JP3768450B2 - Manufacturing method of optical waveguide component - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing an optical waveguide component used in the field of optical communication, and more particularly to a method of manufacturing an optical waveguide component that reduces loss and suppresses polarization dependence of loss.
[0002]
[Prior art]
In forming optical waveguides, in recent years, femtosecond pulsed laser light is focused and irradiated inside a transparent material such as glass by a lens to induce a region with a high refractive index, which is then scanned and scanned using a precision stage. A method of directly forming a three-dimensional optical waveguide inside a material has been proposed, and this technique is disclosed in Japanese Patent Laid-Open No. 9-311237.
[0003]
[Problems to be solved by the invention]
However, an optical waveguide manufactured by a conventional method has a large propagation loss, and causes problems such as degradation of signal light when used in an optical communication system as an optical waveguide component. Further, there is a problem that the characteristic of the optical waveguide changes depending on the polarization state of the signal light because the loss has a large polarization dependency.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method of manufacturing an optical waveguide component capable of reducing loss and suppressing the polarization dependence of loss.
[0004]
[Means for Solving the Problems]
In order to solve the above-described problems, the invention described in claim 1 condenses and irradiates a substrate made of quartz glass with femtosecond laser light in the near-infrared wavelength region, and scans the substrate or the laser light introducing optical system. Then, after continuously inducing a high refractive region in the substrate to form an optical waveguide core, the substrate on which the optical waveguide core is formed is heat-treated within a temperature range of 600 ° C. to 1000 ° C. for 2 hours or more. An optical waveguide component manufacturing method characterized by the following.
Thereby, the manufacturing method of the optical waveguide component which can reduce propagation loss and can suppress the polarization dependence of propagation loss is realizable.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
FIG. 1 shows an example of an apparatus used in the method for manufacturing an optical waveguide component of the present invention.
In FIG. 1, reference numeral 1 is a light source, and reference numeral 2 is a laser beam sent from the light source 1. The laser beam 2 is reflected by the half mirror 3 and condensed by the objective lens 4. The laser beam 2 collected by the objective lens 4 is condensed and irradiated onto a substrate 5 on which a waveguide is formed. As the substrate 5, for example, optically polished glass is used. However, the invention is not limited to this, and the substrate 5 is transparent in the used wavelength band, and can induce a refractive index increase region by condensing irradiation of laser light. As long as it is a thing, it is not limited to quartz glass, quartz glass mainly composed of quartz, and other materials such as polymer resin may be used.
Reference numeral 6 denotes a precision stage, and the position of the substrate 5 is monitored by the CCD camera 7 and the position is adjusted based on the result. By scanning the precision stage 6 in the X-axis direction, the Y-axis direction, or the Z-axis direction, the condensing point of the laser light 2 is relatively moved inside the substrate 5, and a continuous high refractive index region that functions as an optical waveguide is formed. By forming the substrate 5 inside, an optical waveguide component is manufactured.
[0008]
In the manufacturing method of the optical waveguide component of this example, the optical waveguide is manufactured by performing heat treatment on the optical waveguide component manufactured by condensing and irradiating the femtosecond laser on the substrate 5 made of quartz glass or the like by the above-described method. Propagation loss and polarization dependency of propagation loss are reduced. The polarization dependence of the propagation loss is defined as the difference between the maximum value and the minimum value of the propagation loss when any polarization is propagated.
As will be described later, the temperature range of the heat treatment is preferably in the temperature range of 600 ° C. to 1000 ° C., and the heat treatment time is preferably 2 hours or more.
[0009]
Here, a femtosecond laser having a central wavelength of 800 nm, a pulse width of 170 fs, and a repetition frequency of 200 kHz is condensed by an NA0.5 objective lens 4 and irradiated onto the substrate 5, and this substrate 5 is scanned at 30 μm / s. A straight waveguide having a length of 20 mm was formed. This condition was fixed, and an optical waveguide was produced and heat-treated under the following conditions.
The specific example is shown below.
[0010]
Example 1
A femtosecond laser emitted from the light source 1 was condensed and irradiated onto the substrate 5 using the objective lens 4 to form an optical waveguide. The intensity of the laser beam irradiated inside the substrate 5 is 85 mW.
The propagation loss of the fabricated optical waveguide and the polarization dependence of the propagation loss were evaluated. After heat treatment at 600 ° C. for 2 hours, the polarization dependence of the propagation loss and propagation loss of the optical waveguide was evaluated again. 2 and 3 show the propagation loss before and after the heat treatment, and the polarization dependence of the propagation loss. Propagation loss before heat treatment is 6 to 9 dB and the polarization dependence of propagation loss before heat treatment is 0.3 dB, whereas propagation loss is 4 to 5 dB after heat treatment at 600 ° C. for 2 hours. The polarization dependence was 0.1 dB, confirming the effect of heat treatment.
[0011]
(Example 2)
A femtosecond laser emitted from the light source 1 was condensed and irradiated onto the substrate 5 using the objective lens 4 to form an optical waveguide. The intensity of the laser beam irradiated inside the substrate 5 is 80 mW.
The propagation loss of the fabricated optical waveguide and the polarization dependence of the propagation loss were evaluated. After heat treatment at 850 ° C. for 2 hours, the polarization dependence of the propagation loss and propagation loss of the optical waveguide was evaluated again. 4 and 5 show the propagation loss before and after the heat treatment and the polarization dependence of the propagation loss. Propagation loss before heat treatment is 5 to 7 dB, polarization dependence of propagation loss before heat treatment is 0.1 to 0.2 dB, whereas propagation loss is 4 to 5 dB after heat treatment at 850 ° C. for 2 hours, The polarization dependence of propagation loss was 0.1 dB, confirming the effect of heat treatment.
[0012]
Example 3
A femtosecond laser emitted from the light source 1 was condensed and irradiated onto the substrate 5 using the objective lens 4 to form an optical waveguide. The intensity of the laser beam irradiated on the surface of the substrate 5 is 85 mW.
The propagation loss of the fabricated optical waveguide and the polarization dependence of the propagation loss were evaluated. After heat treatment at 1000 ° C for 2 hours, the polarization dependence of the propagation loss and propagation loss of the optical waveguide was evaluated again. 6 and 7 show the propagation loss before and after the heat treatment, and the polarization dependence of the propagation loss. Propagation loss is 8 to 10 dB before heat treatment and the polarization dependence of propagation loss is 0.1 dB, whereas propagation loss is 5 to 6 dB after heat treatment at 1000 ° C. for 2 hours, and polarization dependence of propagation loss Was 0.05 dB, confirming the effect of heat treatment.
[0013]
According to the manufacturing method of the optical waveguide component of this example, the laser beam 2 is condensed and irradiated onto the substrate 5 made of a transparent material, the substrate 5 or the laser beam introducing optical system is scanned, and the high refractive index region is continuously formed inside the substrate 5. The optical waveguide core is formed by induction, and then the substrate 5 on which the optical waveguide core is formed is subjected to heat treatment for a certain time, thereby reducing the propagation loss and suppressing the polarization dependence of the propagation loss. A method for manufacturing a possible optical waveguide component can be realized.
This effect can be obtained preferably by setting the temperature range of the heat treatment to a temperature range of 600 ° C. to 1000 ° C. and setting the heat treatment time to 2 hours or more.
[0014]
【The invention's effect】
As described above, according to the present invention, a laser beam is focused on a substrate made of a transparent material, scanned by a substrate or a laser beam introduction optical system, and a high refractive index region is continuously induced inside the substrate. After forming the optical waveguide core, the substrate on which the optical waveguide core is formed is subjected to heat treatment for a certain period of time, thereby reducing the propagation loss and suppressing the polarization dependence of the propagation loss. A manufacturing method can be realized.
This effect can be obtained preferably by setting the temperature range of the heat treatment to a temperature range of 600 ° C. to 1000 ° C. and setting the heat treatment time to 2 hours or more.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of an apparatus used in a method for manufacturing an optical waveguide component according to the present invention.
FIG. 2 is a diagram showing propagation loss when heated at 600 ° C. for 2 hours in the method of manufacturing an optical waveguide component of the present invention compared with propagation loss before heat treatment.
FIG. 3 is a diagram showing the polarization dependence of propagation loss when heated at 600 ° C. for 2 hours in the method of manufacturing an optical waveguide component of the present invention, compared with the polarization dependence of propagation loss before heat treatment. It is.
FIG. 4 is a diagram showing the propagation loss when heated at 850 ° C. for 2 hours in the method of manufacturing an optical waveguide component of the present invention in comparison with the propagation loss before heat treatment.
FIG. 5 is a diagram showing the polarization dependence of propagation loss when heated at 850 ° C. for 2 hours in the optical waveguide component manufacturing method of the present invention, compared with the polarization dependence of propagation loss before heat treatment. It is.
FIG. 6 is a diagram showing propagation loss when heated at 1000 ° C. for 2 hours in the method of manufacturing an optical waveguide component of the present invention, compared with propagation loss before heat treatment.
FIG. 7 is a diagram showing the polarization dependence of propagation loss when heated at 1000 ° C. for 2 hours in the method of manufacturing an optical waveguide component of the present invention in comparison with the polarization dependence of propagation loss before heat treatment. It is.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Laser beam, 3 ... Half mirror, 4 ... Objective lens,
5 ... Substrate, 6 ... Precision stage, 7 ... CCD camera.

Claims (1)

Femtosecond laser light in the near-infrared wavelength region is focused and irradiated onto a quartz glass substrate, the substrate or laser light introducing optical system is scanned, and a high refractive region is continuously induced inside the substrate to produce an optical waveguide. A method for producing an optical waveguide component, comprising: forming a core, and then heat-treating the substrate on which the optical waveguide core is formed within a temperature range of 600 ° C. to 1000 ° C. for 2 hours or more .

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