JP2005189353A - Optical isolator element and its manufacture method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture an optical isolator element, which can be mounted without being adjusted, with good mass-productivity. <P>SOLUTION: The optical isolator manufacture method includes (1) a step for forming a laminated body by sticking a large-sized polarizer base plate whose plane is quadrangular on both surfaces of a large-sized Faraday rotator base plate 2 whose plane is quadrangular through an adhesive for temporary fixing, (2) a step for obtaining the strip-like body of the laminated body cut in parallel with one side of the plane of the laminated body, (3) a step for obtaining the assembly of a plurality of strip-like bodies arrayed in a state where their optical surfaces abut on each other and their cut surfaces turn up and down and also masking the optical surfaces of at least both ends of the assembly, (4) a step for forming a metallic multilayer film only on the cut surface of the assembly after the stage (3), (5) a step for obtaining the block body of the strip-like body cut in parallel with the short side of the plane of the strip-like body after the stage (4), and (6) a step for washing the block body and removing the adhesive for temporary fixing. The optical isolator is manufactured by utilizing the method. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical isolator used for removing return light generated when light emitted from a light source is introduced into various optical elements and optical fibers, and a manufacturing method thereof.

  In an optical communication module or the like, light emitted from a light source such as a laser light source is incident on various optical elements or optical fibers, but a part of the incident light is reflected on the end surfaces or inside of the various optical elements or optical fibers. It is scattered. A part of the reflected or scattered light tries to return to the light source as return light, and an optical isolator is used to prevent the return light.

  Conventionally, this type of optical isolator has a configuration in which a flat Faraday rotator is disposed between two flat polarizers, and these three components are housed in a cylindrical magnet via a component holder. there were. Normally, the Faraday rotator is adjusted to a thickness that rotates the polarization plane of light having a predetermined wavelength in the saturation magnetic field by 45 degrees, and the transmission polarization directions of the two polarizers are relatively shifted from each other by 45 degrees. The rotation is adjusted as follows.

  The optical isolator having such a configuration requires a Faraday rotator and two polarizers as separate parts and requires a holder for each element. Therefore, the number of parts is increased and the number of assembly steps is increased. Adjustment work is also complicated, which not only increases costs but also makes it difficult to reduce the size. Further, when incorporating the light source module into the light source module, it is necessary to adjust the position of the magnet for forming the saturation magnetic field, that is, to adjust the polarization plane of the optical isolator, and the mounting process is complicated.

  For this reason, various optical isolators have been proposed in which optical elements of a Faraday rotator and a polarizer and a cuboid magnet are installed on a flat plate-like alignment substrate.

  For example, Patent Document 1 shows a conventional optical isolator 18 as shown in FIG. 5. The optical isolator 18 includes optical elements of a Faraday rotator 12, a polarizer 13, and an analyzer 14, and a rectangular magnet 17. Are arranged on a flat plate-like alignment substrate 16 and fixed with a bonding material 15. Here, the polarizer 13 and the analyzer 14 have a function of absorbing a polarization component in one direction of transmitted light and transmitting a polarization component orthogonal to the polarization component, and the Faraday rotator 12 is It has a function of rotating the polarization plane of light of a predetermined wavelength by about 45 degrees at the saturation magnetic field strength. Further, the polarizer 13 and the analyzer 14 are cut out so that their respective surfaces in contact with the alignment substrate 16 serve as reference surfaces, and the transmitted polarization directions are 0 degrees and 45 degrees, respectively, with respect to the reference surfaces.

  As described in paragraph 0020 in Patent Document 1, conventionally, a polarizer 13, an analyzer 14, and a Faraday rotator 12 are vertically and horizontally separated from each other by a large polarizer substrate or a Faraday rotator substrate (not shown). After being cut, each of the rectangular polarizers 12, analyzers 14, and Faraday rotators 12 cut out as described in paragraph 0013 is subjected to metallization processing for bonding to the alignment substrate 16. It was something to do. Note that the term analyzer refers to a polarizer disposed on the exit side.

  Further, Patent Document 2 shows a manufacturing process of a conventional optical isolator element as shown in FIG. As shown in FIG. 4A, the procedure for manufacturing the optical isolator element is performed by alternately attaching the large polarizer substrates 1 and 3 and the large Faraday rotator substrate 2 using the adhesive 7 for temporary fixing. The laminated body 10 is formed by curing and bonding the adhesive 7 as shown in FIG. Then, as shown in FIG.4 (c), it is set as the strip 6 cut in parallel with one side of the plane of the laminated body 10. FIG. Next, the adhesive 7 is washed and removed as shown in FIG. 4 (f), and then aligned and fixed again on the substrate and collectively cut into blocks. Specifically, the relative positional relationship at the time of temporary fixing is reproduced by bringing the cut surface of the strip into contact with the flat surface, and the angular arrangement between the pair of polarizers is accurately performed.

As the adhesive 7 used here, an organic adhesive is used because it needs to have a temporary fixing function. However, an inorganic adhesive is used as an adhesive finally bonded to the Faraday rotator or the polarizer. The reason for this is that a semiconductor laser chip made of GaAs or the like is used as the laser that passes through the optical isolator. However, an oxide film is formed on the surface of the semiconductor laser chip by a slight residual oxygen, and the oscillation efficiency is reduced. It can be seen. Therefore, the package in which the semiconductor laser chip is installed is hermetically sealed with an inert gas such as nitrogen gas. Naturally, it is impossible to install a component that generates outgas in the sealed package. Therefore, outgas is mainly generated from organic adhesives, so organic resin adhesives cannot be used even in optical isolators built in packages, and inorganic adhesives such as low melting glass and metal brazing materials should be used. become. Therefore, it is necessary to completely clean the temporarily fixed adhesive 7 in the step of FIG.
JP 2001-91899 A Japanese Patent Laid-Open No. 11-101953

  However, in Patent Document 1, as described above, a large polarizer substrate and a Faraday rotator substrate are separately cut vertically and horizontally and processed into a rectangular plate shape, and after the cutting processing, the bonding surface with the alignment substrate 16 is obtained. The bottom surfaces of the polarizers 13 and 14 and the Faraday rotator 12 to be processed are subjected to metallization and the like. Not only the process is complicated, but the optical isolator element 11 cut out separately varies in the processing shape of the bottom surface. However, simply placing the optical isolator element 11 on the alignment substrate 16 easily causes variations in the optical performance of the optical isolator 18.

  In addition, if metallization is separately applied to the polarizer and Faraday rotator, it is necessary to set a metal mask accurately on the optical surface of each optical element, which is not only complicated, but also requires four cut surfaces. Since it is difficult to mask, it is easy to form a metal multilayer film with a width exceeding 0.05 mm from the cut surface to the optical surface, and when joining the alignment substrate 16 with solder or the like, There was also a problem that the effective aperture diameter was reduced by climbing up the formed metal multilayer film and entering the aperture diameter of the optical surface to be used. As a result, stress is applied to the central portion of the optical isolator element 11, and the Faraday rotator 12 has a problem that the Faraday rotation angle decreases.

  Moreover, the manufacturing method of the optical isolator element 11 described in Patent Document 2 does not describe a process of metallizing each optical element, and temporarily maintains the temporary fixing with the adhesive 7 of the optical isolator element 11. In the case where the metallization process is performed in the state where it is left, it is impossible to introduce the optical isolator element 11 into a high-temperature film forming process generally exceeding 150 ° C. because the adhesive base material and the adhesive material are subject to thermal destruction, When the adhesive 7 for temporary fixing is removed, it is necessary to metallize in a dispersed state, and the same problem as described above is caused.

  In this way, the organic adhesive 7 used for temporary fixing is not left after assembly completion, it is highly reliable under high-temperature and high-humidity conditions, and the characteristics deteriorate even when used in high-power, long-time laser light. There has been a demand for a production method that is excellent in mass productivity of optical isolators that do not have any optical isolator.

The present invention has been devised in view of these problems, and the optical isolator according to the present invention is formed by joining the optical surfaces of a flat-plate Faraday rotator and a polarizer facing each other on an alignment substrate. In an optical isolator in which an optical isolator element and a magnet that applies a magnetic field to a Faraday rotator of the optical isolator element are fixed via a bonding material, a metal multilayer film is formed only on the bonding surface of the optical isolator element. In addition, the present invention provides a method for manufacturing an optical isolator characterized by including at least the following steps (1) to (6).

(1) Step of forming a laminated body on both surfaces of a large-sized Faraday rotator substrate having a quadrangular plane using a temporary fixing adhesive on both sides of the large-sized polarizer substrate having a quadrangular plane. Step (3) to make strips cut parallel to one side of the plane Abutting the optical surfaces of the plurality of strips to make an assembly aligned with the cut surfaces up and down, and at least at both ends of the assembly Parallel to the short side of the plane of the strip after the steps (5) and (4) of forming the metal multilayer film only on the cut surface of the aggregate after the steps (4) and (3) of masking the optical surface (6) The step of cleaning the block body and removing the temporary bonding adhesive The process temperature of forming the metal multilayer film is equal to or lower than the glass transition point of the temporary bonding adhesive. It is characterized by being.

 As described above, according to the optical isolator and the manufacturing method thereof according to the present invention, the following effects are obtained.

 (1) In the method for manufacturing an optical isolator element, optical adjustment of a large number of optical isolator elements can be performed at a time, and the number of assembling steps can be reduced.

  (2) Since a metal multilayer film can be formed in a lump on an optical isolator element composed of a Faraday rotator and a polarizer, a large number of optical isolator elements can be manufactured with high productivity.

 (3) The organic adhesive used for temporary fixing is finally removed, and the optical elements are integrated with each other outside the light-transmitting surface and using an inorganic material. Excellent.

 (4) The organic adhesive used for temporary fixing is finally removed, and all members constituting the optical isolator element are made of an inorganic material, so that organic outgas is not generated. Therefore, an optical isolator element can be installed in the semiconductor laser package, and the device can be downsized and the characteristics can be stabilized.

  (5) Since a metal multilayer film is formed only on one surface of the optical isolator element and hardly protrudes from the optical surface, stress at the center of the optical isolator element can be suppressed.

  (6) Since the metal multilayer film is formed only on one surface of the optical isolator element, it is possible to suppress a decrease in effective aperture diameter due to the metal multilayer film protruding to the optical surface.

  (7) Since the metallization process is performed in a temperature range that does not exceed the glass transition temperature of the temporary bonding adhesive, batch film formation can be performed while temporarily bonded.

  Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A to 1F are diagrams for explaining the manufacturing process of the optical isolator of the present invention, and FIG. 2 is a diagram for explaining the cutting from a strip into a block body during the manufacturing process of the present invention. is there. In addition, the same code | symbol is used about the code | symbol similar to a prior art.

  As shown in FIG. 1, in the case of an optical isolator called a one-stage type, an optical isolator element is, as is well known, a large flat plate-like polarizer substrate 1 and a Faraday rotator substrate 2 in the direction of light emission. The polarizer substrates 3 are arranged in this order. These form the laminated body 10 laminated | stacked with the adhesive 7 for temporary fixing, and bonded together.

  The transmission polarization direction of the polarizer substrate 1 is set in a direction parallel to one side (referred to as a reference side) parallel to the film formation surface 4 shown in FIG. The transmission polarization direction is set to a direction of 45 degrees with respect to the reference side. Here, by fixing the reference sides of the polarizer substrate 1 and the polarizer substrate 3 so as to substantially coincide with each other, the transmission polarization directions of the polarizer substrate 1 and the polarizer substrate 3 are shifted from each other by 45 degrees without adjusting the rotation. Thus, when the Faraday rotation angle of the Faraday rotator substrate 2 is approximately 45 degrees, the best insertion loss characteristic and isolation characteristic can be obtained.

  The polarizer substrates 1 and 3 are composed of an absorption polarizer having a function of absorbing a unidirectional polarization component of incident light, or a birefringent polarizer that separates or synthesizes a unidirectional polarization component of incident light. Is done. The absorptive polarizer is made of, for example, polarizing glass having a structure in which ellipsoidal metal particles are dispersed in glass. This polarizing glass is a glass having polarization characteristics by arranging long stretched metal particles in one direction in the glass itself, light having a polarization plane perpendicular to the stretch direction of the metal particles is transmitted, Light with a parallel polarization plane is absorbed. For example, it is made of polarizing glass having a structure in which ellipsoidal metal particles are dispersed in glass. This polarizing glass is a glass having polarization characteristics by arranging long stretched metal particles in one direction in the glass itself, light having a polarization plane perpendicular to the stretch direction of the metal particles is transmitted, Light with a parallel polarization plane is absorbed.

  The Faraday rotator substrate 2 is adjusted to a thickness at which the polarization direction of light incident at room temperature rotates 45 degrees. When isolation is required, it is necessary to precisely adjust the rotational deviation of the polarizer substrate 1 and the polarizer substrate 3 to 45-α degrees with respect to the polarization rotation angle 45 + α degrees of the Faraday rotator substrate 2. There is a method in which light is incident from the opposite direction (from the side of the polarizer substrate 3), and the polarizer 1 is rotationally adjusted so that the transmitted light is minimized. Therefore, the transmission polarization direction of the polarizer 1 and the polarizer substrate 3 is cut out by shifting by 45-α degrees in advance, and for example, the transmission polarization direction of the polarizer substrate 3 can be set to 45-α degrees with respect to the reference side. is there. In addition, the accuracy ± α of the polarization rotation angle of the Faraday rotator is desirably about 1 degree due to the characteristics of the optical isolator.

  The Faraday rotator substrate 2 is, for example, a bismuth-substituted garnet crystal, and the thickness thereof is set so that the polarization plane of incident light having a predetermined wavelength rotates 45 degrees. In general, in order to rotate the plane of polarization, it is necessary to apply a sufficient magnetic field in the direction of the optical axis of incident light.

  Here, both surfaces of the Faraday rotator substrate 2, the polarizer 1 and the polarizer substrate 3 are provided with antireflection films for the refractive index n = 1, and the polarizer 1, the polarizer substrate 3 and the Faraday rotator substrate are provided. When the two are in close contact, the entrance / exit surface where the polarizer is in contact with air is provided with an antireflection film for the refractive index n = 1, and the antireflection film for the counter-polarizer is provided on both sides of the Faraday rotator. .

  Next, the manufacturing method of the optical isolator of this invention is demonstrated.

  First, as shown in FIG. 1 (a), one flat-plate Faraday rotator substrate 2 and two polarizer substrates 1 and 3 are prepared, and the optical elements are laminated via an adhesive 7 for temporary fixing. . Regarding the two polarizer substrates 1 and 3, it is desirable that their transmitted polarization directions (not shown) are shifted by 45 ° in a superposed state. Accordingly, as shown in FIG. 1B, the transmitted polarization direction of the polarizer substrates 1 and 3 is confirmed while allowing the laser light of the wavelength to be used to pass in the direction of the optical axis L and confirming the intensity and polarization plane of the transmitted laser light. The position is adjusted so as to be rotated by 45 ° relative to the optical axis L.

  Thereafter, the temporary fixing adhesive 7 is cured to obtain the laminate 10. However, when the optical characteristics required for the optical isolator are low, the optical adjustment using the laser beam may not be performed, and the arrangement of the optical elements may be matched from the appearance and the temporary fixing adhesive 7 may be cured. This temporary fixing adhesive is not removed until the step shown in FIG.

  Subsequently, as shown in FIG. 1C, the strip 10 is cut in parallel to one side of the plane of the laminate 10. Next, in FIG. 1D, a plurality of strips 6 are arranged, their cut surfaces are set as upper and lower surfaces and brought into contact with each other's optical surfaces, and aligned so that the upper and lower surfaces are substantially flat. Constitute. Then, the jig 8 is pressed so as not to be separated, and the optical surfaces at both ends of the assembly 60 are masked.

In FIG. 1E, a metal multilayer film is formed on the film formation surfaces 4 of a plurality of strips 6 at once. At this time, since the tackiness of the temporarily fixing adhesive 7 and the performance of the masking material 8 do not deteriorate at high temperatures, the film forming method is a low temperature sputtering method in which the processing temperature does not exceed the glass transition point of the temporarily bonding adhesive 7 or Wet plating is desirable. Polymer materials are composed of dense crystalline parts and sparse amorphous parts where molecules gather, and the low thermal mobility of the amorphous parts is called the glass state, and the temperature at which it becomes rubbery. the called glass transition point T _g, and the temperature at which the fluidity is damaged more crystalline portion in a high temperature range of the melting point T _m. The temporary fixing adhesive 7 used in the present invention is an organic resin adhesive, and the masking performance starts to deteriorate at a temperature exceeding the glass transition point described above. It fails to function due to thermal destruction. Therefore, if the film forming process is performed in a temperature range not exceeding the glass transition point, the adhesion strength of the metal multilayer film 40 can be improved while maintaining the masking performance and tackiness even when the organic temporary fixing adhesive 7 is used. be able to.

  Next, in FIG. 1 (f), a plurality of block bodies 9 are cut out by cutting in parallel with the short side of the flat surface of the integrated strip 6 as indicated by the cutting line 5. Finally, in FIG. 1G, the temporarily fixing adhesive 7 is completely washed and removed and separated into the Faraday rotator 2 and the polarizers 1 and 3.

  In the optical isolator element of the present invention, as described above, optical adjustment is performed on a large substrate, and then a large number of optical isolator elements with uniform and excellent characteristics are easily produced because of the process of cutting out a large number of them. It is possible to reduce assembly man-hours and excel in mass productivity.

  In this embodiment, the configuration of an optical isolator element having two polarizers and one Faraday rotator is used. However, the present invention is not limited to this, and more polarizers and Faraday rotators are used. Even in the case of an optical isolator element, it is possible to obtain the same effect as in the above embodiment.

  FIG. 2 is a diagram for explaining the cutting from the strip 6 to the block during the manufacturing process of the present invention.

  As shown in FIGS. 1 and 2, the Faraday rotator 121 and the polarizers 131 and 141 are bonded to each other by the adhesive 7. Since the metal multilayer film 40 is formed on the film formation surface 4 (joint surface) of the strip 6 at a time, it is not necessary to mask each optical element separately. The strip 6 is cut into a plurality of block bodies 9 by a cutting line indicated by 5 in FIG.

  FIG. 3 is a diagram showing the protrusion width of the metal multilayer film. In the present invention, as described above, the film is formed only on the film formation surface 4 (joint surface). However, the metal multilayer film 40 is not completely formed on the film formation surface 4, and some errors may occur. Is formed only on the film formation surface 4 (joint surface). For example, in the polarizer 13, the metal multilayer film 40 is provided on one surface of the cut surface, but the amount of protrusion to the optical surface also exists with a width W. If this protrusion amount is suppressed to 0.05 mm or less, the effective aperture diameter D can be secured even if the size of one optical element is reduced and the number of cuts from a large substrate is increased.

  That is, in the surface mount optical isolator built in the semiconductor laser package, it is necessary to secure an effective aperture diameter D of 0.8 to 0.9 mm, and the size of the optical element to be used is made as small as possible to cut from a large substrate. It is desirable in terms of cost that the above-mentioned effective opening diameter D can be obtained after increasing the number of removals. Considering that the tolerance of the cut-out dimension is ± 0.02 mm and that the solder bulge is about 0.03 mm, if the protrusion width of the metal multilayer film is 0.05 mm or less, the optical element size is 1 mm square. The above effective opening diameter can be achieved.

  The outer dimensions of the strips 6 have a tolerance of ± 0.02 mm, a plurality of strips 6 are arranged, the cut surfaces are the top and bottom surfaces, and the optical surfaces are in contact with each other, and the top and bottom surfaces are substantially flat. An assembly is formed by arranging so that Then, the jig 8 is pressed so as not to be separated, and further masks the optical surfaces at both ends of the assembly 60, but sandwiches a glass member or the like so as not to damage the optical surfaces at both ends. You may fix with the jig | tool 8. FIG. In this way, by pressing the masking effect of the temporary fixing adhesive and the optical surfaces of the strips 6 together, the protruding amount of the metal multilayer film can be suppressed to 0.05 mm or less.

  As an example of the present invention, the optical isolator shown in FIG. 1 was prototyped and subjected to characteristic evaluation and reliability test. Each component and configuration will be described below.

  A polar core (product name) manufactured by Corning was used for the polarizer substrate, and the size was 10 mm square and the thickness was 0.2 mm. Further, the Faraday rotator substrate was a bismuth-substituted garnet and had a size of 10 mm square and a thickness of 0.4 mm. In this case, the polarization rotation angle in the saturation magnetic field strength was 45 degrees. Both are elements that operate with respect to light having a wavelength of 1.55 μm, and antireflection films for air (n = 1) are applied to both surfaces of the polarizer and the Faraday rotator.

  First, a Faraday rotator substrate was sandwiched between two polarizer substrates, and after optical adjustment, the optical surfaces were bonded to each other with an adhesive for temporary fixing. Adel KM series was used as a temporary fixing adhesive.

  Cut this layered laminate into strips, align the cut surfaces into strips, align them, press them with jigs from both ends, and fix and mask them. A continuous metallization process of Ti—Pt—Au was performed at once. At this time, the sputtering temperature is 120 ° C. or lower, which is lower than the glass transition point of the temporarily fixing adhesive, and when the protrusion width W is measured after the film formation, the protrusion width W to the optical surface of the metal multilayer film is 0 at the maximum. .38 μm.

  Next, the strip-shaped optical elements were cut into block-shaped pieces while being aligned. The block-shaped optical element was separated into each element by being immersed in a one-to-one aqueous solution of water and alcohol at 40 ° C. for 1 hour.

Zirconia ceramics is used as the material for the alignment substrate, and a Ti—Pt—Au multilayer metal film is formed on the surface thereof in advance. The thermal expansion coefficient of zirconia is 10.5 × 10 ⁻⁶ / ° C., which is almost the same as the thermal expansion coefficient of the Faraday rotator, and the Faraday rotator is not affected by the stress from the substrate.

  The size of the alignment substrate was a width W = 3 mm, a length D = 1.5 mm, and a thickness t = 0.25 mm. An Au / 20Sn foil brazing material having a width W = 1.0 mm and a length D = 2.5 mm was placed almost at the center of the substrate. Two magnets having a substantially rectangular parallelepiped shape having a width W = 0.8 mm, a length D = 1.4 mm, and a thickness t = 1.4 mm were used.

  Next, as shown in FIG. 5, the optical isolator element was disposed on the substrate, and the magnet was placed on the substrate, and the optical element and the magnet were fixed to the substrate by heating and melting at 300 ° C. in a nitrogen atmosphere. At this stage, the adhesive for temporary fixing has already been removed, and Au / 20Sn or Au / 12Ge that melts in a temperature range exceeding 300 ° C. can be used.

  In this manner, 50 optical isolators were manufactured and the characteristics were measured. As a result, it was confirmed that all the optical isolators had good and uniform characteristics with an insertion loss of 0.3 dB or less and an isolation of 35 dB or more. While the average value of the isolation characteristic was as low as 31 dB when the prototype was manufactured with the conventional configuration, the average value was as high as 42 dB with the configuration according to the present invention, and good results were obtained.

  Next, the reliability of the produced optical isolator was evaluated.

  The tests were conducted vibration test, impact test, temperature cycle test, high temperature holding test, low temperature holding test, high temperature high humidity test shown in Telcordia 1221. In all tests, the amount of change in insertion loss is ± 0.2 dB or less, A good result was obtained in which the amount of change in isolation was ± 3 dB or less.

  The above trial manufacture eliminates the need for optical adjustment at each assembly, stabilizes optical characteristics, facilitates assembly, reduces man-hours, and eliminates optical element dropout, cracks, and deterioration of characteristics. An optical isolator can be provided.

(A)-(f) is a figure explaining the manufacturing process of the optical isolator of this invention. It is a figure explaining cut | disconnecting from a strip to a block body in the manufacturing process of this invention. It is a figure which shows the protrusion width | variety of a metal multilayer film. It is a figure which shows the manufacturing procedure of the conventional optical isolator element. It is a figure which shows the conventional optical isolator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 3 Polarizer board | substrate 2 Faraday rotator board | substrate 4 Film-forming surface 40 Metal multilayer film 5 Cutting line 6 Strip body 60 Aggregate 11 Optical isolator element 7 Adhesive 8 Jig 9 Block body 10 Laminate body

Claims (3)

An optical isolator element formed by bonding the optical surfaces of a flat-plate Faraday rotator and a polarizer to face each other on an alignment substrate, and a magnet for applying a magnetic field to the Faraday rotator of the optical isolator element via a bonding material. In the optical isolator formed by fixing, a metal multilayer film is formed only on the joint surface of the optical isolator element. An optical isolator manufacturing method comprising at least the following steps (1) to (6):
(1) Step of forming a laminated body on both surfaces of a large-sized Faraday rotator substrate having a quadrangular plane using a temporary fixing adhesive on both sides of the large-sized polarizer substrate having a quadrangular plane. Step (3) to make strips cut parallel to one side of the plane Abutting the optical surfaces of the plurality of strips to make an assembly aligned with the cut surfaces up and down, and at least at both ends of the assembly Parallel to the short side of the plane of the strip after the steps (5) and (4) of forming the metal multilayer film only on the cut surface of the aggregate after the steps (4) and (3) of masking the optical surface (6) The step of cleaning the block body and removing the adhesive for temporary bonding 3. The method of manufacturing an optical isolator element according to claim 2, wherein a process temperature for forming the metal multilayer film is not higher than a glass transition point of the temporary bonding adhesive.

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