JP2013213980A - Optical circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress loss arising from a groove provided so as to cross a plurality of optical waveguides on a substrate in an optical circuit provided with the optical waveguides.SOLUTION: An optical circuit 200 comprises: a first optical waveguide 211 and a second optical waveguide 212 that are provided on a substrate 201; and a groove 220 that crosses the first optical waveguide 211 and the second optical waveguide 212. In the groove 220, for example, an insertion member 231 such as a half-wavelength plate and the like is inserted on an optical path of the first optical waveguide 211. Further, on an optical path of the second optical waveguide 212, a covered member 232 is arranged on the groove 220 so as to cover the groove 220. An adhesive 240 is filled in the groove 220 and the insertion member 231 is fixed. On the second optical waveguide 212 into which the insertion member 231 is not inserted, by arranging the covered member 232, the adhesive 240 is raised by surface tension, an occurence of an air part on the optical path of the second optical waveguide 212 can be prevented, and thus, an increase in loss of an optical signal is prevented.

Description

  The present invention relates to an optical circuit, and more particularly to an optical circuit in which a plurality of optical waveguides are provided on a substrate.

  The use of polarization-multiplexed optical signals is progressing toward large-capacity optical communications. With the practical application of the polarization multiplexing optical communication system, the device for handling the polarization has been put into practical use. In such a device, it may be necessary to perform polarization conversion on only some of the optical waveguides that travel in parallel in the optical circuit.

  Conventionally, in such a case, a groove is formed only in an optical waveguide that requires polarization conversion, and a half-wave plate is inserted therein and fixed with an adhesive.

  In addition to polarization conversion, an insertion member such as a wave plate may be inserted into a groove formed in the optical waveguide, and examples thereof include wavelength filtering in which a dielectric multilayer film plate is inserted (see Patent Document 1).

Japanese Patent Laid-Open No. 10-282350

  However, conventionally, in many layouts, grooves are also formed in optical waveguides into which wave plates or the like are not inserted, but the adhesive concentrates on wave plates or the like that are inserted in close proximity due to surface tension. In addition, there is a problem that an air portion is generated on the optical path without being sufficiently filled with an adhesive for fixing the wavelength plate, and loss occurs (see FIG. 1). In addition, the adhesive may be scraped off during the cleaning process of the manufactured optical circuit, and an air portion may be generated.

  The present invention has been made in view of such problems, and the object thereof is due to a groove provided so as to intersect the optical waveguide in an optical circuit in which a plurality of optical waveguides are provided on a substrate. It is in suppressing the loss.

  In order to achieve such an object, according to a first aspect of the present invention, a first optical waveguide and a second optical waveguide provided on a substrate, and the first optical waveguide and the second optical waveguide are provided. A groove intersecting the waveguide, an insertion member inserted into the groove on the optical path of the first optical waveguide, and a covering member arranged to cover the groove on the optical path of the second optical waveguide; An optical circuit comprising an adhesive filled in the groove.

  According to a second aspect of the present invention, in the first aspect, the covering member includes a first portion that covers the groove and a second portion that contacts the side surface of the substrate. And

  In addition, according to a third aspect of the present invention, in the first aspect, the covering member includes a first portion that covers the groove, and a protruding portion that protrudes toward the inside of the groove. Features.

  According to a fourth aspect of the present invention, in the first aspect, the covering member has a columnar shape and is disposed along the direction of the groove.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the adhesive is a translucent UV curable adhesive.

  According to the present invention, in the second optical waveguide in which the insertion member is not inserted, by arranging the covering member, the adhesive is lifted by the surface tension, and an air portion is generated on the optical path of the second optical waveguide. This prevents the occurrence of an increase in optical signal loss. At the same time, it is possible to prevent the adhesive from being scraped off in the cleaning step.

It is a figure which shows the conventional optical circuit. It is a figure which shows the optical circuit which concerns on 1st Embodiment. It is a figure which shows the modification of the optical circuit which concerns on 1st Embodiment. It is a figure which shows the modification of the optical circuit which concerns on 1st Embodiment. It is a figure which shows the modification of the optical circuit which concerns on 1st Embodiment.

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

(First embodiment)
FIG. 2 shows an optical circuit according to the first embodiment. The optical circuit 200 includes a first optical waveguide 211 and a second optical waveguide 212 provided on the substrate 201, and a groove 220 that intersects with the first optical waveguide 211 and the second optical waveguide 212. An insertion member 231 such as a half-wave plate is inserted into the groove 220 on the optical path of the first optical waveguide 211. In addition, on the optical path of the second optical waveguide 212, the covering member 232 is disposed on the groove 220 so as to cover the groove 220. The adhesive 240 is filled in the groove 220, and the insertion member 231 is fixed.

  By disposing the covering member 232 in the second optical waveguide 212 in which the insertion member 231 is not inserted, the adhesive 240 is lifted by the surface tension, and an air portion is generated on the optical path of the second optical waveguide 212. This can prevent the occurrence of an increase in optical signal loss.

  In the description with reference to FIG. 2, the number of the optical waveguides provided on the substrate 201 is two, but the number of the optical waveguides is not particularly limited other than two. Further, the number of the insertion members 231 and the number of the covering members 232 are not particularly limited as long as the total number of optical waveguides is 1 or more and less than the number of optical waveguides. In other words, it is sufficient that the insertion member 231 is inserted or the covering member 232 is disposed in all the optical waveguides intersecting the groove 220.

  Further, the insertion member 231 can be composed of a polyimide plate in the case of a half-wave plate and a dielectric multilayer film in the case of an optical filter.

  The covering member 232 can be formed of, for example, a resin molded part, but it is desirable to use a material that matches the thermal expansion coefficient of the material of the substrate 201 or the optical waveguides 211 and 212 from the viewpoint of reliability. In general, the material of the substrate or the optical waveguide includes silicon, quartz, lithium niobate, epoxy resin, acrylic resin, polyimide resin, and silicon resin.

  The adhesive 240 is required to be translucent because it exists on the optical path, and can be, for example, a UV curable adhesive or a thermosetting adhesive.

(Modification of the first embodiment)
The modified embodiment will be described with reference to FIGS. In any case, the covering member 232 is the same as the first embodiment except that the covering member 232 is different from the first embodiment described with reference to FIG.

  In the form of FIG. 3, the covering member 232 includes a second portion 232 </ b> B that contacts the side surface of the substrate 201 in addition to the first portion 232 </ b> A that covers the groove 220. The presence of the second portion 232B can increase the positioning accuracy of the covering member 232.

  In the form of FIG. 4, the covering member 232 includes a protruding portion 232 </ b> C that protrudes toward the inside of the groove 220 in addition to the first portion 232 </ b> A that covers the groove 220. Due to the presence of the protruding portion 232C, it is possible to prevent an air portion from being generated on the optical path of the second optical waveguide 212 even when the flow rate of the adhesive 240 is smaller than a predetermined value. Moreover, the positioning accuracy can be increased.

  In the form of FIG. 5, the covering member 232 is cylindrical. Since the cylindrical covering member 232 is disposed along the direction of the groove 220 so as to cover the groove 220 and project toward the inside of the groove 220, the structure is the same as that of the embodiment shown in FIG. A covering member that fulfills the above functions can be manufactured.

200 Optical Circuit 201 Substrate 211 First Optical Waveguide 212 Second Optical Waveguide 220 Groove 231 Insertion Member 232 Cover Member 232A First Part 232B Second Part 232C Protrusion 240 Adhesive

Claims (5)

A first optical waveguide and a second optical waveguide provided on the substrate;
Grooves intersecting the first optical waveguide and the second optical waveguide;
An insertion member inserted into the groove on the optical path of the first optical waveguide;
A covering member arranged to cover the groove on the optical path of the second optical waveguide;
An optical circuit comprising: an adhesive filled in the groove.   The optical circuit according to claim 1, wherein the covering member includes a first portion that covers the groove and a second portion that contacts a side surface of the substrate.   2. The optical circuit according to claim 1, wherein the covering member includes a first portion that covers the groove and a protruding portion that protrudes toward the inside of the groove.   The optical circuit according to claim 1, wherein the covering member has a cylindrical shape and is disposed along the direction of the groove.   The optical circuit according to claim 1, wherein the adhesive is a translucent UV curable adhesive.

Images