JPH0555121U - Optical isolator - Google Patents

Abstract

(57) [Abstract] [Purpose] An object is to provide an optical isolator that is extremely easy to assemble. [Structure] Faraday rotator 105 in a cylindrical magnet 106
And a guide pipe 103 to which the Faraday rotator 105 and the polarizer 102 are respectively adhered and fixed, and an optical isolator in which a polarizer 102 and an analyzer 202 are arranged on both sides of the Faraday rotator. A first holder 101 holding a guide pipe 103 facing the child 102 and a second holder 20 holding an analyzer 202.
1 and the first holder 101 has a guide pipe 10
3 is inserted into the opening of one end of the magnet and is fixed to the magnet. In the second holder 201, the analyzer 202 has the polarization plane around the optical axis with respect to the polarizer 102 on the opening side of the other end of the magnet. It is an optical isolator that is fixed to a magnet by tilting at 45 °.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an optical isolator used in an optical communication system or the like.

[0002]

[Prior Art]

 The basic structure of the optical isolator is that the polarization planes of the polarizer and the analyzer are arranged at an angle of 45 degrees to each other, and a Faraday rotator having a thickness that gives a Faraday rotation angle of 45 degrees is placed between them, and the Faraday rotator is used. Is formed by placing a permanent magnet sufficient for saturation magnetization outside, for example, an absorption type polarizer, a Faraday rotator made of YIG (yttrium-iron-garnet) crystal, an absorption type For example, an analyzer using a polarizer is housed and fixed in this order in a cylindrical magnet.

[0003]

[Problems to be Solved by the Invention]

 However, conventional optical isolators have extremely poor workability in that they position the Faraday rotator, polarizer, and analyzer within a small magnet, and then adjust the angle of the polarization plane to fix them. ..

In view of the above problems, an object of the present invention is to provide an optical isolator that is easy to assemble.

[0005]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention provides a Faraday rotator for rotating a polarization plane of light passing through a magnet by 45 ° in an magnet having an opening penetrating from one end to the other end, and a light incident on the Faraday rotator. A pair of optical elements that regulate the angle of the plane of polarization of the Faraday rotator are inserted between them, and the planes of polarization are held with the planes of polarization inclined at 45 ° to each other to allow the forward light to pass. Also, in the optical isolator for removing light in the opposite direction, a pipe having a length approximately half that of the magnet and having an outer diameter slightly smaller than the diameter of the opening and having the Faraday rotator on the inner surfaces of both ends. And a guide pipe in which one of the optical elements is held, and the guide pipe having an opening and holding the Faraday rotator and one of the optical elements, and the optical element is held in the forward direction. First One holder and a second holder having an opening and holding the other optical element, the first holder inserting the guide pipe from one end of the opening of the magnet. The second optical element is fixed to the magnet by tilting the polarization plane of the other optical element with respect to the one optical element at an angle of 45 ° around the optical axis at the other end side of the opening of the magnet. It is a fixed optical isolator.

[0006]

【Example】

 An embodiment of the present invention will be described below with reference to FIG. The optical isolator of one embodiment of the present invention is assembled as follows. First, the polarizer 102 and the guide pipe 103 are bonded and fixed to the opening of the first holder 101, the spacer pipe 104 is inserted into the guide pipe 103, and the Faraday rotator 105 is further inserted to rotate the Faraday. Fix the child and the guide pipe. The first holder 101 and the polarizer 102 are adhered to each other by applying an adhesive to the corners of the polarizer 102 so that the adhesive does not stick out inside the end face of the polarizer and reduce the effective aperture diameter. Also, when bonding the guide pipe 103 to the polarizer 102 and the Faraday rotator 105, the adhesive is applied to the corners so that the adhesive does not run out to the inside of each end face and reduce the effective opening diameter. Adhesively fixed to the guide pipe 103 at the side surface.

The spacer pipe 104 has an inner diameter larger than the opening of the holder 101 in order not to reduce the effective opening diameter of the optical isolator, and an outer diameter smaller than the inner diameter of the guide pipe so that it can be inserted into the guide pipe 103. To do. When the Faraday rotator 105 is inserted into the guide pipe 103 and held in a position where it comes into contact with the spacer pipe, and the Faraday rotator 105 is inserted and fixed in the cylindrical magnet 106, the length of the Faraday rotator 105 is increased. The length is set so as to be located at the center of 106.

The guide pipe 103 has an inner diameter larger than the outer diameter of the polarizer 102, the Faraday rotator 105, and the spacer pipe 104 so that they can be easily inserted, and the outer diameter of the guide pipe 103 can be easily inserted into the cylindrical magnet 106. Be smaller than the inner diameter of the magnet. The length should be such that the Faraday rotator 105 is inserted and is in contact with the spacer pipe, and about half the thickness of the Faraday rotator comes out from the tip of the guide pipe. The amount of adhesive applied to the Faraday rotator is reduced to prevent the adhesive from squeezing out.

After the Faraday rotator 105 and the guide pipe 103 are bonded, the guide pipe 103 is inserted into the cylindrical magnet 106, the cylindrical magnet 106 and the first holder 101 are bonded and fixed, and the cylinder 107 is fixed to the case 107. The magnet 106 is inserted and the case and the first holder are bonded and fixed to form a first assembly.

Next, the analyzer 202 is bonded and fixed to the opening of the second holder 201 in the same manner as the above-described bonding method of the polarizer 102, and this is used as a second assembly.

When the first assembly and the second assembly are completed, the adhesive is applied to the second holder 201 and inserted into the first assembly, and the second assembly is rotated before the adhesive is hardened. Then, the optical isolator is completed by bonding and fixing it to the polarizer 102 at a position where the polarization plane of the analyzer 202 has an optimum rotation angle. At this time, the angle of the polarization plane is adjusted by rotating the first assembly while allowing linearly polarized light to enter the first assembly from the Faraday rotator 105 side, and at this time, the optical power emitted from the polarizer 102 is maximum. The rotation is stopped at the position, and then the second assembly coated with the adhesive is inserted into the first assembly and rotated, and the linearly polarized light incident from the analyzer 202 is emitted from the polarizer 102. At this time, the rotation is stopped at the position where the optical power becomes the minimum, and the adhesive is hardened and fixed.

In the above embodiment, the polarizer and the Faraday rotator are attached to the guide pipe and held in the first holder, but the analyzer and the Faraday rotator are placed in the guide pipe. It may be adhesively fixed and held in a holder.

Further, although the guide pipe and the spacer pipe are used respectively, a pipe in which the guide pipe and the spacer pipe are integrated may be used. The advantage of using the spacer pipe is that the polarizer and the Faraday rotator are positioned by contacting the spacer pipe in the guide pipe, so not only is positioning and fixation easy, but also the parallelism between them. Also has the effect of improving the optical characteristics.

[0014]

[Effect of the device]

 As described above, according to the present invention, the position of the polarizer, the Faraday rotator, and the analyzer in the magnet can be easily adjusted, and the angle of the polarization plane can be easily adjusted, so that the assembling work becomes extremely easy.

[Brief description of drawings]

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

[Explanation of symbols]

 101 First Holder 102 Polarizer 103 Guide Pipe 104 Spacer Pipe 105 Faraday Rotor 106 Cylindrical Magnet 107 Case 201 Second Holder 202 Analyzer

Claims (1)

[Scope of utility model registration request] 1. A Faraday rotator for rotating a polarization plane of light passing through a magnet having an opening penetrating from one end to the other end by 45 °, and an angle of a polarization plane of light incident on the Faraday rotator is regulated. A pair of optical elements insert a Faraday rotator between them and hold them with their polarization planes tilted by 45 ° with respect to the optical axis so that light in the forward direction passes and light in the reverse direction is removed. In optical isolators,
A guide pipe that is approximately half the length of the magnet and has an outer diameter slightly smaller than the diameter of the opening, and the Faraday rotator and one optical element are respectively held on the inner surfaces of both ends. , A first holder having an opening portion in which the guide pipe holds the Faraday rotator and one of the optical elements, and the optical element is held at a front position; A second holder holding an optical element, wherein the first holder is fixed to the magnet by inserting the guide pipe from one end of the opening of the magnet, and the second holder is the other optical member. An optical isolator, wherein the element is fixed to the magnet at the other end side of the opening of the magnet with its polarization plane tilted by 45 ° around the optical axis with respect to the one optical element.