JP2008191456A - Optical isolator and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical isolator whose effective diameter is extended without having to change the size of parts, and to provide a manufacturing method of the optical isolator. <P>SOLUTION: The optical isolator is provided with an almost rectangular parallelepiped-shaped optical isolator element 101 which has two polarizers 11 and 13 and one Faraday rotator 12 and is configured, in such a manner that the two polarizers 11 and 13 and the Faraday rotator 12 are stuck to each other in the light-transmitting surfaces of them and a cylindrical permanent magnet 40, which has a circular-shaped through-hole in which the optical isolator element is stored and magnetically saturates the Faraday rotator of the optical isolator element. In the optical isolator, the optical isolator element is bonded to the inner wall of the through-hole of the cylindrical permanent magnet by an adhesive 10, having a viscosity of 20-95 Pa s in uncured state at normal temperature, and a Shore hardness of A30-45 in a cured state. In the optical isolator, a holder for fixing the optical isolator element, the cylindrical permanent magnet, and the like, is dispensed with, so that manufacturing cost is reduced, products are miniaturized and the effective diameter can be extended. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical isolator incorporated in a semiconductor module used in optical communication, an optical information system, and the like, and more particularly, to an optical isolator having an effective diameter expanded from a conventional product without changing a component size and a manufacturing method thereof. Is.

  The optical isolator is generally composed of a Faraday rotator, a permanent magnet for saturating the Faraday rotator, an incident side polarizer, and an output side polarizer. As the Faraday rotator, a Faraday rotator whose thickness is adjusted so that the plane of polarization of light rotates by 45 degrees is used.

  Then, in the optical isolator, the linearly polarized light that has passed through the incident side polarizer and entered the forward direction with respect to the Faraday rotator is rotated by 45 degrees in the polarization plane of the incident linearly polarized light by passing through the Faraday rotator, The light is transmitted through the exit-side polarizer adjusted so that the amount of transmitted light is maximized at the rotational position. Therefore, it is transmitted to the next optical system as light with almost no loss.

  In addition, in the optical isolator, when there is reflected return light, the linearly polarized light that has passed through the output side polarizer is transmitted through the Faraday rotator, so that the plane of polarization is rotated by 45 degrees, thereby being orthogonal to the incident side polarizer. It becomes extinct because it becomes. In this way, the function of the optical isolator is fulfilled.

  1A and 1B show an optical isolator according to a conventional example.

  The optical isolator shown in FIGS. 1A and 1B is called a cylindrical type, and includes a disk-shaped holder 6 having a circular opening through which light passes, centered on a light transmission path, and the disk-shaped holder 6. And a substantially rectangular parallelepiped optical element (hereinafter referred to as an optical isolator element) 100 in which the incident side polarizer 1, the Faraday rotator 2, and the emission side polarizer 3 are integrated with an adhesive. The main part is composed of a cylindrical permanent magnet 4 which is bonded and fixed to a disk-shaped holder 6 and magnetically saturates the Faraday rotator 2.

  By the way, in the cylindrical optical isolator, the opening diameter of the disk-shaped holder 6 is the effective diameter of the light transmitting portion. However, in order to ensure the ease of position adjustment when mounting the optical isolator on the semiconductor module, the above-mentioned effective There is a need to expand the diameter.

  In this case, the effective diameter is expanded by increasing the opening diameter of the disk-shaped holder 6, but the bonding area between the holder 6 and the optical isolator element 100 becomes narrow, and the optical isolator element 100 is easily dropped from the holder 6. End up. In addition, when the opening diameter of the holder 6 is increased, it is necessary to increase the size of the optical isolator element 100 that occupies most of the component cost of the optical isolator, which causes a problem of increasing the cost. Further, when the size of the optical isolator element 100 is increased, it is necessary to increase the size of the magnet 4 in order to maintain the magnetic saturation of the Faraday rotator 2, and there is a problem that the external dimension of the optical isolator increases. End up.

  As a measure for expanding the effective diameter without increasing the cost or enlarging the outer dimensions of the optical isolator, a method of eliminating the holder that restricts the effective diameter is conceivable. An example of such an optical isolator is described in JP-A-4-333818.

JP-A-4-333818 discloses an optical isolator in which an optical isolator element is inserted into the through hole of a cylindrical magnet having a rectangular through hole, and the cylindrical magnet and the optical isolator element are fixed with an adhesive. It is disclosed. In the optical isolator having such a structure, since the light transmission surface of the optical isolator element is not shielded by a holder or the like, the effective diameter can be expanded without increasing the size of the optical isolator element.
JP-A-4-333818

  However, the optical isolator described in Japanese Patent Laid-Open No. 4-333818 in which a substantially rectangular parallelepiped optical isolator element is inserted into a rectangular through hole and fixed with an adhesive has the following drawbacks, and is still in practical use. The current situation is that it has not been realized.

  For example, when a substantially rectangular parallelepiped optical isolator element is inserted into a rectangular through hole in a cylindrical magnet, if the gap between the through hole and the optical isolator element is narrow, a low-viscosity adhesive is applied between the magnet and the optical isolator element. However, there is a risk that the adhesive adheres to the light transmission surface of the optical isolator element and contaminates the optical surface. In addition, when the gap between the through hole and the optical isolator element is wide, it is easy to inject adhesive, but it becomes difficult to place the optical isolator element at the center of the through hole. As a result, the center of the cylindrical magnet And the center of the optical isolator element do not coincide with each other and the effective diameter changes. Furthermore, when the hardness of the adhesive after curing is high, when the optical characteristics are evaluated after manufacturing the optical isolator, a large stress is applied to the Faraday rotator, so that the isolation, which is a characteristic that blocks the reflected return light, deteriorates by about 4 to 5 dB. There was something to do.

  The present invention has been made paying attention to such problems, and the object of the present invention is to provide an optical isolator having an effective diameter expanded from that of a conventional product without changing the component size, and this optical isolator. An object of the present invention is to provide a method capable of easily manufacturing an isolator.

That is, the invention according to claim 1
A substantially rectangular parallelepiped optical isolator element having at least two polarizers and one Faraday rotator, which are bonded together on the light transmission surface thereof, and a circular through hole in which the optical isolator element is accommodated. And an optical isolator comprising a cylindrical permanent magnet that magnetically saturates the Faraday rotator of the optical isolator element,
The optical isolator element is bonded to the inner wall of the through hole of the cylindrical permanent magnet by an adhesive having an uncured viscosity at room temperature of 20 to 95 Pa · s and a cured shore hardness of A30 to 45. ,
The invention according to claim 2
On the premise of the optical isolator according to the invention of claim 1,
A gap portion between the Faraday rotator and the inner wall of the through hole of the cylindrical permanent magnet in the optical isolator element is filled with the adhesive without any gap.

The invention according to claim 3
Based on the manufacturing method of the optical isolator according to claim 1 or 2,
The cylindrical permanent magnet is composed of the two non-magnetized first cylindrical permanent magnets and the second cylindrical permanent magnet, and the unmagnetized first cylindrical permanent magnet and the optical isolator element are in the center. A first step of accommodating the first cylindrical permanent magnet and the optical isolator element in a bonding jig placed in a state where the axes are matched and the relative position in the central axis direction is regulated;
The uncured viscosity at normal temperature is 20 to 95 Pa on both the through hole open end of the first cylindrical permanent magnet housed in the bonding jig and the outer surface of the optical isolator element adjacent to the through hole open end. s and an adhesive having a Shore hardness after curing of A30 to 45 is applied, and the opening end of the through hole of the second cylindrical permanent magnet is aligned with the opening end of the through hole of the first cylindrical permanent magnet. A second step of combining the first cylindrical permanent magnet and the second cylindrical permanent magnet with
After the adhesive is cured and the optical isolator element, the first cylindrical permanent magnet and the second cylindrical permanent magnet are integrated, the integrated assembly is removed from the bonding jig and the cylinder is removed. A third step of magnetizing the cylindrical permanent magnet.

According to the optical isolator according to claim 1 or claim 2,
When the optical isolator element is joined to the inner wall of the through hole of the cylindrical permanent magnet, an uncured adhesive having a viscosity of 20 to 95 Pa · s at normal temperature is used. When applied to an element, the adhesive does not sag due to the surface tension of the adhesive, so there is a significant risk that the adhesive will adhere to the light transmitting surface of the optical isolator element and contaminate the optical surface. It becomes possible to reduce. Moreover, since the adhesive whose Shore hardness after hardening is A30-45 is used, a big stress is not applied to a Faraday rotator and degradation of isolation is suppressed.

According to the method for manufacturing an optical isolator according to claim 3,
In the first step, a bonding jig is used in which the unmagnetized first cylindrical permanent magnet and the optical isolator element are placed in a state where their center axes coincide with each other and their relative positions in the center axis direction are restricted. Therefore, since the optical isolator element can be arranged at the center of the through hole in the cylindrical permanent magnet, it is possible to avoid the adverse effect of changing the effective diameter.

  Therefore, the optical isolator according to claim 1 or 2 can be easily manufactured.

  Hereinafter, embodiments of the present invention will be described in detail.

  First, the optical isolator according to the present invention has a first cylindrical permanent magnet 41 and a second cylindrical permanent magnet which have a circular through hole and are divided into two as shown in FIGS. 2 (A) and 2 (B). 42, a cylindrical permanent magnet 40, an incident side polarizer 11, a Faraday rotator 12, and an output side polarizer 13 are integrated with an adhesive and inserted into the through hole of the cylindrical permanent magnet 40. The optical isolator element 101 has a shape and an adhesive 10 that joins the optical isolator element 101 to the inner wall of the through hole of the cylindrical permanent magnet 40. The adhesive 10 has an uncured viscosity of 20 to 20 at room temperature. It is characterized by being comprised with the adhesive agent (for example, acrylic modified silicone resin) which is 95 Pa.s and the Shore hardness after hardening is A30-45.

  That is, in the optical isolator according to the present invention, as shown in FIG. 3C, the incident side polarizer 11, the Faraday rotator 12, and the emission side polarizer 13 can be the same as those used in the prior art. Regarding the cylindrical permanent magnet 40 for magnetically saturating the Faraday rotator 12, when an optical isolator element having the same size as that of the conventional product is used, the length is half that of the conventional size, that is, the outer diameter and inner diameter. Prepare two items with the same size and half the length of the conventional size. Even if the length of the first cylindrical permanent magnet 41 and the second cylindrical permanent magnet 42 is half as shown in FIG. 3A, the two are combined and used as shown in FIG. Therefore, the ability to magnetically saturate the Faraday rotator 12 is the same as before. The first cylindrical permanent magnet 41 and the second cylindrical permanent magnet 42 are not magnetized, and the adhesive 10 is cured to provide the optical isolator element 101, the first cylindrical permanent magnet 41, and the second cylindrical permanent magnet 41. The cylindrical permanent magnet 42 is magnetized after being integrated.

  Hereinafter, a method for manufacturing an optical isolator according to the present invention will be described.

  First, as shown in FIGS. 3D and 6A, the optical isolator element 101 is placed on the bonding jig 50. As shown in FIGS. 4 and 5, the bonding jig 50 is provided with a rectangular element mounting groove 51 so that the optical isolator element 101 can be arranged at the center of the jig, and is mounted in the next step. The ring-shaped magnet mounting groove 52 is provided so that the center axis of the first cylindrical permanent magnet 41 to be arranged can coincide with the center axis of the optical isolator element 101 and the relative position in the center axis direction is restricted. It has been.

  Next, as shown in FIGS. 3D and 6B, the first cylindrical permanent magnet 41 before magnetization is placed in the magnet placement groove 52 of the bonding jig 50, and thereafter, FIG. C) The adhesive 10 having an uncured viscosity at normal temperature of 20 to 95 Pa · s and a cured shore hardness of A30 to 45 is used as the through hole open end of the first cylindrical permanent magnet 41 as shown in FIG. Application is performed so that both the side surface of the optical isolator element 101 protruding above the portion and the open end of the through hole are connected. Here, by using an uncured adhesive having a viscosity of 20 to 95 Pa · s at room temperature, the adhesive does not flow down to the bottom of the bonding jig 50 due to the surface tension, and therefore the first cylindrical permanent It becomes possible to directly join the gap portion between the magnet 41 and the optical isolator element 101. Moreover, when the adhesive whose Shore hardness after hardening is A30-45 is used, since the stress added to an optical isolator element at the time of hardening of an adhesive agent is suppressed, the deterioration of isolation mentioned above does not arise.

  Finally, after the adhesive is applied also to the other second cylindrical permanent magnet 42, the open end of the through hole of the second cylindrical permanent magnet 42 is placed on the first cylindrical permanent magnet 41 already placed. The first cylindrical permanent magnet 41 and the second cylindrical permanent magnet 42 are combined with each other in a state of being aligned with the through hole open end, and the adhesive is cured.

  And after integrating the optical isolator element 101, the 1st cylindrical permanent magnet 41, and the 2nd cylindrical permanent magnet 42, these assemblies are removed from the said adhesion jig | tool 50, and a 1st cylindrical permanent magnet is obtained. If the cylindrical permanent magnet 40 composed of the magnet 41 and the second cylindrical permanent magnet 42 is magnetized, the optical isolator of the present invention shown in FIGS. 2A and 2B is completed.

  According to the optical isolator of the present invention, since the conventional disk-type holder is not required, it is possible to make use of the effective diameter of the light transmission part in the conventional product, and change the part size. It is possible to ensure an effective diameter of the light transmission portion larger than that of the conventional product without doing so. Furthermore, since the holder is not necessary, the cost can be reduced and the product can be downsized.

  Examples of the present invention will be specifically described below.

  An 11 mm square incident-side polarizer 11, Faraday rotator 12, and output-side polarizer 13 are bonded together with an adhesive and cut by a dicing saw, so that the optical isolator element 101 has a light transmission surface size of 1.4 mm square. (See FIG. 3C). In addition, a first cylindrical permanent magnet 41 and a second cylindrical permanent magnet 42 having a non-magnetized outer diameter of 3 mm and an inner diameter of 2 mm and a height of 1 mm were prepared (see FIG. 3A). The inner diameters of the first cylindrical permanent magnet 41 and the second cylindrical permanent magnet 42 are slightly larger than the diagonal length of the light transmission surface of the optical isolator element 101.

  First, as shown in FIG. 4, an element mounting groove 51 is provided so that the optical isolator element can be arranged at the center of the jig, and the central axis of the first cylindrical permanent magnet coincides with the central axis of the optical isolator element; A bonding jig 50 provided with a magnet mounting groove 52 is prepared so that the relative position in the central axis direction is regulated, and light is applied to the bonding jig 50 as shown in FIG. The isolator element 101 is mounted.

  After confirming that the optical isolator element 101 fits in the bonding jig 50 and that the side surface of the optical isolator element 101 is perpendicular to the bottom surface of the jig, the first cylindrical shape as shown in FIG. The permanent magnet 41 is placed on the bonding jig 50.

  After placing the optical isolator element 101 and the first cylindrical permanent magnet 41, the optical isolator element 101 is positioned at the center of the first cylindrical permanent magnet 41, and the first cylindrical permanent magnet 41 and the optical isolator element 101 are Make sure that the gaps between them are even.

  After confirmation, in the gap between the optical isolator element 101 and the first cylindrical permanent magnet 41, an adhesive (cemedine) having an uncured viscosity at room temperature of 20 to 95 Pa · s and a cured shore hardness of A30 to 45 Co., Ltd. (trade name SuperXL) is injected and the gap is completely closed with an adhesive as shown in FIG. At this time, there is a risk that the adhesive drips down and the bonding jig 50 and the optical isolator element 101 are bonded together, but the above-mentioned adhesive having an uncured viscosity of 20 to 95 Pa · s at room temperature is used. In addition, by adjusting the coating amount, the gap portion between the optical isolator element 101 and the first cylindrical permanent magnet 41 can be bonded without causing the adhesive to sag due to surface tension.

  Simultaneously with the injection of the adhesive, the adhesive is also applied to the open end of the through hole of the first cylindrical permanent magnet 41, and the other second cylindrical permanent magnet 42 is placed thereon. At this time, when the first cylindrical permanent magnet 41 and the second cylindrical permanent magnet 42 are joined together, the amount of adhesive applied to the open end of the through hole is set so that the adhesive does not protrude outward. Make small amount (see FIG. 6D).

  When the adhesive is solidified in this state, the aggregate of the integrated optical isolator element 101, the first cylindrical permanent magnet 41 and the second cylindrical permanent magnet 42 is removed from the bonding jig 50, and finally the first cylinder. An optical isolator is completed by magnetizing a cylindrical permanent magnet 40 composed of a cylindrical permanent magnet 41 and a second cylindrical permanent magnet 42.

  In the obtained optical isolator, unlike the conventional example, it is not necessary to bond the optical isolator element to the holder. For this reason, it becomes possible to make the holder unnecessary, and it is possible to effectively use the light transmission surface of the optical isolator element. Moreover, in the optical characteristic, since the said adhesive agent which has the softness | flexibility whose Shore hardness after hardening is A30-45 is used, the deterioration of isolation can be prevented.

  When an optical isolator element having a light transmission surface size of 1.4 mm square is used, an effective diameter of 1.2 mmφ or more is obtained even if chipping occurs in the peripheral portion of the optical isolator element by cutting with a dicing saw. It can be secured.

  On the other hand, in the optical isolator according to the conventional example, since it is necessary to provide the optical isolator element with a bonding margin to the holder, the effective diameter remains at most 1.0 mmφ.

  According to the optical isolator of the present invention, the effective diameter is expanded from the conventional product without changing the component size, and the holder is omitted, so that the manufacturing cost can be reduced and the product can be downsized. It has industrial applicability to be incorporated in semiconductor modules used in systems and the like.

FIG. 1A is a front view of an optical isolator according to a conventional example, and FIG. 1B is a cross-sectional view taken along the II plane of FIG. 2A is a front view of the optical isolator according to the present invention, and FIG. 2B is a cross-sectional view taken along the line II-II in FIG. 3A is a schematic perspective view of the first cylindrical permanent magnet and the second cylindrical permanent magnet incorporated in the optical isolator according to the present invention, and FIG. 3B is the first cylindrical permanent magnet and the second cylindrical shape. FIG. 3C is a schematic perspective view of an optical isolator element incorporated in the optical isolator according to the present invention, and FIG. 3D is a schematic perspective view of a cylindrical permanent magnet constructed by combining permanent magnets. The schematic perspective view of the 1st cylindrical permanent magnet and optical isolator element which were mounted in the adhesion jig | tool. The schematic perspective view of the adhesion jig applied with the manufacturing method of the present invention. The schematic perspective view of the 1st cylindrical permanent magnet and optical isolator element which were mounted in the adhesion jig | tool shown in FIG. 6 (A) to 6 (D) are process explanatory views of a method of manufacturing an optical isolator according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Adhesive 11 Polarizer 12 Faraday rotator 13 Polarizer 40 Cylindrical permanent magnet 41 1st cylindrical permanent magnet 42 2nd cylindrical permanent magnet 101 Optical isolator element

Claims (3)

A substantially rectangular parallelepiped optical isolator element having at least two polarizers and one Faraday rotator, which are bonded together on the light transmission surface thereof, and a circular through hole in which the optical isolator element is accommodated. And an optical isolator comprising a cylindrical permanent magnet that magnetically saturates the Faraday rotator of the optical isolator element,
The optical isolator element is bonded to the inner wall of the through hole of the cylindrical permanent magnet by an adhesive having an uncured viscosity at room temperature of 20 to 95 Pa · s and a cured shore hardness of A30 to 45. Optical isolator.   The optical isolator according to claim 1, wherein a gap between the Faraday rotator and the inner wall of the through hole of the cylindrical permanent magnet in the optical isolator element is filled with the adhesive without any gap. In the manufacturing method of the optical isolator according to claim 1 or 2,
The cylindrical permanent magnet is composed of the two non-magnetized first cylindrical permanent magnets and the second cylindrical permanent magnet, and the unmagnetized first cylindrical permanent magnet and the optical isolator element are in the center. A first step of accommodating the first cylindrical permanent magnet and the optical isolator element in an adhesive jig placed in a state where the axes are matched and the relative position in the central axis direction is regulated;
The uncured viscosity at normal temperature is 20 to 95 Pa on both the through hole open end of the first cylindrical permanent magnet housed in the bonding jig and the outer surface of the optical isolator element adjacent to the through hole open end. s and an adhesive having a Shore hardness after curing of A30 to 45 is applied, and the opening end of the through hole of the second cylindrical permanent magnet is aligned with the opening end of the through hole of the first cylindrical permanent magnet. A second step of combining the first cylindrical permanent magnet and the second cylindrical permanent magnet with
After the adhesive is cured and the optical isolator element, the first cylindrical permanent magnet and the second cylindrical permanent magnet are integrated, the integrated assembly is removed from the bonding jig and the cylinder is removed. A third step of magnetizing a cylindrical permanent magnet,
An optical isolator manufacturing method comprising:

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