JP2000298215A - OPTICAL WAVEGUIDE TYPE WAVELENGTH FILTER WITH RING RESONATOR AND 1xN OPTICAL WAVEGUIDE TYPE WAVELENGTH FILTER - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new optical waveguide type wavelength filter having a ring resonator which can easily actualize a 1×N optical waveguide type wavelength filter and the 1×N optical waveguide type wavelength filter which is composed of the optical waveguide type wavelength filter with the ring resonator, and is small-sized and has superior filter response. SOLUTION: This optical waveguide type wavelength filter performs mutual ADD/DROP operations between an input-side optical waveguide 1 and an output- side optical waveguide 2 via a ring resonator 3. In this case, the input-side optical waveguide 1 and the output-side optical waveguide 2 cross each other and those input-side optical waveguide 1 and output-side optical waveguide 2, and the ring resonator 3 are stacked one over another.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical waveguide type wavelength filter with a ring resonator, a 1 * N optical waveguide type wavelength filter, and an optical waveguide type optical switch. More specifically, the invention of this application is constituted by a new optical waveguide type wavelength filter with a ring resonator, which can realize a 1 × N optical waveguide type wavelength filter, and an optical waveguide type wavelength filter with the ring resonator. Also, the present invention relates to a new 1 × N optical waveguide type wavelength filter having a small size and excellent filter response, and an optical switch constituted by these wavelength filters.

[0002]

2. Description of the Related Art Conventionally, only an optical signal of a specific wavelength is transferred between optical waveguides so that ADD / D
As an example of an optical waveguide type wavelength filter that performs the ROP operation, a ring resonator (3) is provided between an input optical waveguide (1) and an output optical waveguide (2) as exemplified in FIG. Is known.

In this optical waveguide type wavelength filter with a ring resonator, the ring resonator (3) has an input side optical waveguide (1).
And an optical coupling section between the output side optical waveguide (2) and the ring resonator when the wavelength-division multiplexed optical signal λ _{1... N} is input to the input port of the input side optical waveguide (1). Only the optical signal λ _j having a wavelength that matches the resonance wavelength of (3) is
The light is transferred from the DROP port to the output optical waveguide (2) via the ring resonator (3). The optical signals λ _{1... J-1, j + 1... N} of other wavelengths flow through the through port of the input side optical waveguide (1) as they are. Further, an optical signal input from the ADD port of the output side optical waveguide (2) is multiplexed with the through port of the input side optical waveguide (1) only when it matches the resonance wavelength of the ring resonator (3). .

In such an optical waveguide type wavelength filter with a ring resonator, for example, as shown in FIG. 18, a plurality of connected ring resonators (3a) (3b) (3)
c). . . (Three in the example of FIG. 18) may be provided between the input optical waveguide (1) and the output optical waveguide (2), in which case the filter response is Only one peak wavelength can be extracted from the wavelength characteristics that become the periodic characteristics, and a box-shaped characteristic can be realized.

[0005] With the remarkable progress of advanced information technology in recent years, there is a strong demand for further increase in capacity and function of optical communication. It has become essential to develop a so-called 1 × N wavelength filter capable of separately multiplexing and demultiplexing optical signals. However, the conventional optical waveguide type wavelength filter with a ring resonator as illustrated in FIGS. 17 and 18 can multiplex / demultiplex only an optical signal of one wavelength with respect to an input multiplexed optical signal. In order to construct a 1 × N wavelength filter, it is necessary to connect a plurality of wavelength filters with ring resonators with a curved waveguide or the like, and there is a problem that high-density integration is difficult.

[0006]

SUMMARY OF THE INVENTION Accordingly, the invention of this application has been made in view of the above circumstances, and has been made in order to solve the problems of the prior art and to realize a 1 × N wavelength filter. The following provides a new optical waveguide type wavelength filter with a ring resonator. That is, first, the invention of this application is an optical waveguide type wavelength filter with a ring resonator that performs an ADD / DROP operation between an input optical waveguide and an output optical waveguide via a ring resonator. And an output-side optical waveguide intersects, and the input-side optical waveguide, the output-side optical waveguide, and the ring resonator are stacked so as to overlap each other. Claim 1 provides the optical waveguide type wavelength filter,
In this case, the input side optical waveguide and the output side optical waveguide intersect at 90 degrees (claim 2), and a plurality of ring resonators are arranged in series (claim 3). .

In addition, the invention of this application provides a plurality of the above-described optical waveguide type wavelength filters with ring resonators, the through bus of the input side optical waveguide of one adjacent optical waveguide type wavelength filter with ring resonator and the other ring. The input waveguide of the optical waveguide type wavelength filter with resonator is connected to and connected to the input bus of the input side optical waveguide, and the resonance wavelengths of the ring resonators of the optical waveguide type wavelength filter with ring resonator are different from each other. The present invention provides a 1 × N optical waveguide type wavelength filter (claim 4), wherein an optical waveguide type wavelength filter with a ring resonator located at the end of the 1 × N optical waveguide type wavelength filter has an output side. The DROP bus of the optical waveguide and the input bus of the input optical waveguide of the adjacent optical waveguide type wavelength filter with a ring resonator are connected and connected to each other. It is also provided as an aspect that the resonance wavelengths of the ring resonators of the optical waveguide type wavelength filter with ring resonator and the adjacent optical waveguide type wavelength filter with ring resonator are the same or different (claim 5).

Further, in the above-described optical waveguide type wavelength filter with a ring resonator and the 1 × N optical waveguide type wavelength filter, the core layer and / or the cladding layer of each optical waveguide are made of a material having an electro-optic effect or a thermo-optic material. The resonance wavelength of the ring resonator is variable according to control of external electrolysis, control of temperature, or control of external stress. This is provided as an embodiment.

The invention of this application comprises the above-described optical waveguide type wavelength filter with a ring resonator or a 1 × N optical waveguide type wavelength filter, and the core layer or the cladding layer or both of the optical waveguides are provided. It is made of a material having an electro-optic effect, a material having a thermo-optic effect, or a material having a photoelastic effect. The resonance wavelength of the ring resonator is variable according to the control of external electrolysis or the control of temperature or the control of external stress. There is also provided an optical switch (claim 7) characterized in that:

[0010]

Embodiments of the present invention will be described below in more detail with reference to the accompanying drawings.

[0011]

[Embodiment 1] FIGS. 1, 2 and 3 are a perspective view, a plan view and a sectional view, respectively, illustrating an optical waveguide type wavelength filter with a ring resonator according to an embodiment of the present invention. It is. For example, as exemplified in FIGS. 1 to 3, in the optical waveguide type wavelength filter with a ring resonator according to the present invention, the input optical waveguide (1) and the output optical waveguide (2).
The input side optical waveguide (1) and the output side optical waveguide (2) and the ring resonator (3) are stacked so as to overlap each other.

More specifically, in the example shown in FIGS. 1 to 3, the input side optical waveguide (1) and the output side optical waveguide (2) intersect at 90 degrees. The ring resonator (3) has an input bus (11) partially having an input port of the input optical waveguide (1) and an output optical waveguide (2).
Are stacked so as to overlap with a DROP bus (21) having a DROP port.

As the input side optical waveguide (1) and the output side optical waveguide (2), for example, a buried channel optical waveguide is used, and as the ring resonator (3), for example, a loaded stripe optical waveguide or a ridge optical waveguide is used. be able to. Thereby, each optical waveguide is in a different light confinement state. Further, in the input-side optical waveguide (1) and the output-side optical waveguide (2), the difference in the refractive index between the core and the clad can be made small.
Better optical coupling between the input side optical waveguide (1) and the output side optical waveguide (2) and the external optical waveguide can be realized.

In the ring resonator (3), by making the refractive index of the core higher and the refractive index of the cladding lower, the Q factor of the resonator is required for excellent optical confinement. It can be a high value. Of course, the input side optical waveguide (1) and the output side optical waveguide (2)
And the ring resonator (3) need not have the same configuration,
Various configurations are possible.

In the optical waveguide type wavelength filter with a ring resonator according to the present invention, since the input side optical waveguide (1) and the output side optical waveguide (2) cross each other, a plurality of them are connected as described later. A 1 × N optical waveguide type wavelength filter can be easily configured. The optical coupling between the input side optical waveguide (1) and the output side optical waveguide (2) and the ring resonator (3) is based on the input side optical waveguide (1) and the output side optical waveguide (2) and the ring resonator ( 3) can be controlled by adjusting the interval.

By the way, a plurality of ring resonators (3) may be arranged in series as illustrated in FIGS. 4 and 5, for example. In the example shown in FIG. 4, two ring resonators (3a) and (3b) overlap with the input bus (11) of the input side optical waveguide (1) and the other ADD of the output side optical waveguide (2). So that it overlaps the bus (22)
It is laminated on the input side optical waveguide (1) and the output side optical waveguide (2). In the example shown in FIG. 5, three ring resonators (3a), (3b) and (3c) are connected, and one ring resonator (3a) is connected to the input bus (11) of the input side optical waveguide (1). , Another ring resonator (3c) overlaps the DROP bus (21) of the output side optical waveguide (2).

Each of the ring resonators (3a) (3b)... May be the same or different. Each ring resonator (3
a) (3b)... are different from each other, there is an advantage that resonance at wavelengths other than the resonance wavelength can be suppressed, and only when all the ring resonators (3a) (3b). The optical signals having the resonance wavelength are multiplexed and demultiplexed. In addition, the free spectral width (FSR) of the optical waveguide filter is significantly increased due to the Vernier effect.

On the other hand, each ring resonator (3a) (3b)...
Are the same, all ring resonators (3a)
(3b) ... independently resonate at the same wavelength,
Mutual coupling occurs when they are arranged close enough to divide the resonance peak. The plurality of resonance peaks in the resonance region are composite mode peaks of the coupling ring resonators (3a) (3b).

The optical coupling between the ring resonators (3a) (3b)... Can be adjusted so that the propagation constants of the complex modes are close to each other. This results in the peaks being a single peak, but having a box-shaped filter response. FIG.
Represents three ring resonators (3a) as illustrated in FIG.
(3b) This is an example of the filter response in the case where (3c) is provided. As shown in FIG. 6, the filter response has a box shape. The more ring resonators (3), the more box-shaped.

[Embodiment 2] A plurality of the optical waveguide type wavelength filters with a ring resonator according to the present invention described above can be connected, whereby a 1 × N optical waveguide type wavelength filter can be realized. In this case, as will be further described, for example, as illustrated in FIG. 7, a plurality of the above-described optical waveguide type wavelength filters with ring resonators, a through bus (12a) of one adjacent input-side optical waveguide (1a) (1b). (12
b) are connected to and connected to the input buses (11a) (11b)... of the other input-side optical waveguides (1b) (1c). The resonance wavelengths of the ring resonators (3a), (3b).

In such a 1 × N optical waveguide type wavelength filter, the input bus (11a) of the input side optical waveguide (1a) of the optical waveguide type wavelength filter with a ring resonator located at the end.
The input wavelength multiplexed optical signals λ _{1... N} incident from a) propagate through the input side optical waveguides (1a) (1b).
The optical signals λ ₁ , λ ₂ ,... Λ _N−1 , λ _N having the same wavelengths as the resonance wavelengths of the ring resonators (3a), (3b). Output side optical waveguides (2a) (2b)... DROP bus (21a) (21
b), and similarly each wavelength is AD
When input from the D buses (22a) (22b)..., They are multiplexed with the through buses (12a) (12b).

Since this 1 × N optical waveguide type wavelength filter only needs to be connected to the above-described optical waveguide type wavelength filter with a ring resonator of the present invention, it can be made very small. For example, Si with a refractive index of 1.45
14 μm radius, 15 nm FSR, FWH on O ₂ substrate
A wavelength filter having a glass ring resonator with M of 1 nm or less can be realized. Thus, for example, 100 GH
1 × 8 optical waveguide type wavelength filter of z band, 1 mm × 1
It can be configured with the coupling of the output optical fiber in the range of mm.

In the example shown in FIG. 8, two optical waveguide type wavelength filters with a ring resonator are connected, and two wavelengths having different wavelengths are provided by ring resonators (3a) and (3b) having different resonance wavelengths. Two optical signals can be multiplexed and demultiplexed separately. Further, as exemplified in FIGS. 9 and 10, for example, as described above, a plurality of ring resonators (3aa) (3ab) (3ac).
An optical waveguide type wavelength filter with a ring resonator having (3bb), (3bc)... May be connected to form a 1 × N optical waveguide type wavelength filter. In this case, as described above, since the filter response of each optical waveguide type wavelength filter with a ring resonator is box-shaped, the filter response of the 1 × N optical waveguide type wavelength filter is also box-shaped. The positions of the DROP port and the ADD port of the output side optical waveguide (2) follow the number of ring resonators (3).

[Embodiment 3] FIGS. 11 and 12 are plan views of a principal part illustrating a 1 × N optical waveguide type wavelength filter according to another embodiment of the present invention. The 1 × N optical waveguide type wavelength filter illustrated in FIGS. 11 and 12 is different from the 1 × N optical waveguide type wavelength filter of FIG.
The optical waveguide type wavelength filter with the ring resonator located at the end is connected to the DROP bus (2) of the output side optical waveguide (2a).
1a) and an input bus (11b) of an input side optical waveguide (1b) of an adjacent optical waveguide type wavelength filter with a ring resonator.
Are connected and connected. In the example of FIG. 11, the ring resonator (3a) of the optical waveguide type wavelength filter with the ring resonator at the extreme end position is the input bus (11
a) and the DROP bus (21a), and in the example of FIG. 12, overlap with the ADD bus (22a) and the through bus (12a).

In the 1 × N optical waveguide type wavelength filter having such a configuration, the resonance wavelength of the ring resonator (3a) of the optical waveguide type wavelength filter with ring resonator at the extreme end position and the adjacent optical waveguide with ring resonator are provided. If the free spectral widths (FSR) of the ring resonators (3b) of the type wavelength filter are different and only one resonance peak wavelength matches, a plurality of peaks of the periodic filter characteristic (so-called comb-shaped characteristic) are obtained. , Only one peak can be extracted. Further, if the respective resonance wavelengths are the same, the band becomes narrower than in the case of one stage, and furthermore, if there is a slight shift, the shape becomes a box.

[Embodiment 4] In each of the above embodiments, the optical waveguide type wavelength filter with each ring resonator is provided with a ring on the input optical waveguide (1) and the output optical waveguide (2) crossed in the same layer. Although the resonator (3) is configured to be stacked, other than this configuration, for example, as illustrated in FIG. 13, the ring resonator (3) is placed on the input optical waveguide (1) in the lowermost layer. ) Are stacked, and the ring resonator (3)
The output side optical waveguide (2) may be laminated on the above. Of course, a part of the ring resonator (3) overlaps with the input optical waveguide (1) and the output optical waveguide (2). Either the input side optical waveguide (1) or the output side optical waveguide (2) may be upside down.

[Embodiment 5] In the above-described optical waveguide type wavelength filter with ring resonator or 1 × N optical waveguide type wavelength filter according to the present invention, each optical waveguide (1)
(2) the core layer and / or the clad layer,
It is made of a material having an electro-optic effect, a material having a thermo-optic effect, or a material having a photoelastic effect, and the resonance wavelength of the ring resonator (3) is variable according to control of external electrolysis, control of temperature, or control of external stress. Thus, a variable wavelength filter and an optical switch can be realized.

FIGS. 14, 15 and 16 respectively show
FIG. 2 is a main part configuration diagram showing an embodiment of the variable wavelength filter. In each embodiment, the core layer or the cladding layer or both of the input side optical waveguide (1) and the output side optical waveguide (2) have a material having an electro-optic effect or a material having a thermo-optic effect or have a photoelastic effect. It is made of material. In the example shown in FIG. 14, a heating element (4) as a thermal control means is provided on the ring resonator (3), and the resonance wavelength of the ring resonator (3) can be controlled by the heating element (4). It has become. At this time, in order to prevent the Q value of the ring resonator (3) from being reduced due to the heating element (4), a low level is provided between the ring resonator (3) and the heating element (4). It is preferable to provide a buffer layer having a refractive index. Further, the heating element (4) may be provided on a cover layer (for example, SiO ₂ or the like) of the ring resonator (3). In this case, the heating element (4)
Need not be located directly above the ring resonator (3),
For example, it can be formed in a ring shape surrounding the ring resonator (3).

On the other hand, since the ring resonator (3) has a characteristic of high sensitivity, the resonance frequency can be adjusted by providing a metal plate or a dielectric thin plate on the ring resonator (3). Can be. The tunable wavelength filter illustrated in FIG. 15 includes a micro-electromechanical (MEM) piston (51) and a glass or polymer thin plate (52) held by the MEM piston (51). A control means (5) is provided above the ring resonator (3), and the thin plate (52) moves up and down above the ring resonator (3) according to the piston movement of the MEM piston (51), whereby By controlling the changing distance between the ring resonator (3) and the thin plate (52), the resonance frequency of the ring resonator (3) is controlled.

The thin plate (52) covers the entire surface of the ring resonator (3) so that the ring resonator (3) is not disturbed unevenly and reflection is not caused. Is desirable. Further, when a polymer plate is used as the thin plate member (52), the polymer thin plate member (52) and the ring resonator (3) can always be kept in contact with each other. The refractive index of the body (52) can be lower than the refractive index of the ring resonator (3). By pressing the polymer thin plate (52), the resonance wavelength of the ring resonator (3) can be controlled in accordance with the photoelastic effect of the polymer whose refractive index changes depending on the pressure.

The variable wavelength filter illustrated in FIG. 16 is one in which the resonance wavelength of the ring resonator (3) is made variable by an electro-optical element (6) whose refractive index is electrically variable.
Electro-optical element (6) as the electro-optical control means
Is made of, for example, a material such as an electro-optic polymer that is electrically controlled by a voltage applied through the electrode (61), and is provided on the ring resonator (3).

Although each of the above-mentioned examples in the fifth embodiment is a case of a variable wavelength filter, an optical waveguide type optical switch can be realized in the same manner by adjusting the phase and the like of the ring resonator. . The present invention is not limited to the above examples, and various embodiments can be made in detail.

[0033]

As described in detail above, according to the present invention, a 1 × N optical waveguide type wavelength filter capable of easily realizing a 1 × N optical waveguide type wavelength filter, a new optical waveguide type wavelength filter with a ring resonator, and an optical waveguide with the ring resonator are provided. A 1 × N optical waveguide type wavelength filter having a small size and excellent filter response constituted by a waveguide type wavelength filter is provided, and a variable wavelength filter and an optical switch using them can be realized. Further increase in capacity of optical communication,
High functionality can be achieved.

[Brief description of the drawings]

FIG. 1 is an essential part perspective view illustrating an optical waveguide type wavelength filter with a ring resonator according to an embodiment of the present invention.

FIG. 2 is a plan view of an essential part illustrating an optical waveguide type wavelength filter with a ring resonator of FIG. 1;

FIG. 3 is a cross-sectional view of a principal part illustrating the optical waveguide wavelength filter with a ring resonator of FIG. 1;

FIG. 4 is a perspective view of an essential part showing an embodiment of an optical waveguide wavelength filter with a ring resonator provided with two ring resonators.

FIG. 5 is a perspective view of an essential part showing one embodiment of an optical waveguide type wavelength filter with a ring resonator provided with three ring resonators.

6 is a diagram illustrating an example of a filter response in the optical waveguide wavelength filter with a ring resonator of FIG. 5;

FIG. 7 is a plan view of an essential part showing an example of a 1 × N optical waveguide type wavelength filter of the present invention.

FIG. 8 is a perspective view of an essential part showing one embodiment of a 1 × N optical waveguide type wavelength filter in which two optical waveguide type wavelength filters with ring resonators are connected.

FIG. 9 is a perspective view of an essential part showing an embodiment of a 1 × N optical waveguide type wavelength filter in a case where each optical waveguide type wavelength filter with a ring resonator includes two ring resonators.

FIG. 10 is an essential part perspective view showing one embodiment of a 1 × N optical waveguide type wavelength filter when each optical waveguide type wavelength filter with a ring resonator includes three ring resonators.

FIG. 11 is a main part plan view showing another embodiment of the 1 × N optical waveguide type wavelength filter of the present invention.

FIG. 12 is a plan view of a principal part showing still another embodiment of the 1 × N optical waveguide type wavelength filter of the present invention.

FIG. 13 is a main part side view illustrating an optical waveguide wavelength filter with a ring resonator according to another embodiment of the present invention.

FIG. 14 is a perspective view of an essential part illustrating a tunable wavelength filter of the present invention.

FIG. 15 is a main part perspective view showing another example of the variable wavelength filter of the present invention.

FIG. 16 is a perspective view of a main part showing still another example of the variable wavelength filter of the present invention.

FIG. 17 is a plan view of a main part showing an example of a conventional optical waveguide wavelength filter with a ring resonator.

FIG. 18 is a main part plan view showing another example of a conventional optical waveguide type wavelength filter with a ring resonator having three ring resonators.

[Explanation of symbols]

1, 1a, 1b Input optical waveguides 11, 11a, 11b Input bus 12, 12a, 12b Through bus 2, 2a, 2b Output optical waveguides 21, 21a, 21b DROP bus 22, 22a, 22b ADD bus 3, 3a, 3b _, 3c, 3d Ring resonator 3aa, 3ab, 3ac Ring resonator 3ba, 3bb, 3bc Ring resonator 4 Heating element 5 Mechano-optical control means 51 MEM piston 52 Thin plate 6 Electro-optical element 61 Electrode

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Taro Kaneko 5-2016-2, Iriya, Zama City, Kanagawa Prefecture (72) Inventor Yasuo Kokubu 1-3-5 Kosugaya, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Inventor Shinya Sato Exelheim 305 3-6-16 Sakado, Takatsu-ku, Kawasaki City, Kanagawa Prefecture

Claims (7)

[Claims] An optical waveguide type wavelength filter with a ring resonator for performing an ADD / DROP operation between an input optical waveguide and an output optical waveguide via a ring resonator, comprising: an input optical waveguide and an output optical waveguide. Wherein the input side optical waveguide, the output side optical waveguide, and the ring resonator are stacked so as to overlap each other. 2. An optical waveguide type wavelength filter with a ring resonator according to claim 1, wherein the input side optical waveguide and the output side optical waveguide intersect at 90 degrees. 3. An optical waveguide wavelength filter with a ring resonator according to claim 1, wherein a plurality of ring resonators are arranged in series. 4. The through-bus of the input-side optical waveguide of one of the adjacent optical waveguide type wavelength filters with a ring resonator, and the other of the plurality of optical waveguide type wavelength filters with a ring resonator according to claim 1. The input waveguide of the optical waveguide type wavelength filter with a ring resonator is connected to and connected to the input bus of the input side optical waveguide, and the resonance wavelengths of the ring resonators of the optical waveguide type wavelength filter with a ring resonator are different from each other. 1 × N optical waveguide type wavelength filter characterized by the above-mentioned. 5. An optical waveguide type wavelength filter with a ring resonator located at the extreme end includes a DROP bus of an output side optical waveguide and an input bus of an input side optical waveguide of an adjacent optical waveguide type wavelength filter with a ring resonator. Are connected, and the resonance wavelengths of the ring resonators of the optical waveguide type wavelength filter with ring resonator at the extreme end position and the adjacent optical waveguide type wavelength filter with ring resonator are the same or different. The 1 × N optical waveguide type wavelength filter according to claim 4. 6. The core layer and / or the cladding layer of each optical waveguide are made of a material having an electro-optic effect, a material having a thermo-optic effect, or a material having a photoelastic effect, for controlling external electrolysis or 4. An optical waveguide type wavelength filter with a ring resonator according to claim 1, wherein the resonance wavelength of the ring resonator is variable according to control of temperature or control of external stress.
1 × N optical waveguide type wavelength filter. 7. An optical waveguide type wavelength filter with a ring resonator according to any one of claims 1 to 3, or a 1 × N optical waveguide type wavelength filter according to claims 4 to 5, wherein a core layer of each optical waveguide is provided. Or the cladding layer or both are made of a material having an electro-optic effect, a material having a thermo-optic effect, or a material having a photoelastic effect, and the ring resonance is controlled according to the control of external electrolysis or the control of temperature or the control of external stress. An optical switch characterized in that the resonance wavelength of the device is variable.