JP2003040648A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove PbO from low melting point glass for environmental protection, and to solve the problems that in a conventional optical device and a holder uses a PbO-B2 O3 based low melting point glass, it is difficult to reduce a calcinations temperature to 450 deg.C or less. SOLUTION: The optical device is composed of the optical device 1 and the holder 2 by using the low melting point glass whose lead content is 0.1 mass% or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device in which an optical element used in various modules for optical fiber communication and a holder are joined by a low melting point glass.

[0002]

2. Description of the Related Art As an optical device in which a conventional optical element is held by a holder, there is one that is bonded to the holder by using a low melting point glass. The structure is shown in FIG. For example, the optical element 1 is a lens having a thermal expansion coefficient of 120 × 10 ⁻⁷ / ° C., the holder 2 is made of stainless steel having a thermal expansion coefficient of 170 × 10 ⁻⁷ / ° C., and the low-melting glass 3 has a softening point. It is made mainly of lead glass having a thermal expansion coefficient of 110 × 10 ⁻⁷ / ° C. at 350 ° C.

Although the pipe-shaped holder 2 is used, the holder 2 is not limited to this, and stainless steel is used as the material. However, if the coefficient of thermal expansion of the low-melting glass 3 is close, other metals or Even ceramic may be used. The low melting point glass 3 has a thermal expansion coefficient of 11 at a softening point of 350 ° C.
The main component was 0 × 10 ⁻⁷ / ° C. lead glass, but the coefficient of thermal expansion was 80 to 13 at a softening point of 250 to 400 ° C.
Any low melting point glass in the range of 0 × 10 ⁻⁷ / ° C. may be used.

As the conventional optical device comprising the optical element 1 and the holder 2 described above, a method of using an adhesive and a method of using an alloy solder of lead and tin in place of the low melting point glass 3 are known. However, when an adhesive is used, the adhesive generally has a high hygroscopic property, and thus tends to become brittle depending on environmental conditions. Moreover, since the glass transition temperature is low, the operating temperature of the optical device using the adhesive becomes relatively narrow. Also,
Since there is also a problem of outgassing, there is also a problem of lack of long-term reliability.

On the other hand, since the solder alloy of lead and tin has a relatively low melting point, a creep phenomenon occurs in which the solder is distorted with time, especially when a load such as gravity is constantly applied to the solder joint. easy. Therefore, when the optical element 1 and the holder 2 are fixed by this solder, the position of the optical element 1 changes with time, and there is a problem that the stability of the optical system cannot be secured for a long period of time. Furthermore, the alloy solder of lead and tin is 250 × 10 ⁻⁷ / ° C.
There is a big difference compared with the thermal expansion coefficient of 120 × 10 ⁻⁷ / ° C. Therefore, when the optical element 1 and the solder are fixed to each other, stress may be applied to the optical element during cooling of the solder due to the difference in thermal expansion coefficient, and problems such as cracking and birefringence may occur. Further, when the ambient temperature changes due to temperature change or heat generation of the electronic circuit, tensile and compressive stress is repeatedly applied to the solder joint. There is also a problem in that the thermal fatigue causes a crack in the solder to change the position of the optical element 1 and shift the optical axis (see JP-A-2-281201).

For the above reasons, the optical device using the above-mentioned low melting point glass 3 is used.

[0007]

With the recent optical elements,
As shown in FIG. 6, most of the optical elements 1 are provided with the antireflection film 4, but the antireflection film 4 has a heat resistance of 40%.
It is 0 ° C or lower. On the other hand, PbO-which is normally used
For the B ₂ O ₃ -based low melting point glass 3, it is difficult to set the firing temperature to 450 ° C. or lower, and it has not been possible to set the temperature below the heat resistant temperature of the antireflection film 4. Further, from the viewpoint of environmental protection, it has been desired to exclude PbO from the low melting point glass (see JP-A-8-259262).

Further, as shown in FIGS. 5 and 6, the low melting glass 3 has an outside air exposed surface other than the bonding surface with the optical element 1 and the holder 2, and the low melting glass 3 deteriorates in a high humidity environment. Could be promoted.

[0009]

In view of the above problems, the present invention provides an optical device comprising an optical element and a holder for holding the same, using a low melting point glass containing 0.1% by weight or less of lead. The optical element and the holder are joined together.

Further, the low melting point glass is composed of P ₂ O ₅ and Sn.
It is characterized in that at least one of O, Ag ₂ O and MoO ₃ is contained as a main component.

Further, the coefficient of thermal expansion of the low melting point glass is
It is characterized by being in the range of 50 × 10 ^{−7 to} 130 × 10 ⁻⁷ / ° C.

The lead content of the optical element is 0.1.
It is characterized by being less than or equal to wt%.

Further, the low melting point glass is characterized in that a covering member is provided on the exposed surface of the outside air.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an optical device according to an embodiment of the present invention.
FIG. As shown in Fig. 1, the basics of this optical device
The structure is such that the optical element 1, the holder 2 for holding the same, and the both
It consists of a low melting point glass 3 for fixing the person. For example, optical element
A cylindrical glass lens is used for the child 1, and Fe- is used for the holder 2.
As the low melting point glass 3, a Ni alloy is used, for example, P ₂
O_FiveWith lead as a main component and a low lead content of 0.1% by weight or less.
The joining is performed using a melting point glass.

Although a cylindrical glass lens is used as the optical element 1, various lenses such as a ball lens, a flat plate lens, and a rectangular lens may be used depending on the application.
Further, not only the lens but also an optical glass such as an airtight window, a prism, a polarizer, a birefringent glass, an optical crystal such as a Faraday rotator, or the like can be used. Further, it is desirable to use a lead content of 0.1% by weight or less as the material of these optical components in order to prevent adverse effects on the environment.

The holder 2 is selected according to the thermal expansion coefficient and mechanical strength of the various optical elements 1.
Further, the material of the holder 2 should also be selected depending on the method of attaching the optical device of the present invention to another device. In addition to the Fe-Ni alloy described above, any metal such as stainless steel, copper alloy, brass, aluminum alloy, and not only metal but also various ceramics such as alumina and zirconia can be selected.

Further, in the present invention, by using the low melting point glass 3 having a lead content of 0.1% by weight or less, the firing temperature can be kept at 400 ° C. or lower than the heat resistant temperature of the antireflection film 4. In addition, it is possible to prevent adverse effects on the environment. In addition, in the above-mentioned low melting point glass 3, P ₂ O ₅
In addition to those containing SnO as a main component, those containing SnO as a main component,
Alternatively, those containing Ag ₂ O as a main component, or MoO ₃
Those containing as a main component can also be selected. In addition, the main component in this invention shows the thing with the largest content (weight%) in the content of various components contained in the low melting glass 3.

These main components have the effect of further lowering the temperature than the low-melting glass 3 containing PbO as the main component, and the preferable contents of each of them are 20 to 70% by weight of P ₂ O _{5 and} 10 to 50 of SnO. wt%, Ag ₂ O 8 to 60% by weight, MoO ₃ 20 to 50 wt%. The material of the low melting point glass 3 includes ZnO and TeO in addition to the above main components.
Components such as ₂ , V ₂ O _{5 and the} like may be contained as auxiliary components.
The preferred contents of these subcomponents are ZnO 1 to 6% by weight, TeO ₂ 30 to 55% by weight, V ₂ O _{5 5 to} 19% by weight.
It is a weight% and has an effect of stabilizing the low melting point glass 3.

The above-mentioned main components and sub-components are selected with different mixing ratios depending on the firing temperature, expansion coefficient and the like.

The low melting point glass 3 composed of these components is
Difficult to use PbO-based low melting point glass 3 containing lead 2
Firing temperatures of 50-400 ° C can be achieved. With this baking temperature, it is possible to suppress the temperature to the heat resistant temperature of the antireflection film 4 processed on the optical surface of the optical element 1 or lower.

Further, the coefficient of thermal expansion of the low melting point glass 3 is set in the range of 50 × 10 ^{−7 to} 130 × 10 ⁻⁷ / ° C. in order to relieve the stress due to the joining of the optical element 1 and the holder 2. preferable. Further, by setting the coefficient of thermal expansion of the holder 2 to be in the range of 0.6 to 1.4 times the coefficient of thermal expansion of the low melting point glass 3, distortion can be reduced. At this time, the coefficient of thermal expansion of the optical element 1 is also 50 to 130.
The strain can be similarly reduced by setting the thermal expansion coefficient within a range of 0.6 to 1.4 times the thermal expansion coefficient of the low melting point glass 3 in the range of × 10 ^-7 / ° C.

The optical surface of this optical element 1 is processed
The antireflection film 4 usually has three or more layers,
SiO depending on the material and target reflectance₂, TiO₂, Z
rO ₂, Ta₂O_FiveEtc. can be selected. Also this
The antireflection film 4 may be used for the optical element 1 depending on required characteristics and applications.
It may be applied on both sides or one side of the optical surface, or
In some cases, the anti-reflection film 4 may not be applied.

A sectional view of another embodiment is shown in FIG. The optical element 1 provided with the antireflection film 4 and the holder 2 are bonded together by a low melting point glass 3, and the covering member 5 is provided on the exposed surface of the low melting point glass 3 to the outside air. This covering member 5 is intended to protect the surface of the low-melting glass 3 exposed to the outside air from humidity, which may deteriorate the low-melting glass 3. This covering member 5 is ring-shaped, and like the holder 2, in addition to Fe-Ni alloys, all metals such as stainless steel, copper alloys, brass, aluminum alloys, etc., and not limited to metals, various ceramics such as alumina and zirconia. Besides, it is possible to form by various methods such as vapor deposition of various metals.

The joining method is as follows. The optical element 1 is mounted on the holder 2, and the ring-shaped low-melting glass 3 is attached to the optical element 1.
It is placed at the joint between the holder 2 and the holder 2 and put in a temperature-controllable firing furnace to raise the temperature to 350 ° C. at 5 to 10 ° C./minute, hold at 350 ° C. for 10 minutes, and then to room temperature at 20 to 50 ° C./minute. After being lowered, it is taken out from the firing furnace. The joining method is not limited to this, and a paste-like material in which a binder is mixed as the low melting point glass may be used. Further, it is not limited to the firing furnace, and any high temperature device with a heater such as a hot plate may be used. The temperature condition is not limited to the above, and may be changed according to the member used and the device.

Further, the covering member 5 may be formed by firing bonding at the same time as the low-melting glass 3 or by separately forming after bonding the low-melting glass 3.

[0027]

EXAMPLES Here, an optical device according to the present invention was prototyped, a reliability test was carried out, and the reflectance was evaluated.

The optical element 1 is a cylindrical glass lens having an outer diameter of 1.8 mm and a thermal expansion coefficient of 88 × 10 ⁻⁷ / ° C., and the holder 2 is a Fe—Ni alloy having a thermal expansion coefficient of 97 × 10 ⁻⁷ / ° C. Firing temperature 380 containing 60 wt% of P ₂ O ₅ in the melting point glass 3
An optical device was manufactured by using the one at ℃. This is Embodiment 1 of the present invention.

Further, the optical element 1 is a cylindrical glass lens having an outer diameter of 1.8 mm and a thermal expansion coefficient of 88 × 10 ⁻⁷ / ° C., and the holder 2 is a Fe—Ni alloy having a thermal expansion coefficient of 97 × 10 ⁻⁷ / ° C. ,
An optical device was manufactured using a low melting point glass 3 containing 30% by weight of MoO ₃ at a firing temperature of 370 ° C. This is Embodiment 2 of the present invention.

On the other hand, as a comparative example, the optical element 1 has a cylindrical glass lens having an outer diameter of 1.8 mm and a thermal expansion coefficient of 88 × 10 ⁻⁷ / ° C., and the holder 2 has a thermal expansion coefficient of 97 × 10 ⁻⁷ /.
An optical device was prepared by using a Fe-Ni alloy at 60 ° C. and a low melting point glass 3 containing 60 wt% of PbO at a firing temperature of 450 ° C.

First, 100 of each of Example 1 of the present invention, Example 2 of the present invention, and Comparative Example were produced, and the reflectance of the antireflection film 4 after the production was measured. It is converted into a variation value from the reflectance before firing, which is shown in FIG.

In Example 1 of the present invention and Example 2 of the present invention, the reflectance fluctuation was suppressed to 0.2% or less, but in the comparative example, the reflectance fluctuation was 0.5 to 1.0%. Three out of 100 variations in reflectance occurred.

Next, all those whose fluctuation in reflectance was 0.2% or less were put into a constant temperature and humidity test at 85 ° C., 85% for 2000 hours, and the reflectance was measured after that. FIG. 4 shows the values converted into reflectance fluctuation values.

In Example 1 of the present invention and Example 2 of the present invention, the reflectance fluctuation was suppressed to 0.2% or less, but in the comparative example, it was 0.3 to 1.8%. 32 of 97 reflectances were generated.

From these results, the optical device of the present invention clearly has improved performance in optical characteristics such as reflectance fluctuation, as compared with the conventional one.

[0036]

As described above, according to the present invention, the optical device is constructed by bonding the optical elements with the low melting point glass containing 0.1% by weight or less of lead, so that the firing temperature is 400%. It was possible to suppress the temperature to below 0 ° C. and improve the reliability of optical characteristics.

Further, by using a low melting point glass having a lead content of 0.1% by weight or less, it becomes possible to manufacture an optical device which is friendly to the global environment.

[Brief description of drawings]

FIG. 1 is a sectional view showing an optical device of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the optical device of the present invention.

FIG. 3 is a graph showing reflectance fluctuations in the optical devices of the present invention and the comparative example.

FIG. 4 is a graph showing reflectance fluctuations after a reliability test in optical devices of the present invention and a comparative example.

FIG. 5 is a cross-sectional view showing a conventional optical device.

FIG. 6 is a cross-sectional view showing a conventional optical device provided with an antireflection film.

[Explanation of symbols]

1: Optical element 2: Holder 3: Low melting glass 4: Antireflection film 5: Cover member

Continued front page    F-term (reference) 2H043 AE02 AE23                 4G061 AA00 BA07 BA12 CA03 CB13                       CC03 CD05 CD10 DA32                 4G062 AA08 BB09 DA01 DB01 DC01                       DD04 DD05 DD06 DE03 DF01                       DF02 EA01 EA10 EB01 EC01                       ED01 EE01 EF01 EG01 FA01                       FB01 FC01 FD01 FE04 FE05                       FF03 FF04 FG01 FH01 FJ01                       FK01 FL01 GA01 GB01 GC01                       GD05 GD06 GE01 HH01 HH03                       HH04 HH05 HH07 HH08 HH09                       HH11 HH13 HH15 HH17 HH20                       JJ01 JJ03 JJ05 JJ07 JJ10                       KK01 KK03 KK05 KK07 KK10                       MM04 NN29 NN32

Claims (5)

[Claims] 1. An optical device comprising an optical element and a holder for holding the optical element, wherein the optical element and the holder are joined using a low melting point glass having a lead content of 0.1% by weight or less. Optical device. 2. The low-melting glass is P ₂ O ₅ , SnO, A
The optical device according to claim 1, wherein at least one of g ₂ O and MoO ₃ is a main component. 3. The thermal expansion coefficient of the low melting glass is 50 ×
The optical device according to claim 1, which is in the range of 10 ^{-7 to} 130 × 10 ^-7 / ° C. 4. The optical device according to claim 1, wherein the lead content of the optical element is 0.1% by weight or less. 5. The optical device according to claim 1, wherein a covering member is provided on the exposed surface of the low melting point glass to the outside air.