JP2001305361A - Array waveguide type diffraction grating and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an array waveguide type diffraction grating capable of setting a light transmission central wavelength into a set wavelength by correcting a shift between the light transmission central wavelength and the set wavelength of an array waveguide type diffraction grating. SOLUTION: A waveguide forming part 10, which is formed by connecting in order a light input waveguide 2, a first slab waveguide 3, plural juxtaposed array waveguides 4 mutually different in length, a second slab waveguide 5 and plural juxtaposed light output waveguides 6, is formed on a substrate 1. The first slab waveguide 3 is cut and separated by a cutting surface 8 which crosses the path of light passing through the first slab waveguide 3, and the waveguide forming area 10 is also separated into a first waveguide forming area 10a and a second waveguide forming area 10b. Cut surfaces 8 of separated slab waveguides 3a, 3b are mutually faced and are connected in the state that the positions of the separated slab waveguides are shifted in the direction of the substrate surface along the cut surfaces 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an arrayed waveguide type diffraction grating used as an optical multiplexer / demultiplexer in, for example, wavelength division multiplexing optical communication, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, in optical communications, research and development on optical wavelength division multiplexing has been actively conducted as a method for dramatically increasing the transmission capacity, and practical use thereof has been progressing. Optical wavelength division multiplexing is, for example, a method of multiplexing and transmitting a plurality of lights having different wavelengths from each other. In order to extract the light, a light transmission device or the like that transmits only light of a predetermined wavelength,
It is essential to have it in the system.

As an example of a light transmitting device, a planar optical waveguide circuit (PLC; Planar Li) as shown in FIG.
Array Waveguide Grating (AWG; Arrayed Waveguide)
Grating). The arrayed waveguide type diffraction grating is formed by forming a waveguide forming region 10 having a waveguide configuration as shown in FIG. 1 on a substrate 1 made of silicon or the like with a core made of quartz glass or the like.

The waveguide configuration of the arrayed waveguide type diffraction grating is as follows.
At least one of the light input waveguides 2 arranged side by side
Of the first slab waveguide 3 is connected to a plurality of array waveguides 4 arranged in parallel, and the output side of the array waveguide 4 is connected to a second slab waveguide 3. 5
Are connected, and a plurality of juxtaposed optical output waveguides 6 are formed on the emission side of the second slab waveguide 5.

[0005] The arrayed waveguides 4 are for propagating light derived from the first slab waveguides 3 and are formed to have different lengths, and the lengths of adjacent arrayed waveguides 4 are different from each other by ΔL. ing. The optical input waveguide 2 and the optical output waveguide 6 are provided in correspondence with the number of signal lights having different wavelengths to be split or multiplexed by, for example, an arrayed waveguide type diffraction grating. Wave 4
Are usually provided, for example, as many as 100. In the figure, for the sake of simplicity, the number of each of the optical input waveguide 2, the array waveguide 4, and the optical output waveguide 6 is shown. Is simply shown.

An optical fiber (not shown) on the transmission side, for example, is connected to the optical input waveguide 2 so that wavelength-division multiplexed light is introduced. The light introduced into the slab waveguide 3 spreads due to the diffraction effect and enters each array waveguide 4, and the array waveguide 4
Is propagated.

The light that has propagated through the array waveguide 4 is transmitted to the second
Reaches the slab waveguide 5, and is further condensed and output to the optical output waveguide 6. Since the lengths of all the array waveguides 4 are different from each other, each of the individual The phase of the light is shifted, and the wavefront of the converged light is tilted according to the amount of the shift.

For this reason, the light condensing positions of the lights having different wavelengths are different from each other. By forming the light output waveguide 6 at that position, the light having different wavelengths (demultiplexed light) is different for each wavelength. The light can be output from the optical output waveguide 6.

That is, the arrayed waveguide type diffraction grating separates the light of one or more wavelengths from the multiplexed light having a plurality of different wavelengths input from the optical input waveguide 2 to each optical output waveguide. 6 has a light demultiplexing function, and the center wavelength of the demultiplexed light is equal to the difference (Δ
L) and is proportional to the effective refractive index _{n c.}

Since the arrayed waveguide type diffraction grating has the above characteristics, the arrayed waveguide type diffraction grating can be used as a wavelength division multiplexing / demultiplexing device for wavelength division multiplexing transmission. For example, as shown in FIG. ... Λn (n is an integer of 2 or more) from one optical input waveguide 2, the light of each of these wavelengths is The light is expanded by the slab waveguide 3, reaches the arrayed waveguide 4, passes through the second slab waveguide 5, is condensed at different positions depending on the wavelength as described above, and is incident on the different optical output waveguides 6. Through each light output waveguide 6,
The light is output from the output end of the optical output waveguide 6.

Then, by connecting an optical fiber (not shown) for optical output to the output end of each optical output waveguide 6,
The light of each wavelength is extracted through the optical fiber. When connecting an optical fiber to each of the optical output waveguides 6 and the above-described optical input waveguide 2, for example, one optical fiber is connected.
An optical fiber array arranged and fixed in a three-dimensional array is prepared, and this optical fiber array is fixed to the connection end face side of the optical output waveguide 6 and the optical input waveguide 2 so that the optical fiber and the optical output waveguide 6 and the optical input Wave path 2 is connected.

In the above-mentioned arrayed waveguide type diffraction grating, the light transmission characteristics of the light output from each light output waveguide 6 (wavelength characteristics of the transmitted light intensity of the arrayed waveguide type diffraction grating) are shown in, for example, FIG. ), And centering on each light transmission center wavelength (for example, λ1, λ2, λ3,... Λn),
The light transmission characteristics show that the light transmittance decreases as the wavelength shifts from the corresponding light transmission center wavelength. The light transmission characteristic does not always have one maximum value, and may have two or more maximum values, for example, as shown in FIG.

The light transmission characteristics (wavelength characteristics of the transmitted light intensity of the arrayed waveguide type diffraction grating) of the light output from each light output waveguide 6 are, for example, as shown in FIG. , Λ2, λ3,... Λn). In the figure, the wavelength characteristics output from different optical output waveguides 6 are shown in an overlapping manner.

Since the arrayed waveguide type diffraction grating utilizes the principle of reciprocity (reversibility) of light, it has not only a function as an optical demultiplexer but also a function as an optical multiplexer. . That is, contrary to FIG. 9, light of a plurality of wavelengths different from each other is supplied to each optical output waveguide 6 for each wavelength.
, These lights pass through the reverse propagation path, are multiplexed by the arrayed waveguide 4, and are emitted from one optical input waveguide 2.

In such an arrayed waveguide type diffraction grating, as described above, since the wavelength resolution of the diffraction grating is proportional to the difference (ΔL) between the lengths of the arrayed waveguides 4 constituting the diffraction grating, ΔL is set to The large design enables the optical multiplexing and demultiplexing of wavelength-division multiplexed light with a narrow wavelength interval, which could not be realized by conventional diffraction gratings. , Ie, a function of demultiplexing or multiplexing a plurality of optical signals having a wavelength interval of 1 nm or less.

When fabricating an arrayed waveguide type diffraction grating as described above, for example, first, an under-cladding film is formed on a substrate 1 such as silicon using a flame hydrolysis deposition method.
A core film is formed in order, and then the array waveguide diffraction grating pattern is transferred to the core film using photolithography and reactive ion etching through a photomask on which the waveguide configuration of the arrayed waveguide grating is drawn. . afterwards,
The waveguide formation region is formed by forming the over clad film again by the flame hydrolysis deposition method, and the arrayed waveguide type diffraction grating is manufactured.

[0017]

Incidentally, the above-mentioned arrayed waveguide type diffraction grating is mainly made of a silica glass material, and therefore, the array waveguide is caused by the temperature dependence of the silica glass material. The light transmission center wavelength of the waveguide grating shifts depending on the temperature. The temperature dependence is such that the transmission center wavelength of light output from one optical output waveguide 6 is λ, the equivalent refractive index of the core forming the arrayed waveguide 4 is n _c , and the substrate (for example, silicon substrate) 1 Where α _s is the thermal expansion coefficient and T is the temperature change of the arrayed waveguide type diffraction grating.

[0018]

(Equation 1)

Here, a conventional general array waveguide type circuit is used.
In the folded grating, the temperature of the light transmission center wavelength is calculated from (Equation 1).
Let's look for degree dependence. Conventional general array waveguide type
In a diffraction grating, dn_c/ DT = 1 × 10^-5(℃
^-1), Α_s= 3.0 × 10 ^-6(℃^-1), N_c=
1.451 (value at a wavelength of 1.55 μm)
Then, these values are substituted into (Equation 1).

Although the wavelength λ differs for each optical output waveguide 6, the temperature dependence of each wavelength λ is equal.
The array waveguide type diffraction grating currently used is often used for demultiplexing or multiplexing wavelength-division multiplexed light in a wavelength band centered at 1550 nm. = 1550 nm is substituted for (Equation 1). Then, the temperature dependence of the light transmission center wavelength of the conventional general array waveguide type diffraction grating becomes a value shown in (Equation 2).

[0021]

(Equation 2)

The unit of dλ / dT is nm / ° C. For example, when the use environment temperature of the arrayed waveguide type diffraction grating is 2
If the temperature changes by 0 ° C., the central wavelength of light transmitted from each optical output waveguide 6 shifts to the longer wavelength side by 0.30 nm. The shift amount of the center wavelength becomes 1 nm or more.

The arrayed waveguide type diffraction grating is characterized in that wavelengths can be demultiplexed or multiplexed at very narrow intervals of 1 nm or less. Since this feature is used for wavelength division multiplexing optical communication, As described above, it is fatal that the light transmission center wavelength changes by the shift amount due to a change in the use environment temperature.

Therefore, conventionally, an arrayed waveguide type diffraction grating provided with a temperature control means for keeping the temperature of the arrayed waveguide type diffraction grating constant so that the light transmission center wavelength does not change with temperature has been proposed. . This temperature adjusting means is configured by, for example, providing a Peltier element, a heater, and the like, and all of them perform control for maintaining the arrayed waveguide type diffraction grating at a predetermined set temperature (room temperature or higher). .

For example, FIG. 12 shows a Peltier module 16 having a Peltier element and an arrayed waveguide type diffraction grating having a thermistor 18. The Peltier module 16 and the thermistor 18 are connected to a temperature controller (FIG. (Not shown). The thermistor 18 is mounted on a heat equalizing plate 42 interposed between the Peltier module 16 and the substrate 1, and between the substrate 1 and the heat equalizing plate 42 and between the heat equalizing plate 42 and the Peltier module 16. In between, to improve heat conduction,
Normally, a thermally conductive silicone oil on compound or a thermally conductive silicone RTV (Room Temperature)
re Vulcanizing) is provided.

In the arrayed waveguide type diffraction grating provided with such a temperature control means, the temperature of the heat equalizing plate 42 is detected by the thermistor 18 and this value is fed back by the temperature controller to the Peltier module 16.
, And precise temperature control is performed so that the temperature of the arrayed waveguide grating becomes constant.

Further, due to a manufacturing error (error in film thickness, width, refractive index, etc.) of the arrayed waveguide section constituting the arrayed waveguide type diffraction grating, the light transmission center wavelength is set to an ITU grid wavelength or the like. Even when the wavelength is deviated from the wavelength, the temperature at which the light transmission center wavelength becomes the set wavelength is calculated using (Equation 2), and the temperature of the arrayed waveguide type diffraction grating is set to the calculated temperature by using a Peltier element or the like. If the temperature is adjusted by a temperature adjusting means having a heater or the like, the light transmission center wavelength can be adjusted to the grid wavelength.

However, in the case where the temperature of the arrayed waveguide type diffraction grating is kept constant by using a temperature control means such as a Peltier element or a heater, a current of, for example, 1 W is always supplied to the Peltier element or the heater for temperature control. However, there is a problem that the cost must be increased.

In addition, in order to use electric components such as a Peltier element and a heater, a controller, a control thermistor, a thermocouple, and the like are required, and light transmission due to misalignment of these components is required. In some cases, the center wavelength shift cannot be suppressed accurately.

Further, the heat dissipation capability of the Peltier element is limited, and when the size of the module having the arrayed waveguide type diffraction grating is taken into consideration, the operating environment temperature is from 0 ° C. to 70 ° C.
In the case where the temperature changes up to 100 ° C., the temperature control of the arrayed waveguide type diffraction grating must be limited to a range of 40 ° C. to 50 ° C. If the wavelength is largely (0.5 nm or more) deviated from a set wavelength such as a wavelength, it is difficult to adjust the light transmission center wavelength of the arrayed waveguide type diffraction grating to a set wavelength such as an ITU grid wavelength using a Peltier element. Array waveguide type diffraction gratings are often defective.

On the other hand, recently, as shown in FIG. 13, a groove 43 traversing the array waveguide 4 is provided in the middle of the array waveguide 4.
An array waveguide type diffraction grating of a type that compensates the center wavelength shift due to the temperature change by filling the groove 43 with a silicone resin 44 or the like having a different refractive index from the array waveguide 4 is proposed. ing. The silicone resin 44 has a negative refractive index temperature coefficient, and
3 is formed in a triangular shape, and the longer the length of the arrayed waveguide 4 is, the longer the interposed length of the silicone resin 44 is. The wavelength is uniformly temperature-compensated to compensate for the light transmission center wavelength.

However, in this type of arrayed waveguide diffraction grating, the groove 43 must be formed very accurately because the silicone resin 44 provided in the groove 43 compensates for the temperature of the light transmission center wavelength. However, it is very difficult to manufacture and mass-produce, so that the cost is increased.

Further, in such an arrayed waveguide type diffraction grating, it is inevitable that a manufacturing error occurs even if the waveguide configuration of the arrayed waveguide type diffraction grating and the groove 43 are formed with extremely high precision. Due to this manufacturing error or the like, when the light transmission center wavelength deviates from the grid wavelength, the light transmission center wavelength and the grid wavelength cannot be matched. Therefore, when the light transmission center wavelength deviates from the grid wavelength, it becomes necessary to provide the Peltier module 16 and the like, similarly to the arrayed waveguide type diffraction grating shown in FIG. 12, and the cost is further increased.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an inexpensive arrayed waveguide type which can adjust a light transmission center wavelength to a desired setting wavelength such as an ITU grid wavelength. Provided is a diffraction grating and a method of manufacturing the same.Furthermore, in the arrayed waveguide type diffraction grating, the temperature dependence of the light transmission center wavelength is accurately suppressed, and the light transmission center wavelength is always set to the set wavelength regardless of the temperature. To be able to do it.

[0035]

In order to achieve the above-mentioned object, the present invention has the following structure to solve the problem. That is, in the first invention of the arrayed waveguide type diffraction grating, the first slab waveguide is connected to the emission side of one or more optical input waveguides arranged side by side, and the emission of the first slab waveguide is performed. A plurality of side-by-side arrayed waveguides of different lengths for transmitting light derived from the first slab waveguide are connected to the side, and a second side is connected to an output side of the plurality of arrayed waveguides. A waveguide structure in which a slab waveguide is connected, and a plurality of light output waveguides arranged side by side are formed on an output side of the second slab waveguide on the substrate; At least one of the second slab waveguide and the second slab waveguide is cut at a cutting surface that intersects a light path passing through the slab waveguide to form a separated slab waveguide, and the separated slab waveguides are connected with the cut surfaces facing each other. It is a means to solve the problem with the configuration described.

According to a second aspect of the array waveguide type diffraction grating, in addition to the configuration of the first aspect, the separated slab waveguides are displaced in the direction of the substrate surface along the cut surface. It is a means for solving the problem with the connected configuration.

Further, in the third invention of the arrayed waveguide type diffraction grating, in addition to the constitution of the first or second invention, a state in which the end faces of the opposed separated slab waveguides are in contact with each other or a state where the end faces are separated by an interval. Thus, a configuration in which the separated slab waveguides are connected to each other is a means for solving the problem.

Further, in the fourth invention of the arrayed waveguide type diffraction grating, in addition to the structure of the first, second or third invention, at least one cut surface of the separated slab waveguide is a polished surface or a cut surface. This is a means for solving the problem with the configuration of the grinding surface.

Further, according to a fifth aspect of the array waveguide type diffraction grating, in addition to the structure of any one of the first to fourth aspects, the arrayed waveguide type diffraction grating is provided by connecting the separated slab waveguides. This is a means for solving the problem with a configuration in which the light transmission center wavelength of the grating is shifted.

In a sixth aspect of the array waveguide type diffraction grating, in addition to the configuration of any one of the first to fifth aspects, a set wavelength of a light transmission center wavelength of the array waveguide type diffraction grating is provided. This configuration solves the problem with a configuration in which the separated slab waveguides are connected to each other in a direction in which the deviation from the slab waveguide is corrected.

According to a seventh aspect of the array waveguide type diffraction grating, in addition to the configuration of any one of the first to sixth aspects, at least one side of the separated slab waveguide is cut along a cut surface. This is a means for solving the problem with a configuration in which a slide moving mechanism for moving is provided.

In an eighth aspect of the array waveguide type diffraction grating, in addition to the configuration of the seventh aspect, the slide movement mechanism adjusts a center wavelength for shifting a light transmission center wavelength of the array waveguide type diffraction grating. Means for solving the problem is provided by means of the means.

Further, according to a ninth aspect of the array waveguide type diffraction grating, in addition to the configuration of the seventh or ninth aspect, the slide moving mechanism has a temperature higher than that of the waveguide forming region and the substrate having the waveguide configuration. This is a means for solving the problem with a configuration having a temperature-dependent elastic member that expands and contracts greatly depending on the temperature.

Further, the tenth aspect of the arrayed waveguide type diffraction grating is described.
According to a seventh aspect of the present invention, in addition to the configuration of the seventh, eighth, or ninth aspect, the slide movement mechanism controls a slide movement amount and a slide movement direction of the separated slab waveguide in accordance with a change in temperature, thereby providing an array guide. Means for solving the problem is a means for moving at least one of the separated slab waveguides in a direction to reduce the temperature-dependent fluctuation of the light transmission center wavelength of the waveguide grating.

Further, in a first invention of a method for manufacturing an arrayed waveguide type diffraction grating, a first slab waveguide is connected to an emission side of one or more optical input waveguides arranged side by side. A plurality of side-by-side arrayed waveguides of different lengths for transmitting light derived from the first slab waveguide are connected to the output side of the slab waveguide. A second slab waveguide is connected to the side, and a waveguide configuration in which a plurality of juxtaposed optical output waveguides are connected to the output side of the second slab waveguide is formed on the substrate. After that, at least one of the first slab waveguide and the second slab waveguide is cut at a cut surface intersecting a light path passing through the slab waveguide to form a separated slab waveguide, and the separated slab waveguide is formed. The waveguides are connected to each other to connect the array waveguide according to any one of the first to tenth aspects. And a means for solving the problems with the construction of making a road type diffraction grating.

Further, a second invention of a method for manufacturing an arrayed waveguide type diffraction grating is characterized in that at least one of the first slab waveguide and the second slab waveguide in the waveguide configuration of the arrayed waveguide type diffraction grating is provided. In the form formed as a separated slab waveguide by cutting at a cutting plane that intersects the path of light passing through the slab waveguide,
The partial waveguide configuration of the arrayed waveguide type diffraction grating having the separated slab waveguide on one side and the partial waveguide configuration of the arrayed waveguide type diffraction grating having the separated slab waveguide on the other side are separately provided on separate substrates. Then, the separated slab waveguides formed on the separate substrates are connected to each other to produce the arrayed waveguide type diffraction grating of any one of the first to tenth aspects. Is a means to solve.

The inventor of the present invention eliminates the deviation of the center wavelength of light transmission of the arrayed waveguide type diffraction grating from the set wavelength,
In order to achieve the two objects of suppressing the temperature dependence of the light transmission center wavelength, attention was paid to the linear dispersion characteristics of the arrayed waveguide type diffraction grating.

In the arrayed waveguide type diffraction grating, light incident from the optical input waveguide is diffracted by the first slab waveguide (input side slab waveguide) to excite the arrayed waveguide.
As described above, the lengths of adjacent array waveguides are different from each other by ΔL. Then, the light that has propagated through the array waveguide satisfies (Equation 3) and is collected at the output end of the second slab waveguide (output side slab waveguide).

[0049]

(Equation 3)

[0050] In equation (3), n _s is the equivalent refractive index of the first slab waveguide and the second slab waveguide, n _c is the effective refractive index of the arrayed waveguide, phi is the diffraction angle, m is the diffraction order ,
d is the interval between adjacent array waveguides, and λ is the transmission center wavelength of light output from each optical output waveguide, as described above.

[0051] Here, when the light transmission center wavelength at which a diffraction angle phi = 0 and lambda _0, lambda ₀ is expressed by equation (4). The wavelength λ ₀ is generally called the center wavelength of the arrayed waveguide grating.

[0052]

(Equation 4)

By the way, in FIG. 8, when the focusing position of the arrayed waveguide grating comprising a diffraction angle phi = 0 and the point O, the light condensing position (second slab having a diffraction angle phi = phi _p The position at the output end of the waveguide 5) is, for example, the position of the point P (the position shifted from the point O in the X direction). Where O
Assuming that the distance between −P in the X direction is x, (Equation 5) is established between the distance and the wavelength λ. In FIG. 8, the reference numerals of the waveguide forming regions are omitted.

[0054]

(Equation 5)

In (Equation 5), L _f is the focal length of the second slab waveguide 5, and _ng is the group refractive index of the arrayed waveguide 4. Note that the group refractive index _ng of the arrayed waveguide 4 is
The equivalent refractive index n _c of the arrayed waveguide 4, is given by equation (6).

[0056]

(Equation 6)

The above (Equation 5) is obtained by arranging the input end of the optical output waveguide 6 at a position dx away from the focal point O of the second slab waveguide 5 in the X direction so that the wavelength differs by dλ. Means that it is possible to take out the light.

Further, the relationship of (Equation 5) holds true for the first slab waveguide 3 as well. That is, for example, assuming that the focal center of the first slab waveguide 3 is a point O ′, and a point located at a position shifted from the point O ′ by a distance dx ′ in the X direction is a point P ′, light is emitted to this point P ′. When incident, the wavelength of the output is shifted by dλ ′. When this relationship is represented by an equation, it becomes as shown in (Equation 7).

[0059]

(Equation 7)

In equation (7), L _f ′ is the focal length of the first slab waveguide 3. This (Formula 7) is formed at the focal point O by arranging and forming the output end of the optical input waveguide 2 at a distance dx 'in the X direction from the focal point O' of the first slab waveguide 3. This means that light having a different wavelength by dλ ′ can be extracted from the optical output waveguide 6.

Therefore, when the light transmission center wavelength of the manufactured arrayed waveguide type diffraction grating is shifted from the set wavelength such as the ITU grid wavelength by Δλ, the optical input waveguide 2 is set so that dλ ′ = Δλ. If the output end position is shifted by the distance dx ′ in the X direction, for example, light with no wavelength shift can be extracted from the optical output waveguide 6 formed at the focal point O, and the same applies to other optical output waveguides 6. Since the action occurs, the light transmission center wavelength shift Δλ can be corrected (eliminated).

In the present invention having the above-described structure, at least one of the first slab waveguide and the second slab waveguide is cut and separated at a cutting plane which intersects a light path passing through the slab waveguide to form a separated slab waveguide. The separated slab waveguides are connected with their cut surfaces facing each other. Therefore,
Assuming that the first slab waveguide is cut and separated, the separated first slab waveguides are connected in a state shifted in the direction of the substrate surface along the cut surface, whereby: If the output end position of the optical input waveguide is shifted by the distance dx ′ in the X direction so that dλ ′ = Δλ, the optical transmission center wavelength shift Δλ can be corrected (eliminated).

As is apparent from the above (Equation 7),
Since the output wavelength shift dλ ′ also changes depending on the focal length of the first slab waveguide 3, in the present invention, the separated slab waveguides are separated from each other while the opposing separated slab waveguide end faces are spaced from each other. By connecting, or by forming a cut surface on at least one side of the separated slab waveguide as a polished surface or a ground surface, the focal length of the slab waveguide before connection and after connection after separation is set to an arrayed waveguide. If the light transmission center wavelength of the diffraction grating is changed by an amount sufficient to shift the same, the light transmission center wavelength shift Δλ of the arrayed waveguide diffraction grating can be similarly corrected (eliminated).

Further, in the present invention, a slide moving mechanism for moving at least one side of the separated slab waveguide along a cut surface is provided, and the separated slab connected to the optical input waveguide is provided by the slide moving mechanism. If the waveguide side (including the optical input waveguide) is slid along the cut surface, it becomes possible to shift the respective light transmission center wavelengths.

Further, when the center wavelength of light transmitted from the light output waveguide of the arrayed waveguide type diffraction grating is shifted by Δλ due to a change in the use environment temperature of the arrayed waveguide type diffraction grating, the slide moving mechanism is used. The separation slab waveguide and the optical input waveguide are cut in such a manner that the temperature-dependent variation (wavelength shift) Δλ of each light transmission center wavelength becomes equal to dλ so as to reduce the temperature-dependent variation of each light transmission center wavelength. If it is moved along the plane, it is possible to eliminate the shift of the light transmission center wavelength due to the temperature change.

Strictly speaking, even when the separation slab waveguide and the optical input waveguide are moved along the cutting plane, by changing the position of the output end of the optical input waveguide, the optical input waveguide is changed. From the output end of the waveguide to the input end of the arrayed waveguide, the focal length L _f ′ of light propagating in the first slab waveguide slightly changes. However, the focal length of the first slab waveguide in the currently used arrayed waveguide grating is on the order of several millimeters, while it moves to correct the light transmission center wavelength of the arrayed waveguide grating. The movement amount of the output end position of the optical input waveguide is several μm to several tens.
It is on the order of μm, which is much smaller than the focal length of the first slab waveguide.

Therefore, in this case, it is considered that there is no problem if the change in the focal length is substantially ignored. From this, as described above, if the separation slab waveguide and the optical input waveguide are moved along the cutting plane in a direction to reduce the temperature-dependent variation of each light transmission center wavelength in the arrayed waveguide type diffraction grating, The light transmission center wavelength shift can be eliminated.

Here, in order to reduce the temperature dependence of the light transmission center wavelength by the slide moving mechanism, the relationship between the temperature change amount and the position correction amount of the optical input waveguide is derived. The temperature dependence of the light transmission center wavelength (the amount of shift of the light transmission center wavelength due to the temperature) is expressed by the above (Equation 2). 8).

[0069]

(Equation 8)

When the temperature change amount T and the position correction amount dx ′ of the optical input waveguide are obtained from (Equation 7) and (Equation 8), (Equation 9)
Is led.

[0071]

(Equation 9)

Accordingly, in the present invention, the separated slab waveguide and the optical input waveguide of the first slab waveguide are moved along the cut surface by the slide moving mechanism by the position correction amount dx ′ represented by (Equation 9). By sliding, the shift of the light transmission center wavelength can be eliminated.

As described above, the arrayed waveguide type diffraction grating is formed by utilizing the reciprocity of light.
A direction in which the second slab waveguide side is cut and separated, and at least one side of the separated separated slab waveguide is reduced along the cut surface by a slide moving mechanism to reduce temperature-dependent fluctuations of the respective light transmission center wavelengths. The same effect can be obtained by sliding the lens to the position described above, and it becomes possible to eliminate the temperature-dependent fluctuation of the respective light transmission center wavelengths.

Further, a slide moving mechanism which operates based on the above principle is provided to suppress the shift of the light transmission center wavelength due to the use environment temperature of the arrayed waveguide type diffraction grating without using a Peltier element or a heater. According to the present invention, in which the center wavelength can be made independent of temperature, unlike the case where a temperature control unit including a Peltier element and a heater is provided, the power supply is not always required, and the temperature correction is performed by an assembly error of the components of the temperature control unit. No errors occur.

[0075]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same reference numerals are given to the same parts as those in the conventional example, and the overlapping description will be omitted. FIG. 1A is a plan view showing a configuration of a main part of a first embodiment of an arrayed waveguide type diffraction grating according to the present invention.

In this embodiment, a waveguide forming region 10 having a waveguide configuration substantially similar to that of the conventional arrayed waveguide type diffraction grating as shown in FIG. 9 is formed on a substrate 1 made of silicon or the like. The present embodiment is different from the conventional example in that the first slab waveguide 3 has a characteristic that light passing through the first slab waveguide 3 is different from that of the conventional example as shown in FIG. The separated slab waveguide 3a, which is cut at a cut surface 8 intersecting the path,
3b, wherein the separated slab waveguides 3a and 3b are connected with the cut surfaces 8 facing each other.

Further, in this embodiment, the separated slab waveguides 3a and 3b are connected to each other while being shifted along the cut surface 8 by the position adjustment amount dx 'in the direction of the substrate surface. The light transmission center wavelength of the waveguide type diffraction grating is shifted, and the deviation of the light transmission center wavelength from the set wavelength is corrected. And almost match.

The arrayed waveguide type diffraction grating of this embodiment is configured as described above. When manufacturing the arrayed waveguide type diffraction grating, first, the arrayed waveguide type diffraction grating as shown in FIG. A wave-type diffraction grating is manufactured. Next, the light transmission center wavelength of the arrayed waveguide type diffraction grating is measured, and the deviation of the measured wavelength from the set wavelength (in this case, the ITU grid wavelength) is determined, and the value is defined as Δλ.

Thereafter, as shown in FIG. 1A, the first slab waveguide 3 is cut along a cutting plane 8 orthogonal to the central axis in the traveling direction of light passing through the first slab waveguide 3. Accordingly, the arrayed waveguide type diffraction grating is separated into the first waveguide forming region 10a and the substrate 1a thereunder, and the second waveguide forming region 10b and the substrate 1b thereunder. And
By connecting the separated slab waveguides 3a and 3b along the cut surface 8 in a state shifted by the position adjustment amount dx 'in the substrate surface direction, the arrayed waveguide type diffraction grating of this embodiment is manufactured.

The line A in FIG. 1 indicates the light incident on the first slab waveguide 3 from the output end 20 of the input waveguide 2a before the array waveguide type diffraction grating is cut at the cutting plane 8. Shows the direction of the central axis.

Further, as described above, the position adjustment amount dx 'is determined based on the result of the study made by the present inventor focusing on the linear dispersion characteristic of the arrayed waveguide type diffraction grating. By moving the output end position of the waveguide 2 by the position adjustment amount dx ′ in the X direction, each optical output waveguide 6
The output wavelength from is given by dλ ′ (dλ ′ =
Δλ).

In this embodiment, as a method for forming the cut surface 8, cutting using a dicing saw or the like is applied. When connecting the separated slab waveguides 3a and 3b to each other, the first waveguide forming region 10a and the second waveguide forming region 10b are bonded and fixed to each other to separate the separated slab waveguides 3a and 3b.
Or at least the separation slab waveguide 3a
The first waveguide forming region 10a and the second waveguide forming region 10b are clipped in a state where matching oil or matching grease is provided at a connection portion (between the surfaces facing each other) of the and the separated slab waveguide 3b. The connection may be made mechanically via the like.

Further, the first waveguide forming region 10a and the substrate 1a thereunder, and the second waveguide forming region 10b and the substrate 1b thereunder are arranged on a base having a smooth surface, and the separated slab conductor is formed. When the cut surfaces 8 of the waveguides 3a and 3b are opposed to each other and connected, the height of the separated slab waveguides 3a and 3b can be easily aligned.

According to the present embodiment, as described above, the first slab waveguide 3 of the arrayed waveguide type diffraction grating is cut at the cut surface 8 intersecting with the light path thereof to separate the slab waveguide 3.
a, 3b are formed, and the separation slab waveguides 3a, 3b are arranged along the cut surface 8 to adjust the light transmission center wavelength of the arrayed waveguide type diffraction grating to the ITU grid wavelength d.
Since the cut surfaces 8 are connected to each other while being shifted by x ′, an excellent arrayed waveguide type diffraction grating whose light transmission center wavelength substantially matches the ITU grid wavelength at the set temperature is obtained. be able to.

Further, according to the present embodiment, the arrayed waveguide type diffraction grating is cut at the cut surface 8 to separate the separated slab waveguide 3
a, 3b are formed and the separated slab waveguides 3a, 3b are connected to each other while being shifted along the cut surface 8, so that it can be manufactured very easily and the manufacturing yield can be reduced. Can be improved.

FIG. 2 is a plan view showing a main part of a second embodiment of the arrayed waveguide type diffraction grating according to the present invention. In the second embodiment, the same reference numerals are given to the same names as those in the first embodiment.

In the second embodiment, similarly to the first embodiment, an arrayed waveguide type diffraction grating having the structure shown in FIG. At the set temperature, the light transmission center wavelength of the arrayed waveguide type diffraction grating is set to I
Only the position adjustment amount dx 'that can be corrected to the TU grid wavelength,
The cut surfaces 8 are connected to each other with the separated slab waveguide 3a side shifted along the cut surface 8 with respect to the separated slab waveguide 3b side.

The characteristic feature of the second embodiment is that the second waveguide forming region 10b having the separation slab waveguide 3b
And the substrate 1b thereunder is fixed to the base 9, and the first waveguide forming region 10a having the separation slab waveguide 3a and the substrate 1a therebelow are slid along the cut surface 8 in the surface direction of the base 9. The separation slab waveguide 3
The configuration is such that the side a is relatively moved along the cut surface 8 with respect to the separation slab waveguide 3b side.

Specifically, in the second embodiment,
The base 9 is formed of a material having a low coefficient of thermal expansion such as quartz glass or an Invar lot.
The waveguide forming portion 10b on the side where the separated slab waveguide 3b, the arrayed waveguide 4, the second slab waveguide 5, and the optical output waveguide 6 are formed, and the substrate 1b thereunder are fixed.

On the other hand, the waveguide forming portion 10a on the side where the separated slab waveguide 3a is formed and the substrate 1 thereunder are:
It is slidably arranged along the surface of the base 9 in the direction of arrow A and the direction of arrow B in the figure. One end of the waveguide forming portion 10 a is fixed to the high thermal expansion coefficient member 7 via the adhesive 13. The other end is locked by the locking member 14.

The high thermal expansion coefficient member 7 includes an upper plate portion 7a provided along the upper surface of the waveguide forming portion 10a and a side plate portion (not shown) provided along the side surface of the waveguide forming portion 10a. The side plate portion is fixed to the base 9 by the fixing portion 11.

Further, the high thermal expansion coefficient member 7 is a substance that is contracted by a thermal expansion coefficient corresponding to the amount of movement of the separation slab waveguide 3a according to the shift of the center wavelength of light transmission of the arrayed waveguide type diffraction grating. It functions as a temperature-dependent elastic member that expands and contracts more than the waveguide forming region 10 and the substrate 1 depending on the temperature. The high thermal expansion coefficient member 7 is made of, for example, Al (aluminum) having a thermal expansion coefficient of 2.5 × 10 ⁻⁵ (1 / K).

The locking member 14 is connected to the waveguide forming portion 10a.
Is an L-shaped member having an upper plate portion 14a provided along the upper surface of the substrate and a side plate portion (not shown) provided along the side surface of the waveguide forming portion 10a, wherein the side plate portion is a fixed portion. At 12 it is fixed to the base 9. The inner wall of the upper plate portion of the locking member 14 is in contact with the upper surface of the waveguide forming portion 10a, and when the waveguide forming portion 10a slides, the waveguide forming portion 10a is positioned above the base 9 (XY (Z-axis direction perpendicular to the plane). Further, the inner wall of the side plate portion and the side surface of the waveguide forming portion 10a are spaced from each other so that the sliding movement of the waveguide forming portion 10a can be performed without any trouble.

In the second embodiment, as described above,
A slide moving mechanism for relatively moving the separated slab waveguide 3a side along the cut surface 8 with respect to the separated slab waveguide 3b side includes a high thermal expansion coefficient member 7, a base 9, and a locking member 14. ing. The slide moving mechanism includes the high thermal expansion coefficient member 7 having the above-described characteristic configuration, so that the temperature dependence of the center wavelength of light transmission of the arrayed waveguide type diffraction grating can be reduced. 1
And a center wavelength adjusting means for moving the center wavelength of light transmitted by the arrayed waveguide type diffraction grating in a direction to reduce temperature-dependent fluctuation.

In the second embodiment, each parameter in the waveguide configuration is configured as follows. That is, the focal length of the first slab waveguide 3 _{L f} 'and the focal length L _f of the second slab waveguide 5 equal, the value is 9mm (9000μm), also 2
In 5 ° C., the equivalent refractive index and the equivalent refractive index of the second slab waveguide 5 of the first slab waveguide 3 are both n _s, the value is at 1.453 with respect to light having a wavelength of 1.55μm is there.

Further, the optical path length difference ΔL of the array waveguide 4 is
65.2 μm, the distance between adjacent arrayed waveguides 4 is 1
5 μm, diffraction order m is 61, equivalent refraction of array waveguide 4
Rate n _cIs 1.451 for light with a wavelength of 1.55 μm,
Group index n of ray waveguide_gIs for 1.55 μm light.
It is 1.475.

[0097] Thus, in the arrayed waveguide grating of this second embodiment, the light transmission central wavelength lambda ₀ of where the diffraction angle phi = 0, as is apparent from the equation (4), lambda ₀ = 1550.9 nm.

By the way, in order to suppress the temperature dependency of the arrayed waveguide type diffraction grating, the present inventor paid attention to the linear dispersion characteristics of the arrayed waveguide type diffraction grating. As described with reference to FIG. 2, the use environment temperature change amount T of the arrayed waveguide type diffraction grating and the position correction amount dx ′ of the optical input waveguide are described.
And sought a relationship. Then, it was confirmed that this relationship was represented by the above (Equation 9). The position correction amount dx ′ corresponding to the use environment temperature change amount T is used to adjust the light transmission center wavelength to the ITU grid wavelength when the light transmission center wavelength deviates from the ITU grid wavelength at the set temperature. It is determined separately from dx '.

Therefore, in this embodiment, each parameter of the waveguide configuration of the arrayed waveguide type diffraction grating and (Equation 9)
When the relationship between the change amount T of the use environment temperature of the arrayed waveguide type diffraction grating and the position correction amount dx ′ of the optical input waveguide 2 is obtained based on the above, it is found that the relationship shown in (Formula 10) is obtained. .

[0100]

(Equation 10)

Therefore, in the second embodiment,
When the use environment temperature of the arrayed waveguide type diffraction grating changes by 10 ° C., the position of the output end of the optical input waveguide 2 is set to about 3.
If the correction (movement) is performed by 83 μm, the calculation can correct the shift of the center wavelength due to the temperature.

Therefore, in the second embodiment, when the use environment temperature of the arrayed waveguide type diffraction grating rises by 10 ° C., the position of the output end 20 of the optical input waveguide 2 connected to the optical fiber is changed. When the ambient temperature of the arrayed waveguide type diffraction grating decreases by 10 ° C. by about 3.83 μm in the direction of arrow A, the output end 20 of the optical input waveguide 2 moves.
Is moved in the direction of arrow B by about 3.83 μm, the amount of movement on the separation slab waveguide 3a side is determined. Then, the size and the like of the high thermal expansion coefficient member 7 are formed so as to obtain this movement amount, and the slide movement mechanism is slid in the direction of reducing the temperature-dependent fluctuation of each light transmission center wavelength. .

The present inventor assembled a module by applying a temperature compensation package of a fiber grating when producing the arrayed waveguide type diffraction grating of the second embodiment. That is, the first slab waveguide 3 was cut using a dicing saw, and matching grease having a refractive index matched with that of quartz glass was applied to the cut surface 8 in order to prevent reflection at the cut surface 8. In addition, the high thermal expansion coefficient member 7
The adhesive 13 used for bonding between the substrate and the waveguide forming portion 10a is:
A thermosetting adhesive was cured at 100 ° C.

Further, the optical fiber 23 provided on the optical fiber arrangement tool 21 and the optical input waveguide 2 of the arrayed waveguide diffraction grating are aligned, and each optical fiber of the optical fiber tape 24 fixed to the optical fiber arrangement tool 22 ( (Not shown) and the respective optical output waveguides 6 of the arrayed waveguide type diffraction grating were aligned, and the corresponding optical fibers were connected to the waveguides 2 and 6, respectively.

The second embodiment is configured as described above, and the second embodiment also intersects with the light path passing through the first slab waveguide 3 as in the first embodiment. At the cutting plane 8, the first slab waveguide 3 is
a and 3b are cut and separated, and are connected to each other in a state where the light transmission center wavelength of the arrayed waveguide type diffraction grating is shifted by the position adjustment amount dx ′ that can be corrected to the ITU grid wavelength at a set temperature. At the set temperature, an excellent arrayed waveguide type diffraction grating having a light transmission center wavelength substantially equal to the ITU grid wavelength can be obtained.

In the second embodiment, a characteristic slide moving mechanism is provided, and when the operating temperature of the array waveguide type diffraction grating rises and changes, the slide moving mechanism cuts the separated slab waveguide 3a side. When it moves in the direction A along the surface 8 and, on the other hand, the use environment temperature of the arrayed waveguide type diffraction grating decreases, the slide movement mechanism causes
The side of the separated slab waveguide 3a moves in the B direction along the cut surface 8. Then, by this movement, the separation slab waveguide 3a is slid in the direction of reducing the temperature-dependent fluctuation of each light transmission center wavelength of the arrayed waveguide type diffraction grating.

Further, the above-mentioned slide movement amount is the above (Equation 1).
0), and the separated slab waveguide 3a and the optical input waveguide 2 are slid by the slide movement.

Therefore, according to the second embodiment,
Even if the use environment temperature of the arrayed waveguide type diffraction grating changes, the shift of the light transmission center wavelength due to this temperature change can be eliminated, and the so-called temperature-independent array waveguide is independent of the use environment temperature. A diffraction grating can be used, and the center wavelength of light transmission of the arrayed waveguide diffraction grating can always be substantially equal to the ITU grid wavelength regardless of temperature changes.

When the present inventor actually measured the temperature change of the light transmission center wavelength at an environmental temperature of 0 ° C. to 80 ° C., the result shown by the characteristic line a in FIG. 3 was obtained. Shift amount is about 0.01 nm or less,
It was confirmed that the center wavelength of light transmission hardly deviated even when the use environment temperature changed within the range of 0 ° C. to 80 ° C.

FIG. 3 shows a conventional waveguide structure in which the parameters of the waveguide configuration in the arrayed waveguide type diffraction grating are formed in the same manner as in the second embodiment, and the first slab waveguide 3 is not separated. 0 ° C. to 80 ° C. in the arrayed waveguide type diffraction grating
The result of measuring the temperature change of the light transmission center wavelength at an environmental temperature of ° C. is also shown (characteristic line b in FIG. 3). Characteristic line a
As is clear from comparison between the characteristic line b and the characteristic line b, the arrayed waveguide type diffraction grating of the second embodiment has a temperature dependence of the light transmission center wavelength which is a problem in the conventional arrayed waveguide type diffraction grating. It can be seen that this is an excellent arrayed waveguide type diffraction grating suitable for practical use such as optical wavelength division multiplexing communication.

Further, according to the second embodiment, the slide moving mechanism includes the high thermal expansion coefficient member 7, the base 9, and the locking member 14, and the waveguide disposed on the base 9 is provided. The array waveguide has a simple configuration in which one end side of the formation portion 10a and the substrate 1 thereunder are fixed to the base 9 via the high thermal expansion coefficient member 7 and the other end side is locked by the locking member 14. It is possible to avoid complication of the configuration of the diffraction grating.

Further, according to the second embodiment, as described above, the waveguide forming portion 10a and the substrate 1 thereunder are fixed to the base 9 so as to be slidably movable.
Since the substrate and the substrate below it are fixed to the base 9, it can be easily manufactured.

Further, according to the second embodiment, since there is no need to use a Peltier element or a heater, there is no need to constantly supply power, unlike the case where a temperature control means including a Peltier element or a heater is provided. A temperature correction error due to a component assembly error can be suppressed.

FIG. 4 is a plan view showing a configuration of a main part of a third embodiment of an arrayed waveguide type diffraction grating according to the present invention. In the second embodiment, the first and second
The same reference numerals are given to the same names as those in the embodiment.

The third embodiment is substantially the same as the second embodiment. The third embodiment is different from the first embodiment in that the third embodiment has a high thermal expansion coefficient member. 7, a micrometer head 25 is provided to form a slide moving mechanism. In the third embodiment, similarly to the second embodiment, the locking member 1 is used.
4, the locking member 14 is omitted in FIG.

Control means (not shown) is connected to the micrometer head 25. The micrometer head 25 controls the amount of sliding movement of the separated slab waveguide 3a according to a change in temperature based on the control of the control means. And the direction of sliding movement, thereby moving the separation slab waveguide 3a in a direction to reduce the temperature-dependent variation of the light transmission center wavelength of the arrayed waveguide type diffraction grating. For example, information on the amount of slide movement and the direction of slide movement of the separation slab waveguide 3a as shown in (Equation 10) is input to the control means in advance.

The third embodiment is configured as described above. The third embodiment is manufactured in substantially the same manner as the second embodiment, and provides the same effects by the same operation. Can be.

Note that the present invention is not limited to the above-described embodiment, but can adopt various embodiments. For example,
In each of the above embodiments, when manufacturing the arrayed waveguide type diffraction grating, the optical input waveguide 2, the first slab waveguide 3, the arrayed waveguide 4, the second slab waveguide 5, and the optical output waveguide are all used. A waveguide structure having a waveguide 6 is formed on the substrate 1, and thereafter, the first slab waveguide 3 is cut at a cutting plane 8 intersecting a light path passing through the first slab waveguide 3. The separated slab waveguides 3a and 3b were formed by the above method, and the separated slab waveguides 3a and 3b were connected to each other. However, the method of manufacturing the arrayed waveguide type diffraction grating is not particularly limited.

For example, as shown in FIGS. 5A and 5B, the first slab waveguide 3 passes through the first slab waveguide 3 in the waveguide configuration of the arrayed waveguide type diffraction grating. A partial waveguide configuration of an arrayed-waveguide type diffraction grating having one separated slab waveguide 3a, which is cut at a cutting plane 8 intersecting with the light path to form separated slab waveguides 3a and 3b (FIG. (A) of the first waveguide forming region 10 shown in FIG.
a) and a partial waveguide configuration of an arrayed waveguide type diffraction grating having a separate slab waveguide 3b on the other side (a second waveguide forming region 10b shown in (b) of FIG. 1) are separated into separate substrates 1 After that, the separated slab waveguides 3a and 3b formed on the separate substrates 1 may be connected to each other to produce an arrayed waveguide type diffraction grating.

In this way, the productivity of the arrayed waveguide diffraction grating to be manufactured can be improved. That is, the chip size of the arrayed waveguide type diffraction grating in an uncut state is generally 3 cm × 4 cm, and as shown in FIG. 6, at most 4 chips can be arranged on a 4-inch wafer 30 serving as the substrate 1 ( In other words, each chip requires 0.25 wafers 30).

On the other hand, as shown in FIG. 5, the partial waveguide configuration of the arrayed waveguide type diffraction grating having the separated slab waveguide 3a and the partial waveguide configuration of the arrayed waveguide type diffraction grating having the separated slab waveguide 3b are used. When the waveguide structures are formed on separate substrates 1 respectively, 78 chips can be formed per wafer in FIG. 5A, and 10 chips can be formed per wafer in FIG. In other words,
Since only 0.11 wafers 30 are required per chip, the required number of wafers 30 per chip can be significantly reduced as compared with the case of FIG.

In the array waveguide type diffraction grating,
When the production density of the portion where the array waveguide 4 is formed becomes poor,
Even if there is no problem in other parts, the optical characteristics of the arrayed waveguide type diffraction grating often become defective.
In the case where the yield of the formation portion of is poor, the productivity can be further improved by re-creating only the formation portion of the arrayed waveguide 4.

Further, in each of the above embodiments, the separation slab waveguides 3a and 3b are connected to each other along the cut surface 8 while being shifted in the direction of the substrate surface, so that the light of the arrayed waveguide type diffraction grating can be reduced. The deviation of the transmission center wavelength from the set wavelength is corrected. For example, as shown in FIGS. 7A and 7B, the separated slab waveguides 3a and 3
b, the separation slab waveguide 3a,
3b may be connected to each other to correct the deviation of the center wavelength of light transmission of the arrayed waveguide grating from the set wavelength.

In this case, the end faces (cut surfaces 8) of the separated slab waveguides 3a and 3b may be arranged in parallel as shown in FIG. 11A, or as shown in FIG. Alternatively, the end faces of the separation slab waveguides 3a and 3b may be arranged at a predetermined set angle.

Further, at least one cut surface of the separated slab waveguides 3a and 3b is formed as a polished surface or a ground surface, and the polished or ground separated slab waveguides 3a and 3b are formed.
May be made shorter than before the first slab waveguide 3 is cut, thereby correcting the shift of the light transmission center wavelength of the arrayed waveguide type diffraction grating from the set wavelength.

Further, the above-described various embodiments (an embodiment in which the separated slab waveguides 3a and 3b are connected to each other while being displaced in the direction of the substrate surface along the cut surface 8, and the separated slab waveguides 3a and 3b facing each other) In which the separated slab waveguides 3a and 3b are connected to each other with the end faces of the separated slab waveguides 3a and 3b interposed therebetween, and in which at least one cut surface 8 of the separated slab waveguides 3a and 3b is formed as a polished surface or a ground surface. The separation slab waveguides 3a and 3b may be connected to each other by combining the above embodiments.

Further, in each of the above embodiments, the first slab waveguide 3 is cut and separated. However, the arrayed waveguide type diffraction grating is formed by utilizing the reciprocity of light.
Even when the second slab waveguide 5 side is cut and separated, the separated separated slab waveguides are connected to each other with the cut surfaces 8 facing each other in the above-described various modes or in a mode in which the modes are combined. Good.

Further, in each of the above embodiments, the cut surface 8 is formed by a dicing saw or the like, but the cut surface 8 may be a cleavage formation surface formed by cleavage.

Further, when a slide moving mechanism having a high thermal expansion coefficient member 7 is provided as in the second embodiment, the high thermal expansion coefficient member 7 may be provided as in the second embodiment.
The high thermal expansion coefficient member 7 may be formed of a material other than Al without necessarily using an Al plate.

Further, even when the slide moving mechanism is provided as in the second and third embodiments, at least one side of the separated slab waveguide formed by cutting and separating the second slab waveguide 5 side. May be slid along the cut surface in a direction to reduce the temperature-dependent variation of the respective light transmission center wavelengths by the slide moving mechanism. Again,
The same effects as those of the second and third embodiments can be obtained, and the temperature-dependent fluctuations of the respective light transmission center wavelengths can be eliminated.

Further, both the first slab waveguide 3 and the second slab waveguide 5 are cut to form separate slab waveguides, respectively. They may be connected face-to-face, or at least one side of the separated slab waveguide may be slid along the cut surface in a direction to reduce the temperature-dependent variation of each of the light transmission center wavelengths by a slide moving mechanism.

Further, the cut surfaces 8 of the first slab waveguide 3 and the second slab waveguide 5 are different from those of the above-described embodiments.
The plane is not limited to the plane orthogonal to the central axis in the traveling direction of light passing through the slab waveguide, and may be a plane obliquely intersecting with the central axis in the traveling direction. What is necessary is just to cut and separate.

Further, detailed values such as the equivalent refractive index, the number, and the size of each of the waveguides 2, 3, 4, 5, and 6 constituting the arrayed waveguide type diffraction grating of the present invention are not particularly limited. Instead, they are set as appropriate.

[0134]

According to the present invention, at least one of the first slab waveguide and the second slab waveguide forming the waveguide configuration of the arrayed waveguide type diffraction grating has a light path through the slab waveguide. The separated slab waveguides are cut at the intersecting cut surfaces to form a separated slab waveguide, and the separated slab waveguides are connected with the cut surfaces facing each other. Connected in a state shifted in the direction, separated slab waveguides connected to each other in a state where the end faces of the separated slab waveguides facing each other are in contact with each other or with a gap therebetween, or at least one side of the separated slab waveguide. The cut surface can be a polished or ground surface,
The separated slab waveguides can be connected to each other in an appropriate connection state.

Further, by connecting such separated slab waveguides, for example, the light transmission center wavelength of the arrayed waveguide type diffraction grating can be shifted with respect to the light transmission center wavelength before cutting the slab waveguide. In such a shifted configuration, the light transmission center wavelength can be set to an appropriate value.

In the present invention, for example, when the light transmission center wavelength of the arrayed waveguide type diffraction grating before cutting is shifted from the set wavelength, the light transmission center wavelength of the arrayed waveguide type diffraction grating is set. By connecting the separated slab waveguides in a direction in which the shift from the wavelength is corrected, the shift of the light transmission center wavelength can be corrected (eliminated) by connecting the separated slab waveguides.

Further, in a configuration provided with a slide moving mechanism for moving at least one side of the separated slab waveguide along the cut surface, for example, the slide moving mechanism is provided with a light transmission center wavelength of the arrayed waveguide type diffraction grating. This shift can be used to reduce, for example, the temperature-dependent variation of the light transmission center wavelength of the arrayed waveguide type diffraction grating or the light transmission center wavelength of the arrayed waveguide type diffraction grating. The deviation from the set wavelength can be more accurately corrected.

Further, in a structure in which the slide moving mechanism has a waveguide forming region having a waveguide structure and a temperature-dependent expansion / contraction member which expands and contracts more greatly depending on the temperature than the substrate, the temperature-dependent expansion / contraction member Thereby, at least one side of the separated slab waveguide can be slid, the temperature-dependent variation of the light transmission center wavelength of the arrayed waveguide grating can be reduced, and the device configuration can be simplified.

Further, the slide moving mechanism controls the amount and direction of slide movement of the separation slab waveguide in accordance with the change in temperature to reduce the temperature-dependent fluctuation of the light transmission center wavelength of the arrayed waveguide type diffraction grating. In a configuration in which means for moving at least one of the separated slab waveguides is used, this means can reduce the temperature-dependent variation of the light transmission center wavelength of the arrayed waveguide type diffraction grating.

Further, in the method of manufacturing an arrayed waveguide type diffraction grating of the present invention, a waveguide having an optical input waveguide, a first slab waveguide, an arrayed waveguide, a second slab waveguide, and an optical output waveguide. The structure is formed on a substrate, and thereafter, at least one of the first slab waveguide and the second slab waveguide is cut at a cutting plane that intersects a light path passing through the slab waveguide to separate the slab waveguide. In a configuration in which a waveguide is formed and the separated slab waveguides are connected to each other to form an arrayed waveguide type diffraction grating, the present invention can be easily applied to a conventional arrayed waveguide type diffraction grating manufacturing method. Can be manufactured.

Further, in the method of manufacturing an arrayed waveguide type diffraction grating according to the present invention, at least one of the first slab waveguide and the second slab waveguide in the waveguide configuration of the arrayed waveguide type diffraction grating is connected to the slab waveguide. A partial waveguide configuration of an arrayed waveguide type diffraction grating having a separated slab waveguide on one side in the form of a separated slab waveguide formed by cutting at a cut surface that intersects the light path passing through the waveguide, and The partial waveguide configuration of the arrayed waveguide type diffraction grating having the separated slab waveguides is formed on separate substrates, and then the separated slab waveguides formed on the separate substrates are connected to form an array. In the configuration for manufacturing a waveguide-type diffraction grating, for example, it is possible to efficiently form each of the partial waveguide configurations on a wafer forming a substrate, thereby improving the productivity of an arrayed-waveguide-type diffraction grating. It can be.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram showing a first embodiment of an arrayed waveguide type diffraction grating according to the present invention.

FIG. 2 is a main part configuration diagram showing a second embodiment of an arrayed waveguide type diffraction grating according to the present invention.

FIG. 3 is a graph showing the temperature dependence of the light transmission center wavelength of the arrayed waveguide grating of the second embodiment in comparison with the temperature dependence of the light transmission center wavelength of the conventional arrayed waveguide grating. It is.

FIG. 4 is a main part configuration diagram showing a third embodiment of an arrayed waveguide type diffraction grating according to the present invention.

FIG. 5 shows a case where two partial waveguide forming regions each having a configuration in which an arrayed waveguide type diffraction grating is cut along a cut surface intersecting a light path of a first slab waveguide are formed on separate substrate wafers. It is explanatory drawing which shows the example of a design.

FIG. 6 is an explanatory view showing a design example when a waveguide forming region of an arrayed waveguide type diffraction grating is formed on a substrate wafer.

FIG. 7 is a main part configuration diagram showing another embodiment of the arrayed waveguide type diffraction grating of the present invention by a plan view.

FIG. 8 is an explanatory diagram showing a relationship between a light transmission center wavelength shift and positions of an optical input waveguide and an optical output waveguide in an arrayed waveguide type diffraction grating.

FIG. 9 is an illustration showing a configuration of a conventional arrayed waveguide type diffraction grating together with a wavelength division demultiplexing operation.

FIG. 10 is a graph showing an example of light transmission characteristics of an arrayed waveguide grating.

FIG. 11 is a graph collectively showing one example of light transmission characteristics of each light output from each light output waveguide of the arrayed waveguide type diffraction grating.

FIG. 12 is an explanatory diagram showing a conventional arrayed waveguide type diffraction grating provided with a temperature control circuit.

FIG. 13 is an explanatory view showing an example of an arrayed waveguide type diffraction grating conventionally proposed to reduce the temperature dependence of light transmission characteristics.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Optical input waveguide 3 First slab waveguide 3a, 3b Separation slab waveguide 4 Array waveguide 5 Second slab waveguide 6 Optical output waveguide 7 High thermal expansion coefficient member 8 Cut surface 9 Base 10, 10a , 10b Waveguide forming part 14 Locking member 30 Wafer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazutaka Nara 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Inventor Takeshi Nakajima 2-6-1 Marunouchi, Chiyoda-ku, Tokyo F-term in Furukawa Electric Co., Ltd. (reference) 2H047 KA04 KA15 KB09 LA18 NA10 PA00 TA00

Claims (12)

[Claims] 1. A first slab waveguide is connected to an output side of one or more optical input waveguides arranged side by side, and the first slab waveguide is connected to an output side of the first slab waveguide. A plurality of array waveguides having different lengths for transmitting light derived from the array waveguides are connected, and a second slab waveguide is connected to an output side of the plurality of array waveguides. A waveguide structure in which a plurality of juxtaposed optical output waveguides are connected is formed on a substrate on the emission side of the slab waveguide of at least one of the first slab waveguide and the second slab waveguide. Is cut at a cutting plane that intersects a light path passing through the slab waveguide to form a separated slab waveguide, and the separated slab waveguides are connected with the cut planes facing each other. Wave type diffraction grating. 2. The arrayed waveguide type diffraction grating according to claim 1, wherein the separated slab waveguides are connected to each other while being displaced in the direction of the substrate surface along the cut surface. 3. The array waveguide according to claim 1, wherein the separated slab waveguides are connected to each other in a state in which the end faces of the separated slab waveguides facing each other are in contact with each other or in a state where an interval is provided therebetween. Wave type diffraction grating. 4. The array waveguide type diffraction device according to claim 1, wherein at least one cut surface of the separated slab waveguide is a polished surface or a ground surface. lattice. 5. The connection between the separated slab waveguides,
The array waveguide type diffraction grating according to any one of claims 1 to 4, wherein the light transmission center wavelength of the array waveguide type diffraction grating is shifted. 6. The separation slab waveguides are connected to each other in a direction to correct a deviation of a light transmission center wavelength of the arrayed waveguide type diffraction grating from a set wavelength. An arrayed waveguide type diffraction grating according to any one of the preceding claims. 7. The arrayed waveguide according to claim 1, further comprising a slide moving mechanism for moving at least one side of the separated slab waveguide along a cut surface. Diffraction grating. 8. The arrayed-waveguide type diffraction grating according to claim 7, wherein the slide moving mechanism comprises a center wavelength adjusting means for shifting a light transmission center wavelength of the arrayed-waveguide type diffraction grating. 9. The slide moving mechanism includes a waveguide forming region having a waveguide configuration and a temperature-dependent expansion / contraction member that expands and contracts more depending on temperature than the substrate. 9. The arrayed waveguide type diffraction grating according to 8. 10. A slide moving mechanism controls a slide moving amount and a sliding moving direction of a separation slab waveguide according to a change in temperature to reduce a temperature-dependent variation of a light transmission center wavelength of an arrayed waveguide type diffraction grating. 10. The arrayed waveguide type diffraction grating according to claim 7, wherein the arrayed waveguide grating is configured to move at least one of the separated slab waveguides in the direction. 11. A first slab waveguide is connected to an output side of one or more optical input waveguides arranged side by side, and the first slab waveguide is connected to an output side of the first slab waveguide. A plurality of array waveguides having different lengths for transmitting light derived from the array waveguides are connected, and a second slab waveguide is connected to an output side of the plurality of array waveguides. On the output side of the slab waveguide, a waveguide structure in which a plurality of light output waveguides arranged in parallel are connected is formed on a substrate, and thereafter, the first slab waveguide and the second slab waveguide are formed. 11. The separated slab waveguide is formed by cutting at least one of the waveguides at a cutting plane that intersects a light path passing through the slab waveguide to form a separated slab waveguide, and connecting the separated slab waveguides to each other. Array waveguide characterized by producing an arrayed waveguide type diffraction grating according to one aspect A method for manufacturing a path diffraction grating. 12. A method of cutting at least one of a first slab waveguide and a second slab waveguide in a waveguide configuration of an arrayed waveguide type diffraction grating by a cutting plane intersecting a light path passing through the slab waveguide. Partial waveguide configuration of an arrayed waveguide type diffraction grating having a separated slab waveguide on one side and a portion of an arrayed waveguide type diffraction grating having a separated slab waveguide on the other side in the form of a separated slab waveguide 2. The method according to claim 1, further comprising forming the passive waveguide structures on separate substrates, and thereafter connecting the separated slab waveguides formed on the separate substrates.
A method for manufacturing an arrayed waveguide type diffraction grating, comprising: manufacturing the arrayed waveguide type diffraction grating according to any one of claims 10 to 10.