ppmw of a compound containing transition metal elements and / or lanthanide elements other than yttrium, lanthanum, and lutetium. The method of claim 58, Aluminum-borate nonlinear optical crystals having a volume substantially greater than 1 mm ³ . For aluminum-borate nonlinear optical crystals having a volume substantially greater than 0.1 mm ³ , An aluminum-borate nonlinear optical crystal comprising substantially less than 100 ppmw of a single molybdenum containing compound. For YAl ₃ (BO ₃ ) ₄ crystals having a volume substantially greater than 0.1 mm ³ , A nonlinear optical crystal comprising substantially less than 100 ppmw of an element that inhibits the ability of a YAl ₃ (BO ₃ ) ₄ crystal to generate and / or emit light having a wavelength substantially shorter than 300 nm. In nonlinear optical crystals, Substantially less than 100 ppmw of an initial material and an element that inhibits the ability of the nonlinear optical crystal to generate and / or emit light having a wavelength substantially shorter than 300 nm, Nonlinear optical crystals useful for changing the wavelength of a laser beam generated by a laser device. The method of claim 62, Nonlinear Optical Crystals, which are aluminum-borate nonlinear optical crystals. The method of claim 62, Nonlinear optical crystals that are YAl ₃ (BO ₃ ) ₄ crystals. For aluminum-borate nonlinear optical crystals having a volume substantially greater than 1 mm ³ , The input laser beam of the first wavelength can be converted into the output laser beam of the second wavelength, And said second wavelength is substantially shorter than 200 nm. 66. The method of claim 65, Aluminum-borate nonlinear optical crystals that are YAl ₃ (BO ₃ ) ₄ crystals. For aluminum-borate nonlinear optical crystals having a volume substantially greater than 1 mm ³ , The input laser beam of the first wavelength can be converted into the output laser beam of the second wavelength, The second wavelength is substantially shorter than 500 nm, The aluminum-borate nonlinear optical crystal is an aluminum-borate nonlinear optical crystal comprising a tungsten containing compound in addition to the initial material. In the method of making a nonlinear optical crystal, Providing a starting material, and a solvent substantially free of elements that inhibit the ability of the non-linear optical crystal to generate and / or emit light having a wavelength substantially shorter than 300 nm; And Recrystallizing the initial material to form a nonlinear optical crystal that is substantially free of elements that inhibit the ability of the nonlinear optical crystal to generate and / or emit light having a wavelength substantially shorter than 300 nm. In the method of making an aluminum-borate nonlinear optical crystal, Providing a starting material and a solvent that is substantially free of elements that inhibit the ability of the nonlinear optical crystal to generate and / or emit light having a wavelength substantially shorter than 300 nm; And Recrystallizing the initial material to form an aluminum-borate nonlinear optical crystal that is substantially free of elements that inhibit the ability of the nonlinear optical crystal to generate and / or emit light of wavelengths substantially less than 300 nm. How to. The method of claim 69, wherein The solvent comprises LaB ₃ O ₆ , MgB ₂ O ₄ , LiF, or a combination thereof. The method of claim 69, wherein The solvent is substantially free of a single molybdenum containing compound. The method of claim 69, wherein The initial material is YAl ₃ (BO ₃ ) ₄ . The method of claim 72, The solvent comprises LaB ₃ O ₆ . The method of claim 69, wherein The initial material is LuAl ₃ (BO ₃ ) ₄ . The method of claim 74, wherein The solvent comprises LaB ₃ O ₆ . The method of claim 69, wherein Recrystallizing the initial material comprises mixing the initial material with a solvent to form a mixture, and inserting a seed into the mixture. 77. The method of claim 76, Said seed consisting essentially of said initial material. 77. The method of claim 76, Inserting a seed into the mixture comprises floating the seed into the mixture. 77. The method of claim 76, Recrystallizing the initial material further comprises cooling the mixture, and recovering the aluminum-borate nonlinear optical crystal from the mixture. The method of claim 79, Cooling the mixture includes cooling the mixture from a first temperature above or above the melting point of the mixture, over a growth period, to a second temperature below the melting point of the mixture, Wherein said growth period is substantially longer than 10 hours. The method of claim 80, The second temperature is substantially 5 ° C. to 100 ° C. lower than the melting point of the mixture. The method of claim 80, The mixture is cooled to a cooling gradient substantially less than 2 ° C. per hour in a portion of the growth period, Said portion of said growth period being substantially longer than two hours. In the method of making a YAl ₃ (BO ₃ ) ₄ crystal, Mixing YAl ₃ (BO ₃ ) ₄ with a solvent substantially free of compounds containing transition metal elements and / or lanthanide elements other than yttrium, lanthanum, and lutetium to form a mixture; Inserting a seed into the mixture; Cooling the mixture from a first temperature above or above the melting point of the mixture over a growth period to a second temperature below the melting point of the mixture; And After cooling the mixture, recovering YAl ₃ (BO ₃ ) ₄ crystals from the mixture, Wherein said growth period is substantially longer than 10 hours. 84. The method of claim 83, The solvent comprises LaB ₃ O ₆ , MgB ₂ O ₄ , LiF, or a combination thereof. In the method of making an aluminum-borate nonlinear optical crystal, Providing a solvent and an initial material comprising tungsten; And Recrystallizing the initial material to form an aluminum-borate nonlinear optical crystal that is substantially free of compounds containing transition metal elements and / or lanthanide elements other than yttrium, lanthanum, lutetium, and tungsten . 86. The method of claim 85, The initial material is YAl ₃ (BO ₃ ) ₄ . 87. The method of claim 86, The solvent comprises Li ₂ WO ₄ . 88. The method of claim 87 wherein The solvent further comprises B ₂ O ₃ . In the method of making a YAl ₃ (BO ₃ ) ₄ crystal, Providing YAl ₃ (BO ₃ ) ₄ with a solvent substantially free of a single molybdenum containing compound; And Comprises the step of recrystallizing the YAl ₃ (BO _{3) 4} to form substantially contains less than 10 ppmw of molybdenum of a molybdenum-containing compound single YAl ₃ (BO _{3) 4} crystal. In the method of making a compound for nonlinear optics used at 350 nm and below, Providing a plurality of materials comprising a lanthanum containing compound that can be decomposed into at least lanthanum oxide upon heating; Mixing the plurality of materials to form a mixture based on at least information relating to the predetermined ratio; Starting a crystallization process on the mixture to form crystals; And Removing said crystal comprising lanthanum from said mixture. 91. The method of claim 90, Wherein said plurality of materials comprises lanthanum oxide. 92. The method of claim 91 wherein The plurality of materials further comprise boron oxide. 91. The method of claim 90, Positioning the mixture in a furnace. 91. The method of claim 90, Heating the mixture to a predetermined first temperature; And Cooling the mixture to a predetermined second temperature. 91. The method of claim 90, Initiating the crystallization process includes inserting a crystalline seed into the molten surface. 91. The method of claim 90, The crystals include A _x M _(1-x) Al ₃ B ₄ O ₁₂ , x is greater than or equal to 0 and less than or equal to 0.1, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, M is selected from the group consisting of Sc, Y, La, Yb, and Lu. In the method of making a compound for nonlinear optics used at 350 nm and below, Providing a plurality of materials comprising a yttrium containing compound that, upon heating, can be at least decomposed into yttrium oxide; Mixing the plurality of materials to form a mixture based on at least information relating to the predetermined ratio; Starting a crystallization process on the mixture to form crystals; And Removing the crystal comprising yttrium from the mixture. 97. The method of claim 97, Wherein the plurality of materials comprises yttrium oxide. 99. The method of claim 98, The plurality of materials further comprise boron oxide. 97. The method of claim 97, Positioning the mixture in a furnace. 97. The method of claim 97, Heating the mixture to a predetermined first temperature; And Cooling the mixture to a predetermined second temperature. 97. The method of claim 97, Initiating the crystallization process includes inserting a crystalline seed into the molten surface. 97. The method of claim 97, The crystals include A _x M _(1-x) Al ₃ B ₄ O ₁₂ , x is greater than or equal to 0 and less than or equal to 0.1, A is selected from the group consisting of Sc, Y, La, Yb, and Lu, M is selected from the group consisting of Sc, Y, La, Yb, and Lu.

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