JP2003329975A - Optical device and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device which is provided with an optical stack using an adhesive for optical surface and which operates stably even under environmental conditions of a light temperature, a temperature cycle and a high humidity. <P>SOLUTION: The optical device is provided with the optical stack 18 which has a laminar structure consisting of a plurality of optical element layers and adhesive layers and is formed by bonding together optical elements by the optical adhesives at their optical surfaces, i.e., transmission surfaces for light, and a coupling optical system which guides the light to this optical stack 18. The optical stack 18 is fixed to a substrate at the surface exclusive of the optical surfaces in at least one among a plurality of the optical element layers. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device mainly used in an optical communication system or an optical measurement system and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of optical devices such as optical isolators or optical circulators used in optical communication devices, the optical surfaces of optical elements other than the coupling optical system are bonded with an adhesive to form an integrated optical stack. Often handled as.

As an example of a three-terminal or four-terminal optical circulator, an optical circulator using a parallel plate birefringent crystal, a Faraday rotator, and a half-wave plate is widely used. As an example, Japanese Patent No. 2539
There is an optical circulator disclosed in Japanese Patent No. 563.

An optical circulator can be manufactured by fixing such an optical stack and a permanent magnet to a housing, and adjusting and fixing a lens and an optical fiber to the housing. FIG. 5 shows an example thereof.

FIG. 5 is a perspective view showing a fixing structure of an optical stack in a conventional optical circulator. 56a is the first rutile crystal, 56b is the first Faraday rotator,
56c is a pair of first half-wave plates, 56d is a second rutile crystal, 56e is a pair of second half-wave plates, 56f is a second Faraday rotator, and 56g is a third rutile crystal. Is.

Further, 51 is an adhesive for fixing the optical stack,
52a to 52f are optical adhesive layers, 53 is an optical surface, 54 is an alumina plate, and 55 is a casing. Note that the fixing adhesive 5
1 is highlighted and fixed on the entire bottom surface of the optical stack. A non-reflection coating film is formed on the optical surface 53 and the other optical surfaces.

At this time, the bottom surface of the optical stack 58 is fixed to the housing 55 through the alumina plate 54 inserted for the purpose of relaxing the thermal expansion and preventing the optical stack from warping.

Here, an epoxy organic adhesive is used for fixing, and a material having a small coefficient of thermal expansion and a small influence on the optical stack is selected.

[0009]

A conventional optical device such as an optical isolator or an optical circulator, which uses a laminated optical stack of two or more layers in which optical surfaces are bonded together by an adhesive, has a temperature of -40. ℃ to 85 ℃
When it is placed in an environmental condition where it is periodically cycled to, the adhesive on the optical surface deteriorates, causing the adhesive layer to peel off, causing a difference in refractive index and causing reflection, resulting in a decrease in light transmittance. was there.

The same phenomenon occurs under high temperature and high humidity environmental conditions (for example, when the temperature is 85 ° C. and humidity is 85% RH and the temperature is about 2000 hours).

Generally, in an optical communication system equipment, it is required that the decrease in the light transmittance of the device mounted therein is suppressed to an insertion loss of 0.2 dB or less, but in the conventional structure, it is 0.2 dB or more. Was observed.

Therefore, the present invention provides an optical device such as an optical circulator provided with an optical stack using an adhesive on the optical surface, which operates stably even under environmental conditions of temperature cycle, high temperature and high humidity. The challenge is to provide.

[0013]

In order to solve the above problems, the present invention has the following constitution.

That is, the present invention is an optical stack having a layered structure composed of a plurality of optical element layers and an adhesive layer, which is formed by bonding optical elements on an optical surface which is a light transmitting surface with an optical adhesive. In an optical device including a coupling optical system that guides light to the optical stack, the optical stack is fixed to a substrate on a surface other than an optical surface of any one of the plurality of optical element layers. And

The present invention is characterized in that, in the optical device, the fixing surface of the optical element layer to the substrate is any one surface other than the optical surface.

The present invention is characterized in that, in the optical device, a groove is formed on the substrate near the fixing surface to prevent the fixing adhesive from flowing out or permeating.

The present invention is characterized in that, in the optical device, the fixing surface of the optical element layer to the substrate is two surfaces adjacent to each other.

The present invention is characterized in that the optical device is an optical circulator.

According to the present invention, in the method for manufacturing an optical device, a fixing adhesive is applied so as to be distributed only between any one of the optical element layers of the optical stack and the substrate, and the adhesive is fixed to the substrate. Is a method for manufacturing an optical device.

According to the present invention, in the method for manufacturing an optical device, the optical device is an optical circulator.

[0021]

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

(First Embodiment) FIG. 1 shows the first embodiment.
2 shows an optical stack of an optical circulator and a fixed structure thereof. 11 is an adhesive for fixing the optical stack, 12a to 1
2f is an optical adhesive layer, 13 is an optical surface, 14 is an alumina plate,
Reference numeral 15 is a housing portion, 16 is a groove provided in the alumina plate 14,
17 shows the first rutile crystal. The fixing adhesive 11 is shown in an emphasized manner, and an antireflection coating film is formed on the optical surface 13 and the other optical surfaces.

The optical element used in this embodiment is the same as that of the conventional optical stack 58 shown in FIG.
2 rutile crystal parallel plates, 2 placed side by side to form a pair 2
A pair of half-wave plates and two 45 ° Faraday rotation plates.

For each optical element, a non-reflective coating film for air or epoxy resin is formed and then cut into a predetermined size. Next, those optical surfaces are bonded with an epoxy resin.

In parallel with this, the alumina plate 14 and the housing 1 are
5 is also bonded with an epoxy resin. Here, the alumina plate 14 is provided with a groove 16 for preventing the adhesive from flowing out.
Further, the groove serves to prevent the adhesive from penetrating through the narrow gap between the surface of the other optical element layer and the substrate. That is, only on one side of the optical element to be bonded,
It serves to distribute the adhesive for fixing the optical stack.

The optical stack 18 completed by adhering the optical surfaces with an epoxy resin is adhered and fixed with an epoxy resin to the one obtained by adhering the alumina plate 14 and the casing 15. Here, the bonding surface is the bottom surface of the optical stack 18 and is fixed only by the first rutile crystal 17. 10 samples were prepared and temperature cycled, -40 to 85 ° C, 1 cycle 8
An environmental test was performed for 42 cycles for an hour.

As a result, peeling of the optical surface adhesive layer did not occur, and the increase in insertion loss was 0.1 dB or less. By the way, in the conventional fixing method, an increase in the insertion loss of 0.2 dB or more was observed in the two to three elements due to the peeling of the adhesive layer. As described above, the reliability is greatly improved.

FIG. 4A is a perspective view showing the main part of the optical circulator of the first embodiment. 41 is a single-core single-mode optical fiber, 42 is a lens, 43 is an optical stack, 44a is a U-shaped magnet, 45 is a 2-core expanded core optical fiber, 46 is an alumina plate, and 47a is a casing.

Here, B forming a 45 ° Faraday rotation plate
A U-shaped magnet 44a for applying a magnetic field to the i-substituted rare earth garnet crystal was fixed to the housing and used.

Finally, the coupling optical system was adjusted and fixed by laser welding. The coupling optical system used at this time is a one-core optical fiber having a mode field diameter of about 10 μm, a two-core expanded optical fiber (TEC optical fiber) having a mode field diameter of about 30 μm, and stainless SUS3.
It consists of an aspherical lens with a 04 frame.

(Second Embodiment) FIG. 2 shows the second embodiment.
FIG. 3 is a perspective view showing an optical stack of the optical circulator and a fixing structure thereof. Reference numeral 21 is an optical stack fixing adhesive, 22a to 22f are optical adhesive layers, 23 is an optical surface, and 24 is an optical surface.
Indicates the housing. The adhesive 21 for fixing the optical stack
Is highlighted, and a non-reflection coating film is formed on the optical surface 23 and other optical surfaces.

An optical stack was manufactured in the same manner as in the first embodiment. The optical stack 28 is adhesively fixed to the housing 24 with an epoxy resin. Here, the surfaces to be bonded are the bottom surface and the side surface of the optical stack 28, and are fixed only by the first rutile crystal 25. This sample is 1
0 pieces were produced and the environmental test of temperature cycle, -40-85 degreeC, 1 cycle 8 hours, and 42 cycles was performed.

As a result, peeling of the optical surface adhesive layer did not occur, and the increase in insertion loss was 0.1 dB or less. As described above, the reliability is greatly improved.

The structure of the main part of the optical circulator is shown in FIG. 4 (b). 43 is an optical stack, 47b is a housing, and a cylindrical magnet 44b is used as a magnetic field applying means.

(Third Embodiment) FIG. 3 shows the third embodiment.
FIG. 3 is a perspective view showing an optical stack of the optical circulator and a fixing structure thereof. 31 is an adhesive for fixing the optical stack, 32a to 32f are optical adhesive layers, 33 is an optical surface, 34
Indicates the housing. The fixing adhesive 31 is shown in an emphasized manner, and a non-reflection coating film is formed on the optical surface 33 and other optical surfaces.

An optical stack was obtained in the same manner as in the first embodiment. The optical stack 38 is adhesively fixed to the housing 34 with an epoxy resin. Here, the surfaces to be bonded are the two surfaces of the bottom surface and the side surface of the optical stack 38, and are fixed only by the second rutile crystal 35. 10 samples were prepared and temperature cycled, -40 to 85 ° C, 1 cycle 8
An environmental test was performed for 42 cycles for an hour.

As a result, peeling of the optical surface adhesive layer did not occur, the increase in insertion loss was 0.1 dB or less, and the reliability was greatly improved.

The structure of the main part of the optical circulator is as shown in FIG. 4 (c). 43 is an optical stack, 47c
Is a casing, and the magnetic field applying means is a cylindrical magnet 44.
c and 44d were used.

Although an example of the optical circulator has been described in the above-mentioned embodiments, the optical device having an optical stack such as an optical switch also has the highly reliable optical stack according to the present invention. Clearly, an optical device is obtained.

[0040]

As described above, according to the present invention, in an optical device such as an optical circulator provided with an optical stack using an adhesive on the optical surface, the optical device can be stably operated even under environmental conditions of temperature cycle, high temperature and high humidity. It is possible to provide an optical device that operates and is greatly improved in reliability.

[Brief description of drawings]

FIG. 1 is a diagram showing an optical stack and its fixing structure according to a first embodiment. 1A is a front view thereof, and FIG. 1B is a perspective view thereof.

FIG. 2 is a diagram showing an optical stack and its fixing structure according to a second embodiment. 2A is a front view thereof, and FIG. 2B is a perspective view thereof.

FIG. 3 is a diagram showing an optical stack and its fixing structure according to a third embodiment. 3A is a front view thereof, and FIG. 3B is a perspective view thereof.

FIG. 4 is a perspective view showing a main part of the optical circulator of the present invention. FIG. 4A is a diagram in the first embodiment, and FIG.
Is a diagram in the second embodiment, and FIG. 4C is a diagram in the third embodiment.
Figure at.

FIG. 5 is a perspective view showing an optical stack and a fixing structure thereof in a conventional optical circulator.

[Explanation of symbols]

11, 21, 31 Fixing adhesives 12a to 12f, 22a to 22f, 32a to 32f
Optical adhesive layer 13, 23, 33 Optical surface 14, 46 Alumina plate 15, 24, 34 Housing 16 Groove 17, 25 First rutile crystal 18, 28, 38 Optical stack 35 Second rutile crystal 41 1-core Single-mode optical fiber 42 Lens 43 Optical stack 44a U-shaped magnets 44b, 44c, 44d Cylindrical magnet 45 Two-core expanded optical fiber 47a, 47b, 47c Housing part

Claims (7)

[Claims] 1. An optical stack, which has a layered structure composed of a plurality of optical element layers and an adhesive layer, and is formed by bonding optical elements on an optical surface, which is a light transmitting surface, with an optical adhesive, and to the optical stack. An optical device including a coupling optical system that guides light, wherein the optical stack is fixed to a substrate by a surface other than an optical surface of any one of the plurality of optical element layers. . 2. The optical device according to claim 1, wherein the optical element layer has one fixed surface to the substrate. 3. The optical device according to claim 2, wherein a groove for preventing the fixing adhesive from flowing out and permeating is formed on the substrate near the fixing surface. 4. The optical device according to claim 1, wherein the fixing surface of the optical element layer to the base is two surfaces adjacent to each other. 5. The optical device according to claim 1, wherein the optical device is an optical circulator. 6. The method for manufacturing an optical device according to claim 1, wherein the fixing adhesive is applied so that the fixing adhesive is distributed only between any one optical element layer of the optical stack and the substrate. A method of manufacturing an optical device, characterized by performing adhesive fixing. 7. The method of manufacturing an optical device according to claim 6, wherein the optical device is an optical circulator.