JP2003043275A - Optical multiplexer/demultiplexer, and method for manufacturing optical multiplexer/demultiplexer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical multiplexer/demultiplexer whose size is reduced by integrating a mechanism to monitor the signal light of each channel even when the number of channels is increased. SOLUTION: The signal light propagates in a core 16 for every wavelength, part of the signal light is guided to a tap waveguide 18 as monitor light, received by a light receiving element 13, and then the signal light of each channel is monitored. The tap waveguide 18 is formed so as to branch and guide only very partial light of the light propagating in the core 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical multiplexer / demultiplexer used in the field of optical wavelength division multiplexing, and more particularly to an optical multiplexer / demultiplexer having a function of monitoring signals of respective channels and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in the case of monitoring the signal light of each channel in a high-density WDM communication system, conventionally, a tap coupler for guiding a part of the signal light and a monitor photo are provided after the optical multiplexer / demultiplexer. It has been common practice to connect a diode by fusion splicing and monitor the signal light using the light guided by the tap coupler.

[0003]

However, when the number of channels increases as in the high-density wavelength-division multiplex communication system in recent years, the optical multiplexer / demultiplexer replaces the dielectric multilayer filter or the optical fiber grating with the arrayed waveguide diffraction. By using a grating (hereinafter abbreviated as “AWG”), the number of parts can be reduced and downsizing can be achieved. However, if a mechanism for monitoring the signal light of each channel is provided, the number of channels will increase. As a result, the number of tap couplers and monitor photodiodes used has increased, and the size of the entire optical module has increased. The present invention has been made to solve such a problem, and an optical multiplexer / demultiplexer capable of downsizing by integrating a mechanism for monitoring the signal light of each channel even if the number of channels increases. The purpose is to provide.

[0004]

In order to solve the above-mentioned problems, the invention according to claim 1 is such that a tap waveguide for branching a part of the signal light propagating in the core is formed in the clad. The optical multiplexer / demultiplexer is characterized in that a light receiving element is arranged in a groove provided in the clad, and the monitor light guided by the tap waveguide is received by the light receiving element to monitor the signal light for each channel. is there. Accordingly, the monitor mechanism can be provided on the substrate of the optical multiplexer / demultiplexer, the number of components can be reduced, and the optical multiplexer / demultiplexer that can be downsized can be realized. According to a second aspect of the present invention, in the optical multiplexer / demultiplexer according to the first aspect, the tap waveguide is formed in a substantially S shape. According to a third aspect of the present invention, in the optical multiplexer / demultiplexer according to the first or second aspect, the tap waveguide is formed by converging and irradiating a pulse laser to induce a refractive index increasing region in the cladding. It is characterized by being According to a fourth aspect of the invention, in the optical multiplexer / demultiplexer according to the third aspect, the pulse laser is a femtosecond laser. The invention according to claim 5 is the invention according to claim 1, 2,
The optical multiplexer / demultiplexer described in 3 or 4 is characterized in that the tap waveguide is formed in the cladding of the input optical waveguide or the output optical waveguide.

According to a sixth aspect of the present invention, a tap waveguide for branching a part of the signal light propagating in the core is formed in the clad, and a light receiving element is arranged in a groove provided in the clad. A method of manufacturing an optical multiplexer / demultiplexer in which a monitor light guided by a tap waveguide is received by a light receiving element and a signal light is monitored for each channel. It is a method of manufacturing an optical multiplexer / demultiplexer characterized by forming a tap waveguide by inducing a refractive index increasing region. According to a seventh aspect of the present invention, in the method of manufacturing the optical multiplexer / demultiplexer according to the sixth aspect, the tap waveguide is formed by irradiating a pulse laser while adjusting a branching ratio between the output light intensity and the monitor light intensity. It is characterized by being done. As a result, it is possible to realize a method for manufacturing an optical multiplexer / demultiplexer in which the branching ratio between the output light intensity and the monitor light intensity can be easily set to a desired value. The invention according to claim 8 is the method for manufacturing an optical multiplexer / demultiplexer according to claim 6 or 7, wherein the pulse laser is a femtosecond laser.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
FIG. 1 shows an example of the optical multiplexer / demultiplexer of the present invention. In FIG. 1, reference numeral 1 is an optical multiplexer / demultiplexer, and an AWG type optical multiplexer / demultiplexer is shown as an example. Reference numeral 2 is an input side optical fiber array, and this input side optical fiber array 2 is an optical multiplexer / demultiplexer 1.
Is connected to the input end of. Reference numeral 3 is an input optical fiber connected to the input side optical fiber array 2. Reference numeral 4 is an output side optical fiber array, and this output side optical fiber array 4 is connected to the output end of the optical multiplexer / demultiplexer 1. Reference numeral 5 is an output optical fiber connected to the output side optical fiber array 4, and reference numeral 6 is a substrate of the optical multiplexer / demultiplexer, which is made of, for example, a silicon wafer. On this substrate 6, an input optical waveguide 7, a development slab waveguide 8 for branching this input light into a plurality of waveguides, and a plurality of array conductors of different lengths arranged in the subsequent stage. A waveguide 9, a slab optical waveguide 10 for causing lights emitted from the arrayed waveguide 9 to interfere with each other, and a plurality of output optical waveguides 11 are formed. Reference numeral 12 is a groove provided on the substrate 6, and light receiving elements 13 are arranged in the groove 12 by the number of output side channels.

FIG. 2 shows the substrate 6 in the portion A shown in FIG.
It is a figure which shows the cross section of the direction perpendicular | vertical to. In FIG. 2, reference numeral 6 is a substrate, a lower clad 15 is formed on the substrate 6, and a core 16 is formed on the lower clad 15. Reference numeral 17 is an upper clad formed on the core 16, and a tap waveguide 18 is formed in the upper clad 17. The tap waveguide 18 refers to a waveguide formed so that only a part of the light propagating in the core 16 is demultiplexed and guided. The thickness of the upper clad 17 is determined in consideration of the relative refractive index difference between the clad material and the core material, the waveguide structure, etc. so that the optical transmission loss is sufficiently small at the used wavelength.
Usually, it is about 20 μm, but in this example, the upper cladding 1
Since the light receiving element 13 is arranged in 7, the thickness is further increased,
The thickness is preferably 30 μm to 40 μm.

The shape of the tap waveguide 18 is preferably substantially S-shaped when viewed from the cross section shown in FIG. 2 in order to guide the monitor light effectively. Further, the tip end portion of the tap waveguide 18 may be formed to have a region overlapping with the core 16 as shown in FIG. 2, and the tip end portion of the tap waveguide 18 may be brought close to the core 16. You may form so. Reference numeral 12 is a groove, and the light receiving element 13 is provided in the groove 12.
Are arranged. As the light receiving element 13, for example, a photodiode is used. The groove 12 is provided immediately above the portion of the output optical waveguide 11 where the waveguides are linearly aligned at a pitch of 127 μm or 250 μm, for example, by a grinding machine in a direction perpendicular to the waveguide. The light receiving element 13 is arranged in the groove 12. At this time, the thickness of the upper clad 17 at the position where the groove 12 is provided is 1
It is preferably about 0 μm.

In the optical multiplexer / demultiplexer of this example, a tap waveguide 18 is formed in order to monitor signal light and a light receiving element 13 is arranged. A method of manufacturing the tap waveguide 18 will be described below. . The tap waveguide 18 is formed by focusing and irradiating a pulsed laser such as a femtosecond laser from above the upper cladding 17 to induce a refractive index increase region. This femtosecond laser irradiation is performed with a precision stage that is movable in at least three axes in X, Y, and Z directions.
An optical system including a microscope for observation for alignment,
This is performed using a femtosecond laser device and an objective lens for converging and emitting the femtosecond laser. The objective lens for converging and irradiating the femtosecond laser can also serve as the objective lens of the microscope used for alignment.In this case, the femtosecond laser is guided by using a mirror on the microscope tube. Be illuminated. In order to form the tap waveguide 18, the focusing point is adjusted so that the femtosecond laser is focused inside the upper cladding 17. By relatively moving this condensing point inside the upper clad 17, a continuous high refractive index region functioning as an optical waveguide is formed inside the upper clad 17. The relative movement of the focusing point is performed by continuously moving the upper cladding 17 with respect to the focusing point of the laser light or by continuously moving the focusing point of the laser light inside the upper cladding 17. .

In order to form the smooth and continuous tap waveguide 18, the pulse interval of the laser light to be irradiated is narrowed,
That is, it is desirable to irradiate with a short repetition period, and for that purpose, it is preferable to irradiate with a high repetition type femtosecond laser. The tap waveguide 18 is formed by the input side optical fiber array 2 and the output side optical fiber array 4.
Alternatively, it may be performed after mounting the light receiving element 13. In this case, the wavelength-multiplexed light is input, or the light of one wavelength is sequentially input, and the femtosecond laser is also monitored while monitoring the intensity of the demultiplexed output light and also the level of the light receiving element 13. Irradiate. Irradiation of this femtosecond laser is 1
It is preferable to weaken the intensity of the femtosecond laser per irradiation and to irradiate the femtosecond laser a plurality of times so that the branching ratio can be adjusted. In this way, tap waveguide 1
8 is formed, it becomes easy to set the branching ratio of the light branched from the core 16 by the tap waveguide 18 to a desired value.

Next, the operation of the example of the optical multiplexer / demultiplexer of the present invention will be described. In FIG. 1, the signal light sent from the input optical fiber 3 is input to the input optical waveguide 7 of the optical multiplexer / demultiplexer 1 via the input side optical fiber array 2, and this input light is expanded slab waveguide. 8 is branched into a plurality of waveguides, demultiplexed for each wavelength by the arrayed waveguide 9 and the slab optical waveguide 10, from the output optical waveguide 11 to the output optical fiber 5 via the output side optical fiber array 4. Is output. In FIG. 2, the signal light propagates in the core 16 for each wavelength, but a part of the signal light is guided to the tap waveguide 18 as monitor light and is received by the light receiving element 13 to generate the signal light of each channel. Monitoring is done.

In the above description, the optical demultiplexer is A
Although the case of using the WG has been described, the present invention is not limited to this, and the present invention is also applicable to other types of optical demultiplexers such as a 1-input 8-output type optical demultiplexer in which Y branches are stacked in multiple stages. is there. Further, the present invention is not limited to the case of monitoring all channels, but can be applied to the case of monitoring only one channel. Further, each channel on the input side can be monitored by the monitoring means described above. This case can be realized by reversing the direction in which the tap waveguide 18 for guiding the monitor light to the light receiving element is formed. According to the optical multiplexer / demultiplexer of this example, the tap waveguide 18 for branching a part of the signal light propagating in the core 16 is formed in the upper clad 17, and the tap waveguide 18 is formed in the groove 12 provided in the upper clad 17. By arranging the light receiving element 13, the monitor light guided by the tap waveguide 18 is received by the light receiving element 13 and the signal light intensity is monitored for each channel, so that a monitor mechanism is provided on the substrate of the optical multiplexer / demultiplexer. It is possible to provide an optical multiplexer / demultiplexer that can be provided, can reduce the number of components, and can be downsized. Further, the tap waveguide 18 is formed by irradiating a pulse laser while adjusting the branching ratio of the output light intensity and the monitor light intensity, so that the branching ratio of the output light intensity and the monitor light intensity has a desired value. It is possible to realize a method of manufacturing an optical multiplexer / demultiplexer that is easy to obtain.

[0013]

As described above, according to the present invention,
A tap waveguide for branching a part of the signal light propagating in the core is formed in the clad, and a light receiving element is arranged in a groove provided in the clad, and a monitor guided by the tap waveguide is provided. By receiving the light with the light receiving element and monitoring the signal light intensity for each channel, a monitor mechanism can be provided on the substrate of the optical multiplexer / demultiplexer, reducing the number of parts and miniaturizing the optical multiplexer / demultiplexer. Can be realized. Also,
The tap waveguide is formed by irradiating a pulse laser while adjusting the branching ratio between the output light intensity and the monitor light intensity, thereby setting the branching ratio between the output light intensity and the monitor light intensity to a desired value. It is possible to realize a method for manufacturing an optical multiplexer / demultiplexer that is easy to manufacture.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an optical multiplexer / demultiplexer of the present invention.

FIG. 2 is a diagram illustrating a mechanism of monitoring with an tap waveguide in an example of the optical multiplexer / demultiplexer of the present invention.

[Explanation of symbols]

6 ... Substrate, 12 ... Groove, 13 ... Photodetector, 15 ... Lower cladding, 16 ... Core, 17 ... Upper cladding, 18 ... Tap waveguide

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomoko Shikata             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office (72) Inventor Hideyuki Hosoya             Fuji Co., Ltd. 1440 Rokuzaki, Sakura City, Chiba Prefecture             Kura Sakura Office F term (reference) 2H047 KA04 KA12 LA19 MA05 PA22                       QA04 RA08 TA01 TA11 TA41

Claims (8)

[Claims] 1. A tap waveguide for branching a part of signal light propagating in a core is formed in a clad, and a light receiving element is arranged in a groove provided in the clad, and the tap waveguide guides the light. An optical multiplexer / demultiplexer characterized in that the waved monitor light is received by the light receiving element and the signal light is monitored for each channel. 2. The optical multiplexer / demultiplexer according to claim 1, wherein the tap waveguide is formed in a substantially S shape. 3. The optical coupling / decoupling device according to claim 1, wherein the tap waveguide is formed by converging and irradiating a pulse laser to induce a refractive index increasing region in the cladding. Wave instrument. 4. The optical multiplexer / demultiplexer according to claim 3, wherein the pulse laser is a femtosecond laser. 5. The optical multiplexer / demultiplexer according to claim 1, wherein the tap waveguide is formed in a clad of an input optical waveguide or an output optical waveguide. 6. A tap waveguide for branching a part of signal light propagating in a core is formed in a clad, and a light receiving element is arranged in a groove provided in the clad, and the tap waveguide is formed by the tap waveguide. A method for manufacturing an optical multiplexer / demultiplexer in which a guided light is received by a light receiving element and a signal light is monitored for each channel. A pulse laser is focused and irradiated on the clad, and a refractive index rises in the clad. A method for manufacturing an optical multiplexer / demultiplexer, wherein the tap waveguide is formed by inducing a region. 7. The optical multiplexer / demultiplexer according to claim 6, wherein the tap waveguide is formed by irradiating a pulse laser while adjusting a branching ratio of output light intensity and monitor light intensity. Manufacturing method. 8. The method of manufacturing an optical multiplexer / demultiplexer according to claim 6, wherein the pulsed laser is a femtosecond laser.