JP6493653B2 - Temperature compensation member and optical device for optical communication using the same - Google Patents

Description

  The present invention relates to a temperature compensation member used for an optical waveguide device or the like in an optical communication network.

  In recent years, with the development of optical communication technology, networks using optical fibers are being rapidly developed. In this network, wavelength multiplexing technology that transmits light of a plurality of wavelengths at once is used, and wavelength filters, couplers, waveguides, and the like are becoming important devices.

  Among optical devices for this type of optical communication, there are some devices whose characteristics change depending on temperature and hinder outdoor use. Therefore, there is a need for a technique for keeping the characteristics of optical devices for optical communication constant regardless of temperature changes, so-called temperature compensation technique.

  Typical optical devices for optical communication that require temperature compensation include waveguide devices such as arrayed wave guides and planar optical circuits, fiber Bragg gratings, and Fabry-Perot etalons (hereinafter referred to as etalons).

  These optical communication optical devices have a problem that when the ambient temperature changes, the optical path length changes as the refractive index and the thermal expansion coefficient change, as shown in the following formula (1).

dS / dT = dn / dT + nα (1)
Here, S represents the optical path length, T represents the temperature, n represents the refractive index, and α represents the thermal expansion coefficient.

  Therefore, a temperature compensating member is used in the optical device for optical communication in order to suppress a change in optical path length. For example, an etalon has a structure in which half mirrors are formed on opposite end surfaces of a bulk (rectangular column, cylinder, etc.) etalon material that is a temperature compensation member. Conventionally, in etalon, quartz glass is used as a temperature compensation member (see, for example, Patent Document 1).

JP 2000-47029 A

Quartz glass has a low thermal expansion coefficient of 6 × 10 ⁻⁷ / ° C. in the temperature range of −40 ° C. to 100 ° C., but has a large refractive index temperature coefficient dn / dT. large. Therefore, when quartz glass is used as a temperature compensation member of an optical device for optical communication, there is a problem that optical characteristics are likely to change depending on the ambient temperature, resulting in poor demultiplexing accuracy.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a temperature compensating member capable of imparting excellent demultiplexing characteristics to an optical device for optical communication.

  As a result of intensive studies by the present inventors, it has been found that if a P-Sn glass having a predetermined composition is used as a temperature compensation member, a temperature coefficient of a desired refractive index can be achieved and the above problems can be solved.

That is, the temperature compensation member of the present invention is made of glass containing cation%, P ⁵⁺ 0.1% or more, and Sn ²⁺ 1% or more, and the temperature coefficient dn / dT of the refractive index at 20 to 60 ° C. It is characterized by being −5 × 10 ⁻⁶ / ° C. or less.

Since the temperature compensation glass of the present invention contains P ⁵⁺ and Sn ²⁺ as essential components in the above range, the temperature coefficient dn / dT of the refractive index can be effectively reduced. As a result, the absolute value of the temperature coefficient dS / dT of the optical path length can be reduced, and excellent wavelength division characteristics can be imparted to the optical device for optical communication.

In the temperature compensation member of the present invention, the temperature coefficient dS / dT of the optical path length at 20 to 60 ° C. represented by the following formula (1) is −15 × 10 ⁻⁶ to 15 × 10 ⁻⁶ / ° C. preferable.

dS / dT = dn / dT + nα (1)
Here, S represents the optical path length, T represents the temperature, n represents the refractive index, and α represents the thermal expansion coefficient.

The temperature compensating member of the present invention is preferably cation% and contains P ⁵⁺ 10 to 70% and Sn ²⁺ 10 to 90%.

Temperature compensating member of the present invention, ^anionic%, O 2-30 to 100%, and ^F - ⁺ Cl - preferably contains 0-70%.

The temperature compensating member of the present invention preferably contains B ³⁺ + Si ⁴⁺ + Al ³⁺ + Zn ²⁺ + Ti ⁴⁺ 0 to 50% in terms of cation%.

  The temperature compensating member of the present invention preferably has a refractive index nd of 1.6 or more.

The temperature compensation member of the present invention preferably has a thermal expansion coefficient at −40 to 100 ° C. of 80 to 200 × 10 ⁻⁷ / ° C.

  The temperature compensating member of the present invention preferably has a yield point of 500 ° C. or lower.

  The temperature compensating member of the present invention preferably has an internal transmittance of 98% or more at a thickness of 10 mm at wavelengths of 1310 nm and 1550 nm.

  The temperature compensating member of the present invention preferably has a water resistance based on JOGIS of 3 or higher and an acid resistance of 2 or higher.

  An optical device for optical communication according to the present invention is characterized by using the temperature compensating member.

  ADVANTAGE OF THE INVENTION According to this invention, the member for temperature compensation which can provide the outstanding demultiplexing characteristic with respect to the optical device for optical communications can be provided.

The temperature compensating member of the present invention is made of glass containing cation%, P ⁵⁺ 0.1% or more, and Sn ²⁺ 1% or more. Below, the reason which specified content of each component as mentioned above is demonstrated. Unless otherwise specified, in the following description regarding the content of each component, “%” means “cation%” or “anion%”.

P ⁵⁺ is a constituent component of the glass skeleton. Further, dn / dT can be reduced, and as a result, there is an effect of reducing the absolute value of dS / dT. Moreover, it has the effect of increasing the light transmittance. In particular, in the case of a glass having a high refractive index, the effect of improving light transmittance by P ⁵⁺ is easily obtained. It also has the effect of suppressing devitrification. The content of P ⁵⁺ is 0.1% or more, preferably 1% or more, more preferably 5% or more, further preferably 10% or more, and preferably 20% or more. Particularly preferred. When there is too little content of ^{P5 +} , the said effect will become difficult to be acquired. On the other hand, when the content of P ⁵⁺ is too large, the content of Sn ²⁺ becomes relatively small, and the refractive index tends to be lowered, and the weather resistance is likely to be lowered. Therefore, the content of P ⁵⁺ is preferably 70% or less, more preferably 65% or less, further preferably 60% or less, particularly preferably 55% or less, and 50% or less. Most preferably.

Sn ²⁺ can also effectively reduce dn / dT, and as a result, has the effect of reducing the absolute value of dS / dT. In addition, there are effects such as higher refractive index, lower yield point, improved chemical durability and weather resistance. The content of Sn ²⁺ is 1% or more, preferably 5% or more, more preferably 10% or more, further preferably 15% or more, and particularly preferably 20% or more. 25% or more is most preferable. When the content of Sn ²⁺ is too small, the above effect is difficult to obtain. On the other hand, when there is too much content of Sn2 ⁺ , it will become difficult to vitrify or devitrification resistance will fall easily. Therefore, the Sn ²⁺ content is preferably 90% or less, more preferably 87.5% or less, further preferably 85% or less, and particularly preferably 82.5% or less. .

In the present invention, in order to obtain a glass having excellent devitrification resistance and high mechanical strength, it is preferable to adjust the content of P ⁵⁺ + Sn ²⁺ . Specifically, the content of P ⁵⁺ + Sn ²⁺ is preferably 30% or more, more preferably 40% or more, further preferably 50% or more, and particularly preferably 70% or more. Preferably, 80% or more is most preferable. The upper limit is not particularly limited, and the content of P ⁵⁺ + Sn ²⁺ may be 100%, but when it contains other components, it is preferably 99.9% or less, and is 99% or less. More preferably, it is more preferably 95% or less, and particularly preferably 90% or less.

  In addition to the above components, the glass constituting the temperature compensating member of the present invention can contain the following cation components.

B ³⁺ is a component constituting the glass skeleton. Moreover, there exists an effect which improves a weather resistance, and especially the effect which suppresses that components, such as ^{P5 +} in glass, elute selectively into water is large. The content of B ³⁺ is preferably 0 to 50%, more preferably 0.1 to 45%, and still more preferably 0.5 to 40%. When there is too much content of ^{B3 +} , a refractive index will fall easily. Further, the devitrification resistance is likely to be lowered.

Si ^{4+ is} also a component constituting the glass skeleton. Moreover, there exists an effect which improves a weather resistance, and especially the effect which suppresses that components, such as ^{P5 +} in glass, elute selectively into water is large. The content of Si ⁴⁺ is preferably 0 to 20%, and more preferably 0.1 to 15%. When there is too much content of ^{Si4 +} , a refractive index will fall or a yield point will become high easily. In addition, undissolved striae and bubbles may remain in the glass, and may not satisfy the required quality as a constituent member of the optical device for optical communication.

Al ³⁺ is a component capable of constituting a glass skeleton together with Si ⁴⁺ and B ³⁺ . Moreover, there exists an effect which improves a weather resistance, and especially the effect which suppresses that components, such as ^{P5 +} in glass, elute selectively into water is large. The content of Al ³⁺ is preferably 0 to 20%, and more preferably 0.1 to 15%. When there is too much content of ^{Al3 +} , it will become easy to devitrify. Moreover, there exists a tendency for light transmittance to fall. Further, the melting temperature is increased, and striae and bubbles due to undissolution are likely to remain in the glass. As a result, there is a possibility that the required quality as a constituent member of the optical device for optical communication may not be satisfied.

Zn ²⁺ is a component that acts as a flux. Moreover, there exists an effect which improves a weather resistance, suppresses the elution of the glass component in various washing | cleaning solutions, such as polishing washing water, and suppresses the quality change of the glass surface in a hot and humid state. Zn ²⁺ also has the effect of stabilizing vitrification. In view of the above, the content of Zn ²⁺ is preferably 0 to 40%, more preferably 0.1 to 30%, and still more preferably 0.2 to 20%. When there is too much content of Zn ^<2+> , light transmittance will fall or it will become easy to devitrify.

Ti ⁴⁺ has the effect of increasing the refractive index and improving devitrification resistance. However, when the content is too large, the light transmittance tends to decrease. In particular, when the glass contains a large amount of Fe ions as impurities (for example, 20 ppm or more), the light transmittance tends to be significantly reduced. Further, the devitrification resistance is likely to be lowered. Therefore, the content of Ti ⁴⁺ is preferably 0 to 20%, more preferably 0.1 to 15%, and further preferably 1 to 10%.

The content of B ³⁺ + Si ⁴⁺ + Al ³⁺ + Zn ²⁺ + Ti ⁴⁺ is preferably 0 to 50%, more preferably 0 to 30%, still more preferably 0.1 to 25%, and It is particularly preferably 5 to 20%, and most preferably 0.75 to 15%. When the content of ^{B 3+ + Si 4+ + Al 3+} + Zn 2+ + Ti 4+ is too large, the devitrification resistance tends to decrease. Moreover, Sn metal etc. precipitate with a raise of melting temperature, and light transmittance becomes easy to fall. From the viewpoint of improving the weather resistance, it is preferable to contain B ³⁺ + Si ⁴⁺ + Al ³⁺ + Zn ²⁺ + Ti ⁴⁺ in an amount of 0.1% or more.

Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ (alkaline earth metal ions) are components that act as fluxes. Moreover, there exists an effect which improves a weather resistance, suppresses the elution of the glass component in various washing | cleaning solutions, such as polishing washing water, and suppresses the quality change of the glass surface in a hot and humid state. However, when there is too much content of these components, liquidus temperature rises (liquidus viscosity falls), and there exists a tendency for a devitrification thing to precipitate easily during a melting or shaping | molding process. As a result, mass production is difficult. These components have a feature that the refractive index does not fluctuate greatly. In view of the above, the content of Mg ²⁺ + Ca ²⁺ + Sr ²⁺ + Ba ²⁺ is preferably 0 to 10%, more preferably 0 to 7.5%, and further preferably 0.1 to 5%. The content is preferably 0.2 to 1.5%.

Zr ⁴⁺ is a component that improves weather resistance. However, when the content is too large, the devitrification resistance tends to be lowered. Moreover, Sn metal etc. precipitate with a raise of melting temperature, and light transmittance becomes easy to fall. Therefore, the content of Zr ⁴⁺ is preferably 0 to 2%, more preferably 0 to 1.5%, still more preferably 0.1 to 1%, and more preferably 0.2 to 0. 5% is particularly preferable.

The glass constituting the temperature compensating member of the present invention can contain various components in addition to the above components as long as the effects of the invention are not impaired. For example, La ³⁺ , Gd ³⁺ , Ta ⁵⁺ , W ⁶⁺ , Nb ⁵⁺ , Y ³⁺ , Yb ³⁺ , Ge ⁴⁺ and S ⁶⁺ may be included.

Since Li ⁺ , Na ⁺ and K ⁺ are components that reduce chemical durability, the content thereof is preferably 10% or less, more preferably 5% or less, and more preferably 1% or less. More preferably, it is particularly preferable not to contain.

Te ⁴⁺ , Bi ³⁺ , In ³⁺ and Ga ³⁺ are components that ^tend to lower the light transmittance, and therefore their content is preferably 10% or less, more preferably 5% or less, and more preferably 1%. More preferably, it is particularly preferably not included.

Fe ³⁺ , Ni ²⁺ and Co ²⁺ are components that significantly reduce the light transmittance. Therefore, the content of these components is preferably less than 0.1%, and more preferably not contained.

Moreover, since rare earth components such as Ce ⁴⁺ , Pr ³⁺ , Nd ³⁺ , Eu ³⁺ , Tb ^3+, and Er ³⁺ may also reduce the light transmittance, the content of these components is less than 0.1%, respectively. It is preferable that it is not contained.

For environmental reasons, the contents of Pb ²⁺ and As ³⁺ are each preferably less than 0.1%, and more preferably not contained.

Glass constituting the temperature compensating member of the present invention, ^anionic%, O 2-30 to 100%, and ^F - ⁺ Cl - to preferably contains ^0~70%, O 2- 40~99.9% , And F ⁻ + Cl ⁻ 0.1 to 60%, more preferably O ² −50 to 99.5%, and F ⁻ + Cl ⁻ 0.5 to 50%, ² 70% to 99%, and ^F - ⁺ Cl - is particularly preferable to contain 1 to ^30% O 2 80 to 98% and ^F - ⁺ Cl - and most preferably contains 2 to 20%. By positively containing F ⁻ and Cl ⁻ , dn / dT is easily lowered. However, if the content is too large, the volatility at the time of melting becomes high and striae easily occurs. In addition, as a raw material for introducing F ⁻ and Cl ⁻ , fluorides of La, Gd, Ta, W, Nb, Y, Yb, Ge, Mg, Ca, Sr or Ba are available in addition to SnF ₂ and SnCl _2. And chloride.

In addition to the above components, Br ^- or the like may be contained.

The temperature compensating member of the present invention has a refractive index temperature coefficient dn / dT of −5 × 10 ⁻⁶ / ° C. or lower, preferably −6 × 10 ⁻⁶ / ° C. or lower at 20 to 60 ° C., It is more preferably −7 × 10 ⁻⁶ / ° C. or lower, and further preferably −8 × 10 ⁻⁶ / ° C. or lower. When dn / dT is too large, the temperature coefficient dS / dT of the optical path length becomes large, and it becomes difficult to satisfy the required quality as a constituent member of the optical device for optical communication.

In the temperature compensation member of the present invention, the temperature coefficient dS / dT of the optical path length represented by the following formula (1) at 20 to 60 ° C. is −15 × 10 ⁻⁶ to 15 × 10 ⁻⁶ / ° C. Preferably, it is −10 × 10 ⁻⁶ to 10 × 10 ⁻⁶ / ° C., more preferably −9 × 10 ^{−6 to} 9 × 10 ⁻⁶ / ° C., and −8 × 10 ^−6. particularly preferably from ~8 × ^{10 -6} / ℃, and most preferably ^{-7 × 10 -6 ~7 × 10 -6} / ℃. If dS / dT is too small or too large (that is, the absolute value of dS / dT is too large), it becomes difficult to satisfy the required quality as a component of the optical device for optical communication.

dS / dT = dn / dT + nα (1)
Here, S represents the optical path length, T represents the temperature, n represents the refractive index, and α represents the thermal expansion coefficient.

  Since the optical path length is shortened by increasing the refractive index of the temperature compensating member, it is possible to reduce the thickness of the temperature compensating member. However, if the refractive index of the temperature compensating member is too high, the glass tends to become unstable. In view of the above, the refractive index (nd) of the temperature compensating member of the present invention is preferably from 1.6 to 1.95, more preferably from 1.65 to 1.9, and from 1.7 to 1 Is more preferably 1.75 to 1.9. Moreover, it is preferable that the refractive index in wavelength 1310nm and 1550nm of the temperature compensation member of this invention is 1.55-1.95 respectively, It is more preferable that it is 1.6-1.95, 1.65- It is more preferably 1.9, particularly preferably 1.7 to 1.9, and most preferably 1.75 to 1.9.

The coefficient of thermal expansion of the temperature compensation member of the present invention at −40 to 100 ° C. is preferably 80 to 200 × 10 ⁻⁷ / ° C., more preferably 100 to 180 × 10 ⁻⁷ / ° C., 120 More preferably, it is ˜160 × 10 ⁻⁷ / ° C. If the thermal expansion coefficient is too small, dn / dT tends to increase. On the other hand, if the thermal expansion coefficient is too large, it is likely to be damaged by thermal shock. Moreover, when using it for the optical device for optical communications, it becomes difficult to match a thermal expansion coefficient with a to-be-joined member.

Difference between thermal expansion coefficient α _-40 to 20 at ₋₄₀ to 20 ° C. and thermal expansion coefficient α ₂₀ to _{100 at 20} to 100 ° C. | α _{−40 to 20} −α _{20 to 100} | preferably is less than 5 × ^{10 -7} / ℃, is preferably 2.5 × ^{10 -7} / ℃ or less. When the difference in thermal expansion coefficient | α _{−40 to 20} −α _{20 to 100} | is within the above range, an excellent temperature compensation function can be exhibited near room temperature.

Difference between thermal expansion coefficient α- ₄₀ to 100 at ₋₄₀ to 100 ° C. and thermal expansion coefficient α ₁₀₀ to _{200 at 100} to 200 ° C. of the temperature compensation member of the present invention | α _{−40 to 100} −α _{100 to 200} | preferably is less than 5 × ^{10 -7} / ℃, is preferably 2.5 × ^{10 -7} / ℃ or less. When the difference in thermal expansion coefficient | α _{−40 to 100} −α _{100 to 200} | is within the above range, an excellent temperature compensation function can be exhibited in a high temperature environment (for example, around 100 ° C.).

  The yield point of the temperature compensating member of the present invention is preferably 500 ° C. or less, more preferably 450 ° C. or less, further preferably 425 ° C. or less, and particularly preferably 420 ° C. or less. If the yield point of the temperature compensation member is too high, secondary processing such as mold press molding or draw molding tends to be difficult.

  The internal transmittance at a thickness of 10 mm at wavelengths of 1310 nm and 1550 nm of the temperature compensating member of the present invention is preferably 98% or more, more preferably 99% or more, and 99.5% or more. Is more preferable. When the internal transmittance of the temperature compensation member of the present invention at wavelengths 1310 nm and 1550 nm is too low, it becomes difficult to satisfy the required quality as a component member of the optical device for optical communication.

  The temperature compensation member according to the present invention preferably has a water resistance based on JOGIS of 3 or higher and an acid resistance of 2 or higher. When the water resistance and acid resistance of the temperature compensation member are out of the above ranges, surface deterioration is likely to occur due to cleaning after polishing and use under high temperature and high humidity.

The temperature compensating member of the present invention can be obtained by preparing raw materials so as to have a desired composition, melting in a melting furnace, and forming into a desired shape (for example, a plate shape). By using stannous pyrophosphate (Sn ₂ P ₂ O ₇ ) as a raw material, the resulting glass tends to be homogeneous. Further, by using a raw material made of fluoride or chloride as the raw material, dn / dT can be effectively reduced. In addition, after producing a cullet by primary melting and performing secondary melting using the cullet, adjustment of each characteristic and homogenization of the composition can be achieved. By homogenizing the composition, a glass having a high light transmittance can be obtained.

The melting atmosphere is preferably an inert atmosphere or a reducing atmosphere. For example, it is easy to obtain a homogeneous glass by melting in an inert atmosphere such as nitrogen or argon. As the glass melting container, metals such as platinum and gold, refractories, quartz glass, glassy carbon and the like can be used. Among metal containers, a gold container is particularly preferable because an alloy reaction with the Sn component hardly occurs. As the metal container, it is preferable to use a reinforced metal material in which an oxide such as ZrO ₂ is dispersed.

  The temperature compensating member of the present invention can be used as a constituent member of a waveguide device such as an arrayed wave guide or a planar optical circuit, a fiber Bragg grating, or an etalon. For example, an etalon has a structure in which half mirrors are formed on opposite end faces of a temperature compensation member formed in a prismatic shape, a cylindrical shape, or the like.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

  Tables 1 to 4 show examples (No. 1 to 36) and comparative examples (No. 37) of the present invention.

  Each sample was produced as follows.

First, raw materials such as oxides, fluorides, and chlorides were prepared so as to have the respective compositions shown in the table, and were melted at 700 to 1000 ° C. for 1 hour in a nitrogen atmosphere using a quartz crucible. As the fluoride raw material SnF _2, as the chloride material was used SnCl _2. The obtained molten glass was poured out on a preheated metal plate, and after annealing, a sample suitable for each measurement was produced.

  The obtained sample was measured for refractive index, thermal expansion coefficient, yield point, dn / dT, dS / dT, internal transmittance, acid resistance and water resistance. The results are shown in Tables 1-4.

  Refractive index was shown by the measured value with respect to d line | wire (587.6nm) of a helium lamp and LD light source (1310nm, 1550nm) using Shimadzu Corporation KPR-2000.

The thermal expansion coefficient and yield point were measured using a thermal expansion measuring device (dilat meter). Thermal expansion _{coefficient, -40~100 ℃ (α -40~100),} 100~200 ℃ (α 100~200), - 40~20 ℃ (α -40~20), and 20 to 100 ° C. (alpha _{20 ˜100} ) for each range.

dn / dT is calculated from the equation dn / dT = (nd ₂ −nd ₁ ) / (60−20) using the values of the refractive index nd ₁ at 20 ° C. and the refractive index nd ₂ at 60 ° C. of the d line. did.

dS / dT was calculated from the equation: dS / dT = dn / dT + nd ₁ × α using the value of dn / dT, the refractive index nd _{1 at} 20 ° C., and the value of thermal expansion coefficient (−40 to ₁₀₀ ° C.). .

  The internal transmittance was measured as follows. First, using a spectrophotometer (UV-3100 manufactured by Shimadzu Corporation), the transmittance including the surface reflection loss was set to 0. 0 for each of the 5 mm ± 0.1 mm and 10 mm ± 0.1 mm optically polished samples. Measurement was performed at intervals of 5 nm, and the internal transmittance at wavelengths of 1310 nm and 1500 nm was calculated from the obtained measurement values.

  Water resistance and acid resistance were measured based on the powder method defined in JOGIS.

As shown in Tables 1 to 4, No. Samples 1 to 36 had a small dn / dT of −10 × 10 ⁻⁶ / ° C. or less and a dS / dT of 1 to 14 × 10 ⁻⁶ / ° C. and a small absolute value. On the other hand, No. which is a comparative example. Sample 37 had a large absolute value of dn / dT as large as 7.5 × 10 ⁻⁶ / ° C. and dS / dT as 20 × 10 ⁻⁶ / ° C.

  The temperature compensating member of the present invention can be used as an optical pickup lens for various optical disk systems, a video camera, a photographing lens for a general camera, or the like by appropriately forming it into a predetermined shape. In addition, by combining a powdery temperature compensating member with a phosphor powder, it can be used as a wavelength conversion member for changing the wavelength of ultraviolet light or visible light.

Claims (10)

It is made of glass containing P ⁵⁺ 20% or more and Sn ²⁺ 20% or more in ^{terms of} cation%. The refractive index temperature coefficient dn / dT at 20 to 60 ° C. is −5 × 10 ⁻⁶ / ° C. or less. A characteristic temperature compensation member. 2. The temperature coefficient dS / dT of the optical path length at 20 to 60 ° C. represented by the following formula (1) is −15 × 10 ⁻⁶ to 15 × 10 ⁻⁶ / ° C. 2. Temperature compensation member.
dS / dT = dn / dT + nα (1)
Here, S represents the optical path length, T represents the temperature, n represents the refractive index, and α represents the thermal expansion coefficient. 3. The temperature compensation member according to claim 1, comprising: P ⁵⁺ 20 to 70% and Sn ²⁺ 20 to 90% in terms of cation%. 4. ^Anionic%, O 2- ^30~100%, and ^F - ⁺ Cl - temperature compensating member according to claim 1, characterized in that it contains 0-70%.   The temperature compensation member according to any one of claims 1 to 4, wherein a refractive index nd is 1.6 or more. The temperature expansion member according to any one of claims 1 to 5, wherein a coefficient of thermal expansion at -40 to 100 ° C is 80 to 200 × 10 ^-7 / ° C.   The temperature compensation member according to any one of claims 1 to 6, wherein a yield point is 500 ° C or lower. The temperature compensation member according to any one of claims 1 to 7, wherein the internal transmittance at a thickness of 10 mm at wavelengths of 1310 nm and 1550 nm is 98% or more.   The temperature compensation member according to any one of claims 1 to 8, wherein the water resistance based on JOGIS is 3 or more and the acid resistance is 2 or more. An optical device for optical communication using the temperature compensating member according to any one of claims 1 to 9.