JP2005208254A - Multi-channel optical path converting device and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing, with a high positional precision, the channels and mirrors of a multi-channel optical path converting device capable of converting an optical path by using a mirror. <P>SOLUTION: The multi-channel optical path converting device is composed of a plurality of resin optical waveguides and mirrors, and converts the direction of the optical path. An L-shaped optical waveguide is formed on the surface of a first waveguide substrate. A second substrate having a waveguide material film formed on the surface thereof is stuck to the first substrate. Then the next L-shaped optical waveguide is formed so that the positional relation between the waveguides are kept with high precision. The above processes are repeated as many times as desired. Thereafter, the resultant product is made to be a chip, and the mirror surface is formed on each chip. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In order to connect optical elements efficiently, a multi-channel optical path conversion element that converts the traveling direction of an optical circuit is required for the widespread use of optical waveguide devices. The present invention relates to a multi-channel optical path conversion element with low loss and uniform characteristics, and an effective manufacturing method thereof.

  As optical communication technology has permeated as the basic technology of information communication systems, optical waveguides are becoming increasingly important as optical network key devices, and at the same time, they are being developed for applications in fields such as optoelectronic circuit wiring boards. It has been. The spread of optical waveguide devices is demanded for low cost and mass production, and resin optical waveguides that are easy to handle are being developed as promising candidates. As the resin material for the waveguide, fluorinated polyimide resin, deuterated polysiloxane resin, epoxy resin, perfluorinated alicyclic resin, acrylic resin, silicone resin and the like are used.

  The spread of optical waveguide devices is an optical path changing technique that bends an optical circuit abruptly in order to connect elements efficiently, especially various optical signals such as 2-16 channels can be transmitted and received in parallel. Such a multi-channel optical path conversion element is required, and further, there is a demand for low loss and uniform characteristics between channels. Maintaining the accuracy of the positional relationship between cores directly affects the uniformity between device channels. In general, in coupling with the multimode fiber used in this application, it is necessary to make the uniformity between channels ± 0.2 dB or less, and for this purpose, the cross-sectional shape of the waveguide is 40 × 40 μm square. The positional relationship between the multiple cores of the multimode optical waveguide must be formed with high accuracy of ± 2.5 μm or less.

As an optical path conversion component, there has been proposed a method in which substrates on which optical waveguides are formed are bonded together and then a mirror is formed. (See Patent Document 1)
However, it is necessary to control the accuracy between the waveguides in the thickness direction and the position accuracy of the L-shaped bonding at the same time, which requires complicated and precise work. . In order to maintain the accuracy of ± 2.5 μm or less required as a device by this method, an expensive apparatus is required, and it is difficult to obtain a device with sufficient throughput.
JP 2003-315578 A

  In a multi-channel optical path conversion element that converts a plurality of optical paths using a mirror, an optical path conversion element with low loss and uniform characteristics between channels, and a manufacturing method that combines ease of manufacture and low cost are provided. Let it be an issue.

The present invention relates to a multi-channel optical path conversion element configured by a plurality of resin optical waveguides and mirrors and converting the direction of an optical path. The method includes forming a waveguide on the surface of the second substrate so that the substrates are bonded together and then maintained in positional relation with the waveguide of the first substrate.
That is, the present invention
1) An optical waveguide is formed on the substrate,
2) Laminate the next substrate on which the cladding material is formed,
3) An optical waveguide is formed on this substrate,
4) After repeating steps 2) and 3) until the required number of channels is satisfied, after coating the clad resin,
5) Cut out the chip of each multi-channel optical path conversion element,
6) A mirror is formed on each chip.
The method includes at least six steps, and provides a high-performance multi-channel optical path conversion element by these methods.

  According to this method, the positional accuracy of each channel can be maintained by separately performing the step of bonding the substrates and the step of patterning the core. That is, the accuracy in the thickness direction of the lamination corresponding to the core pitch between the channels is kept constant by a grinding apparatus, and the position accuracy of the L-shaped waveguide between channels is implemented by mask alignment in photolithography. The multi-channel optical path conversion element can be manufactured with high accuracy without the necessity of

  By sequentially producing waveguides for each layer, it is possible to provide a multi-channel optical path conversion element that has stable characteristics, high accuracy, low loss, and low cost.

  Hereinafter, the present invention will be described in detail.

  FIG. 1 is a diagram for explaining an example of the manufacturing process of the multi-channel optical path conversion element of the present invention, and the 4-channel optical path conversion element will be described. Other channel numbers can be manufactured in the same manner. Although the actual manufacturing process is performed in the state of a wafer, FIG. 1 shows the device portion in an enlarged manner. First, in FIG. 1A, a resin material 2 of a clad material is formed on a substrate 1. In order to prevent positional displacement, the substrate 1 serving as a position reference should use an inorganic material such as glass or silicon having a water absorption rate of 0.1% or less and a linear thermal expansion coefficient of 20 ppm or less within the process temperature range. preferable.

In (b), after forming a trench type waveguide pattern by lithography and reactive ion etching (RIE) technique, the core resin material is embedded by spin coating, and the excess core material is etched. The L-shaped waveguide 3 is formed by removing by back. In (c), the bonding substrate 4 on which the clad resin material 2 is formed in advance is bonded with the clad resin material (d), and the clad resin material 2 is ground with a grinding device so that the pitch between the channels is predetermined. Make the film thickness. The clad resin material that covers the waveguide of (b) may be adjusted by the thickness of the resin material for lamination, but it is possible to use a material in which the clad resin material is previously formed on the bonding substrate 4. It is simple and preferable in terms of accuracy. In addition, it is more preferable to use a clad resin material formed on both surfaces because warpage of the substrate can be prevented.
In (e), the waveguide 5 is formed by the same method as in (b) so as to maintain the same positional relationship as the core pattern in (b).

  In (f), the same steps as in (c), (d), and (e) are repeated twice, and finally a clad resin material is deposited to form a 4-channel waveguide, and the wafer is diced. (4) to obtain a 4-channel waveguide (g). Mirror surface 6 forms a mirror by cutting the wafer into chips and then polishing the obliquely diced surface, sputtering gold or a dielectric film, or attaching a block on which the mirror surface is formed. be able to.

[Example 1]
A four-channel optical path conversion element in which the length from the midpoint of the mirror surface of the horizontal waveguide and the vertical waveguide was 3.5 mm and 1.6 mm, respectively, was manufactured. The clad material and core material used epoxy resin. The core pitch between the channels is 250 μm.
First, a clad material was formed on a glass substrate having a thickness of 1 mm and a diameter of 100 mm. The film is formed by spin coating, and the thickness of the cladding layer is 50 μm. Thereafter, a mask material was formed on the clad material and patterned by photolithography. Al (aluminum) is used as the mask material, and O ₂ gas is introduced to etch the cladding part that is not protected by the mask layer (O ₂ -RIE), thereby forming an L-shaped trench core pattern on the cladding layer. Then, the core material was filled into the trench type core pattern by spin coating. Excess core material was removed by etchback (O ₂ -RIE) to produce a 40 × 40 μm square core.

 Then, a substrate (a total thickness of 240 μm) on which a clad material was formed on a glass substrate having a thickness of 140 μm was bonded to the clad material (adhesion layer 10 μm). Thereafter, the overall thickness was set to 1300 μm ± 2.5 μm with a grinding apparatus. Thereafter, a mask material was formed on the clad material, and the second-layer core was patterned by photolithography so that the L-shaped core position of the first layer and the core position of the second layer coincided with each other with a mask aligner. The core material was filled there in the same way as in the first layer, and etched back to produce a second layer core. Further, the procedure for producing the second core layer was repeated twice, and finally an optical waveguide substrate in which four layers of L-shaped cores were laminated was formed by forming a clad material of 50 μm.

  Next, the L-shaped portion was cut with a dicing saw to produce a mirror portion, and then cut into a chip shape. After polishing the mirror part of the cut-out chip, the glass block on which the dielectric film was formed was laminated with a clad material. By polishing the entrance surface and the exit surface, 130 optical path conversion elements having four channels of horizontal and vertical waveguides were obtained.

The accuracy of the core arrangement of the obtained right-angle optical path conversion waveguide was 2.0 μm or less between all the channels. In addition, light with a wavelength of 1.3 μm is inserted into a right-angle optical path conversion waveguide by a 4-mode fiber array of multimode fibers (core pitch 250 μm) and received by the 4-core multimode fiber array. The variation in insertion loss between channels at 0.1 dB or less was 79 (60%), and a low-loss and uniform four-channel optical path conversion element could be manufactured with a good yield.
[Example 2]
Except for changing the material for the second and subsequent layers from glass to fluorinated polyimide, the same procedure as in Example 1 was carried out, and the L-shaped core between the four layers was an epoxy resin and a fluorinated polyimide. An optical waveguide substrate was produced. Next, the L-shaped portion was cut with a dicing saw to produce a mirror portion, and then cut into a chip shape. After polishing the mirror part of the cut-out chip, a glass block on which a dielectric film was formed was laminated with a clad material. By polishing the entrance surface and the exit surface, 130 optical path conversion elements having four channels of L-shaped waveguides were obtained.

The accuracy of the core arrangement of the obtained right-angle optical path conversion waveguide was 2.5 μm or less between all the channels. In addition, when a light with a wavelength of 1.3 μm is inserted into a right-angle optical path conversion waveguide using a 4-mode fiber array of multimode fibers (core pitch 250 μm) and received by the 4-core multimode fiber array, each element has an insertion loss of 3 dB or less. The variation of insertion loss between channels within 0.1 dB was as high as 68 (52%), and a low-loss and uniform four-channel optical path conversion element could be manufactured with good yield.
[Comparative Example 1]
An epoxy resin as a clad material was formed on each of four fluorinated polyimide substrates having a thickness of 190 μm. The film was formed by spin coating, and the thickness of the clad material was 50 μm. Thereafter, a mask material was formed on the clad material and patterned by photolithography. Al was used for the mask material, and O ₂ gas was introduced to etch the portion not protected by the mask layer (O ₂ -RIE), thereby producing a trench-shaped and L-shaped core pattern on the cladding material. The core material was filled into the trench type core pattern by spin coating. Excess core material was removed by etch back (O ₂ -RIE), and four substrates with an L-shaped core pattern of 40 × 40 μm formed on a fluorinated polyimide substrate were prepared and used at the end face One of them was overcoated with a clad material. These were laminated with a clad material using a substrate laminating apparatus to produce an optical waveguide substrate in which four L-shaped cores were laminated.

  Next, the intersection part of the L-shape was cut with a dicing saw to produce a mirror part, and then cut into a chip shape. After polishing the mirror part of the cut-out chip, a glass block on which a dielectric film was formed was laminated with a clad material. By polishing the entrance surface and the exit surface, 130 right-angle optical path conversion waveguides having four horizontal and vertical waveguides were obtained.

  The core pitch of the obtained right-angle optical path conversion waveguide was 250 ± 20 μm. In addition, when a 4-mode fiber array with a multimode fiber (core pitch 250 ± 0.5 μm) is used, light with a wavelength of 1.3 μm is inserted into a right-angle optical path conversion waveguide and received by a 4-core multimode fiber array. Although the loss was about 3 dB, the error in the core arrangement was so large that only a single channel was optically coupled to the fiber array, so that they were all unsuitable as multichannel optical path conversion elements.

FIG. 1 is a diagram showing an example of a manufacturing process of a multichannel optical path conversion element according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass or silicon substrate 2 Cladding material 3 L-shaped waveguide 4 Pasting substrate 5 Second L-shaped waveguide 6 Mirror surface

Claims (3)

In a multi-channel optical path conversion optical waveguide composed of a plurality of resin optical waveguides and mirrors, the second substrate is bonded to the first waveguide substrate in which the cores before and after the mirror are integrally formed, and then the first A method for producing a multi-channel optical path conversion element, comprising a method of forming a waveguide on the surface of a second substrate so as to maintain a positional relationship with the waveguide of the substrate, and repeating this multiple times. A method of manufacturing a multi-channel optical path conversion element configured by a plurality of resin optical waveguides and mirrors and converting the direction of an optical path,
1) An optical waveguide is formed on the substrate,
2) Laminate the next substrate on which the cladding material is formed,
3) An optical waveguide is formed on this substrate,
4) Repeat steps 2) and 3) until the required number of channels is satisfied.
5) Cut out into multi-channel chips,
6) A mirror is formed on each chip.
The method for producing a resin-made multichannel optical path conversion element according to claim 1, comprising at least six steps. A resin-made multi-channel optical path conversion element manufactured by the method according to claim 1.