JP3520055B2 - Optical attenuator and optical attenuator module - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical attenuator and an optical attenuator module used for an optical communication system, an optical measuring system, etc., for attenuating the intensity of light by a set amount.

[0002]

2. Description of the Related Art Conventionally, as an optical attenuation device (optical attenuator) used in an optical communication system, an optical measurement system, etc.,
Devices of various principles have been proposed and used,
Currently, the following three types of device configurations are mainstream.
That is, a configuration in which the optical fibers are arranged to face each other with a space therebetween, and a magneto-optical crystal is provided between the optical fibers,
A structure using the thermo-optic effect, a structure in which optical fibers are arranged opposite to each other with a gap between them, and a medium having an optical attenuation function such as an optical attenuation film or an optical attenuation plate is provided between the optical fibers is mainly used. There is.

An optical attenuator having the above-mentioned optical attenuation film is, for example, as shown in FIG. 9, a flat glass substrate 1
The light incident surface 3 and the light emitting surface 4 of the glass substrate 1 are parallel to each other. On the surface of the glass substrate 1 (the light incident surface 3 and the light emitting surface 4), antireflection films 14a and 14b having a light reflectance of, for example, about 0.1% are formed, and the light incident surface 3 is attenuated by light. The film 2 is formed.

The light-attenuating film 2 shown in the figure has a film thickness distribution in the X direction in the figure, and as a result, a light attenuation rate distribution (change in light attenuation rate) in the X direction. The light attenuating film 2 may be formed on the light emitting surface 4, and the light attenuating film 2 may be formed on at least one of the light incident surface 3 and the light emitting surface 4.

However, in this type of conventional optical attenuator, since the light incident surface 3 and the light emitting surface 4 of the glass substrate 1 are parallel to each other, light is not emitted between the light incident surface 3 and the light emitting surface 4. Multiple interference was caused, and as a result, the optical attenuation factor of the optical attenuator had wavelength dependence, as shown in FIG.

That is, the optical attenuation factor of the optical attenuator is
It changes periodically depending on the wavelength, and the difference between the maximum value and the minimum value of the optical attenuation rate becomes about 0.3 dB. This optical attenuation rate wavelength dependency is a big problem when applied to an optical communication system. Became. In the light transmission spectrum shown in the figure, the wavelength-dependent period of the light attenuation factor is 1.5 nm.

Therefore, Japanese Patent No. 2933919 proposes a structure for suppressing the wavelength dependence of the optical attenuation factor. In this proposal, in the optical attenuator having the glass substrate 1 and the light attenuating film 2 as in the device shown in FIG. 9, the light incident surface 3 and the light emitting surface 4 of the glass substrate 1 are formed in a tapered shape without being parallel to each other. ing.

[0008]

However, in the above proposed optical attenuator, the value of the angle formed by the light incident surface 3 and the light emitting surface 4 of the glass substrate 1 has not been studied in detail. However, the following problems occurred depending on this angle. That is, when the angle formed by the light incident surface 3 and the light emitting surface 4 of the glass substrate 1 is increased, the light attenuation due to the wavelength dependence of the refractive index at the interface between the glass substrate 1 and the atmosphere due to the chromatic dispersion of the glass substrate 1. The wavelength dependence of the rate appears.

Therefore, the above proposed optical attenuator is
Depending on the angle formed by the light incident surface 3 and the light emitting surface 4 of the glass substrate 1, rather than suppressing the wavelength dependence of the light attenuation rate,
There is a possibility that the wavelength flatness of the light attenuation factor may be deteriorated.

In recent optical communication systems,
The signal light intensity tends to increase. The light-attenuating film 2 absorbs incident light to attenuate its intensity, and the absorbed light is converted into heat in the light-attenuating film 2, so that the high-intensity light as described above is converted into heat. When incident on the optical attenuation film 2, the light attenuation film 2 is heated by that amount. Then, there is a problem that oxygen is taken from the atmosphere with which the light attenuating film 2 is in contact and is oxidized, and the light attenuating rate of the light attenuating film 2 is locally reduced.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a highly reliable optical attenuator which has good wavelength flatness of optical attenuation factor and can withstand high intensity optical input. It is to provide an optical attenuator module.

[0012]

In order to achieve the above object, the present invention has the following constitution as means for solving the problem. That is, the optical attenuator of the first invention has a substrate and a light attenuating film that attenuates incident light at a set light attenuation rate, and the optical attenuator is provided on at least one of a light incident surface and a light emitting surface of the substrate. optical attenuation film is formed, light decrease
Light attenuation for light with intensity higher than 50 mW on the surface of the eccentric membrane
A protective film for preventing film deterioration is formed, and an angle formed by the light incident surface and the light emitting surface of the substrate is larger than 0.15 ° and is 0.5 or more.
Formed in less than °, wavelengths between 1520nm and 1580nm
The value of the optical attenuation factor wavelength flatness at the angle of 0.5 °
The configuration is set to be smaller than the value of the optical attenuation factor wavelength flatness at that time as means for solving the problem. Also, the second departure
Ming light attenuator sets the substrate and incident light, optical attenuation factor
And a light-attenuating film for attenuating with, the light-incident surface of the substrate and
The light attenuating film is formed on at least one surface of the light emitting surface.
The angle formed by the light incident surface and the light emitting surface of the substrate is
It has a structure formed at 0.2 ° or more and 0.4 ° or less.
It is a means to solve the problem.

Further, the optical attenuator of the third invention has a structure in which, in addition to the structure of the second invention, a protective film for preventing deterioration of the light attenuating film is formed on the surface of the light attenuating film. As a means.

Further, the optical attenuator of the fourth invention is
In addition to the structure of the first or third invention, a structure in which the film thickness of the protective film is 10 nm or more is a means for solving the problem.

Further, the optical attenuator of the fifth invention is
In addition to the configuration of the first, second, third or fourth invention, the light attenuating film has a light attenuating factor distribution in at least one direction along the substrate surface as means for solving the problem. There is.

Further, the optical attenuator of the sixth invention is
In addition to the configuration of the fifth aspect of the invention, the optical attenuation factor distribution has a configuration in which the optical attenuation factor continuously changes in at least one direction along the surface of the substrate as a means for solving the problem. .

Further, the optical attenuator module of the seventh invention has a structure having the optical attenuator of any one of the first to sixth inventions and an optical attenuator moving means for moving the optical attenuator. As a means.

Further, in the optical attenuator module of the eighth invention, in addition to the configuration of the seventh invention, the optical attenuating film of the optical attenuator has a light attenuation factor distribution in at least one direction along the substrate surface. The optical attenuator moving means has means for moving the optical attenuator in a direction crossing the light attenuation rate distribution region of the light attenuating film.

Furthermore, an optical attenuator module according to a ninth aspect of the present invention is the optical attenuator according to any one of the first to sixth aspects of the present invention, in which light is branched and one of the branched lights is incident on the optical attenuator. The first light branching means, the second light branching means for branching the light transmitted through the optical attenuator, and the incident light to the light attenuator among the branched light branched by the first light branching means. First light detecting means for receiving the excluded light and detecting the intensity thereof, and second light detecting means for receiving one of the branched lights branched by the second light branching means and detecting the intensity thereof. The above-mentioned configuration is used as means for solving the problem.

Furthermore, an optical attenuator module of a tenth aspect of the invention is the optical attenuator of any one of the first to sixth aspects of the invention, and branches the light into one of the branched lights to enter the optical attenuator. A light splitting means, a light reflecting means for reflecting the light transmitted through the light attenuator, and a light except the incident light to the light attenuator among the split light split by the light splitting means, A structure having a light detecting means for detecting is used as means for solving the problem.

Furthermore, an optical attenuator module of an eleventh aspect of the invention is the optical attenuator of any one of the first to sixth aspects of the invention, and a light that reflects light and makes the reflected light incident on the optical attenuator. An object of the present invention is to provide a structure having a reflecting means, an optical branching means for branching the light transmitted through the optical attenuator, and a light detecting means for receiving one of the branched lights branched by the optical branching means and detecting its intensity. It is a means to solve.

Further, an optical attenuator module of a twelfth invention is the optical attenuator of the fifth or sixth invention, wherein the light is branched and one of the branched lights is made incident light to the optical attenuator. 1 optical branching means, 2nd optical branching means for branching the light that has passed through the optical attenuator, and light that is the branched light branched by the first optical branching means, excluding the light that is incident on the optical attenuator. First light detecting means for receiving the light and detecting the intensity thereof, second light detecting means for receiving one of the branched lights branched by the second light branching means and detecting the intensity thereof, and the light An optical attenuator moving unit that moves the attenuator in a direction crossing the optical attenuation factor distribution region of the optical attenuating film is used as means for solving the problem.

Furthermore, an optical attenuator module of a thirteenth aspect of the invention is an optical attenuator of the fifth or sixth aspect of the invention, and an optical branching device that splits the light into one of the split lights as incident light to the optical attenuator. Means, light reflecting means for reflecting the light transmitted through the optical attenuator, and light detection for receiving the light excluding the incident light to the optical attenuator among the branched lights branched by the optical branching means and detecting the intensity thereof. Means and means for moving the optical attenuator in a direction crossing the optical attenuation factor distribution region of the optical attenuating film are provided as means for solving the problem.

Further, the optical attenuator module of the fourteenth invention comprises the optical attenuator of the fifth or sixth invention, and a light reflecting means for reflecting the light and making the reflected light the incident light to the optical attenuator. An optical branching unit for branching the light transmitted through the optical attenuator, a light detecting unit for receiving one of the branched lights branched by the optical branching unit and detecting its intensity, and an optical attenuator for the optical attenuating film. An optical attenuator moving unit that moves in a direction crossing the attenuation factor distribution region is provided as means for solving the problem.

Further, the optical attenuator module of the fifteenth invention has the optical attenuator of the fifth or sixth invention, and shows the relational data between the arrangement position of the optical attenuator and the attenuation rate distribution of the optical attenuation film. An optical attenuator position detecting means for detecting a position where the optical attenuator is provided is provided in advance,
The optical attenuator moving means moves the optical attenuator so that the optical attenuation rate of the optical attenuator module becomes a set optical attenuation rate based on the detection data by the optical attenuator position detecting means and the relational data. As a means.

Furthermore, in the optical attenuator module of the 16th aspect of the invention, in addition to the configuration of the 12th, 13th or 14th aspects of the invention, the relational data between the arrangement position of the optical attenuator and the attenuation rate distribution of the optical attenuation film is provided. Is provided in advance, and an optical attenuator position detecting means for detecting the arrangement position of the optical attenuator is provided, and the optical attenuation rate of the optical attenuator module is set based on the detection data by the optical attenuator position detecting means and the relational data. The optical attenuator is moved by the optical attenuator moving means so that the problem is solved.

Furthermore, the optical attenuator module of the seventeenth aspect of the invention is the optical attenuator module of the twelfth aspect of the invention, in addition to the first aspect of the invention.
Optical attenuator detecting means for obtaining the optical attenuating rate of the optical attenuator based on the optical intensity detected by the optical detecting means and the optical intensity detected by the second optical detecting means, and the optical attenuator moving means has the optical attenuating means. The means for solving the problem is configured to move the optical attenuator based on the optical attenuation rate obtained by the rate detecting means.

Furthermore, in the optical attenuator module of the eighteenth invention, in addition to the configuration of any one of the twelfth to sixteenth inventions, the relationship between the arrangement position of the optical attenuator and the attenuation factor distribution of the optical attenuation film is provided. Optical attenuator position detecting means for detecting the position where the optical attenuator is arranged is provided in advance, and the optical attenuation rate of the optical attenuator module is set based on the detection data by the optical attenuator position detecting means and the relational data. The configuration is provided with a feedback control unit that moves the optical attenuator by the optical attenuator moving unit so as to achieve the above-mentioned ratio.

The optical attenuator of the present invention having the above-mentioned structure has an optical attenuating film for attenuating the incident light at a set attenuation rate. Therefore, by applying this optical attenuator, a desired optical attenuation rate (set optical attenuation rate) can be obtained. Rate) can be obtained.

Further, like the optical attenuator of the present invention,
In an optical attenuator having a light-attenuating film and a substrate of the light-attenuating film, the substrate is generally formed of a glass substrate, and when the light-incident surface and the light-exiting surface of the substrate are parallel to each other, due to multiple interference in the glass substrate, As a result, the wavelength dependence of the light transmittance increases. On the other hand, when the angle between the light incident surface and the light emitting surface of the substrate is increased, the wavelength dependence of the light attenuation factor due to the wavelength dependency of the refractive index appears at the interface between the substrate and the atmosphere due to the chromatic dispersion of the substrate. It deteriorates the wavelength flatness of the optical attenuation factor.

Therefore, the present inventor considers that in order to improve the wavelength flatness of the optical attenuation factor of the optical attenuator, the optimization of the angle formed by the light incident surface and the light emitting surface of the substrate is an important issue. It was

Then, as shown in FIG. 2, the wavelength 1 when the angle (taper angle) formed by the light incident surface and the light emitting surface of the substrate (here, the glass substrate) is changed from 0 ° to 1 °
The light attenuation factor wavelength flatness at 520 nm to 1580 nm was determined. The difference between the maximum value and the minimum value in the optical attenuation rate spectrum after passing through the optical attenuator was defined as the optical attenuation rate wavelength flatness.

[0033] As a result, by an angle less than 0.5 ° greater than 0.15 ° formed between the light incident surface and light exit surface of the substrate, can be very good light attenuation factor wavelength flatness Confirmed .

In the figure, in the vicinity of the taper angle of 0 °, the optical attenuation factor wavelength flatness is large due to the periodic structure of the optical attenuation factor spectrum due to the multiple interference in the glass substrate (the flatness is not good). )it is conceivable that.

When the taper angle is increased, the influence of the periodic structure of the optical attenuation rate spectrum decreases. The effect of this periodic structure disappears when the taper angle is 0.2 °, and the optical attenuation rate wavelength Although the flatness is almost 0 dB, as the taper angle is further increased, the change in the optical attenuation rate due to the wavelength dependence of the refraction angle at the interface between the glass substrate and the atmosphere begins to contribute to the optical attenuation rate wavelength flatness. It is considered that the optical flatness of the optical attenuation factor deteriorates.

The optical attenuator of the present invention is based on the examination results, the angle greater than 0.5 ° than (the taper angle) of 0.15 ° formed between the light incident surface and the light exit surface of the substrate Since it is formed as described above, it is possible to make the optical attenuation factor wavelength flatness very good.

In the optical attenuator of the present invention,
In the structure in which the protective film for preventing the deterioration of the light attenuating film is formed on the surface of the light attenuating film, the deterioration of the light attenuating film is suppressed by the protective film even if the high intensity light is input, so that the high intensity light input is performed. It becomes a reliable optical attenuator that can withstand even.

Here, the protective film has a surface of the light attenuating film which is oxidized when an input light of high intensity (intensity exceeding 50 mW of light generally used in the past, for example, 200 mW) is incident. It is to prevent the chemical change of. Oxidation of the light attenuating film occurs because the light attenuating film is in contact with oxygen in the atmosphere.Therefore, a protective film should be formed on the surface of the light attenuating film so that the light attenuating film does not come into direct contact with oxygen in the atmosphere. By doing so, it becomes possible to suppress the oxidation of the light attenuating film and suppress the change of the light attenuating ratio such as the decrease of the light attenuating ratio of the light attenuating film.

Further, by forming a protective film on the surface of the light attenuating film, it becomes possible to protect against physical factors such as dust, dust and water. Furthermore, by making the material and the film thickness of the protective film appropriate, the protective film can also serve as an antireflection coating. Therefore, the protective film may be formed on the surface of the substrate opposite to the surface on which the light attenuation film is formed.

Further, the optical attenuator module of the present invention is configured by providing the above optical attenuator,
It is a highly reliable optical attenuator module that has good wavelength flatness of the optical attenuation factor and can withstand high intensity optical input.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the description of the example of the present embodiment, the same names as those in the conventional example are denoted by the same reference numerals, and the duplicate description thereof will be omitted. FIG. 1 shows an embodiment of an optical attenuator according to the present invention. Note that FIG. 1A schematically shows a perspective view of the optical attenuator 8 of the present embodiment, and a sectional view of the optical attenuator 8 is schematically shown in FIG. Has been done.

As shown in these figures, the optical attenuator 8 of the present embodiment has a glass substrate 1 as a substrate,
A light attenuating film 2 for attenuating incident light at a set light attenuating rate, and a light attenuating film on at least one of the light incident surface 3 and the light emitting surface 4 (here, the light incident surface 3) of the glass substrate 1. 2 is formed. The optical attenuator 8 of the present embodiment example
Are provided on the optical path between the optical fibers to be optically coupled, for example.

A side view of the glass substrate 1 is shown in FIG. 1B. As shown in FIGS. 1A, 1B and 1C, the optical attenuator of this embodiment is shown. 8 is most characteristic in that the angle formed by the light incident surface 3 and the light emitting surface 4 of the glass substrate 1 is formed to a value of 0.15 ° or more and 0.5 ° or less (for example, 0.3 °). Is.

In this embodiment, the glass substrate 1 has a substantially rectangular parallelepiped shape, but the light incident surface 3 and the light emitting surface 4 are not parallel but tapered, and the taper angle is the glass substrate. 1 is the angle formed by the light incident surface 3 and the light emitting surface 4.

The light attenuating film 2 has a metal as its constituent component, and is made of a material having a very small wavelength dependence of the light attenuating rate in a used wavelength band such as a wavelength of 1500 nm to 1650 nm. Specifically, Cr (chrome), Inconel, or the like is applied. The light attenuation film 2 is formed on the glass substrate 1 by a method such as vapor deposition, sputtering or plating.

The light attenuation film 2 has a light attenuation factor distribution in the X direction along the surface of the glass substrate 1. In the present embodiment example, this light attenuation factor distribution has a distribution form in which the light attenuation factor continuously changes in the X direction along the substrate surface of the glass substrate 1, as shown in FIG. ing. The horizontal axis (length in the X direction) of the graph shown in the figure shows the length from the upper end of the glass substrate 1 in FIG. 1 (b).

A protective film 5 for preventing deterioration of the light attenuating film 2 is formed on the surface of the light attenuating film 2. Further, in the present embodiment, the protective film 5 is a light attenuating film formed on the glass substrate 1. It is also formed on the surface opposite to the side surface (light emission surface 4).

The protective film 5 is made of SiO ₂ , TiO ₂ , Ta ₂
It is made of a dielectric material such as O ₅ or MgF ₂ or an organic material such as polyimide or PMMA (polymethylmethacrylate). When the protective film 5 is formed of these dielectrics or organic substances, it can be formed by vapor deposition, sputtering, spin coating, or the like.

The protective film 5 may be made of various materials capable of preventing the deterioration of the light attenuating film 2. The protective film 5 made of a dielectric material or an organic material may be dust, dust, water or the like. Can have a physical protection effect against. Further, when the protective film 5 is formed of the above-mentioned dielectric or organic substance,
By appropriately setting the film formation form for a well-known antireflection coat (for example, forming a plurality of layers in multiple layers), it is possible to serve as an antireflection coat.

Since the light attenuating film 2 is made of metal, the surface of the light attenuating film 2 may be intentionally oxidized to provide an oxide film layer, and this oxide film layer may be used as the protective film 5. Further, the oxide film layer and the protective film 5 of the dielectric or organic material may be used together. The thickness of the protective film 5 is 10 nm or more.

The present embodiment is configured as described above, and when incident light is incident on the optical attenuator 8 of the present embodiment, this light is transmitted by the light attenuating film 2 according to the incident position on the light attenuating film 2. The light is attenuated at the set light attenuation rate and emitted.

Then, in the present embodiment, the angle formed by the light incident surface 3 and the light emitting surface 4 of the glass substrate 1 is 0.15 ° or more and 0.5 ° or less based on the above-mentioned examination by the present inventor. And the influence of the periodic structure of the optical attenuation factor spectrum on the optical attenuation factor wavelength flatness due to the multiple interference in the glass substrate 1 and the wavelength dependence of the refraction angle at the interface between the glass substrate 1 and the atmosphere. Since it is possible to suppress the influence of the accompanying change in the optical attenuation rate on the optical attenuation rate wavelength flatness, an excellent optical attenuator having extremely small optical attenuation rate wavelength dependency can be obtained.

FIG. 3 shows the result of measurement of the optical attenuation factor wavelength dependence of the optical attenuator 8 of the present embodiment example. As is clear from the figure, the optical attenuator 8 of the present embodiment example is It was confirmed that the optical attenuator was an excellent optical attenuator with almost no wavelength dependence.

Further, the optical attenuator 8 of the present embodiment example
Forms the protective film 5 on the surface of the light attenuating film 2 to prevent the deterioration of the light attenuating film 2, the optical attenuator 8 of the present embodiment example has the protective film 5 even if high intensity light is input. Thus, the deterioration of the light attenuating film 2 can be suppressed, and a highly reliable optical attenuator 8 that can withstand high intensity light input can be obtained.

FIG. 4 shows the results of examining the change in the optical attenuation rate with respect to the incident time of light, using the optical attenuator 8 of the present embodiment and the conventional optical attenuator having the configuration shown in FIG. There is. This examination was conducted by injecting light having a wavelength of 1550 nm, an intensity of 200 mW, and a beam diameter (diameter) of 0.5 mm into both the optical attenuators. A characteristic line a shows the characteristic of the optical attenuator 8 of this embodiment, and a characteristic line b shows the characteristic of the conventional optical attenuator.

As shown by the characteristic line b in FIG. 4, in the conventional optical attenuator, the light attenuation rate begins to decrease immediately after the start of light incidence, and the light attenuation rate rapidly increases up to about 100 hours after the start of light incidence. Decrease. At this time, the change in optical attenuation factor immediately after the incidence was 0.12 dB. It should be noted that about 100
The reason why the change in the light attenuation factor is stable after the elapse of time is that the oxide film is formed on the light attenuation film 2 to further suppress the oxidation.

On the other hand, in the optical attenuator of the present embodiment, the optical attenuation rate hardly changes even after about 180 hours have elapsed since the start of the incident, and the optical attenuation rate change after the incidence time of 180 hours is 0.02 dB. Met.

As described above, the optical attenuator 8 of the present embodiment can prevent the deterioration of the light attenuating film 2 by forming the protective film 5 on the surface of the light attenuating film 2, and thereby, even if It was confirmed that the optical attenuator 8 is highly reliable and can withstand high-intensity light input with almost no change in light attenuation rate even when intense light is input.

Therefore, by constructing an optical attenuator module using the optical attenuator 8 of the present embodiment, the optical attenuator having a good wavelength flatness of the optical attenuation factor and capable of withstanding a high intensity optical input is provided. Modules can be formed.

FIG. 6 shows a first embodiment of an optical attenuator module using the optical attenuator of the above embodiment. The optical attenuator module of the present embodiment example has a frame 41 having an L-shape when viewed from the direction C in the figure, and is formed by disposing and fixing the optical attenuator 8 of the above embodiment example on the frame 41. Has been done. Fitting holes (not shown) for arranging and fixing the collimators 20, 21 are formed on the side surface of the frame 41, and the collimators 20, 21 are inserted and fixed in the fitting holes.

The collimators 20 and 21 are respectively
The lens provided in the collimator 20 is composed of the optical fibers 15 and 16 and a lens (not shown).
The light emitted from the optical fiber 15 on the incident side with a divergence angle is defined as parallel rays. On the other hand, the lens provided in the collimator 21 is configured to collect the light incident on the lens and make it enter the optical fiber 16 on the exit side.

When the optical attenuator module is provided in the optical communication system or the optical measuring system, it is desirable that the optical fiber 15 on the incident side and the optical fiber 16 on the outgoing side are provided in the same optical attenuator module substantially parallel to each other. In this embodiment, the optical fibers 15 and 16 are provided in parallel in the same optical attenuator module. Then, mirrors 6 and 7 serving as light reflecting means are arranged at an angle of 45 ° with respect to the optical axes of the optical fibers 15 and 16, and are fixed to the frame 41.

In the optical attenuator module of the present embodiment, the light incident from the optical fiber 15 on the incident side is collimated by the lens of the collimator 20 to be incident on the mirror 6, reflected by the mirror 6 and reflected by the optical attenuator 8. Incident on. The light passing through the optical attenuator 8 is reflected by the mirror 7, condensed by the lens of the collimator 21, and emitted from the optical fiber 16 on the emission side.

The example of the present embodiment is configured as described above, and since the optical attenuator module of the example of the present embodiment uses the optical attenuator 8 of the above-described example of the embodiment, the wavelength flatness of the optical attenuation factor is improved. An optical attenuator module that is good and has high reliability that can withstand high intensity light input can be provided.

FIG. 7 shows a second embodiment of the optical attenuator module according to the present invention. In the description of the second embodiment, the same names as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted or simplified.

As shown in the figure, the optical attenuator module according to the second embodiment is similar to the optical attenuator module according to the first embodiment, and the frame 41 and the above-described embodiment arranged on the frame 41. It has an example optical attenuator 8 and collimators 20 and 21.

The optical attenuator module of the second embodiment is provided with beam splitters 11 and 12 instead of the mirrors 6 and 7 provided in the optical attenuator module of the first embodiment. The optical attenuator module of the second embodiment is a photodiode 1
7 and 18, and optical attenuator moving means 10.

The beam splitter 11 functions as a first light splitting means for splitting the light and making one of the split lights incident on the optical attenuator 8.
Reference numeral 2 functions as a second light branching unit that branches the light transmitted through the optical attenuator 8. In this embodiment, the beam splitters 11 and 12 are both the beam splitter 1
5% of the light incident on 1, 12 is transmitted, and the remaining 95%
To reflect.

The photodiode 17 uses the optical attenuator 8 of the split light split by the beam splitter 11.
It functions as a first light detecting means for receiving the light except the incident light (here, the transmitted light of the beam splitter 11) and detecting its intensity. The photodiode 18 functions as a second light detection unit that receives one of the split lights split by the beam splitter 12 (here, the transmitted light of the beam splitter 12) and detects the intensity thereof. In the figure, 30,
Reference numerals 31, 32, and 33 respectively indicate electrode pins.

The optical attenuator moving means 10 moves the optical attenuator 8 in a direction (here, the X direction) which crosses the optical attenuation rate distribution region of the optical attenuation film.

The optical attenuator module according to the second embodiment is constructed as described above. The optical attenuator module according to the second embodiment includes, for example, an optical attenuation as an external system as shown in FIG. The rate detecting means 9 is connected.

The light attenuation rate detecting means 9 obtains the light attenuation rate of the optical attenuator 8 based on the light intensity detected by the photodiode 17 and the light intensity detected by the photodiode 18.

In the optical attenuator module of the second embodiment, the optical attenuator moving means 10 sets the optical attenuator 8 to the optical attenuating rate of the optical attenuating film based on the optical attenuating rate obtained by the optical attenuating rate detecting means 9. It was configured to move in the X direction across the distribution region.

The second embodiment can also obtain the same effect by the same operation as that of the first embodiment. In addition, in the second embodiment, beam splitters 11 and 12 are provided instead of the mirrors 6 and 7 in the above embodiment, and one of the branched lights branched by the beam splitters 11 and 12 is photodiode 17 respectively. , 18 to detect the respective intensities of the received light, the optical attenuation rate detecting means 9 can obtain the optical attenuation rate of the optical attenuator 8 based on the detected light intensities.

Therefore, in the second embodiment, the optical attenuator moving means 10 crosses the optical attenuator 8 across the optical attenuation rate distribution region of the optical attenuation film based on the optical attenuation rate obtained by the optical attenuation rate detecting means 9. It is possible to move in the X direction so that the optical attenuation factor becomes a desired value, and for example, the optical attenuation factor by the optical attenuator 8 can always be matched very accurately with the set optical attenuation factor.

FIG. 8 shows a third embodiment of the optical attenuator module according to the present invention. In the description of the third embodiment, the same reference numerals are given to the same names as those of the first and second embodiments, and the description thereof will be omitted or simplified.

As shown in the figure, the optical attenuator module of the third embodiment is similar to the optical attenuator module of the second embodiment, but includes a frame 41 and an optical attenuator 8 arranged on the frame 41. 2, beam splitters 11 and 12, collimators 20 and 21, photodiodes 17 and 18, and optical attenuator moving means 10.

Further, in the third embodiment, a potentiometer 25 is provided as an optical attenuator position detecting means for detecting the position where the optical attenuator 8 is arranged. The potentiometer 25 is a measuring instrument that converts a physical position into a voltage and measures the voltage. An electrode is provided on the back surface of the optical attenuating film 2 of the optical attenuator 8, and the tip of the electrode is attached to the potentiometer 25.
To be in contact with. Then, for example, if 5V is applied to the potentiometer in advance, a value from 0V to 5V is output according to the position where the electrode is in contact with the potentiometer 25.

In the third embodiment, the optical attenuation rate distribution of the optical attenuation film 2 of the optical attenuator 8 is a stepwise distribution as shown in FIG.
As the output of the potentiometer 25, the relational data between this output and the attenuation rate distribution of the light attenuating film 2 is given in advance.

The third embodiment is configured as described above, and the optical attenuator module of the third embodiment includes an optical feedback controller 23 as an external system and an optical attenuator module as shown in FIG. The attenuation amount detecting means 9 is connected.

The feedback control unit 23 sets the optical attenuation rate of the optical attenuator module to the set optical attenuation rate based on the detection data (detection voltage) by the potentiometer 25 and the relational data shown in FIG. 5B. The optical attenuator moving means 10 moves the optical attenuator 8 so that

The optical attenuation amount detecting means 9 obtains the optical attenuation rate of the optical attenuator 8 based on the optical intensities detected by the photodiodes 17 and 18, respectively, as in the second embodiment.

The third embodiment can also obtain the same effect by the same operation as that of the second embodiment. Further, in the third embodiment, the optical attenuator moving means 10 detects the position where the optical attenuator 8 is disposed by the potentiometer 25, and the optical attenuator moving means 10 determines whether the optical attenuator 8 is operated based on the detection result (for example, by the control of the feedback control unit 23). Since the optical attenuator 8 is moved so that the optical attenuation rate of the attenuator module becomes the set optical attenuation rate, the optical attenuation rate of the optical attenuator 8 can always be more accurately matched with the set optical attenuation rate.

Further, in the third embodiment, the position of the optical attenuator 8 is detected by the potentiometer 25, and the optical attenuation factor detecting means 9 detects the optical intensity based on the optical intensity detected by the photodiodes 17, 18. Since the optical attenuation factor of the attenuator 8 can also be obtained, the optical attenuator 8 can be moved more accurately by the optical attenuator moving means 10.

The present invention is not limited to the above-mentioned embodiments, but can take various modes. For example, in each of the above embodiments, the optical attenuation film 2 of the optical attenuator 8 is used.
Has an optical attenuation rate distribution as shown in FIGS. 5A and 5B, the optical attenuation rate distribution of the optical attenuation film 2 of the optical attenuator 8 is not particularly limited and is set appropriately. It is what is done. For example, the light attenuation film may have a light attenuation rate distribution other than the X direction in the drawing, or may be the light attenuation film 2 having a uniform light attenuation rate without the light attenuation rate distribution.

Further, in each of the above-described embodiments, the optical attenuator 8 has the optical attenuation film 2 on the light incident surface 3 of the glass substrate 1.
The light attenuating film 2 is formed on the light emitting surface 4 of the glass substrate 1.
It may be formed on the upper surface or on both surfaces of the light incident surface 3 and the light emitting surface 4.

Further, in each of the above embodiments, the optical attenuator 8 also has the protective film 5 formed on the surface of the glass substrate 1 opposite to the light attenuation film forming surface (light emitting surface 4 in the above embodiments). However, the protective film 5 can be omitted.

Further, in each of the above embodiments, the glass substrate 1 has the rectangular light incident surface 3 and the light emitting surface 4, but the shape of the glass substrate 1 and the light attenuation film 2 is not particularly limited. The light incident surface 3 and the light emitting surface 4 of the glass substrate 1 may be formed in a circular shape or a fan shape, for example.

When the light incident surface 3 and the light emitting surface 4 of the glass substrate 1 are circular or fan-shaped as described above, the light attenuation rate distribution of the light attenuating film 2 is the circumferential direction of the glass substrate 1 or It may be formed in the radial direction.

Further, the configuration of the optical attenuator module using the optical attenuator of the present invention is not limited to the above-mentioned embodiments, but may be set appropriately. In the optical attenuator module of the third embodiment, the potentiometer 25 is provided as the optical attenuator position detecting means for detecting the arrangement position of the optical attenuator 8, but the optical attenuator position detecting means is limited to the potentiometer 25. Instead, it is set appropriately.

Further, for example, in the optical attenuator module of the third embodiment, the optical attenuation factor distribution of the optical attenuation film 2 of the optical attenuator 8 is applied to the optical attenuator 8 applied to the first and second embodiments. The distribution may be the same as that of the film 2.

In addition, the beam splitters 11 and 1 as in the optical attenuator module of the second and third embodiments.
When the optical attenuator module is configured by providing 2,
The light transmittance may be different from the values in the second and third embodiments, or the beam splitters 11 and 12 may be used.
Other optical branching means may be provided.

Furthermore, in the optical attenuator modules of the second and third embodiments, the beam splitter 1
Either one of 1 and 12 may be a light reflecting means such as a mirror, or one of the beam splitters 11 and 12 may be a light reflecting means such as a mirror and the other may be a light splitting means other than the beam splitter. Good.

Further, in the above description, the optical attenuation amount detecting means 9 is connected to the optical attenuator module of the second embodiment as an external system, and the optical attenuator module of the third embodiment has the optical attenuator module 9 connected to it. Although the optical attenuation amount detecting means 9 and the feedback control unit 23 are connected as an external system, the external system connected to the optical attenuator module of the present invention is not particularly limited and may be appropriately set.

Further, the above-mentioned external system can be included not as an external system but as a constituent element of the optical attenuator module.

Further, when the optical attenuator position detecting means such as the potentiometer 25 is provided to form the optical attenuator module as in the third embodiment, the optical attenuator position detecting means detects the optical attenuator position detecting means. The optical attenuator is moved so that the optical attenuation factor of the optical attenuator module becomes the set optical attenuation factor based on the data and the relational data of the optical attenuator arrangement position and the attenuation factor distribution of the optical attenuation film given in advance. It can be moved by means.

Therefore, in the third embodiment, the light attenuation amount detecting means 9 may not be connected, and the light splitting means such as the beam splitters 11 and 12 and the light detecting means such as the photodiodes 17 and 18 may be omitted. First and second
Instead of the light branching means, a light reflecting means such as a mirror may be provided.

Further, in the optical attenuator module of the present invention, the light reflecting means and the light branching means can be omitted if the light is incident from one end side and is emitted from the other end side. However, like the optical attenuator module of each of the above embodiments, when the light reflecting means and the optical branching means are provided, and an optical fiber or the like is provided in parallel at one end side of the optical attenuator module, the device is downsized and other devices are used. The connection workability can be improved.

[0099]

The optical attenuator of the present invention forms the angle between the light incident surface and the light emitting surface of the substrate to more than 0.15 ° and less than 0.5 ° based on the result of the study by the present inventor. And the optical attenuation factor at wavelengths of 1520 nm to 1580 nm
The value of wavelength flatness is the optical attenuation factor when the angle is 0.5 °.
It is smaller than the value of wavelength flatness, and it depends on the influence of the periodic structure of the optical attenuation factor spectrum on the optical attenuation factor wavelength flatness caused by multiple interference in the substrate and the wavelength dependence of the refraction angle at the substrate-atmosphere interface. Since the influence of the change in the optical attenuation factor on the wavelength flatness of the optical attenuation factor can be suppressed, an excellent optical attenuator with extremely small wavelength dependency of the optical attenuation factor can be obtained.

In the optical attenuator of the present invention,
According to the configuration in which the protective film for preventing the deterioration of the light attenuating film is formed on the surface of the light attenuating film, the deterioration of the light attenuating film is suppressed by the protective film even if the high intensity light is input. The optical attenuator with high reliability can withstand input. In particular, if the thickness of the protective film is 10 nm or more, the effect of suppressing deterioration of the light attenuating film can be effectively exhibited.

Further, according to the optical attenuator having the optical attenuation film having the optical attenuation rate distribution, an appropriate optical attenuation rate can be obtained according to the optical attenuation rate distribution.

Further, according to the optical attenuator having a configuration in which the light attenuation rate distribution of the light attenuation film is such that the light attenuation rate continuously changes in at least one direction along the substrate surface, for example, the light attenuation rate distribution By moving the optical attenuator in a direction traversing the optical attenuator, the incident position of the incident light on the optical attenuating film can be changed to easily adjust the optical attenuating rate.

Further, according to the optical attenuator module of the present invention, by providing the optical attenuator having the above-mentioned excellent effect, the wavelength flatness of the optical attenuation factor is good, and high intensity optical input can be endured. The optical attenuator module can have high reliability.

Further, in the optical attenuator module of the present invention, according to the configuration in which the optical attenuator moving means is provided, for example, the optical attenuator moving means forms the optical attenuating rate distribution in the optical attenuating film of the optical attenuator and the optical attenuating means moves the optical attenuator. Effects such as moving the optical attenuator as necessary to move the optical attenuator in a direction that crosses the optical attenuation factor distribution area of the attenuating film, and changing the optical attenuation factor, or always maintaining the set optical attenuation factor accurately. Can be played.

Further, in the optical attenuator module of the present invention, optical branching means is provided on at least one of the incident side and the outgoing side of the optical attenuator, and one intensity of the branched light branched by the optical branching means is detected by the photodetecting means. According to the configuration, since it is possible to detect at least one of the incident light intensity to the optical attenuator and the outgoing light intensity from the optical attenuator,
Based on this detection result, for example, the optical attenuation factor of the optical attenuator can be grasped.

In particular, the first light branching means is provided on the incident side of the optical attenuator to detect one of the branched lights, which is branched by the first light detecting means, and the second light branching means is provided on the emitting side of the optical attenuator. When one of the branched light beams provided by the above is detected by the second light detecting means, the optical attenuation factor of the optical attenuator can be accurately grasped based on the detection result.

Therefore, based on the grasp of the optical attenuator of the optical attenuator, the optical attenuator is appropriately moved by the optical attenuator moving means or the like to change the optical attenuator or to always maintain the set optical attenuator accurately. It is possible to exert an effect.

Further, in the optical attenuator module of the present invention, the optical attenuator position detecting means for detecting the arrangement position of the optical attenuator by previously providing relational data between the arrangement position of the optical attenuator and the attenuation factor distribution of the optical attenuation film is provided. According to the configuration provided, for example, the optical attenuator is moved by the optical attenuator moving means so that the optical attenuation rate of the optical attenuator module becomes the set optical attenuation rate based on the detection data by the optical attenuator position detection means and the relational data. By doing so, it is possible to provide an optical attenuator module that can always maintain the optical attenuation rate accurately at the set optical attenuation rate.

Further, according to the optical attenuator position detecting means for detecting the arrangement position of the optical attenuator, and the optical attenuator module provided with the optical feedback control section so that the optical attenuation rate of the optical attenuator module becomes the set optical attenuation rate. The feedback control unit can accurately control the optical attenuation factor of the optical attenuator module to be maintained at the set optical attenuation factor.

[Brief description of drawings]

FIG. 1 is a main part configuration diagram showing an embodiment of an optical attenuator according to the present invention.

FIG. 2 is a graph showing the relationship between the substrate taper angle of the optical attenuator and the optical attenuation factor wavelength flatness.

FIG. 3 is a graph showing the wavelength dependence of the optical attenuation factor of the optical attenuator of the above embodiment.

FIG. 4 is a graph showing variations in the optical attenuation rate of the optical attenuator of the above-described embodiment in comparison with variations in the optical attenuation rate of the conventional optical attenuator.

FIG. 5 is a graph showing an example of optical attenuation factor distribution of the optical attenuator according to the present invention.

FIG. 6 is a first optical attenuator module according to the present invention.
It is a principal part block diagram which shows an example of embodiment.

FIG. 7 is a second optical attenuator module according to the present invention.
It is a principal part block diagram which shows an example of embodiment.

FIG. 8 is a third optical attenuator module according to the present invention.
It is a principal part block diagram which shows an example of embodiment.

FIG. 9 is an explanatory diagram showing a cross-sectional configuration of a conventional optical attenuator.

FIG. 10 is a graph showing the wavelength dependence of the optical attenuation factor of a conventional optical attenuator.

[Explanation of symbols]

1 glass substrate 2 light attenuating film 3 light incident surface 4 light emitting surface 5 protective film 6,7 mirror 8 optical attenuator 10 moving means 11, 12 beam splitter 25 potentiometer (optical attenuator position detecting means)

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B 5/00 G02B 26/02

Claims (18)

(57) [Claims] 1. A substrate and an incident light are attenuated at a set optical attenuation factor.
A light-attenuating film, and a light-incident surface and a light-exiting surface of the substrate.
The light-attenuating film is formed on at least one surface ofThe
Light for light with intensity higher than 50 mW on the surface of the light attenuation film
A protective film is formed to prevent deterioration of the attenuation film,Light incident on the substrate
The angle between the surface and the light exit surface is 0.15 °Greater than
0.5 °Less thanFormed inWavelength 1520nm-1580
The value of the optical attenuation factor wavelength flatness in nm is 0.
The value was smaller than the value of the optical attenuation factor wavelength flatness at 5 °.
Optical attenuator characterized by that. 2. The substrate and the incident light are attenuated at a set light attenuation rate.
A light-attenuating film, and a light-incident surface and a light-exiting surface of the substrate.
The light-attenuating film is formed on at least one surface of
The angle between the light incident surface and the light emitting surface of the substrate is 0.2 ° or less.
An optical fiber characterized by being formed at an angle of 0.4 ° or less.
Attenuator. 3. The optical attenuator according to claim 2 , wherein a protective film for preventing deterioration of the light attenuating film is formed on the surface of the light attenuating film. 4. The method of claim 1 or claim 3 optical attenuator wherein the thickness of the protective layer was not less than 10 nm. 5. The optical attenuation films claim 1 or claim 2 or claim 3 or claim 4 light described, characterized in that it has at least one direction light attenuation factor distribution along the substrate surface Attenuator. 6. The optical attenuator of claim 5, wherein the light attenuation factor distribution, characterized in that the forms and distribution form light attenuation factor in at least one direction along the substrate surface changes continuously. 7. An optical attenuator module, comprising: the optical attenuator according to any one of claims 1 to 6 ; and an optical attenuator moving means for moving the optical attenuator. 8. The light attenuating film of the optical attenuator has a light attenuating rate distribution in at least one direction along the substrate surface, and the optical attenuator moving means crosses the light attenuator across the light attenuating rate distribution region of the light attenuating film. The optical attenuator module according to claim 7 , wherein the optical attenuator module moves in a direction. 9. A light attenuator according to any one of claims 1 to 6, 1 of the branched light branched light
One of the first light branching means for making the incident light to the light attenuator, the second light branching means for branching the light transmitted through the light attenuator, and the branched light branched by the first light branching means First light detecting means for receiving light other than light incident on the optical attenuator to detect its intensity, and one of the branched lights branched by the second light branching means to detect its intensity. And an optical attenuator module having a second light detecting means. 10. An optical attenuator according to any one of claims 1 to 6 , and an optical branching unit for branching the light and using one of the branched lights as incident light to the optical attenuator.
A light reflecting means for reflecting the light transmitted through the optical attenuator, and a light detecting means for receiving the light excluding the incident light to the optical attenuator among the branched lights branched by the light branching means and detecting the intensity thereof. An optical attenuator module having. 11. An optical attenuator according to any one of claims 1 to 6 , a light reflecting means for reflecting light and converting the reflected light into incident light to the optical attenuator, and the optical attenuator. An optical attenuator module comprising: a light branching unit for branching the transmitted light; and a light detecting unit for receiving one of the branched lights branched by the light branching unit and detecting the intensity thereof. 12. The optical attenuator according to claim 5 or 6 , a first optical branching unit for branching the light and making one of the branched lights incident on the optical attenuator, and the optical attenuator. Second light branching means for branching the light that has passed through, and first light for detecting the intensity of the branched light branched by the first light branching means excluding the light incident on the optical attenuator and detecting its intensity. Optical detecting means, second optical detecting means for receiving one of the branched lights branched by the second optical branching means and detecting its intensity, and the optical attenuator for the optical attenuation rate distribution of the optical attenuation film. An optical attenuator module comprising: an optical attenuator moving unit that moves in a direction crossing the region. 13. The optical attenuator according to claim 5 or 6 , an optical branching unit for branching light into one of the branched lights to be incident light to the optical attenuator, and a light transmitted through the optical attenuator. A light reflecting means for reflecting light, a light detecting means for receiving light other than the incident light to the optical attenuator among the branched light branched by the light branching means, and detecting the intensity thereof, and an optical attenuating film for the optical attenuator. And an optical attenuator moving unit that moves in a direction crossing the optical attenuation factor distribution region of the optical attenuator module. 14. The optical attenuator according to claim 5 or 6 , a light reflecting means for reflecting light and making the reflected light incident on the optical attenuator, and a light transmitted through the optical attenuator are branched. The light branching means, the light detecting means for receiving one of the branched lights branched by the light branching means and detecting the intensity thereof, and the light attenuator are moved in a direction crossing the light attenuation rate distribution region of the light attenuating film. An optical attenuator module having an optical attenuator moving means. 15. The optical attenuator according to claim 5 or 6 , wherein the relational data between the arrangement position of the optical attenuator and the attenuation factor distribution of the optical attenuation film is given in advance, and the arrangement position of the optical attenuator is determined. An optical attenuator position detecting means for detecting is provided, and the optical attenuator is moved so that the optical attenuation rate of the optical attenuator module becomes a set optical attenuation rate based on the detection data by the optical attenuator position detecting means and the relational data. An optical attenuator module characterized by being moved by means. 16. Optical attenuator position detecting means for detecting relation between the arrangement position of the optical attenuator and the attenuation factor distribution of the optical attenuating film and detecting the arrangement position of the optical attenuator, and the optical attenuator position detecting means. claim 12 or claim 13 or, characterized in that to move the optical attenuator moving means an optical attenuator so that the light attenuation factor of the optical attenuator module is set light attenuation rate based on said relationship data and the detection data by The optical attenuator module according to claim 14 . 17. An optical attenuation rate detecting means for obtaining an optical attenuation rate of an optical attenuator based on the optical intensity detected by the first optical detecting means and the optical intensity detected by the second optical detecting means, 13. The optical attenuator module according to claim 12, wherein the attenuator moving means moves the optical attenuator based on the optical attenuation rate obtained by the optical attenuation rate detecting means. 18. Optical attenuator position detecting means for detecting relation between the arrangement position of the optical attenuator and the attenuation factor distribution of the optical attenuation film and detecting the arrangement position of the optical attenuator, and the optical attenuator position detecting means. 13. A feedback control unit for moving the optical attenuator by the optical attenuator moving means so that the optical attenuator of the optical attenuator module becomes a set optical attenuator based on the detection data and the relational data according to claim 12. The optical attenuator module according to claim 16 .