JPS6367347B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a garnet crystal for wavelength tunable lasers.

Conventional technology Several types of garnet crystals for wavelength tunable lasers using Cr ³⁺ as the active ion have been known, but among them, Gd ₃ Sc ₂ Ga ₃ O ₁₂ has high laser performance. It is expected that

However, this crystal contains scandium (Sc), which is an extremely expensive and limited resource. Therefore, it has the disadvantage that the crystal is expensive.

Purpose of the Invention The present invention aims to reduce the amount of Sc used in a Gd ₃ Sc ₂ Ga ₃ O ₁₂ crystal by introducing a substituting element for a portion of Sc, thereby creating a relatively inexpensive garnet crystal for wavelength tunable lasers. It is not intended to be provided.

Structure of the Invention As a result of research to achieve the above object, the present inventor has
In that crystal, the crystal lattice occupied by Sc is 8
It was discovered that the lattice is surrounded by oxygen ions, and that it may be possible to replace it with a metal ion with a similar ionic radius, which is also inexpensive. Since Sc is a trivalent cation, we considered that the substituted metal ion must compensate for the valence of Sc in just the right amount, so we investigated cations that can be substituted.

As a result of experimental investigation, Li ⁺ or Mg ²⁺ and Ti ⁴⁺ ,
Tetravalent metal ions of Zr ⁴⁺ , Hf ⁴⁺ or Nb ⁵⁺ , Ta ⁵⁺
It was found that by combining with a pentavalent metal, the lattice points of Sc ions can be filled in just the right amount, and the valence can be compensated for just the right amount, and that it is not possible to replace the composition to a composition where Sc is completely absent. The present invention was completed based on this knowledge.

The gist of the present invention is that in a Gd ₃ Sc ₂ Ga ₃ O ₁₂ crystal used as a medium crystal for a wavelength tunable laser with Cr ³⁺ as an active ion, a part of the Sc ions are replaced with Li ⁺ or Mg ²⁺ and Ti ^{4 +} ,
Substituting metal ions selected from Zr ⁴⁺ , Hf ⁴⁺ , Nb ⁵⁺ and Ta ⁵⁺ or in combination with two or more metal ions to maintain a neutralized charge within the crystal. Garnet crystal for wavelength tunable lasers is characterized by:

In the present invention, a wavelength tunable laser medium containing Cr ³⁺ as an active ion is one that has an electronic structure that enables a phonon-mediated laser emission process and enables fluorescence in a wide spectral range.
A solid medium with the necessary crystal field for Cr ³⁺ ions to be realized inside.
Gd ₃ Sc ₂ Ga ₃ O ₁₂ is such a solid medium, and it is known that its crystal structure is garnet type.

The composition after substitution in the present invention is represented by Gd ₃ Sc _2-x A _x Ga ₃ O ₁₂ (x<2).

A is 1/2 (B ⁴⁺ + Mg ²⁺ ) (B is Zr ⁴⁺ ,
Ti ⁴⁺ or Hf ⁴⁺ ), which represents 1 mole of Sc ⁺³
is replaced with 1/2 mole of B ⁴⁺ and 1/2 mole of Mg ²⁺ to show that the balance of moles is maintained before and after the substitution. Also, 1/2 (C ⁵⁺ + Li) (where C represents Nb ⁵⁺ or Ta ⁵⁺ ), 1/3 (B ⁴⁺ + B' ⁴⁺ + Li ⁺ ), or 1/3 (C' ^{5 +} +2Mg ²⁺ ), where B' represents the same cation as B, and C' represents the same pentavalent cation as C)
It can be expressed as In other words, it is necessary to compensate for the valence in just the right amount.

Any method can be used to grow a single crystal having such a composition as long as it grows a homogeneous crystal. Preferred is a growth technique from a melt, such as a pulling method or a floating zone method.
In particular, the pulling method is convenient for growing large crystals, but when applying this method, it is desirable that the garnet crystals with the substituted composition melt simultaneously (the crystal and the melt have the same composition).

When growing a single crystal using the crystal composition of the present invention, Ca, Sr, Ba,
Na, K, Al, Fe, V, Mn, Co, Ni, Cu, Zn,
By incorporating trace components of Si or Ge,
Characteristics of single crystals can be improved.

Effects of the invention The garnet crystal of the present invention has been used as a wavelength tunable laser crystal.
Compared to Gd ₃ Sc ₂ Ga ₃ O ₁₂ crystal, it is much cheaper and has comparable performance, and can replace the function as a medium crystal for Cr ³ wavelength tunable laser, which is the crystal's intended use. It has excellent effects.

Examples Example 1 In Gd ₃ Sc _2-x Zr _1/2x Mg _1/2x Ga ₃ O ₁₂ , using a sample with a composition with an A colorless and transparent single crystal without contamination was obtained. The crystal structure was confirmed to be garnet type by X-rays.

Introducing 0.1 at% Cr ³⁺ into a sample with this composition,
A pale green transparent single crystal was obtained using the condensing floating zone method. When the resulting crystals were irradiated with light from a mercury lamp, strong fluorescence over a wavelength range of 700 to 900 nm was observed. This results in
It has become clear that, like Gd ₃ Sc ₂ Ga ₃ O ₁₂ , it can be used as a crystal for wavelength tunable lasers.

Example 2 For Gd ₃ Sc _2-x Ti _1/2x Mg _1/2x Ga ₃ O ₁₂ , single crystals were produced in the same manner as in Example 1 for compositions with x values up to 1.90, and samples with these compositions were prepared. By introducing 0.1 atomic percent Cr ³⁺ into the material, a single crystal was created. As a result, similar to Example 1, strong fluorescence was observed.

Example 3 For Gd ₃ Sc _2-x Hf _1/2x Mg _1/2x Ga ₃ O ₁₂ , single crystals were produced in the same manner as in Example 1 for compositions with x values up to 1.85, and samples with these compositions were prepared. By introducing 0.1 atomic percent Cr ³⁺ into the material, a single crystal was created. As a result, similar to Example 1, strong fluorescence was observed.

Example 4 For Gd ₃ Sc _2-x Nb _1/2x Li _1/2x Ga ₃ O ₁₂ , single crystals were made in the same manner as in Example 1 for compositions with x values up to 1.70, and samples with these compositions were prepared. By introducing 0.1 atomic percent Cr ³⁺ into the material, a single crystal was created. As a result, similar to Example 1, strong fluorescence was observed.

Example 5 In Gd ₃ Sc _2-x Ta _1/2x Li _1/2x Ga ₃ O ₁₂ , single crystals were made in the same manner as in Example 1 for compositions with x values up to 1.70, and samples with these compositions were prepared. By introducing 0.1 atomic percent Cr ³⁺ into the material, a single crystal was created. As a result, similar to Example 1, strong fluorescence was observed.

Example 6 For Gd ₃ Sc _2-x Zr _2/3x Li _1/3x Ga ₃ O ₁₂ , single crystals were made in the same manner as in Example 1 for compositions with x values up to 1.60, and samples with these compositions were prepared. By introducing 0.1 atomic percent Cr ³⁺ into the material, a single crystal was created. As a result, similar to Example 1, strong fluorescence was observed.

Example 7 For Gd ₃ Sc _2-x Ti _2/3x Li _1/3x Ga ₃ O ₁₂ , single crystals were made in the same manner as in Example 1 for compositions with x values up to 1.65, and samples with these compositions were prepared. By introducing 0.1 atomic percent Cr ₃ ⁺ into the material, a single crystal was created. As a result, similar to Example 1, strong fluorescence was observed.

Example 8 In Gd ₃ Sc _2-x Hf _2/3x Li _1/3x Ga ₃ O ₁₂ , single crystals were produced in the same manner as in Example 1 for compositions with x values up to 1.55, and samples with these compositions were prepared. By introducing 0.1 atomic percent Cr ³⁺ into the material, a single crystal was created. As a result, similar to Example 1, strong fluorescence was observed.

Example 9 For Gd ₃ Sc _2-x Nb _1/3x Mg _2/3x Ga ₃ O ₁₂ , single crystals were produced in the same manner as in Example 1 for compositions with x values up to 1.50, and samples with these compositions were prepared. 0.1 to
A single crystal was created by introducing atomic percent Cr ³⁺ . As a result, similar to Example 1, strong fluorescence was observed.

Example 10 In Gd ₃ Sc _2-x Ta _1/3x Mg _2/3x Ga ₃ O ₁₂ , single crystals were made in the same manner as in Example 1 for compositions with x values up to 1.50, and samples with these compositions were prepared. By introducing 0.1 atomic percent Cr ³⁺ into the material, a single crystal was created. As a result, similar to Example 1, strong fluorescence was observed.

Example 11 In Gd ₃ Sc _2-x Nb _1/2x Li _1/2x Zr _1/2y Mg _1/2y Ga ₃ O ₁₂ , single crystals were prepared in the same manner as in Example 1 for the composition up to the x+y value of 1.50. 0.1 atomic percent of Cr ³⁺ was introduced into samples with these compositions to produce single crystals. As in Example 1, strong fluorescence was observed in the crystal.

Example 12 Regarding the composition of Gd ₃ Sc _2-xy Ta _1/3x Ti _1/2y Mg _2/3x+1/2y Ga ₃ O ₁₂ with x+y value up to 1.50,
Thereafter, single crystals were produced in the same manner as in Example 1, and 0.1 atomic % of Cr ³⁺ was introduced into samples having these compositions to produce single crystals. As a result, similar to Example 1, strong fluorescence was observed.

Claims (1)

[Claims] 1. In a Gd ₃ Sc ₂ Ga ₃ O ₁₂ crystal used as a medium crystal for a wavelength tunable laser with Cr ³⁺ as the active ion, part of the Sc ions are replaced with Li ⁺ or Mg ²⁺ .
The electric charge within the crystal is maintained at a neutral level by using it alone or in combination with two or more metal ions selected from Ti ⁴⁺ , Zr ⁴⁺ , Hf ⁴⁺ , Nb ⁵⁺ and Ta ⁵⁺ . A garnet crystal for wavelength tunable lasers characterized by substitution.