JPH11231156A - Dispersion compensating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dispersion compensating device which is small-sized and has high precision by controlling the temperature of a temperature control part and compensating the dispersion of a super high-rate light signal up to dispersion of higher order. SOLUTION: This device consists of an array waveguide diffraction grating 103, an array waveguide diffraction grating 105, one input waveguide 102 which guides light to the array waveguide circuit diffraction grating 103, connection waveguides 104 which connect the array waveguide diffraction gratings 103 and 105, one output waveguide 106 which guides light from the array waveguide diffraction grating 105, a temperature control part, and a temperature control circuit which controls the temperature of the temperature control part. Then light after frequency dispersion by the spectral diffracting function of the array waveguide diffraction grating 103 at specific temperature is distributed to the connection waveguides 104. So that the loss of a connection from a slave waveguide 103b to the connection waveguide 104 so as to be small, monochromatic light is made incident on the input optical waveguide 102 and the moke ratio of the connection waveguides 104 is set to 60:40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersion compensator for equalizing waveform distortion in a transmission path of a high-speed optical signal.

[0002]

2. Description of the Related Art In an ultrahigh-speed optical transmission device, the first factor that limits the transmission distance is waveform distortion due to group velocity dispersion in an optical fiber. The dispersion characteristic of the transmission line is caused by a change in environmental temperature and a change in material and coating over time. The dispersion characteristic of the transmission line also changes when switching to another optical fiber accompanying the switching of the transmission device. Alternatively, the dispersion value perceived by the signal light also changes due to a change in the wavelength of the light source or a change in the filter characteristics, even if the dispersion of the optical fiber does not change. Even a commonly used dispersion-shifted optical fiber having a small dispersion can be used for ± 1 ps / nm / k.
Since there is a secondary dispersion of about m, the dispersion becomes ± 80 ps / nm in a transmission section of 80 km. 20Gbit / s
Since the optical band of the signal light having a pulse width of 10 ps is about 1 nm, a pulse spread of a maximum of about 80 ps occurs. However, the time slot of a 20 Gbit / s signal is 50 p.
Because of s, a great deal of intersymbol interference occurs and a large error occurs. For this reason, a device for compensating (equalizing) the dispersion of a transmission line is indispensable for an ultra-high-speed transmission device. Furthermore, third-order higher-order dispersion is
It is about 0.07 ps / nm ² / km, and when a pulse of about 5 ps or less is used for long-distance transmission near the zero-dispersion wavelength, it causes a dominant waveform distortion.

As a conventional technique, there is an apparatus as shown in FIG. In this device, the two arrayed waveguide diffraction gratings 201 and 202 are connected by a plurality of connection waveguides 203, and the refractive index of each of the waveguides 203 is arbitrarily controlled. In the figure, reference numeral 204 denotes a temperature control unit (such as a heater), 205 denotes electric wiring, and 206 denotes a control circuit. The arrayed waveguide gratings 201 and 202 have a function of dispersing a signal incident on an input waveguide into constituent frequency components, and have been conventionally applied to wavelength division multiplex communication. That is, due to the spectral function of the arrayed waveguide diffraction gratings 201 and 202, frequency-resolved signal light is incident on each of the connection waveguides 203. When signal light is transmitted through a transmission line with dispersion,
Assuming that the center frequency is ν ₀ , the center frequency undergoes a transfer change δφ (ν) shown by the following equation, and the waveform is distorted.

[0004]

(Equation 5)

Here, the first-order term with respect to the frequency corresponds to the shift of the waveform on the time axis and does not affect the distortion. What matters in transmission is mainly the second and third order terms. In the related art, the refractive index, that is, the phase of each connection waveguide 203 can be independently controlled to give an opposite phase change δφ _c (p) for approximately correcting distortion.

[0006]

(Equation 6)

If the frequency resolution is sufficiently high, δφ
(Ν) = − δφ _c (ν _p ), and dispersion compensation can be performed. Here, p is two array waveguide diffraction gratings 2
The number of the connection waveguide 203 that connects 01 and 202 is such that the number of the waveguide corresponding to the center frequency is 0, and the higher frequency side is + and the lower frequency side is-.

However, the conventional technique has the following problems.

(I) Since the phases of the connection waveguides 203 are independently controlled, the configuration of the electrodes becomes complicated.

(Ii) Since each phase of the waveguide 203 is independently controlled, the control becomes complicated.

(Iii) In accordance with a change in external temperature, the waveguide 2
03 need to be changed.

(Iv) In response to a change in the center frequency of the signal light,
It is necessary to change the refractive index of each of the waveguides 203.

[0013]

SUMMARY OF THE INVENTION The present invention has been made under the above-mentioned background, and is easy to control, has little effect on external temperature changes, and has a method for compensating dispersion of an ultra-high-speed optical signal. It is an object of the present invention to provide a small and high-precision dispersion compensator capable of performing high-order dispersion.

[0014]

In order to solve the above-mentioned problems, a dispersion compensator according to the present invention is a dispersion compensator using an arrayed waveguide diffraction grating. A second arrayed waveguide grating, one input waveguide for guiding light to the first arrayed waveguide grating, and a plurality of connecting waveguides for connecting the first and second arrayed waveguide gratings. A connection waveguide; one output waveguide for guiding light from the second arrayed waveguide diffraction grating; a temperature control unit; and a temperature control circuit for controlling the temperature of the temperature control unit. It is characterized by.

Further, another dispersion compensating device of the present invention is a dispersion compensating device using an arrayed waveguide diffraction grating. The dispersion compensating device includes an arrayed waveguide diffraction grating and a waveguide for guiding light to the arrayed waveguide diffraction grating. A waveguide for input / output, a reflection mirror, a plurality of connection waveguides for connecting the arrayed waveguide diffraction grating and the reflection mirror, a temperature control unit, and a temperature control circuit for controlling the temperature of the temperature control unit And characterized by the following.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the first aspect of the present invention is as follows.
Is a dispersion compensator using an arrayed waveguide diffraction grating, wherein light is transmitted to a first arrayed waveguide diffraction grating, a second arrayed waveguide diffraction grating, and a first arrayed waveguide diffraction grating. One input waveguide for guiding, a plurality of connecting waveguides for connecting the first and second arrayed waveguide gratings, and 1 for guiding light from the second arrayed waveguide grating
It is characterized by comprising an output waveguide of the present invention, a temperature control unit, and a temperature control circuit for controlling the temperature of the temperature control unit.

According to a second aspect of the present invention, there is provided a dispersion compensating apparatus using an arrayed waveguide diffraction grating, wherein the arrayed waveguide diffraction grating comprises: One input / output waveguide for guiding light to the diffraction grating, a reflection mirror, and a plurality of connection waveguides for connecting the arrayed waveguide diffraction grating and the reflection mirror;
It is characterized by comprising a temperature control section and a temperature control circuit for controlling the temperature of the temperature control section.

According to a third aspect of the present invention, there is provided the dispersion compensating apparatus according to the first aspect of the present invention, wherein p-th (where p is an integer, the opposite side is counted as -p-th) from the center of the plurality of connecting waveguides. Is the waveguide length of L _p and the temperature T in the waveguide.
When the signal light wavelength that depends on the λ _eff (T), at a certain reference temperature T _0,

[0019]

(Equation 7)

It is characterized by satisfying.

According to a fourth aspect of the present invention, there is provided the dispersion compensating apparatus according to the second aspect, wherein the p-th number is counted from the center of the plurality of connection waveguides (p is an integer and the opposite side is counted as -p-th). Is the waveguide length of L _p and the temperature T in the waveguide.
Let λ _eff (T) be the signal light wavelength that depends on

[0022]

(Equation 8)

It is characterized by satisfying.

According to a fifth aspect of the present invention, there is provided the dispersion compensating apparatus according to the first or second aspect, wherein each of the connecting waveguides comprises two waveguide portions having different temperature-dependent coefficients. It is characterized by.

According to a sixth aspect of the present invention, there is provided the dispersion compensating apparatus according to any one of the first to fifth aspects.
The temperature control unit includes a Peltier element that controls the temperature of the entire waveguide, and a thermometer.

According to a seventh aspect of the present invention, there is provided the dispersion compensating apparatus according to any one of the first to fifth aspects, wherein
The temperature control unit may include a heater that uniformly heats the entire connection waveguide.

According to an eighth aspect of the present invention, in the dispersion compensating apparatus of the first or second aspect, the temperature controller is a heater provided in each of the connection waveguides, and each of the heaters is connected in series. Is connected to the terminal.

According to a ninth aspect of the present invention, in the dispersion compensating apparatus of the eighth aspect,

[0029]

[Outside 3]

In the p-th waveguide from the center (where p is an integer and the opposite side is counted as -p-th),

[0031]

(Equation 9)

It is characterized by the following.

According to a tenth aspect of the present invention, in the dispersion compensating apparatus according to the first or second aspect, the temperature controller is a heater provided in each of the connection waveguides.
The heaters are connected in parallel.

The dispersion compensator according to claim 11 of the present invention is the dispersion compensator according to claim 10, wherein

[0035]

[Outside 4]

In the p-th waveguide from the center (where p is an integer and the opposite side is counted as -p-th),

[0037]

(Equation 10)

It is characterized by the following.

According to a twelfth aspect of the present invention, there is provided the dispersion compensating apparatus according to any one of the eighth to eleventh aspects, further comprising a plurality of heaters connected in series or in parallel. .

A dispersion compensator according to a thirteenth aspect of the present invention is the dispersion compensator according to any one of the first to twelfth aspects, wherein the plurality of connection waveguides are arranged in the plurality of connection waveguides. S group (s)
When the connection waveguide group is divided into ≧ 2), the waveguides at the center of each of the connection waveguide groups are described.
The length of the waveguide and the length of the heater described in each of the above are defined.

According to a fourteenth aspect of the present invention, there is provided the dispersion compensating apparatus according to any one of the first to thirteenth aspects, wherein the array compensating apparatus controls the refractive index of the arrayed waveguide portion of the arrayed waveguide diffraction grating. It is characterized by further having a waveguide heating heater and an arrayed waveguide temperature control circuit for controlling the heater.

According to a fifteenth aspect of the present invention, in the dispersion compensator according to any one of the first to thirteenth aspects, each waveguide of the arrayed waveguide of the arrayed waveguide grating has a temperature constant. It is characterized by being composed of two different waveguides.

[0043]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings describing the following embodiments, the same or similar components are denoted by the same reference numerals and description thereof will be simplified.

(Embodiment 1) FIG. 1 shows a first embodiment of the present invention. In the drawing, 101 is a substrate, 102 is an input optical waveguide, 103 is a first arrayed waveguide grating, 105 is a second arrayed waveguide grating, and 104 is the first and second arrayed waveguide gratings. A connection optical waveguide for connecting 103 and 105, 106 is an output optical waveguide, and 10
3a is an array waveguide portion of the array waveguide diffraction grating 103,
103b is a slab waveguide constituting the diffraction grating 103.

FIG. 2 is an explanatory diagram of the numbering of the connection waveguide 104. The number of connection waveguides 104 is Nx, the center waveguide is number 0, and -Nx / 2,.
−2, −1, 0, 1, 2, 3,..., Nx / 2. Here, for convenience of explanation, the number of waveguides is assumed to be an odd number, but may be an even number.

FIG. 3 shows a mounting diagram of the device of the first embodiment. In the figure, 107 is a heat sink, 108 is an optical fiber, 109 is a thermistor, 110 is a Peltier element, and 111 is a temperature control circuit.

The array waveguide diffraction gratings 103 and 1
05 can be made of a glass material, a semiconductor material, and an organic material. In the first embodiment, since the temperature change of the entire arrayed waveguide diffraction grating is used, the organic material having a large temperature constant is used. Alternatively, semiconductor materials are suitable.

FIG. 4 shows a cross-sectional shape of the optical waveguide portion when this embodiment is made of an organic material. 112 is a silicon substrate, 113 is a clad, and 114 is a core. For the clad 113 and the core 114, silicone resins having different compositions from each other were used. The manufacturing method of this optical waveguide is as follows.

First, a silicone resin for cladding was applied on the silicon substrate 112 by spin coating to form a film. In the silicone resin for cladding, an alkyl group bonded to a silicon atom has a C ₆ H ₅ (phenyl) group or CH.
₃ The molar ratio of the (methyl) group was adjusted to 55:45. Further, the rotation speed of the spin coater was adjusted so that the film thickness became 20 μm. The formed thin film is 200
This was cured by heating at 2 ° C. for 2 hours to form a lower cladding layer.

Next, a film of a silicone resin for a core was formed thereon under the condition of a thickness of 8 μm. In the silicone resin for the core, the alkyl group bonded to the silicon atom has C ₆ H ₅
The molar ratio of the (phenyl) group or CH ₃ (methyl) group was adjusted to 60:40. 2 at 200 ° C
Cured in time. Subsequently, a copper thin film was deposited by sputtering, and an arrayed waveguide diffraction grating mask pattern was formed by photolithography and ion milling. Further, the core layer other than the mask pattern was removed by reactive ion etching to form a rectangular core ridge having a width of 8 μm and a height of 8 μm.

After removing the etching mask, a silicone resin for cladding was applied thereon and cured as in the case of forming the lower clad to form a buried channel optical waveguide having a core / clad structure. The thickness of the upper clad was 10 μm from the upper surface of the core.

The connection waveguide 104 shown in FIG. 2 is set to a length satisfying the following equation. Assuming that the length of the p-th waveguide from the center is L _p and the signal light wavelength dependent on the temperature T in the waveguide is λ _eff (T), the following expression is satisfied at a certain reference temperature T ₀ .

[0053]

[Equation 11]

In the equation, n _eff (T) is the equivalent refractive index of the waveguide depending on the temperature T, c is the light speed, and v ₀ is the center wavelength of the signal light.

At the temperature T ₀ , the arrayed waveguide diffraction grating 1
The light frequency-resolved by the spectroscopic function 03 is distributed to each connection waveguide 104. The mode field diameter of the connection waveguide 104 and the monochromatic light are input to the input optical waveguide 102 to reduce the loss in the connection from the slab waveguide 103b to the connection waveguide 104, and to the entrance of the connection waveguide 104. It is preferable to set the mode field diameters of the formed images to be sufficiently different. In particular, in order to obtain flat transmission characteristics, the mode field diameter of the connection waveguide 104 is smaller than the mode field diameter.
It is preferable to increase the mode field diameter formed at the entrance of the connection waveguide 104. The center frequency ν _{cp of} light incident on the p-th connection waveguide is represented by the following equation.

[0056]

(Equation 12)

If the optical path difference of each waveguide of the array waveguide portion 103a of the array waveguide diffraction grating 103 is appropriately designed,
It is possible to manufacture the arrayed waveguide grating 103 such that ν _c0 = ν ₀ . In the present embodiment, the second-order dispersion compensation can be particularly easily performed. (Α = 2) The phase φ _rel of the output light from each waveguide with respect to the phase of the output light from the center waveguide is expressed by the following equation.

[0058]

(Equation 13)

That is, in the case of the temperature T ₀ , the phase difference of the light emitted from each waveguide is an integral multiple of 2π, and in the system of this embodiment, the secondary dispersion = 0 and the waveform of the emitted light does not change. FIG. 5 shows a change in phase when the temperature is changed. Considering the temperature dependence of the center frequency, equation (6) can be rewritten as follows.

[0060]

[Equation 14]

In the equation, Δν is the center frequency difference between adjacent waveguides. In this equation (7), terms of first order or less with respect to frequency do not affect waveform distortion.
Extracting only the following terms,

[0062]

(Equation 15)

Is obtained. That is, by changing the temperature,
For β in equation (1),

[0064]

(Equation 16)

By controlling the temperature so as to satisfy the condition (2), secondary dispersion compensation can be performed.

For the present embodiment to function, the incident pulse must be sufficiently long with respect to the optical path difference in the connection waveguide 104. Where k = 1, p _max = 10,
If λ _eff (T ₀ ) = 1 [μm], from equation (3),
The maximum actual delay due to the optical path difference is 0.5 ps. This embodiment is effective when the pulse width is sufficiently long with respect to this delay, that is, for an optical pulse whose pulse width corresponding to the spectrum width is about 5 ps or more.

(Embodiment 2) FIG. 6 shows a structure of an arrayed waveguide portion 103a of an arrayed waveguide diffraction grating 103 according to a second embodiment of the present invention. Other configurations are the same as those of the first embodiment. The present embodiment is characterized in that the arrayed waveguide 103 is composed of waveguides having two different refractive index temperature constants γ ₁ and γ ₂ . Array waveguide diffraction grating 103
Center frequency [nu _c0 of is expressed by the following equation.

[0068]

[Equation 17]

In the equation, δ (n _array L) is an optical path difference between adjacent arrayed waveguides, and m is a diffraction order (integer,> 1). The following equation is obtained from the condition that the optical path difference does not change with temperature.

[0070]

(Equation 18)

In the formula, ΔL ₁ is the difference in length between adjacent waveguides having a refractive index temperature constant γ ₁ , and ΔL ₂ is the adjacent waveguide having a refractive index temperature constant γ _2. Is the difference in length. In general, an organic waveguide has a negative refractive index temperature constant, and therefore has a minus sign on the right side. Also,
When the equation (11) is rewritten using ΔL ₁ and ΔL ₂ , the following equation is obtained.

[0072]

[Equation 19]

From equations (12) and (13), ΔL ₁ and ΔL ₁
L ₂ is required. In this case, since the center frequency does not change, δν (T) = 0 in equation (7) always holds. This embodiment is effective when performing third-order or higher dispersion compensation. When α = 3 in the equation (3), the phase φ _rel of the output light from each waveguide with respect to the phase of the output light from the center waveguide is:
It is shown by the following equation.

[0074]

(Equation 20)

As is clear from equation (14), δν
If (T) is not equal to zero, a change in the center frequency due to a temperature change causes an excessive secondary phase change, distorting the waveform, and making it impossible to perform dispersion compensation. However, in this embodiment, δν (T) =
Since 0 always holds, equation (14) is

[0076]

(Equation 21)

Thus, tertiary phase compensation can be performed by adjusting the temperature.

(Embodiment 3) FIG. 7 shows a third embodiment of the present invention.
Shown in The present embodiment is characterized in that the connecting waveguide 104 is formed of two waveguides having different refractive index temperature constants γ _a and γ _b . In the first embodiment described above, there is a limit to the minimum pulse width due to the difference in the optical path length of the connection waveguide 104.
This embodiment can eliminate this disadvantage. In addition, since the connecting waveguides 104 are not allowed to cross, it is difficult to make the center waveguide longer than the outer waveguide, and the layout of the first embodiment may be difficult in some cases.
In this embodiment, this disadvantage can be eliminated.

The difference between the lengths of the adjacent p-th and p + 1-th waveguides in the refractive index temperature constant γ _a portion is ΔL _pa , and the difference between the adjacent p-th and p + 1-th waveguides in the refractive index temperature constant γ _b portion is the difference in length of .DELTA.l _pb, the effective refractive index of each waveguide n _a
And a n _b.

[0080]

(Equation 22)

For each waveguide (p), it is possible to determine ΔL _pa and ΔL _pb so that equations (17) and (18) hold. At this time, the following equation is established.

[0082]

(Equation 23)

From the equation (19), the phase of the output light from each waveguide with respect to the phase of the light emitted from the center waveguide is expressed by the following equation.

[0084]

(Equation 24)

That is, by controlling the temperature, the phase can be compensated and controlled as shown in the following equation.

[0086]

(Equation 25)

In this embodiment, j = 0 in equation (17).
Then, the optical path length difference between the connection waveguides 104 becomes 0,
Waveform distortion due to a delay time difference in the connection waveguide 104 is eliminated. If j is an arbitrary value, the length of the connecting waveguide can be set so that the layout is easy.

(Embodiment 4) FIGS. 8 and 9 show a fourth embodiment of the present invention. FIG. 9 shows a cross-sectional view of the heater section. In the present embodiment, a heating unit using a thin film heater 115 is provided in the connection waveguide 104, and the refractive index in the connection waveguide 104 is changed to adjust the dispersion control amount. Unlike the conventional technology, the heaters 115 are connected in series without performing independent control. Therefore, the wiring is simplified and the control is facilitated. Since local heating by the heater 115 is necessary, an arrayed waveguide diffraction grating made of a glass material or an organic material having a small heat conductivity is suitable for this embodiment. The heater length of each waveguide is set as follows. Heater 1
15 is usually formed of a gold thin film, but it is difficult to control the film thickness for each waveguide. Since the width of the heater 115 has an upper limit in the waveguide interval, a desired phase change can be obtained by changing the heater length. of course,
Although it is difficult, it goes without saying that the heater thickness and heater width may be set to appropriate values.

When a heater is formed on the upper surface of the waveguide 104, a change in the refractive index per unit length, that is, a change in phase in the waveguide core is proportional to the amount of heat S generated by the heater 115 per unit length. Since the heaters 115 are connected in series, the current flowing through the heaters 115 is I,

[0090]

[Outside 5]

[0091] When the heating value per unit length at the p-th waveguide of the heater and S _p, S _p is expressed by the following equation.

[0092]

(Equation 26)

Here, assuming that the proportional coefficient is θ, the phase change φ _p due to the current in the p-th waveguide is

[0094]

[Equation 27]

Is obtained. That is, if the heater length is set as follows, the i-th dispersion can be controlled.

[0096]

[Equation 28]

At this time, the expression (25) is rewritten into the following expression.

[0098]

(Equation 29)

The phase of the output light from each waveguide with respect to the phase of the output light from the central waveguide is equal to

[0100]

[Equation 30]

Is obtained. That is, a phase represented by the following equation can be variably given by the current with respect to the frequency.

[0102]

(Equation 31)

Therefore, according to the device of the fourth embodiment, the following dispersion compensation / control is possible.

[0104]

(Equation 32)

In the present embodiment, the individual lengths of the connection waveguides 104 need not be equal, but the relative phase difference between the center waveguide and the p-th waveguide must satisfy the following equation. Where μ
Is a real proportional coefficient.

[0106]

[Equation 33]

When the value of μ is made appropriate, it is possible to compensate / control the positive / negative dispersion by the current control.

In FIG. 8, reference numeral 116 denotes an electric wiring;
117 is a temperature control circuit.

(Embodiment 5) FIGS. 9 and 10 show a fifth embodiment of the present invention. FIG. 9 shows a cross-sectional configuration of an optical waveguide portion of the device of this embodiment, and FIG. 10 shows a configuration of the entire device. The present embodiment is characterized in that the connection of the heater 115 is parallel connection in the fourth embodiment. In this case, the heat generation amount S ′ _p is expressed by the following equation, where V is the voltage applied to the heater.

[0110]

(Equation 34)

The phase change φ _p of the p-th waveguide is

[0112]

(Equation 35)

Thus, it can be seen that the heater length may be set as in the following equation.

[0114]

[Equation 36]

(Embodiment 6) FIG. 1 shows a sixth embodiment of the present invention.
It is shown in FIG. In the present embodiment, a plurality of heaters in the above-described fourth and fifth embodiments are arranged, and dispersion of different orders can be controlled simultaneously.

(Embodiment 7) FIG. 1 shows a seventh embodiment of the present invention.
It is shown in FIG. In the drawing, reference numeral 118 denotes a thin-film heater for heating the array waveguide, and 119 denotes an array waveguide temperature control circuit. The present embodiment is characterized in that a heater 118 is provided in the arrayed waveguide portion 103a of the arrayed waveguide diffraction grating 103. The heater 118 can uniformly heat the entire array waveguide section 103a. For this reason, the optical path length difference between the arrayed waveguides, that is, the center frequency of the arrayed waveguide grating 103 can be controlled. When the frequency of the incident light fluctuates, in the dispersion control circuit of the present invention, waveform distortion occurs due to excessive low-order dispersion with respect to third-order or higher dispersion control. According to the frequency of the incident light, the arrayed waveguide diffraction grating 1
By controlling the center frequency of 03, it is possible to suppress the occurrence of excessive dispersion.

(Eighth Embodiment) FIG. 13 shows an eighth embodiment of the present invention. In the figure, 120 is an optical input / output waveguide, 121
Is a mirror unit, and 122 is a circulator. FIG. 14 shows a sectional structure of the mirror section 121. In the figure, 123
Is a gold mirror formed by vapor deposition. In the present embodiment, a mirror 121 is provided which folds the configuration of the other embodiment of the present invention just in the middle of the connection waveguide 104 to reduce the size of the connection waveguide 104 by half and to reduce the size of the connection waveguide 1.
04 facilitates the layout. If the waveguide length and heater length are all halved, the operation is exactly the same as in the other embodiments. For example, when the configuration of the first embodiment is performed in a reflection type, the connection waveguide is configured such that the length of the p-th waveguide from the center is L _p , and the signal light wavelength depending on the temperature T in the waveguide is λ.
_{Assuming that eff} (T), the following equation is satisfied at a certain reference temperature T ₀ .

[0118]

(37)

(Embodiment 9) FIG. 1 shows a ninth embodiment of the present invention.
It is shown in FIG. In this embodiment, in order to be applicable to wavelength division multiplexing communication, the connection waveguide 12 is used for each wavelength of each signal light.
4 is provided. Here, the multiplexed wavelength is λ
₁ , λ ₂ ,..., Λ _n ,
2,..., 124-n are connection waveguides in which signal light of each wavelength is equivalent. The operation for each wavelength channel is the same as in the other embodiments.

[0120]

As described above, according to the present invention, the chirping of the optical signal by the dispersion medium can be compensated to a high-order dispersion by simple temperature control or electric control. Strong resistance to external temperature changes. Further, it is possible to compensate for dispersion by controlling the central wavelength of dispersion compensation by following the change in dispersion of the transmission line with a single circuit. It is possible to follow a change in the wavelength of the signal light. Further, the dispersion compensating device of the present invention has advantages such as being easy to handle and being able to be incorporated into other devices since it can be modularized into a small size, and can be used for a high-speed transmission device. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a connection waveguide according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a waveguide structure according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a phase change of a connection waveguide due to temperature adjustment according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a third embodiment of the present invention.

FIG. 8 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 9 is an explanatory diagram of a heater structure according to a fourth embodiment of the present invention.

FIG. 10 is an explanatory diagram of a fifth embodiment of the present invention.

FIG. 11 is an explanatory diagram of a sixth embodiment of the present invention.

FIG. 12 is an explanatory diagram of a seventh embodiment of the present invention.

FIG. 13 is an explanatory diagram of an eighth embodiment of the present invention.

FIG. 14 is an explanatory diagram of a mirror section according to an eighth embodiment of the present invention.

FIG. 15 is an explanatory diagram of a ninth embodiment of the present invention.

FIG. 16 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Substrate 102 Input optical waveguide 103 First arrayed waveguide diffraction grating 104 Connection optical waveguide 105 Second arrayed waveguide diffraction grating 106 Output optical waveguide 107 Heat sink 108 Optical fiber 109 Thermistor 110 Peltier element 111 Temperature control circuit 112 Silicon Substrate 113 Cladding 114 Core 115 Thin film heater 116 Electrical wiring 117 Temperature control circuit 118 Thin film heater for array waveguide heating 119 Array waveguide section temperature control circuit 120 Optical input / output waveguide 121 Mirror section 122 Circulator 123 Gold mirror 124-1, 124 −2,..., 124-n Connection waveguide 201 Array waveguide diffraction grating 202 Array waveguide diffraction grating 203 Connection waveguide 203 Temperature controller (heater, etc.) 205 Electrical wiring 206 Control circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoki Oba 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Inventor Katsutoshi Okamoto 3-19 Nishi Shinjuku, Shinjuku-ku, Tokyo No. 2 Nippon Telegraph and Telephone Corporation

Claims (15)

[Claims] 1. A dispersion compensator using an arrayed waveguide diffraction grating, wherein light is guided to a first arrayed waveguide diffraction grating, a second arrayed waveguide diffraction grating, and a first arrayed waveguide diffraction grating. One input waveguide that waves, a plurality of connection waveguides that connect the first and second arrayed waveguide gratings, and one output that guides light from the second arrayed waveguide grating A dispersion compensator comprising: a waveguide for use; a temperature control unit; and a temperature control circuit for controlling the temperature of the temperature control unit. 2. A dispersion compensator using an arrayed waveguide grating, comprising: an arrayed waveguide grating; one input / output waveguide for guiding light to the arrayed waveguide grating; A dispersion compensator comprising: a plurality of connection waveguides for connecting the arrayed waveguide diffraction grating and the reflection mirror; a temperature control unit; and a temperature control circuit for controlling a temperature of the temperature control unit. . 3. A signal dependent on a length L _{p of} a p-th waveguide from the center of the plurality of connection waveguides (where p is an integer and the opposite side is counted as −p-th), and a temperature T in the waveguide. _Assuming that the light wavelength is λ _eff (T), at a certain reference temperature T ₀ , 2. The dispersion compensator according to claim 1, wherein the following condition is satisfied. 4. A signal which depends on a length L _{p of} a p-th waveguide (where p is an integer and counts on the opposite side as −p-th) from the center of the plurality of connection waveguides and a temperature T in the waveguide. _Assuming that the light wavelength is λ _eff (T), 3. The dispersion compensator according to claim 2, wherein 5. The dispersion compensator according to claim 1, wherein each of the connection waveguides is constituted by two waveguide portions having two different temperature-dependent coefficients. 6. The dispersion compensator according to claim 1, wherein the temperature controller comprises a Peltier element for controlling the temperature of the entire waveguide, and a thermometer. apparatus. 7. The dispersion compensator according to claim 1, wherein the temperature control unit is configured by a heater that uniformly heats the entire connection waveguide. 8. The dispersion compensator according to claim 1, wherein the temperature controller is a heater provided in each of the connection waveguides, and the heaters are connected in series. 9. Each of the connection waveguides is provided with: In the p-th waveguide from the center (where p is an integer and the opposite side is counted as -p-th), The dispersion compensating apparatus according to claim 8, wherein 10. The dispersion compensator according to claim 1, wherein the temperature controller is a heater provided in each of the connection waveguides, and the heaters are connected in parallel. 11. Each of the connection waveguides is provided with: In the p-th waveguide from the center (where p is an integer and the opposite side is counted as -p-th), The dispersion compensator according to claim 10, wherein: 12. The dispersion compensator according to claim 8, further comprising a plurality of heaters connected in series or in parallel. 13. The dispersion compensating device according to claim 1, wherein the plurality of connection waveguides are formed by combining a plurality of connection waveguides adjacent to each other among the plurality of connection waveguides. And s sets (s ≧ 2) of the connection waveguide groups, the waveguide length and the heater length according to each of claims 1 to 12 with respect to the center waveguide of each connection waveguide group. Is defined. 14. An array waveguide heating heater for controlling a refractive index of an array waveguide portion of the array waveguide diffraction grating, and an array waveguide temperature control circuit for controlling the heater. 14. The method according to claim 1, wherein:
The dispersion compensator according to any one of the above. 15. The array waveguide according to claim 1, wherein each of the arrayed waveguides of the arrayed waveguide diffraction grating comprises two waveguides having different temperature constants. Dispersion compensator.