JP2849655B2 - Manufacturing method of optical isolator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical isolator used for preventing noise due to return light of a semiconductor laser, and particularly to a method for cleaning an optical element which is a main component. Things.

[Conventional technology]

Conventionally, as a method of manufacturing an optical isolator, a polarizer (rutile plate) and an analyzer (rutile plate) are provided on both sides in the optical axis direction of a garnet, which is a Faraday rotator, and the angle between these optical axes is determined by the Faraday rotation angle. And fix it with thermosetting optical adhesive, then use a cutting machine
After cutting into small elements of about × 1.7 mm, the optical surfaces and side surfaces of each of the polarizer and the analyzer are observed with a stereoscopic microscope using a cotton swab moistened with a solvent (acetone, ethyl alcohol, etc.). After gently wiping and cleaning, and after inspecting the appearance of chips, cut layers of adhesive, or flaws due to cutting, good products have the same magnetic field direction as the magnetic field direction of the magnetic field generating element such as a magnet. After adjusting the arrangement of the magnetic field generating element and the optical element, the optical element and the magnetic field generating element are fixed with a thermosetting adhesive, the characteristics are measured, and the optical surfaces of the polarizer and the analyzer are further provided as a final step. It has been used after observing a flaw, dirt, or contamination of a foreign substance into the adhesive layer by a stereoscopic microscope or the like. However, in the above-described conventional method, the cleaning operation of the optical element immediately after cutting is performed manually by using a cotton swab or the like moistened with a solvent, so that the optical element stays at the chipping portion of the optical surface ridge line portion generated at the time of cutting. The cutting waste of the optical material and adhesive is wound up on the optical surface by a cotton swab, causing scratches and dirt, and scattering the incident light.
There is a drawback that the performance as an optical isolator is reduced and the optical isolator cannot be used, and the yield is reduced. In addition, the workability was very poor because each sample was cleaned while being observed with a stereoscopic microscope.

On the other hand, if the optical element is cleaned as it is after cutting by ultrasonic cleaning, pure water and solvent will permeate the adhesive at the bonding part, and the polarizer, analyzer and garnet will be disassembled separately, The adhesion layer is significantly deteriorated due to the generation of stains, and the reliability as an optical isolator has been reduced.

[Problems to be solved by the invention]

The present invention has been proposed in order to eliminate the above-mentioned drawbacks, and it is intended to suppress the generation of scratches and dirt in the cleaning operation of the element after cutting, to improve the yield, and to provide a method of manufacturing an optical isolator with good workability. It is intended to provide.

B. Configuration of the Invention [Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention uses an ultrasonic cleaning method as a method for strongly washing out cutting debris staying in a chipping portion and the like, and has already been optically combined. In order to prevent the adhesive layer from deteriorating, the exposed portion of the adhesive layer of each cut optical element is protected by a resin layer (for example, a thermosetting resin layer), and then the optical element is cleaned by an optical element cleaning method. This is a method for manufacturing an optical isolator using an element.

That is, the present invention is to fix the polarizer and the analyzer on both sides of the Faraday rotator that rotates the polarization plane of light by 45 degrees using a thermosetting optical adhesive, and then bond the adhesive to a desired size. In the manufacturing process of an optical isolator in which a magnetic field generating element is arranged and fixed so that a magnetic field is applied around the optical element in the same direction as the incident direction of light, the optical element A light characterized by using an optical element cleaned by an ultrasonic cleaning method after covering the side surface adhesive portion of the optical element immediately after cutting the bonded body of the Faraday rotator, the polarizer and the analyzer with a resin layer and protecting it. This is a method for manufacturing an isolator.

[Action]

In order not to deteriorate the adhesive layer of the thermosetting optical adhesive to which the optical isolator element is adhered, a protective layer is provided around the adhesive layer with a resin, and can be automated by cleaning with an ultrasonic cleaning power, and the flaw can be obtained. Cleaning work with a high yield can be performed while suppressing the occurrence of cracks.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a view showing main manufacturing steps of an optical isolator according to an embodiment of the present invention, and FIG. 2 is an adhesion of a Faraday rotator, a polarizer and an analyzer for an optical element used in the embodiment of the present invention. FIG. 3 is an explanatory view for explaining the manufacturing process of FIG. 3, and FIG. 3 is an explanatory view for explaining the optical axis alignment of the optical element bonding body shown in FIG.
FIG. 4 is an external perspective view showing a cut state of the adhesive for an optical element, FIG. 5 is an external perspective view showing the optical element immediately after cutting, and FIG. 6 is an optical element immediately after cutting in FIG. FIG. 7 is a perspective view of an optical element protected by a resin layer so as to cover the adhesive layer of FIG. 7, and FIG. 7 is an explanatory diagram for explaining the assembly of a magnet as a magnetic field element to the cleaned optical element.

The optical isolator shown in this embodiment is manufactured by the main steps shown in FIG. 1 of bonding and fixing, bonding of optical axes, cutting of an optical element, protection of an adhesive layer, ultrasonic cleaning, and mounting and fixing of a magnet.

First, as shown in FIG. 2, the Faraday rotator 2 for 1.31 μm (Bi-substituted Gd iron garnet: 11 × 11 × 0.35 mm), which rotates the polarization plane of light by 45 degrees, and the polarizer 1 are sufficiently bonded. And then cured with a thermosetting optical adhesive at 65 ° C for 12 hours. Similarly, the analyzer 3 was semi-cured at 65 ° C for 17 minutes on the opposite side of the Faraday rotator 2 to the polarizer bonding surface. Then, as shown in FIG. 3, the magnets 4 for axial alignment are set outside the polarizer 11 and the analyzer 12 on both sides of the adhesive body 10, and the Faraday rotation angle of the Faraday rotator 2 and the The optical axis is aligned, the laser diode (LD) light source 5 is incident from the analyzer 12 side, and the polarizer 11 is slightly rotated while watching the image reflected on the ITV camera 6 to perform the optical axis alignment. Thereafter, the adhesive was cured at 65 ° C. × 12 hours to fix the adhesive body 10 to prepare it. Then, the adhesive 10 is attached to the cutting jig with an ultraviolet curing tape, and cut into optical elements 8 each having a size of about 1.7 mm × about 1.7 mm as shown in FIG. 4 UV rays from behind
Then, the optical element 8 as shown in FIG. 5 is taken out one by one with tweezers, and the exposed portion of the side adhesive layer of the element is made of a thermosetting adhesive resin layer as shown in FIG.
Was protected around the Faraday rotator 2 by a resin layer 9 and the adhesive was cured at 65 ° C. × 12 hours. Further, ultrasonic cleaning was performed for 3 minutes using ethyl alcohol at 20 ° C. for 3 minutes in an ultrasonic cleaning device having an oscillation frequency of 45 KHz and a high frequency output of 80 W to remove dust such as cutting debris from the chipping portion of the rutile ridge line generated during cutting. However, scars were hardly generated by the cleaning operation, the adhesive on the side adhesive layer remained thinly, and no permeation of ethyl alcohol into the adhesive layer was observed. Thereafter, as shown in FIG. 7, a magnet 71 was bonded and fixed to the center of the optical element 10 to measure the characteristics, and a final inspection was performed. As a result, the isolation was 35.7 dB and the insertion loss was 0.35 dB (at 25.5 ° C.). Normal characteristics were obtained, and a good product was also produced in appearance. As a result of manufacturing 10 lots by the above-described method, a high yield of 90% with an average yield of 5% was obtained with a defect rate of 5% and other defect rates of 5%. The work time per unit was greatly reduced, and the efficiency was greatly improved to about 10 seconds / unit.

(Comparative Example) The cleaning of the optical element 8 immediately after cutting was not performed using ultrasonic cleaning, but was performed using a cotton swab and ethyl alcohol one by one. Rate is 50%, other defective rate is 5% and average yield is
The yield was as low as 45%, and the cleaning work time after cutting was about 3 minutes per piece, which was extremely poor in workability and efficiency.

(Comparative Example 2) When the optical element 8 immediately after cutting was assembled by cleaning the optical element by ultrasonic cleaning under the same conditions as in the example with the adhesive layer of the optical element 8 kept cut, 90% of the whole was peeled off from the adhesive part And could not be used due to dirt on the bonded part. Also, the reliability of the remaining 10% of non-defective products is low,
It was in a state where it could not be used.

C. Effects of the Invention As described above, according to the present invention, in the method for manufacturing an optical isolator, cleaning of the element after cutting is performed by ultrasonic cleaning after protecting the adhesive layer with a thermosetting resin. By doing so, the adhesive is not degraded, and it can be performed precisely, so there is almost no scratching, yield is greatly improved, work in a short time is possible, efficiency is greatly improved, and cost reduction is also achieved. connected.

[Brief description of the drawings]

FIG. 1 is a view showing main manufacturing steps of an optical isolator according to an embodiment of the present invention. FIG. 2 is an explanatory view for explaining a manufacturing process of an adhesive for an optical element used in an embodiment of the present invention. FIG. 3 is an explanatory view for explaining optical axis alignment of the optical element bonding body shown in FIG. 2; FIG. 4 is an external perspective view showing a cut state of an adhesive for an optical element. FIG. 5 is an external perspective view showing the optical element immediately after cutting. FIG. 6 is a perspective view of the optical element protected with a resin layer so as to cover the adhesive layer of the optical element immediately after cutting in FIG. FIG. 7 is an explanatory view for explaining assembly of a magnet as a magnetic field element to the cleaned optical element. 1 ... polarizer, 2 ... Faraday rotator, 3 ... analyzer, 4 ... magnet for alignment, 5 ... laser diode (LD) light source, 6 ... ITV camera, 7,71 ... magnet, 8 ... optical element, 9 ... resin layer, 10 ... adhesive, 11
Polarizers (glued), 12 ... analyzers (glued).

Claims (1)

(57) [Claims] 1. A thermosetting optical adhesive is used to bond and fix a polarizer and an analyzer to both sides of a Faraday rotator for rotating the plane of polarization of light by 45 degrees. In the manufacturing process of an optical isolator in which a magnetic field generating element is arranged and fixed so that a magnetic field is applied in the same direction as the incident direction of light around the optical element by cutting the element into an optical element,
As the above-mentioned optical element, an optical element cleaned by an ultrasonic cleaning method after covering and protecting the side surface adhesive portion of the optical element immediately after cutting the bonded body of the Faraday rotator, the polarizer and the analyzer with a resin layer is used. The manufacturing method of the optical isolator characterized by the above.