JP2001337233A - Array waveguide type diffraction grating module and optical module using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive array waveguide type diffraction grating module capable of correctly restraining a deviation from a set wavelength and temperature dependency of a light transmitting central wavelength. SOLUTION: A waveguide forming area 10 having a light input waveguide 2, first and second slab waveguides 3, 5, plural juxtaposed array waveguides 4 having mutually different lengths, 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 crossing an optical path, a high thermal expansion block 7 is abutted on the end surface of a first waveguide forming area (a) of a separated slab waveguide 3a side, and a low thermal expansion block 12 is abutted on the end surface of a second waveguide forming area 10b of a separated slab waveguide 3b side. Respective light transmitting central wavelength deviations of the array waveguide type diffraction grating are compensated by moving the low thermal expansion block 12 in the longitudinal direction of the cutting surface 8, and variations of temperature dependency of respective light transmitting central wavelengths are compensated by telescopically moving the high thermal expansion block 7 in the longitudinal direction of the cutting surface 8 in accordance with the change of temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrayed waveguide type diffraction grating module used for optical communication and an optical module using 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 has a waveguide formation region 10 having a waveguide configuration as shown in FIG.
It is formed by cladding 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 proportional to the effective refractive index n _c of the light guide 4.

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 splitter 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 array waveguide type diffraction grating, the light transmission characteristics of the light output from each light output waveguide 6 (the wavelength characteristics of the transmitted light intensity of the array waveguide type diffraction grating) are as shown in FIG. 7, for example. And each light transmission center wavelength (for example, λ
1, .lambda.2, .lambda.3,..., .Lambda.n), and shows a light transmission characteristic in which 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.

Since the array 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. 6, 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 array waveguide diffraction grating is manufactured by forming the over clad film again using the flame hydrolysis deposition method.

[0016]

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.

[0017]

(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).

[0020]

(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 utilized 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 provided, for example, by providing a Peltier element, a heater, and the like. For example, by providing these temperature adjusting means on the lower side of the substrate 1, an arrayed waveguide type diffraction grating is determined in advance. Control to keep the temperature at the set temperature (room temperature or higher).

As described above, if the temperature of the arrayed waveguide type diffraction grating is kept constant, the expansion and contraction of the substrate 1 and the change of the equivalent refractive index of the core do not occur due to the temperature. Can be solved.

Further, due to a manufacturing error (errors such as film thickness, width, refractive index, etc.) of the array waveguide portion 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 adjusting 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 adjustment. 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 thermistor for control, 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 connection between the arrayed waveguide type diffraction grating and the optical fiber array is generally performed using an adhesive, and the temperature of the arrayed waveguide type diffraction grating is raised to a temperature higher than room temperature by a Peltier element or a heater. When controlled, the adhesive provided on the connection surface between the arrayed waveguide diffraction grating and the optical fiber expands or softens, for example, at a temperature higher than room temperature. Therefore, when the temperature of the arrayed waveguide type diffraction grating is kept constant by using a Peltier element or the like, the expansion or softening of the adhesive causes the light input waveguide 2 or the optical output of the arrayed waveguide type diffraction grating. There is a problem that the connection loss between the waveguide 6 and the optical fiber increases, and the reliability of the connection between the arrayed waveguide type diffraction grating and the optical fiber is impaired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an inexpensive array drive capable of accurately suppressing the deviation of the central wavelength of light transmission from the set wavelength and the temperature dependency. An object of the present invention is to provide a waveguide grating module and an optical module using the same.

[0030]

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 module, the first slab waveguide is connected to the output side of one or more optical input waveguides arranged in parallel,
The output side of the first slab waveguide is connected to a plurality of side-by-side arrayed waveguides of different lengths for transmitting light derived from the first slab waveguide. A waveguide having a waveguide configuration in which a second slab waveguide is connected to the output side of the waveguide, and a plurality of juxtaposed optical output waveguides is connected to the output side of the second slab waveguide. An optical demultiplexing function having a waveguide formation region and demultiplexing light of one or more wavelengths from light having a plurality of different wavelengths input from the optical input waveguide and outputting the light from each optical output waveguide; The light transmittance of each light output from each of the light output waveguides is at least in a predetermined wavelength region from the corresponding light transmission center wavelengths centered on different light transmission center wavelengths of the demultiplexed light. Array waveguide that becomes smaller as wavelength shifts A diffraction grating, wherein at least one of the first slab waveguide and the second slab waveguide is cut at a cutting plane intersecting a light path passing through the slab waveguide to form a separated slab waveguide, The waveguide forming region is separated into a first waveguide forming region including one side separated slab waveguide and a second waveguide forming region including the other side separated slab waveguide. A position adjusting member for moving at least one side of the first and second waveguide forming regions in the direction of the substrate surface along the cut surface by a moving amount for compensating a deviation amount from the set wavelength. Means for solving the problem is a configuration provided so as to be in contact with the end face of the waveguide forming region on at least one side of the waveguide forming region.

In a second aspect of the arrayed waveguide type diffraction grating module, a first slab waveguide is connected to an output side of one or more optical input waveguides arranged side by side. A plurality of side-by-side arrayed waveguides having different lengths for transmitting light derived from the first slab waveguide are connected to the output side of the waveguide, and the output side of the plurality of arrayed waveguides is connected to the output side of the plurality of arrayed waveguides. Has a waveguide forming region provided with a waveguide configuration in which a second slab waveguide is connected, and a plurality of juxtaposed optical output waveguides are connected on the output side of the second slab waveguide. And a light demultiplexing function of demultiplexing light of one or more wavelengths from light having a plurality of different wavelengths input from the light input waveguide and outputting the light from each light output waveguide, The light transmittance of each light output from each light output waveguide is at least a predetermined wavelength. In the region, there is provided an arrayed waveguide type diffraction grating that becomes smaller as the wavelength deviates from the corresponding light transmission center wavelength with respect to the mutually different light transmission center wavelengths of the demultiplexed light, and the first slab waveguide and the second At least one of the slab waveguides is cut at a cutting plane intersecting a light path passing through the slab waveguide to form a separated slab waveguide, and the waveguide forming region includes a first waveguide including one of the separated slab waveguides. The waveguide is separated into a waveguide forming region and a second waveguide forming region including a separate slab waveguide on the other side, and in the same direction as the longitudinal direction of the cut surface in accordance with a change in environmental temperature of the arrayed waveguide type diffraction grating. The first and second waveguides include a slide moving member that slides at least one of the first and second waveguide forming regions in the direction of the substrate surface along the cut surface by expanding and contracting. The slide moving member is provided so as to be in contact with the end face of the waveguide forming region on at least one side of the forming region, and the slide moving member serves as a means for compensating for temperature-dependent fluctuations of the respective light transmission center wavelengths. It is a means to solve.

Further, the optical module of the present invention accommodates the arrayed-waveguide-type diffraction grating module of the first or second invention in a housing and guides the array guided by vibrations applied to the housing from outside the housing. This is a means for solving the problem by providing a configuration provided with a vibration reducing means for reducing transmission to the waveguide grating module.

The inventor of the present invention intends to eliminate the deviation of the light transmission center wavelength 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.

Light incident from the optical input waveguide in the arrayed waveguide type diffraction grating 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).

[0035]

(Equation 3)

[0036] 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.

[0037] 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.

[0038]

(Equation 4)

[0039] Incidentally, in FIG. 5, 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 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, the following equation (5) is established between the P and the wavelength λ.

[0040]

(Equation 5)

In _equation (5), L _f is the focal length of the second slab waveguide, and _ng is the group refractive index of the arrayed waveguide. Incidentally, the group index n _g of the arrayed waveguide, the effective refractive index n _c of the arrayed waveguide, is given by equation (6).

[0042]

(Equation 6)

The above (Equation 5) is obtained by arranging and forming the input end of the optical output waveguide at a distance dx in the X direction from the focal point O of the second slab waveguide, so that light having a wavelength different by dλ is obtained. Means that it is possible to retrieve

The relationship of (Equation 5) also holds for the first slab waveguide 3. 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).

[0045]

(Equation 7)

In equation (7), L _f ′ is the focal length of the first slab waveguide. This (Equation 7) is the first
By disposing the output end of the optical input waveguide at a position dx 'away from the focal point O' of the slab waveguide in the X direction, dλ 'in the optical output waveguide formed at the focal point O is obtained.
This means that light with different wavelengths can be extracted.

Therefore, when the light transmission center wavelength is shifted from the set wavelength by Δλ due to, for example, a manufacturing error of the arrayed waveguide type diffraction grating, dλ ′ = Δλ.
If the output end position of the optical input waveguide is shifted by the distance dx 'in the X direction, for example, light having no wavelength shift from the set wavelength can be extracted from the optical output waveguide formed at the focal point O, and other light can be extracted. Since the same effect occurs with respect to the output waveguide, the light transmission center wavelength shift Δλ can be compensated.

Similarly, when the center wavelength of light transmitted from the optical output waveguide of the arrayed waveguide type diffraction grating shifts by Δλ due to a change in the use environment temperature of the arrayed waveguide grating, dλ ′ = Δλ If the output end position of the optical input waveguide is shifted by the distance dx ′ in the X direction so that, for example, light without wavelength shift can be extracted from the optical output waveguide formed at the focal point O. Since the same effect occurs with respect to the optical output waveguide, the optical transmission center wavelength shift Δλ can be compensated.

In the first and second aspects of the array waveguide type diffraction grating module having the above-described structure, at least one of the first slab waveguide and the second slab waveguide of the array waveguide type diffraction grating has a slab waveguide. Since the separated slab waveguide is cut and separated at a cut surface intersecting with the light path passing through the wave path, it is assumed here that the first slab waveguide is cut and separated.

In the first invention of the arrayed waveguide type diffraction grating module, the first waveguide including the separated slab waveguide on one side of the separated first slab waveguide by the position adjusting member. At least one of the formation region and the second waveguide formation region including the other side separated slab waveguide is moved along the cut surface in the direction of the substrate surface by the movement amount (dλ ′ = Δλ) (the light transmission center wavelength When the output end position of the optical input waveguide is moved by the distance dx 'in the X direction by moving the optical input waveguide by the distance dx' by moving the optical transmission waveguide by the amount of movement for compensating the amount of deviation from the set wavelength, the light transmission center wavelength deviation Δλ can be compensated. .

Similarly, in the second invention of the arrayed waveguide type diffraction grating module, the same movement is performed by the slide moving member in accordance with a change in the environmental temperature of the arrayed waveguide type diffraction grating. The temperature-dependent fluctuation of the light transmission center wavelength can be compensated.

Strictly speaking, by changing the position of the output end of the optical input waveguide, the light propagates in the first slab waveguide from the output end of the optical input waveguide to the input end of the arrayed waveguide. Although the focal length L _f ′ of light slightly changes, the focal length of the first slab waveguide in the currently used arrayed waveguide type diffraction grating is on the order of several mm, while the arrayed waveguide type diffraction grating is used. The amount of movement of the output end position of the optical input waveguide that moves to correct the light transmission center wavelength is several μm.
It is on the order of m to several tens of μm, which is much smaller than the focal length of the first slab waveguide.

Therefore, 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 cut plane by the amount of movement that compensates for the temperature-dependent variation of each light transmission center wavelength in the arrayed waveguide type diffraction grating. In addition, it is possible to eliminate the deviation of the light transmission center wavelength from the set wavelength and the temperature-dependent fluctuation.

Here, the relationship between the temperature change amount and the position correction amount of the optical input waveguide will be 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).

[0055]

(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.

[0057]

(Equation 9)

Therefore, in the second invention of the arrayed waveguide type diffraction grating module, the first slab waveguide is moved along the cut surface by the slide moving member by the position correction amount dx ′ shown by (Equation 9). By sliding the separated slab waveguide and the optical input waveguide, it is possible to eliminate the wavelength shift of the light transmission center wavelength.

In the first and second embodiments of the arrayed waveguide type diffraction grating module, the light transmission center wavelength of the arrayed waveguide type diffraction grating can be reduced without using a Peltier element or a heater based on the above principle. Since it is possible to suppress the deviation from the set wavelength and the deviation of the light transmission center wavelength due to the use environment temperature, as in the case of providing a temperature control means including a Peltier element and a heater, there is no need for constant energization and the assembly of parts. There is no temperature correction error caused by the error, and there is no possibility that the connection loss between the arrayed waveguide type diffraction grating and the optical fiber is increased by keeping the arrayed waveguide type diffraction grating at a temperature equal to or higher than room temperature.

As described above, the arrayed waveguide type diffraction grating is formed by utilizing the reciprocity of light.
The second slab waveguide side is cut and separated, and at least one side of the separated separated slab waveguide is moved by the moving amount in the direction of the substrate surface along the cut surface by a position adjusting member or a slide moving member. Also in this case, it is possible to eliminate the deviation from the set wavelength of each light transmission center wavelength and the temperature-dependent fluctuation.

[0061]

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. 1 shows a main configuration of an embodiment of an arrayed waveguide type diffraction grating module according to the present invention. In addition, (b) of FIG.
(A) and (c) of the same figure are side views, and (d) of the same figure.
FIG. 2B is a cross-sectional view taken along the line BB shown in FIG. 3B, and FIG. 2E is a cross-sectional view taken along the line AA shown in FIG.

As shown in these figures, the arrayed waveguide type diffraction grating module of the present embodiment has the same arrayed waveguide type diffraction grating as the conventional arrayed waveguide grating. It has a plurality of optical input waveguides 2, a first slab waveguide 3, a plurality of array waveguides 4, a second slab waveguide 5, and a plurality of optical output waveguides 6; The optical output waveguides 6 are arranged side by side with a predetermined waveguide interval.

However, in this embodiment, the first slab waveguide 3 of the arrayed waveguide type diffraction grating intersects with the light path passing through the first slab waveguide 3 (in the figure, the light traveling direction). The substrate 1 and the waveguide forming region 10 are also cut and separated into two at the cutting plane 8 (which intersects perpendicularly with the central axis). The side on which the optical input waveguide 2 is formed including the separation slab waveguide 3a is the first waveguide forming region 10a, the separation slab waveguide 3
b, the side on which the array waveguide 4, the second slab waveguide 5, and the optical output waveguide 6 are formed constitutes a second waveguide formation region 10b, which is located below the waveguide formation region 10. The substrate 1 provided also has the first and second waveguide forming regions 10.
It is cut and separated into two parts corresponding to a and 10b.

In this embodiment, the first waveguide forming region 1 of the arrayed waveguide type diffraction grating cut and separated in this manner is used.
0a and the second waveguide forming region 10b are arranged at the center of the base member 9 with the cut surfaces 8 facing each other.
Also, leaf springs 15 and 16 are provided so that the first waveguide formation region 10a and the second waveguide formation region 10b do not have a height difference or a gap in the cut surface 8, and the first waveguide formation region is formed. 10a and the second waveguide forming region 10b are accurately aligned and connected.

The base member 9 is made of quartz glass or I
The leaf springs 15 and 16 are made of a material having a low coefficient of thermal expansion such as an nvar lot.
9, the base member 9 is fixed to the side wall portion 36 and the block guide portion 41.

The leaf spring 15 is provided in the first waveguide forming region 10a.
And the second waveguide forming region 10b and the substrate 1 thereunder are urged toward the base member 9 to form the first waveguide forming region 10a.
And the second waveguide formation region 10b (in FIG. 1 (b), the displacement in the direction perpendicular to the paper surface) is suppressed. Further, the leaf spring 16 urges the first waveguide forming region 10a and the second waveguide forming region 10b toward the lower side in the drawing of FIG. Second
Of the waveguide forming region 10b is inappropriately moved to the upper side in the drawing.

As shown in FIG. 1B, the lower end surface of the first waveguide forming region 10a is more heat than the first and second waveguide forming regions 10a and 10b and the substrate 1. A high-thermal-expansion block 7 having a high expansion coefficient is provided in contact with the low-thermal-expansion block 12 having a lower thermal expansion coefficient than the high-thermal expansion block 7. Are provided in contact with each other. The high thermal expansion coefficient member 7 is formed of, for example, copper, aluminum, or the like.

High thermal expansion block 7 and low thermal expansion block 1
2 is the same as the longitudinal direction of the cut surface 8. Therefore, the expansion and contraction direction of the high thermal expansion block 7 and the low thermal expansion block 12 due to heat is the same as the longitudinal direction of the cut surface 8. Become. Further, the high thermal expansion block 7 and the low thermal expansion block 12 are formed to have the same thickness as the arrayed waveguide type diffraction grating.

The high thermal expansion block 7 has a curved surface on the side in contact with the end surface of the first waveguide forming region 10a, and the low thermal expansion block 12 has a curved side on the side in contact with the end surface of the second waveguide forming region 10b. It has a curved surface. The block guide portion 41 is provided between the high thermal expansion block 7 and the low thermal expansion block 12 to prevent the high thermal expansion block 7 and the low thermal expansion block 12 from shifting in the left-right direction in the drawing. Further, a leaf spring 17 is provided so that the height difference between the high thermal expansion block 7 and the low thermal expansion block 12 does not occur. The leaf spring 17 is fixed by screws 20.

In the present embodiment, the low thermal expansion block 12 moves the side of the second waveguide forming region 10b to the cut surface 8 by an amount of movement that compensates for the amount of deviation of the respective light transmission center wavelengths from the set wavelength. And a position adjusting member for moving in the direction of the substrate surface. Hereinafter, the configuration of the low thermal expansion block 12 and the operation of moving the second waveguide formation region 10b by the low thermal expansion block 12 will be described.

As shown in FIG. 2, the low-thermal-expansion block 12 is cut and separated into two parts 12a and 12b by a tapered surface 13, and the lower part 12b in the figure expands toward the right in the figure. Conversely, the upper part 1 in the figure
2a is widened toward the left side of the figure. In addition,
When the angle of the tapered surface 13 is θ,
For example, the angle is very small such that tan θ = 0.01, but is exaggerated in FIG. 2 and is not shown in FIG. 1B without being tapered.

The portion 12b of the low thermal expansion block 12
A position adjusting screw 33 is provided in contact with the side surface of the
Is provided, and the tip of the screw fixture 34 is
Is in contact with The locking portion 14 is connected to the portion 12b.

As shown in FIG. 2, when the tip of the position adjusting screw 33 is moved in the direction of the arrow in the figure, the portion 12a of the low thermal expansion block 12 moves upward in the figure in accordance with the amount of movement of the position adjusting screw 33. And a portion 12a of the low thermal expansion block 12
The second waveguide forming region 10b that is in contact with the first portion moves in the direction C of FIG.

Conversely, when the tip of the position adjusting screw 33 is moved in the direction opposite to the arrow in FIG.
3 corresponds to the moving amount of the low thermal expansion block 12
a moves to the lower side in the figure, and the second waveguide forming region 10b in contact with the portion 12a of the low thermal expansion block 12 moves in the direction D in FIG. ing.

Therefore, in the present embodiment, by appropriately setting the amount of movement of the position adjusting screw 33, the low thermal expansion block 12 is moved only by the amount of movement that compensates for the amount of deviation of each light transmission center wavelength from the set wavelength. Second waveguide forming region 1
0b is moved along the cut surface 8 in the direction of the substrate surface. Then, by fixing the position adjusting screw 33 at an appropriate position with the screw fixing tool 34, the second waveguide forming region 10 is fixed.
Fix the position of b.

On the other hand, the high-thermal-expansion block 7 is provided with the cut surface 8 in accordance with the environmental temperature change of the arrayed waveguide type diffraction grating.
By extending and contracting in the same direction as the longitudinal direction, the first waveguide forming region 10a functions as a slide moving member that slides along the cut surface 8 in the surface direction of the substrate 1. The high thermal expansion block 7 as a slide moving member serves as a means for compensating for temperature-dependent fluctuations of the respective light transmission center wavelengths.

In this embodiment, as described above, the block guide portion 41 is provided between the low thermal expansion block 12 and the high thermal expansion block 7, and the cut surface of the low thermal expansion block 12 and the high thermal expansion block 7 is provided. The movement in the longitudinal direction is more reliably guided.

In the present embodiment, fitting recesses 28 and 29 for the optical fiber aligner are formed in the side wall 36 of the base member 9, and the optical fiber aligner 23 is formed in the fitting recess 28. Are fitted, and the optical fiber arrangement tool 24 is fitted into the fitting recess 29. Optical fiber alignment tool 2
Optical fibers 21 and 22 are fixedly arranged on the optical fibers 3 and 24, respectively. The optical fiber 21 is aligned and connected to the optical input waveguide 2 of the arrayed waveguide type diffraction grating, and the optical fiber 22 is a corresponding optical output waveguide. 6 is aligned.

The present embodiment is configured as described above. The first slab waveguide 3 is separated from the separated slab waveguide 3 by the cut surface 8 intersecting the light path passing through the first slab waveguide 3.
a, 3b, which are cut and separated, and based on the results of an examination conducted by paying attention to the linear dispersion characteristics of the arrayed waveguide type diffraction grating, the amount of movement for compensating the deviation amount of each of the light transmission center wavelengths from the set wavelength. The low thermal expansion block 12 is moved in the direction of arrow C or arrow D in FIG. 1 by operating the position adjusting screw 33, and the second waveguide forming region 10 is moved by the amount of movement described above.
Move b.

The position adjustment amount dx ′ obtained from the result of the study focused on the linear dispersion characteristic of the arrayed waveguide type diffraction grating is obtained by dividing the position of the output end 11 of the optical input waveguide 2 by the cut surface 8. Since the amount is moved in the longitudinal direction, when moving the second waveguide forming region 10b side as in the present embodiment, the second amount for compensating the deviation amount of each light transmission center wavelength from the set wavelength is used. The amount of movement of the waveguide forming region 10b is -dx '.

Then, the output wavelength from each optical output waveguide 6 can be shifted by dλ ′ (dλ ′ = Δλ) shown in the above (Equation 7), and each light transmission center wavelength matches the set wavelength. Can be.

In this embodiment, when the operating environment temperature of the arrayed waveguide type diffraction grating changes, the difference between the coefficients of thermal expansion of the high thermal expansion block 7 and the low thermal expansion block 12
The first waveguide forming region 10a moves in the direction of arrow C or arrow D in FIG. 1 by a movement amount capable of suppressing the temperature-dependent variation of each light transmission center wavelength, and the sliding movement causes the separation slab waveguide 3a and the light to move. The input waveguide 2 slides. The first waveguide forming region 10a moves in the direction of arrow C in FIG. 1 at a high temperature, and moves in the direction of arrow D at a low temperature.

Therefore, according to the present embodiment, even if the use environment temperature of the arrayed waveguide type diffraction grating changes, it is possible to eliminate the shift of the light transmission center wavelength due to the change in the use environment temperature. Independent, so-called temperature-independent array waveguide type diffraction grating,
Irrespective of the temperature change, the light transmission center wavelength of the arrayed waveguide diffraction grating can be almost equal to the ITU grid wavelength.

Further, according to the present embodiment, the high thermal expansion block 7 and the low thermal expansion block 12 are formed to have the same thickness as the arrayed waveguide type diffraction grating, and the high thermal expansion block 7 is formed in the first waveguide forming region. 10a is provided in contact with the end face,
Since the low thermal expansion block 12 is provided in contact with the end face of the second waveguide forming region 10b, the thickness of the arrayed waveguide type diffraction grating module can be reduced.

Further, according to the present embodiment, the arrayed waveguide type diffraction grating is cut along the cutting plane 8, and the high thermal expansion block 7 and the low thermal expansion block 12 are respectively divided into the first and second waveguide forming regions 10a, 10a. Since it has a simple configuration provided in contact with the end face of 10b, it is easy to manufacture and a low-cost array waveguide type diffraction grating module can be obtained.

FIG. 3 shows an example of an optical module using the arrayed waveguide type diffraction grating of this embodiment.
It is to be noted that (c) of the figure shows a plan cross-sectional view in a state where the waveguide configuration of the arrayed waveguide type diffraction grating is omitted, and (b) and (d) of the same figure each show a half section. The figure and the other half are side views, and (a) of the figure shows a view from the direction of arrow C in (c).

In this optical module, the arrayed waveguide type diffraction grating of this embodiment is accommodated in a package 26 as a housing, and the arrayed waveguide type diffraction of vibration applied to the package 26 from outside of the package 26 is performed. It is characterized in that vibration reducing means for reducing transmission to the lattice is provided. The vibration reducing means includes a thin leg 31 connected to a plate 40 projecting inward from the side wall 27 of the package 26.
Is formed.

Note that the package 26 is covered with a lid 44, and the package 26 is filled with a matching oil 25 as a refractive index matching agent to be in a liquid-tight state.
The matching oil 25 is injected from an oil inlet 38 provided in the side wall 27 of the package 26 and filled in the package 26. The side wall 27
Is formed with an optical fiber insertion hole 37, which is connected to the optical fiber 21 and the optical output waveguide 6 connected to the optical input waveguide 2 of the arrayed waveguide type diffraction grating. The optical fibers 22 are inserted together and fixed by an optical fiber fixture 39.

When an optical module using an arrayed waveguide type diffraction grating is formed as shown in the figure, the arrayed waveguide type diffraction grating is fixed to the package 26 via the leg 31 so that the package 26 can be externally provided. Package 26
In order to reduce the transmission of the vibration applied to the array waveguide type diffraction grating to the array waveguide type diffraction grating, the vibration from the outside of the package 26 causes the waveguide formation region 10 of the array waveguide type diffraction grating.
It is possible to suppress the displacement of the positions a and 10b.

Further, by filling the matching oil 25 into the package 26, the matching oil 25 enters the cut surface 8 and suppresses an increase in the joint loss of the separated slab waveguides 3a and 3b of the first slab waveguide 3. can do.

Further, as described above, since the thickness of the arrayed waveguide type diffraction grating module can be reduced, the thickness of the optical module in which the arrayed waveguide type diffraction grating module is accommodated in the package 26 is also reduced. be able to.

The present invention is not limited to the above embodiment, but can take various embodiments. For example,
In the above embodiment, the low-thermal-expansion block 12 is cut by the tapered surface 13, and the lower portion 12 b of the tapered surface 13 is
The second waveguide forming region 10b is moved in the vertical direction in the drawing by moving the second waveguide forming region 10b in the vertical direction in the drawing. However, the tapered surface 13 is omitted, and the low thermal expansion block is formed by, for example, a screw moving in the vertical direction in the drawing. 12 may be moved directly in the vertical direction in the figure.

For example, as shown in FIG.
3, the low thermal expansion block 12 is formed, and the curved arm portion 43 is deformed by the YAG laser irradiator 54 to change the longitudinal length of the low thermal expansion block 12 (vertical length in the figure). Is also good. By setting this length as a movement amount for compensating the deviation amount of the center wavelength of light transmission of the arrayed waveguide type diffraction grating from the set wavelength, the center wavelength of light transmission of the arrayed waveguide type diffraction grating is similar to the above embodiment. Can be compensated for from the set wavelength.

As described above, the first waveguide forming region 10a and the second waveguide
The method of moving at least one of the waveguide forming regions 10b is not particularly limited and may be appropriately set.

Furthermore, in the above-described embodiment, the plane perpendicular to the central axis of the light traveling direction of the first slab waveguide 3 is defined as the cut plane 8, but the cut plane 8 is aligned with the central axis of the light travel direction. The cut surface 8 may be an oblique surface, and the cut surface 8 may be a cut surface that intersects the light path of the slab waveguide to be cut.

Further, in the above embodiment, the high thermal expansion block 7 is disposed in contact with the first waveguide forming region 10a, and the low thermal expansion block 12 is disposed in contact with the second waveguide forming region 10b. However, conversely, the low thermal expansion block 12 may be disposed in contact with the first waveguide forming region 10a, and the high thermal expansion block 7 may be disposed in contact with the second waveguide forming region 10b. In this case, the high thermal expansion block 7
Is disposed, for example, on the upper side of FIG. Further, the configuration may be such that the low thermal expansion block 12 is omitted and only the high thermal expansion block 7 is abutted.

Further, in the above embodiment, the position adjustment member formed by the low thermal expansion block 12 compensates for the amount of deviation of the light transmission center wavelength of the arrayed waveguide type diffraction grating from the set wavelength, and is formed by the high thermal expansion block 7. Although the temperature dependence of the optical transmission center wavelength of the arrayed waveguide type diffraction grating is compensated for by the slide moving member described above, for example, when the arrayed waveguide type diffraction grating module is used at a constant temperature, the slide moving member is not required. Can be omitted,
When the center wavelength of light transmission of the arrayed waveguide grating matches the set wavelength, the position adjusting member can be omitted.

However, in general, the light transmission center wavelength of the arrayed waveguide type diffraction grating may be deviated from the set wavelength due to a manufacturing error or the like, and the arrayed waveguide type diffraction grating is used within a certain operating temperature range. Therefore, it is desirable to provide both the position adjusting member and the slide moving member as in the above embodiment.

Further, the first slab waveguide 3 is cut and separated, but the arrayed waveguide type diffraction grating is formed by utilizing the reciprocity of light, and the second slab waveguide 5 side is formed. By cutting and separating, at least one side of the separated separated slab waveguide is moved in the substrate surface direction along the cut surface by a position adjusting member, or in the substrate surface direction along the cut surface by a slide moving member. They may be moved.

In this case as well, the same effects as those of the above embodiment can be obtained, and the deviation of the light transmission center wavelength from the set wavelength and the temperature-dependent fluctuation can be eliminated.

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.

[0102]

According to the first aspect of the arrayed waveguide type diffraction grating module, one of the first and second slab waveguides separated by the cut surface is used to separate the separated slab waveguide on one side. At least one of the first waveguide forming region including the first waveguide forming region and the second waveguide forming region including the separated slab waveguide on the other side is compensated for a shift amount of the light transmission center wavelength from the set wavelength by a position adjusting member. Because it is moved in the direction of the substrate surface along the cutting plane by a moving amount,
The deviation of the center wavelength of light transmission of the arrayed waveguide type diffraction grating from the set wavelength can be compensated very easily and accurately.

Further, in the position adjusting member applied to the first invention of the arrayed waveguide type diffraction grating module, at least one of the first and second layers is provided in contact with the end face of the path forming region. Therefore, the thickness of the arrayed waveguide grating module can be reduced.

The second part of the arrayed waveguide type diffraction grating module
According to the invention, at least one side of the first and second waveguide forming regions is cut by expanding and contracting in the same direction as the longitudinal direction of the cut surface in accordance with the environmental temperature change of the arrayed waveguide type diffraction grating. A slide moving member that slides along the surface in the direction of the substrate surface is provided in contact with an end surface of at least one of the first and second waveguide forming regions on an end face of the waveguide forming region, and the slide moving member is provided with each of the light beams. Since the means for compensating for the temperature-dependent variation of the transmission center wavelength can be very easily and accurately compensated for the temperature dependence of the light transmission center wavelength of the arrayed waveguide grating.

Further, in the slide moving member applied to the second invention of the arrayed waveguide type diffraction grating module, at least one of the first and second layers is provided in contact with the end face of the path forming region. As in the first aspect, the thickness of the arrayed waveguide type diffraction grating module can be reduced.

Further, in the optical module using the arrayed waveguide type diffraction grating module of the present invention, each of the arrayed waveguide type diffraction grating modules exhibiting the above-mentioned excellent effects is housed in a housing, and furthermore, the housing is provided with vibration reducing means. In order to reduce the transmission of vibration from the outside of the body to the arrayed waveguide grating module, the adverse effect of the vibration of the arrayed waveguide grating module is suppressed, and the effect of each arrayed waveguide grating module is reduced. An excellent optical module that can be reliably performed can be provided.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of a position adjusting function of a low thermal expansion block 12 provided in the embodiment.

FIG. 3 is an explanatory diagram showing a configuration example of an optical module using the arrayed waveguide type diffraction grating module of the embodiment.

FIG. 4 is an explanatory diagram of a position adjusting member applied to another embodiment of the arrayed waveguide grating module according to the present invention.

FIG. 5 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. 6 is an explanatory view showing a conventional arrayed waveguide type diffraction grating.

FIG. 7 is a graph showing an example of light transmission characteristics of light output from one light output waveguide of the arrayed waveguide type diffraction grating.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 optical input waveguide 3 first slab waveguide 3a, 3b separated slab waveguide 4 array waveguide 5 second slab waveguide 6 optical output waveguide 7 high thermal expansion block 8 cut surface 9 base member 10a first Waveguide forming area 10b Second waveguide forming area 12 Low thermal expansion block 13 Tapered surface 25 Matching oil 26 Package

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazutaka Nara, 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Tsuneaki Saito 2-6-1, Marunouchi, Chiyoda-ku, Tokyo No. F-term in Furukawa Electric Co., Ltd. (reference) 2H047 KA03 KA12 LA19 MA05 RA08 TA05 TA31 TA42 TA47

Claims (3)

[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. On the emission side of the slab waveguide, a waveguide forming region having a waveguide configuration in which a plurality of light output waveguides arranged in parallel is connected,
A light demultiplexing function of demultiplexing light of one or more wavelengths from light having a plurality of different wavelengths input from the optical input waveguide and outputting the demultiplexed light from each optical output waveguide; The light transmittance of each light output from the output waveguide becomes smaller as the wavelength shifts from the corresponding light transmission center wavelength around the mutually different light transmission center wavelength of the demultiplexed light at least in a predetermined wavelength region. An array waveguide type diffraction grating, wherein the first slab waveguide and the second
At least one of the slab waveguides is cut at a cutting plane that intersects a light path passing through the slab waveguide to form a separated slab waveguide, and the waveguide forming region includes a first separated slab waveguide. Separated into a waveguide forming region and a second waveguide forming region including the other side separated slab waveguide,
A position adjusting member that moves at least one side of the first and second waveguide forming regions in the direction of the substrate surface along the cut surface by a moving amount that compensates for a shift amount of the light transmission center wavelength from the set wavelength. An arrayed waveguide type diffraction grating module, which is provided so as to be in contact with an end face of at least one of the first and second waveguide forming regions on an end face of the waveguide forming region. 2. 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 emission side of the slab waveguide, a waveguide forming region having a waveguide configuration in which a plurality of light output waveguides arranged in parallel is connected,
A light demultiplexing function of demultiplexing light of one or more wavelengths from light having a plurality of different wavelengths input from the optical input waveguide and outputting the demultiplexed light from each optical output waveguide; The light transmittance of each light output from the output waveguide becomes smaller as the wavelength shifts from the corresponding light transmission center wavelength around the mutually different light transmission center wavelength of the demultiplexed light at least in a predetermined wavelength region. An array waveguide type diffraction grating, wherein the first slab waveguide and the second
At least one of the slab waveguides is cut at a cutting plane that intersects a light path passing through the slab waveguide to form a separated slab waveguide, and the waveguide forming region includes a first separated slab waveguide. Separated into a waveguide forming region and a second waveguide forming region including the other side separated slab waveguide,
By expanding and contracting in the same direction as the longitudinal direction of the cut surface in accordance with the environmental temperature change of the arrayed waveguide type diffraction grating,
And a slide moving member that slides at least one side of the second waveguide formation region along the cut surface in the direction of the substrate surface, wherein the slide moving member is at least one side of the first and second waveguide formation regions. An arrayed-waveguide-type diffraction grating module, which is provided in contact with an end face, and wherein the slide moving member serves as means for compensating for temperature-dependent fluctuations of the respective light transmission center wavelengths. 3. The array waveguide type diffraction grating module according to claim 1 or 2 is accommodated in a housing, and vibration applied to the housing from outside of the housing is applied to the array waveguide type diffraction grating module. An optical module comprising a vibration reducing means for reducing transmission.