JP2005241813A - Optical path converting optical waveguide and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical path converting optical waveguide in which positioning of waveguides of the optical path converting portions is not required, transmission loss is made low and no variation exists between the waveguides. <P>SOLUTION: A first optical path is formed by illuminating laser light beams in a converging manner onto the inside of a substrate having at least one surface that totally reflects laser light beams with respect to the optical axis of the laser light beams and by linearly moving a converging lens of the laser light beams or the substrate along the direction in parallel with the optical axis prior to the incident onto the substrate. A second optical path is formed by converting the direction of the laser light beams at the total reflection surface and the first and second optical paths that sandwich the reflection surface are continuously formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an optical path conversion optical waveguide, and provides an optical waveguide that converts an optical path at an angle of 90 ° or close to it without diffusing light.

  It is known that a waveguide can be formed inside the glass by locally forming a high refractive index inside a transparent material such as glass and continuously forming a high refractive index region by condensing laser irradiation. (See Patent Document 1).

  Using the above-described waveguide formation method, first, a first waveguide is formed on a substrate by a laser, and then the substrate is rotated by 90 ° so that the second waveguide is orthogonal to the previously formed waveguide. After that, a method for producing an optical path conversion waveguide by cutting and removing an orthogonal portion so that a 45 ° reflection surface appears, or after polishing the substrate in advance by 45 °, first, Method of forming an optical path conversion waveguide by forming a waveguide and then forming a second waveguide so that the substrate is rotated 90 ° to contact the previously formed waveguide at a 45 ° polished surface (See Patent Documents 2 and 3).

However, in the above method, since a slight misalignment in the reflecting portion leads to an increase in loss, it is necessary to perform alignment between the first waveguide and the second waveguide with high accuracy. In the production of a single-mode type optical path conversion optical waveguide having a core diameter of 10 microns or less, it is not easy to reduce transmission loss and suppress variations in transmission loss among a plurality of optical path conversion waveguides.
JP 09-311237 A JP 2003-315578 A JP 2003-315579 A

  An object of the present invention is to provide a method for manufacturing an optical path conversion waveguide that does not require alignment between the waveguides in the optical path conversion portion, has a low transmission loss, and does not vary between the waveguides.

  The present invention relates to a method for producing an optical path conversion waveguide by continuously forming a region having a high refractive index by increasing the refractive index inside a substrate by condensing irradiation of a laser. A method of manufacturing an optical path conversion element, characterized in that a first optical waveguide and a second optical waveguide whose axis directions are changed are continuously and integrally formed, and at least 1 with respect to the optical axis of the laser. The laser beam is focused and irradiated inside the base material that has a surface that totally reflects the laser beam, and the laser condensing lens or base material is parallel to the laser optical axis before the base material is incident. By moving in a straight line, the first optical path is formed, and then the direction of the laser beam is changed at the total reflection surface, so that the laser beam is moved to the second optical path portion, and the first optical path before and after the reflection surface. The optical waveguide and the second optical waveguide are formed continuously. It is a manufacturing method of the optical path conversion waveguide to. In contrast to this method, it is also effective to form the second waveguide first and then form the first waveguide.

  The present invention also relates to a method of manufacturing a multistage optical path conversion element characterized by converting an optical path at a plurality of portions by repeating these methods in an optical path conversion waveguide having a plurality of reflecting surfaces. The present invention relates to an optical device including an optical path conversion optical waveguide.

  The optical waveguide manufacturing method of the present invention is a method of manufacturing a waveguide by continuously forming a region having a high refractive index by increasing the refractive index inside the substrate by condensing laser irradiation. Of the constituent surfaces of the base material on which the waveguide is to be formed, at least one surface with respect to the optical axis of the laser has a surface that has an incident angle that totally reflects the laser light. By focusing and irradiating the inside of the material, it is possible to create two or more linear waveguides with different traveling directions on the reflecting surface simply by linearly moving the laser condensing lens or base material parallel to the optical axis of the laser. Since they can be coupled, it is possible to produce an optical path conversion waveguide with no variation in waveguide characteristics and low transmission loss.

  Hereinafter, the present invention will be described in detail together with embodiments (examples) with reference to the drawings.

  (Example 1) The figure is a schematic diagram showing a method of manufacturing an optical path converting optical waveguide of Example 1 according to the present invention, and one row shown in FIG. Two rows of high refractive index lines L are formed by the method shown in FIG. First, the substrate 1 made of quartz glass is processed and polished into the shape shown in FIG. In FIG. 1, A is 20 mm, B and C are 10 mm, and the angle of D is 45 °. The entire surface is optically polished.

Next, as shown in FIG. 2A, the base material 1 is placed on the glass substrate 4, reflected from the lower surface of the base material 1 through the objective lens 2, the total reflection surface 5, and the initial focal position of the laser light 3. The positions of the base material 1 and the objective lens 2 are adjusted so that becomes an E point. At this time, the beam diameter before the laser 3 was incident on the objective lens 2 was 5 mm, and a pulse laser having a wavelength of 800 nm, a pulse width of 150 fs, a pulse energy of 2 μJ, and a repetition frequency of 200 kHz was used.
Next, as shown in FIG. 2 (b), the base 1 is linearly moved upward in the figure, so that the condensing point E in FIG. 2 (a) is continuously moved to the point F in FIG. 2 (b). I let you. At that time, the miracle of the condensing point followed the dotted line G, and it was confirmed that a right-angle line was formed in which the miracle of the condensing point had a higher refractive index than the surroundings.

Thereafter, the laser beam 3 is blocked, the positional relationship between the base material 1 and the objective lens 2 is returned to the state shown in FIG. 2A, and only the base material 1 is moved by 250 μm in the Y-axis direction. The operation of (b) was repeated again. This operation was repeated until eight right-angle lines having a high refractive index were formed.
Next, the substrate 1 is moved 250 μm in the X-axis direction, and the operations shown in FIGS. 2A to 2B are performed in the same manner. Further, the operations shown in FIGS. As shown in FIG. 3, two rows of high refractive index lines L in which one row is bent at a right angle are formed as shown in FIG. When laser light having a wavelength of 1300 nm is incident on each line from the H direction in FIG. 3 and the outgoing light in the I direction is measured, the loss of light transmitted through the right angle line is examined. All internal losses were 0.2 dB or less, and it was confirmed that an optical waveguide capable of converting the optical path to a right angle with an efficiency of 95% or more was formed. Further, the mode field diameter of the waveguide was 8 μm, the numerical aperture was 0.1, and no variation was observed between the waveguides.

  In the first embodiment, quartz glass is used as a base material, and 16 right-angle optical path conversion waveguides each consisting of two rows and eight rows are taken up. However, the base material has a high refractive index due to the laser used. The material is not particularly limited as long as it is a material in which a so-called photoinduced refractive index change occurs, and other oxide glass, halide glass, chalcogenide glass, inorganic single crystal material, or organic polymer can also be used. Moreover, it is also possible to form an optical path conversion optical waveguide in the photocurable resin by using an ultraviolet laser. Moreover, as long as it does not deviate from the content of the first embodiment, the incident angle on the total reflection surface may be arbitrary. Further, although the example of 16 waveguides has been taken up, the number of columns and the number of waveguides may be arbitrary as long as they do not deviate from the contents of the first embodiment. The distance does not necessarily have to be constant.

  Furthermore, by increasing the difference in refractive index between the base material and the surroundings, or by applying a multilayer coating on the reflective surface in advance, it is possible to make the laser incident angle satisfying the total reflection condition smaller than 45 ° In this case, it is also possible to produce a waveguide that converts the optical path at an acute angle. Contrary to this method, it is also effective to first form a waveguide parallel to the laser optical axis before incidence on the substrate, and then form a waveguide obtained by converting the optical path.

  In Example 1, a base material having only one total reflection surface is used. However, after the laser is incident on the base material, the surfaces after the first total reflection surface of the laser are continuously connected to the optical axis of the laser. In contrast, since the angle satisfies the total reflection condition, it is possible to form an optical waveguide that is continuously bent a plurality of times by each total reflection surface.

FIG. 1 is a schematic diagram illustrating the shape of a substrate having a reflective surface in Example 1. FIG. FIG. 2 is a schematic diagram illustrating a process of manufacturing an optical path conversion waveguide by focused laser irradiation in the first embodiment. FIG. 3 is a schematic diagram showing 8 × 2 rows of optical path conversion optical waveguides manufactured according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Objective lens 3 Laser beam 4 Glass substrate 5 Reflective surface E First laser condensing point F Final laser condensing point G Laser condensing point locus

Claims (4)

In a method of manufacturing an optical path conversion optical waveguide having different directions of a first optical path and a second optical path sandwiching a reflective surface by increasing the refractive index inside the substrate by condensing irradiation of a laser, the reflective surface is A method of manufacturing an optical path conversion optical waveguide, wherein two sandwiched optical waveguides are formed continuously and integrally. In a method of manufacturing an optical path conversion optical waveguide by continuously forming a region having a high refractive index by increasing the refractive index inside the substrate by condensing laser irradiation, at least with respect to the optical axis of the laser, One or more surfaces condense and irradiate a laser inside a substrate having a surface that totally reflects the laser beam, and the laser condensing lens or substrate is parallel to the optical axis of the laser before incidence on the substrate The first optical path is formed by linearly moving the first optical path, and the second optical path having a different optical axis from the first optical path is formed by changing the direction of the laser light at the total reflection surface. 2. The method of manufacturing an optical path converting optical waveguide according to claim 1, wherein the first optical path and the second optical path sandwiching the first and second optical paths are formed continuously. A method of manufacturing a multistage optical path conversion optical waveguide, wherein the method according to claim 1 or 2 is repeated for an optical path conversion optical waveguide having a plurality of reflecting surfaces. An optical device comprising an optical path conversion optical waveguide produced by the method according to claim 1.