JP2003232943A - Wavelength multiplex communication signal demultiplexer, and optical transmission and reception module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To demultiplex a wavelength multiplex communication signal from a multimode optical fiber without causing any loss or crosstalk and to decreases a manufacturing cost. <P>SOLUTION: In the wavelength multiplex communication signal demultiplexer 1 which demultiplexes a multimode wavelength multiplex optical signal 2 at every wavelength, a multimode waveguide 3, in which the multimode wavelength multiplexed optical signal 2 propagates, is subjected to a Bragg grating 4 for demultiplexing light, and is provided with a light expansion angle decreasing means 6 which decreases the expansion angle of the multimode wavelength multiplexed optical signal 2 which is entered from a light entrance part 5. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexing communication signal demultiplexing device for separating a multimode wavelength division multiplexing optical signal for each wavelength and an optical transmission / reception module using the same.

[0002]

2. Description of the Related Art In recent years, a single mode optical fiber having a large transmission capacity has been used in an optical fiber network connecting large cities or continents, and particularly recently, a dense wavelength multiplexing system (Dense Wavelength) every several nm is used. Division Multiplexin
g) has been adopted. In the case of this method, the fact that there is one mode as the wavelength separation means is used to
A branching element using a phase difference called an (Arrayed Waveguide grating) has been put into practical use.

In order to extract one wave of DWDM light, a single mode optical fiber provided with a filter or a Bragg grating or a waveguide is used.

Further, even in the same single mode, a wavelength division system (Wide Wavelength Division) having a relatively wide wavelength interval is used.
In Multiplexing), there is a device that directly inserts a multilayer film filter into a waveguide to perform demultiplexing, and a device that uses a diffraction grating, by taking advantage of the characteristic that the propagation angle is 1 ° or less.

[0005]

Incidentally, regarding the demultiplexing for multimode, unlike the single mode, there are many propagation modes and there is not a single mode, and the phase difference between the modes is larger than the phase difference between the wavelengths. Therefore, it is impossible to use a device such as an AWG that confine an optical signal in a waveguide to propagate it and demultiplex it by using a phase difference between wavelengths.

Further, in a device in which a filter or a Bragg grating is provided in a single mode optical fiber or a waveguide, the light from the multimode optical fiber has a different propagation angle depending on the mode, and the incident angle of the light to the filter or the Bragg grating is different. The dislocation wavelengths of the transmitted light and the reflected light change depending on the difference of the above, and it is difficult to make the dislocation wavelengths the same in all modes.

Therefore, as shown in JP-A-62-183405 and JP-A-10-319262, the propagating light from the multi-mode optical fiber is converted into pseudo-parallel light through a lens optical system to generate a waveguide. There was a demultiplexing device with a multilayer filter directly inserted into the.

However, in that device, very high precision is required for the alignment between the optical fiber and the lens,
It took a lot of time and labor for the alignment. Further, even if a slight positional deviation occurs, there is a problem in that a positional error in the optical receiver or the optical fiber portion after the demultiplexing becomes large, which causes loss and crosstalk.
Further, since it is necessary to insert as many filters as the demultiplexing number into the demultiplexing element, there is a problem that the manufacturing cost is high.

Therefore, the present invention has been devised to solve the above problems, and an object thereof is to demultiplex a wavelength division multiplexed communication signal from a multimode optical fiber without causing loss or crosstalk, An object of the present invention is to provide a wavelength multiplexing communication signal demultiplexing device that can be manufactured at low cost and an optical transceiver module using the same.

[0010]

[Means for Solving the Problems] To solve the above problems,
The present invention relates to a WDM communication signal demultiplexing device for separating a multimode WDM optical signal for each wavelength, a Bragg for demultiplexing light into a multimode waveguide in which the multimode WDM optical signal is propagated. In addition to providing the grating, a light divergence angle reducing means for reducing the divergence angle of the multimode wavelength division multiplexed optical signal incident from the light incident part is provided.

According to the above structure, the light whose propagation angle is reduced by the light divergence angle reducing means is propagated from the light incident portion of the multimode waveguide to the Bragg grating and from the Bragg grating to the light emitting portion, whereby the lens The alignment accuracy between the optical divergence reducing means such as a lens and the optical fiber is relaxed compared to the conventional device that demultiplexes with a filter as quasi-parallel light using only the optical system. Since it does not occur, loss and crosstalk can be prevented. In addition, the Bragg grating used for demultiplexing can be drawn directly on the waveguide, so it does not require mounting costs such as filter insertion compared to conventional devices that use filters, thus reducing manufacturing costs. Is achieved.

It is preferable that the light divergence angle reducing means is provided with a convex lens between the light incident portion and the multimode waveguide.

Further, it is preferable that the light divergence angle reducing means is formed such that the light incident portion side of the multimode waveguide is formed in a taper shape which gradually becomes thicker along a light traveling direction.

Further, at least one of the core and the clad of the multimode waveguide is formed of a fluorinated acrylic resin, and the multimode waveguide is irradiated with excimer laser light to form a Bragg grating. Is preferred.

At least one of the core and the clad of the multimode waveguide is formed of a photosensitive organic material or an organic-inorganic hybrid material, and the multimode waveguide is covered with a mask when the core is cured. What formed the Bragg grating by changing the amount of ultraviolet rays with which the core is irradiated is preferable.

Further, it is preferable that the light emitting portion of the multimode waveguide is provided with a condensing means for condensing the multimode wavelength multiplexed optical signal.

Further, according to the present invention, a plurality of light sources, a single mode waveguide for propagating and multiplexing optical signals from these light sources, and a wavelength division multiplex communication signal component according to any one of claims 1 to 6 are provided. An optical transceiver module comprising a wave device and the same number of light receivers as the light sources.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a first preferred embodiment of a wavelength division multiplex communication signal demultiplexing apparatus according to the present invention.

As shown in the figure, the wavelength division multiplexing communication signal demultiplexing apparatus 1 is connected between the multimode optical fibers 14 and is an apparatus for separating the multimode wavelength division multiplexing optical signal 2 for each wavelength. Mode WDM optical signal 2
Is applied to the multimode waveguide 3 through which the light is propagated, and the optical divergence angle for reducing the divergence angle of the multimode wavelength division multiplexed optical signal 2 incident from the light incident part 5 is provided. It is characterized in that a reducing means 6 is provided.

In the present embodiment, the light spread angle reducing means 6
As an example, a case where the tapered waveguide 7 is used and the WWDM light separated by 24.5 nm in the 1300 nm band by the Bragg grating 4 is demultiplexed will be described as an example.

At least one of the core and the clad (both in the present embodiment) of the multimode waveguide 3 is formed of a fluorinated acrylic resin. A Bragg grating 4 is formed substantially in the middle of the multimode waveguide 3.

The Bragg grating 4 is formed with an inclination of 5 ° with respect to the propagation direction of the multimode wavelength division multiplexed optical signal 2. The reflection waveguide 12 is branched and formed in the light reflection direction of the Bragg grating 4, and the multimode waveguide 3 is formed in a substantially y shape.

The Bragg grating 4 is formed by masking the multimode waveguide 3 with a phase mask and irradiating it with excimer laser light. The refractive index difference between the excimer laser-irradiated portion and the non-irradiated portion is about 1%, and by applying the Bragg grating 4 in the range of 100 μm, a theoretical reflectance of 100% in the 1300 nm band and a reflection wavelength width of 10 nm are obtained. be able to.

The reflection width of the Bragg grating 4 is determined by the refractive index difference of the grating and is 2 in the 1300 nm band.
When demultiplexing is performed at intervals of 4.5 nm, the difference in refractive index is preferably around 1%. This is because when the difference in refractive index greatly exceeds 1%, the wavelength width of the reflection band becomes large. For example, when the difference in refractive index is 2.5%, it becomes 20 nm or more, which is unusable for WWDM applications with 24.5 nm intervals. This is possible because when the refractive index difference is 0.5% or less, the reflection wavelength width is 10 nm or less, and the reflection band becomes sensitive to the positional deviation of the wavelength of the light source.

The length of the Bragg grating 4 applied to the multi-mode waveguide 3 is 24 in the 1300 nm band.
When performing demultiplexing at intervals of 5 nm, it is preferable to have a wavelength of around 100 μm in terms of reflectance and size of the demultiplexing element. This is 10
This is because when the thickness is 0 μm or less, the reflectance becomes 100% or less, which causes crosstalk and loss, and when the thickness is 100 μm or more, the writing length becomes long and the size of the element itself becomes large.

On the light incident portion 5 side of the multimode waveguide 3, a tapered waveguide 7 formed in a tapered shape gradually thickening along the traveling direction of the optical signal 2 is used as the light spread angle reducing means 6. It is provided.

The light emitting portion 8 (including the light emitting portion on the side of the reflection waveguide 12) of the multimode waveguide 3 is provided with a light collecting means 9 for collecting the reflected light 15 and the transmitted light 16. The condensing means 9 is composed of a tapered waveguide 11 formed in a tapered shape that gradually becomes thinner along the traveling direction of the optical signal 2. That is, the tapered waveguide 1 that serves as the light collecting means 9
1 is formed in a target shape with the tapered waveguide 7 that serves as the light spread angle reducing means 6.

Next, the operation of the wavelength division multiplex communication signal demultiplexing apparatus 1 having the above configuration will be described.

In the wavelength-division-multiplexing communication signal demultiplexer 1, for example, the 2-wavelength multiplexed light 2 from the multi-mode optical fiber 14 having NA 0.27 and a core diameter of 62.5 μm is NA.
When both the core clad of 0.3 and the core cladding enter the multimode waveguide 3 made of resin, the divergence angle of the two-wavelength multiplexed light 2 can be set to 1 ° by the tapered waveguide 7. As a result, the 2-wavelength multiplexed light 2 is transmitted to the Bragg grating 4
Is accurately demultiplexed, and a theoretical reflectance of 100% in the 1300 nm band and a reflection wavelength width of 10 nm can be obtained.

The reflected light 15 reflected by the Bragg grating 4 propagates through the reflection waveguide 12 and its light emitting portion 8
The light is condensed by the tapered waveguide 11 and is incident on the multimode optical fiber 14 having a core diameter of 62.5 μm.

On the other hand, the transmitted light 16 that has passed through the Bragg grating 4 travels straight through the multimode waveguide 3 and propagates, is condensed by the tapered waveguide 11 of the light emitting portion 8 thereof, and has a core diameter of 62.5 μm. It is incident on the mode optical fiber 14.

In this embodiment, since the Bragg grating 4 used for demultiplexing can be directly drawn on the multimode waveguide 3, compared to the conventional device using a filter, insertion of a filter or the like can be performed. There is no mounting cost and a significant reduction in manufacturing cost is achieved.

Further, in the present embodiment, since the multimode waveguide 3 is made of resin, it is easier to manufacture and the accuracy is improved as compared with the case of using the glass material used in the single mode. . In other words, it is necessary to solve the problems such as a longer reactive ion etching time for forming a waveguide pattern that occurs when a glass material is used, and the occurrence of cracks due to strain of glass laminated with a thick film. You can Further, it is possible to easily write the Bragg grating by irradiating various lights according to the resin.

Here, for comparison, a wavelength division multiplexing communication signal demultiplexer without the tapered waveguide 7 (see FIG. 5) was used to demultiplex two light sources with a wavelength interval of 24.5 nm in the 1300 nm band. The wavelength distribution of the transmitted light at that time is shown in FIG.

As shown in the figure, when the taper waveguide 7 which is the light divergence angle reducing means 6 is not used, the transmitted light vector is not a single wavelength, but light of other incident wavelengths is also mixed, and It becomes a cause of talk and cannot be used as a demultiplexer, and it can be seen that the wavelength division multiplexing communication signal demultiplexing device 1 according to the present invention exerts superior operational effects.

FIG. 2 is a block diagram showing a second preferred embodiment of the wavelength division multiplexing communication signal demultiplexer according to the present invention.

As shown in the figure, in the present embodiment, a lens 17 is used as the light divergence angle reducing means 6, and the case where the WWDM light separated by 24.5 nm in the 1300 nm band by the Bragg grating 4 is demultiplexed. An example will be described.

At least one of the core and the clad (both in the present embodiment) of the multimode waveguide 3 is formed of a photosensitive organic material or organic-inorganic hybrid material containing SiO ₂ . A Bragg grating 4 is formed in the approximately middle portion.

When the core of the multimode waveguide 3 is cured, the Bragg grating 4 is written by changing the amount of ultraviolet rays applied to the core by using a mask in which transparent portions and gray portions are repeated in a Bragg wavelength cycle. ing. The difference in the refractive index of the core irradiated with the ultraviolet light by the transparent mask and the gray mask is about 1%, and the Bragg grating 4 is applied in the range of 100 μm to obtain 1
A theoretical reflectance of 100% in the 300 nm band and a reflection wavelength width of 10 nm can be obtained.

The lens 17 having a focal length of 2 mm is used. By disposing the lens 17 at the focal position with respect to the multimode optical fiber 14 on the side of the light incident section 5, the light after passing through the lens can be obtained. 2 spread angle is 0.5
The beam diameter can be 1.5 mm or less.

Further, the lens 17 has a light emitting portion (including a light emitting portion on the side of the reflection waveguide 12) of the multimode waveguide 3 8
Is also provided, and plays a role as a light collecting means 9 that collects the reflected light 15 and the transmitted light 16.

Since the other configurations are similar to those of the wavelength division multiplexing communication signal demultiplexing apparatus 1 of FIG. 1, the same reference numerals are given and the description thereof will be omitted.

According to the present embodiment, for example, NA0.
27, multimode optical fiber 1 with a core diameter of 62.5 μm 1
When the two-wavelength multiplexed light 2 from 4 is incident on the resin-made multimode waveguide 3 with the core cladding of NA 0.3,
With the lens 17, the spread angle of the two-wavelength multiplexed light 2 is set to 0.
It can be set to 5 °, and the two-wavelength multiplexed light 2 is accurately demultiplexed by the Bragg grating 4 and 1300 nm.
A theoretical reflectance of 100% in the band and a reflection wavelength width of 10 nm can be obtained.

In this way, the multimode wavelength division multiplexed optical signal 2 whose propagation angle is reduced by the light spread angle reducing means 6
By propagating from the light incident part 5 of the multimode waveguide 3 to the Bragg grating 4 and from the Bragg grating 4 to the light emitting part 8 as a quasi-parallel light by using only the lens optical system. The alignment accuracy between the optical spreader and the light divergence angle reducing means such as a lens is relaxed more than in the device. Therefore, the alignment becomes easy, and the positional deviation does not occur, so that loss and crosstalk can be prevented.

Further, in the present embodiment, the Bragg grating 4 used for demultiplexing can be directly drawn on the multimode waveguide 3 as in the wavelength division multiplexing communication signal demultiplexing device 1 of FIG. Compared with a conventional device using a filter, a mounting cost such as insertion of a filter is not required, and a significant reduction in manufacturing cost is achieved.

FIG. 3 is a block diagram showing a third preferred embodiment of the wavelength division multiplexing communication signal demultiplexer according to the present invention.

In the present embodiment, 24.
1 shows a wavelength division multiplex communication signal demultiplexing device 1 for separating four waves at 5 nm intervals.

In the multimode waveguide 3, at least one of the core and the clad (both in the present embodiment) is formed of a fluorinated acrylic resin or a photosensitive organic-inorganic hybrid material containing SiO _2. Has been done.

A lens 17 is provided as a light divergence angle reducing means 6 on the light incident portion 5 side of the multimode waveguide 3. This lens 17 is a lens similar to that shown in FIG. In the present embodiment, the tapered waveguide 7 may be used as the light divergence angle reducing means 6.

Bragg gratings 4 are formed on the multimode waveguide 3 at three locations by irradiating excimer laser light or ultraviolet rays. In the light reflection direction of each Bragg grating 4, a reflection waveguide 12 is formed to be branched.

The light emitting portion 8 of each reflection waveguide 12 is provided with a lens 17 as a light converging means 9, and further a light receiver 18 for detecting the light condensed by the lens 17 as an optical signal. It is provided.

A reflecting mirror 21 is provided at the downstream end 19 of the multimode waveguide 3, and its reflecting direction is in the reflecting direction.
The reflection waveguide 22 is formed. This reflection waveguide 22
Also, similarly to the reflection waveguide 12, a lens 17 and a light receiver 18 are provided.

According to the present embodiment, the core diameter is 62.5 μm.
The 4-wavelength multiplexed light 23 incident from the m multimode optical fiber 14 is the lens 17 which is the light spread angle reducing means 6.
Then, it becomes pseudo-parallel light having a propagation angle of 0.5 ° and is incident on the multimode waveguide 3.

Then, with each Bragg grating 4,
One wave is reflected from each of the four-wavelength multiplexed light 23. Each reflected light 24 reflected is propagated through the reflection waveguide 12, condensed by the lens 17, and detected by the light receiver 18. Meanwhile, all Bragg gratings 4
The transmitted light 25 that has passed through is reflected by the reflection mirror 21, propagated through the reflection waveguide 22, condensed by the lens 17, and detected by the light receiver 18.

According to the present embodiment, since the number of Bragg gratings 4 is large, the merit that the multi-mode waveguide 3 can be written in batch is large, and the range of cost reduction is large compared with the conventional device.

By the way, in the present embodiment, the transmitted light 25
Is reflected by the reflecting mirror 21 to the reflection waveguide 22,
It may be reflection by a Bragg grating. According to this, it is possible to write at the same time as writing to another Bragg grating 4, and it is possible to save the labor of installing the reflecting mirror 21.

In the embodiments shown in FIGS. 1 to 3, the fluorinated acrylic resin, the photosensitive organic material, or the organic-inorganic hybrid material is used as the material for the multimode waveguide 3. However, it is not limited to this. For example, polyimide, epoxy, or silicone resin may be used. However, when the Bragg grating is applied, since the amount of change in the refractive index varies depending on the resin, it is necessary to select the wavelength of light irradiation or the like according to each resin.

FIG. 4 is a block diagram showing a preferred embodiment of an optical transmission / reception module using the wavelength division multiplexing communication signal demultiplexing device according to the present invention.

The optical transmission / reception module 26 includes a transmission section 31 and a reception section 32. The transmitter 31 is provided with a plurality of (four in the present embodiment) light sources 27 and a single mode waveguide 28 that propagates and multiplexes optical signals from these light sources. The light source 27 is 1300
In the nm band, it emits light having different wavelengths every 24.5 nm.

The transmitter 31 is provided with 1300 from the light source 27.
A single mode multiplexer 33 is provided for multiplexing four wavelengths of light having wavelengths of 24.5 nm in the nm band.

The receiving section 32 has a wavelength division multiplexing communication signal demultiplexing device 1 connected to the multimode optical fiber shown in FIG.
And the same number of light receivers 29 as the light sources 27.

According to the optical transmission / reception module 26 having the above structure, the transmission light is low loss in both multimode and single mode optical fibers because the single mode waveguide 28 is used in the multiplexing part of the transmission part 31. The optical fiber used for optical communication can be used for both single mode and multimode.

Further, by providing the wavelength division multiplex communication signal demultiplexing device 1 connected to the multimode optical fiber in the receiving section 32 and using the multimode optical fiber for reception,
Optical fibers used for optical communication can be both single mode and multimode. Further, by using the multimode waveguide 3, it is possible to connect with single-mode and multimode optical fibers with almost no loss.

[0065]

In summary, according to the present invention, the wavelength multiplexing communication signal from the multimode optical fiber can be demultiplexed without causing loss or crosstalk, and the manufacturing cost can be reduced. Exert.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first preferred embodiment of a wavelength division multiplexing communication signal demultiplexing device according to the present invention.

FIG. 2 is a configuration diagram showing a second preferred embodiment of a wavelength division multiplexing communication signal demultiplexing device according to the present invention.

FIG. 3 is a configuration diagram showing a preferred third exemplary embodiment of a wavelength division multiplexing communication signal demultiplexing apparatus according to the present invention.

FIG. 4 is a configuration diagram showing a preferred embodiment of an optical transmission / reception module using the wavelength division multiplexing communication signal demultiplexing device according to the present invention.

FIG. 5 is a configuration diagram showing a wavelength division multiplexing communication signal demultiplexing device that does not use a tapered waveguide.

FIG. 6 is a block diagram of the wavelength division multiplex communication signal demultiplexer of FIG.
6 is a graph showing a wavelength distribution of transmitted light when two light sources having a wavelength interval of 24.5 nm are demultiplexed in a 300 nm band.

[Explanation of symbols]

1 WDM communication signal demultiplexer 2 Multimode wavelength multiplexed optical signal 3 Multimode waveguide 4 Bragg grating 5 Light incident part 6 Light spread angle reduction means 7 Tapered waveguide 8 Light emitting part 9 Focusing means 17 lenses 27 light source 28 Single Mode Waveguide 29 Light receiver

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuzo Ito             1-6-1, Otemachi, Chiyoda-ku, Tokyo             Standing Wire Co., Ltd. F term (reference) 2H047 KA03 KA13 LA02 LA18 MA03                       MA05 PA02 PA05 PA12 PA15                       PA24 PA28 QA04 QA05 RA08                       TA01 TA31

Claims (7)

[Claims] 1. A wavelength division multiplexing communication signal demultiplexing device for demultiplexing a multimode wavelength division multiplexing optical signal for each wavelength, for demultiplexing light into a multimode waveguide in which the multimode wavelength division multiplexing optical signal is propagated. A wavelength division multiplexing communication signal demultiplexing device, which is provided with a Bragg grating and an optical divergence angle reducing means for reducing a divergence angle of a multimode wavelength multiplexed optical signal incident from a light incident part. 2. The wavelength division multiplexing communication signal demultiplexing device according to claim 1, wherein said light divergence angle reducing means comprises a convex lens provided between said light incident part and said multimode waveguide. 3. The wavelength division multiplex according to claim 1, wherein the light divergence angle reducing means is formed such that the light incident portion side of the multimode waveguide is tapered so as to be gradually thicker along a light traveling direction. Communication signal demultiplexer. 4. A Bragg grating is formed by irradiating the multimode waveguide with excimer laser light, at least one of a core and a clad of the multimode waveguide being formed of a fluorinated acrylic resin. Item 5. A wavelength division multiplexing communication signal demultiplexer according to any one of items 1 to 3. 5. At least one of a core and a clad of the multi-mode waveguide is formed of a photosensitive organic material or an organic-inorganic hybrid material, and the multi-mode waveguide is covered with a mask when the core is cured. The wavelength division multiplexing communication signal demultiplexing device according to any one of claims 1 to 3, wherein a Bragg grating is formed by changing the amount of ultraviolet rays applied to the core. 6. The light emitting portion of the multimode waveguide,
6. The wavelength division multiplexing communication signal demultiplexing device according to claim 1, further comprising a condensing means for condensing the multimode wavelength division multiplexed optical signal. 7. A plurality of light sources, and a single-mode waveguide that propagates and multiplexes optical signals from the light sources,
An optical transceiver module comprising: the wavelength division multiplexing communication signal demultiplexing device according to any one of claims 1 to 6; and the same number of light receivers as the light sources.