JP2003167221A - Waveguide type optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waveguide type optical element which can easily control the phase of an interference device and easily acquire a desired optical frequency characteristic. <P>SOLUTION: An optical phase shifter 11a (11b to 11d) uses a refractive index change caused by an electro-optic effect, a photoelastic effect, or a magneto- optical effect without using the heat of a heater. Thereby, certain optical phase shifter 11a (11b to 11d) vanishingly affects other adjacent optical phase shifters 11a (11b to 11d). Accordingly, the phase control becomes easy and it becomes easy to acquire the desired optical frequency characteristic. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type optical device.

[0002]

2. Description of the Related Art In the field of optical communication, a so-called wavelength division multiplexing system has been studied in which a plurality of signals are put on lights having different wavelengths and transmitted by one optical fiber to increase the information capacity. . In this wavelength division multiplexing method, in order to realize high-speed and large-capacity signals while suppressing signal deterioration, there is a technique and a transmission system that dynamically flatten the gain characteristics of optical fiber amplifiers connected at relay points. The technology of compensating for the chromatic dispersion of light generated in 1. plays an important role. Variable gain equalizers and dispersion compensators with various configurations have been proposed as optical devices for dynamically flattening gain characteristics and dispersion compensation.

In particular, a silica-based planar lightwave circuit (PLC)
, Mach-Zehnder interferometer, arrayed waveguide grating,
A waveguide-type optical element that has an optical interferometer such as a ring resonator as a basic structure and an optical phase shifter formed in the middle of the channel waveguides that compose these structures Frequency characteristics (frequency-loss characteristics and frequency-dispersion characteristics) can be realized, and active R & D is underway as the PLC formation technology matures.

FIG. 5 is a plan view showing a conventional example of a Mach-Zehnder type variable gain equalizer using a silica-based PLC, which is used for controlling the frequency-loss characteristic.

The present variable gain equalizer is a 2-input / 2-output 2 ×
2 optical distributor 3a1 and 2 × 2 optical distributor 3a having 2 inputs and 2 outputs
Channel waveguides 4a1 and 4a2 on one side (lower side in the figure) of the Mach-Zehnder interferometer composed of the waveguide between the two
In the middle of the above, the optical waveguides 3b1 to 3b4 and the arrayed waveguide type optical multiplexer / demultiplexers 6a1 and 6a2 formed by the channel waveguides 5a1 and 5a2 having different lengths by a predetermined length are inserted.

That is, the present variable gain equalizer has two input channel waveguides 1 (1) formed on the substrate 9 so that the input end is exposed on one end face (left end face in the figure) of the substrate 9.
a, 1b), a 2 × 2 optical distributor 3a1 whose input end is connected to the output end of the input channel waveguide 1, and whose input end is 2 ×
A channel waveguide 4a1 connected to the output end of one (lower end in the figure) of the two optical distributors 3a1, and an arrayed waveguide type optical multiplexer / demultiplexer 6a1 whose input end is connected to the output end of the channel waveguide 4a1. Array side optical multiplexer / demultiplexer 6a1 on the input side
, A plurality of channel waveguides 5b connected to the output end of the array waveguide, an array waveguide type multiplexer / demultiplexer 6a2 whose input side is connected to the output side of the channel waveguide 5b, and one input end of the array waveguide type optical multiplexer / demultiplexer. 2 × 2 optical distributor 4a2 connected to the output end of the wave filter 6a2, and the input end connected to the output end of the 2 × 2 optical distributor 3a2 and the output end of the other end face of the substrate 9 (right end face in the figure) Two output channel waveguides 2 (2a, 2b) formed so as to be exposed to the other, the other output end (upper side in the figure) of the 2 × 2 optical distributor 3a1 and the 2 × 2 optical distributor 3a2. It is composed of a channel waveguide 4b connected between the other input end (upper side in the drawing) and a heater 8 formed so as to cover a part of the channel waveguides 4b and 5b.

In this variable gain equalizer, the channel waveguide 4
b, 5b and the heater 8 constitute an optical phase shifter.

The input signal light is distributed to both channel waveguides 4a1 and 4b of the Mach-Zehnder interferometer. One signal light is demultiplexed for each wavelength by the arrayed waveguide type optical multiplexer / demultiplexer 6a1, undergoes a phase change by an optical phase shifter on the way, and is again multiplexed by the arrayed waveguide type optical multiplexer / demultiplexer 6a2. The combined light and the light passing through the channel waveguide 4b interfere with each other and are output from the output channel waveguide 2.

Here, by adjusting the current applied to each heater 8, the phase of the signal light is adjusted, the interference state changes for each wavelength, and various optical frequency characteristics can be realized. Regarding this circuit configuration, C.I. R. Doerr
Et al. "Integrated WDM dynam"
ic power equalizer withpo
tentially low insertion l
oss ", IEEPHOTO.Technol.L
ett. , Vol. 10, No. 10, pp. 1443
-1445, 1998.

FIG. 6 is a plan view showing a conventional example of a transversal type variable gain equalizer.

In this variable gain equalizer, the input channel waveguide 1 formed on the substrate 9 so that the input end is exposed on one end face (left end face in the figure) of the substrate 9 and the input end is for input. A 1 × 5 optical distributor 3c1 that is connected to the other end (right end in the figure) of the channel waveguide 1 and distributes the input signal light into five, and an input end is connected to an output end of the 1 × 5 optical distributor 3c1. Five channel waveguides 5c1 having different lengths by a predetermined length,
A plurality of zero-order operation Mach-Zehnder interferometers 21 connected to the output end of the channel waveguide 5c1 and a channel guide having an input side connected to the output side of the Mach-Zehnder interferometer 21 and having different lengths by a predetermined length. The waveguide 5c2 and a 5 × 1 optical distributor (1 × 5) connected to the output side of the channel waveguide 5c2.
The light distributor 3c1 is formed so that its input and output sides are opposite to each other. ) 3c2 and an output channel conductor formed on the substrate 9 such that the input end is connected to the output end of the 5 × 1 optical distributor 3c2 and the output end is exposed at the other end face of the substrate 9 (right end face in the figure). And the waveguide 2.

The Mach-Zehnder interferometer 21 is provided on the substrate 9 so as to face five 1 × 2 optical distributors 3d1 with 1 input and 2 outputs formed in the center of the substrate 9. 3d of the five 2 × 1 light distributors (the input and output sides of the 1 × 2 light distributor 3d1 are formed opposite to each other).
2, each 1 × 2 optical distributor 3d1 and each 2 × 1 optical distributor 3d
A plurality of pairs of channel waveguides 5e inserted between 2 and
1 arranged so as to cover a part of each channel waveguide 5e
It is composed of zero heaters 8. An optical phase shifter is configured by forming the heater 8 on the channel waveguide 5e of the Mach-Zehnder interferometer 21.

The heater 8 on the Mach-Zehnder interferometer 21
The amplitude and phase of the light passing through each channel waveguide 5e can be adjusted at the same time by adjusting the current applied to. The output light is represented by a Fourier series having the amplitude and phase of the light passing through each channel waveguide 5c2 as components, and various optical frequency characteristics can be realized by adjusting the current of each heater 8.

FIG. 7 is a plan view showing a conventional example of a lattice type variable gain equalizer.

This variable gain equalizer has a configuration in which Mach-Zehnder interferometers are connected in series, and has a circuit configuration similar to that of a lattice filter often used as a digital filter.

That is, the present variable gain equalizer has two input channel waveguides 1 (1) formed on the substrate 9 so that the input end is exposed on one end face (left end face in the figure) of the substrate 9.
a, 1b) and a 2 × 2 optical distributor 3a1 having 2 inputs and 2 outputs, the input end of which is formed at the output end of the input channel waveguide 1.
And two channel waveguides 5f1 whose one end is connected to the output end of the 2 × 2 optical distributor 3a1, and 2 × 2 optical distributor 3a2 whose input end is connected to the output end of the channel waveguide 5f1.
And two channel waveguides 5f2 whose input ends are connected to the output ends of the 2 × 2 optical distributor 3a2, and 2 × 2 optical distributors 3a whose input ends are connected to the output ends of the channel waveguides 5f2.
3, two channel waveguides 5f3 whose input ends are connected to the output ends of the 2 × 2 optical distributor 3a3, and 2 × 2 optical distributors 3a4 whose input ends are connected to the output ends of the channel waveguides 5f3
And two output channels formed on the substrate 9 so that the input end is connected to the output end of the 2 × 2 optical distributor 3a4 and the other end is exposed at the other end face of the substrate 9 (right end face in the figure). The waveguide 2 (2a, 2b) and the six heaters 8a to 8f formed on the channel waveguides 5f1 to 5f3, respectively. The optical phase shifter is configured by forming the heaters 8a to 8f on the channel waveguides 5f1 to 5f3, respectively. The variable gain equalizer can realize various optical frequency characteristics by adjusting the currents of the heaters 8a to 8f formed in the Mach-Zehnder interferometer.

Regarding the circuit configuration of this variable gain equalizer,
L. "Synthesis o" by Junguji et al.
f coherent two-port latti
ce-form optical delay-lin
e circuit ", J. Lightwave Te
chnol. , Vol. 13, No. 1, pp. 73-
82, 1995.

In any of the configurations, the current applied to the heater can be adjusted to adjust the phase change of light in the optical phase shifter, and a desired frequency-loss characteristic can be realized.

[0019]

By the way, in the conventional variable gain equalizer and dispersion compensator using the silica-based PLC, the heater is formed on the channel waveguide as described above as a phase adjusting method. There has been a method of adjusting the current applied to the heater to adjust the heat generation of the heater. This method utilizes the change in the refractive index of quartz due to the thermo-optic effect.

However, in this method, since the heat generated from the heater is used for the phase change, the heat is often diffused to the waveguide other than the optical phase shifter or other optical phase shifters.

Specifically, when the distance between the adjacent optical phase shifters (the distance between the channel waveguides) is about 1 mm or less, the influence of heat occurs between the adjacent optical phase shifters. For example, when the distance between adjacent optical phase shifters is 1 mm or less, and the phase fluctuation amount of the optical phase shifter when the heater of the optical phase shifter is heated is 100%,
The optical phase shifter adjacent to the optical phase shifter also has a phase fluctuation amount of 10% or more, and the influence of heat between the adjacent optical phase shifters cannot be ignored.

As described above, if the heat generated by the heater heats the waveguide other than the desired optical phase shifter, the refractive index changes also in the waveguides constituting the optical phase shifter, and the waveguide other than the desired optical phase shifter is changed. However, a phase change will occur. Therefore, there is a problem that phase control in the interferometer becomes difficult and it becomes difficult to obtain a desired optical frequency characteristic.

Therefore, an object of the present invention is to solve the above problems and to provide a waveguide type optical element in which phase control in an interferometer is easy and desired optical frequency characteristics can be easily obtained.

[0024]

In order to achieve the above object, in a waveguide type optical element of the present invention, a plurality of channel waveguides are arranged adjacent to each other at a predetermined interval, and electrodes are provided on the channel waveguides. A waveguide type optical element including an optical phase shifter formed, wherein the optical phase shifter is composed of a substrate material having an electro-optical effect, a photoelastic effect or a magneto-optical effect.

In addition to the above structure, the waveguide type optical element of the present invention is composed of a waveguide type optical element body and an optical phase shifter separately, and a channel waveguide and a waveguide type optical element body constituting the optical phase shifter. In the end face of the connection part with and, each channel waveguide may be connected obliquely to the end face of the connection part.

In addition to the above structure, the waveguide type optical element body of the waveguide type optical element of the present invention is preferably made of a silica material.

According to the present invention, the optical phase shifter does not utilize the heat from the heater but utilizes the change in the refractive index due to the electro-optical effect, the photoelastic effect or the magneto-optical effect, so that one optical phase shifter can The influence on the adjacent optical phase shifters can be almost ignored. Therefore, phase control is facilitated, and desired optical frequency characteristics are facilitated.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a plan view showing a first embodiment of a waveguide type optical element of the present invention. The same reference numerals are used for the same members as in the conventional example.

The present waveguide type optical element is a Mach-Zehnder type variable gain equalizer, and includes a first waveguide type optical element body (left side in the figure) and a second waveguide type optical element body (see the figure). (On the right side of FIG. 2) are respectively formed on different substrates, and are connected to the first and second waveguide type optical element bodies by an optical phase shifter (center in the figure) composed of a material having an electro-optical effect. Is.

The first waveguide type optical element body is one in which an arrayed waveguide type optical multiplexer / demultiplexer 6a1 is inserted in the middle of one channel waveguide 4a1 of the Mach-Zehnder interferometer.
Two input channel waveguides 1 (1a, 1b) formed on the substrate 9a so that one end is exposed on one end face (left end face in the figure) of the substrate 9a made of quartz, and the input end is an input channel. 2 × 2 optical distributor 3 connected to the other end of the waveguide 1
a1 and an arrayed waveguide type optical multiplexer / demultiplexer 6a1 whose input end is connected to one (lower end in the figure) output end of the 2 × 2 optical distributor 3a1 and an input side of the arrayed waveguide type optical multiplexer / demultiplexer 6a1. The other end face 22a of the substrate 9a is connected to the output end and the output side is the other end face 22a.
Are formed on the substrate 9a so as to be exposed at
A book, but not limited to it. ) Channel waveguide 5b1
And one end of the 2 × 2 optical distributor 3a1 (upper side in the figure)
Of the other end surface 22 of the substrate 9a connected to the output end of
and a channel waveguide 4b1 formed on the substrate 9a so as to be exposed at a.

The vicinity of the output ends of the channel waveguides 4b1 and 5b1 is formed so as to be perpendicular to the end face 22a at the other end of the substrate 9a. In addition, the channel waveguides 4b1 and 5b
b1 is different in length by a predetermined length.

The second waveguide type optical element main body is one in which an arrayed waveguide type optical multiplexer / demultiplexer 6a2 is inserted in the middle of one channel waveguide 4a2 of the Mach-Zehnder interferometer.
A plurality of (five in the figure, but not limited to) channel waveguides 5b2 formed on the substrate 9b so that the input side is exposed to one end surface 22b of the substrate 9b made of quartz, and the input end is the channel waveguide 5b2. Of the arrayed waveguide type optical multiplexer / demultiplexer 6a2, the input end of which is connected to the output end of the arrayed waveguide type optical multiplexer / demultiplexer 6a2, and one input end (in the figure, The lower side) is a 2 × 2 optical distributor 3a2 connected to the output end of the channel waveguide 4a2.
And a channel waveguide 4b2 which is formed on the substrate 9b so that one end is exposed to one end face 22b of the substrate 9b and the other end is connected to the other input end (upper side in the figure) of the 2 × 2 optical distributor 3a2. , Two output channel waveguides 2 formed so that their input ends are connected to the output ends of the 2 × 2 optical distributor 3a2 and the other ends are exposed at the other end face (right end face in the figure) of the substrate 9b ( 2a, 2b).

The vicinity of the input ends of the channel waveguides 4b2, 5b2 is perpendicular to the end face 22b of the substrate 9b, and the channel waveguides 4b1, 5b of the first waveguide type optical element body are provided.
It is formed so as to have an interval equal to the interval near the other end side of 1. The channel waveguides 5b2 and 5a2 are different in length by a predetermined length.

The optical phase shifter 11a is composed of a substrate 9ca made of lithium niobate (LiNbO ₃ ) which is an electro-optic crystal as a material having an electro-optic effect, and a first waveguide type optical element parallel to the substrate 9ca. A channel waveguide 7a formed to have a distance equal to the distance in the vicinity of the other end surface 22a side of the channel waveguides 4b1 and 5b1 of the main body, and an electrode 10a formed on the channel waveguide 7a, respectively.
It consists of and.

Next, the operation of the present waveguide type optical element will be described.

The signal light input to the input channel waveguide 1 is split into two by the 2 × 2 optical splitter 3a1 of the Mach-Zehnder interferometer (first waveguide type optical element body), and the two channel waveguides are guided. It passes through the waveguides 4a1 and 4b1.

Of the signal lights passing through the two channel waveguides 4a1 and 4b1, one signal light is demultiplexed for each wavelength by the arrayed waveguide type optical multiplexer / demultiplexer 6a1 and is passed through the channel waveguides 5b1 respectively. It is input to each channel waveguide 7a of the shifter 11a. The signal light passing through the channel waveguide 7a undergoes a phase change by the optical phase shifter 11a, passes through the channel waveguide 5b2 of the second waveguide type optical element body, and is multiplexed by the arrayed waveguide type optical multiplexer / demultiplexer 6a2. Input to the × 2 optical distributor 3a2.

Of the signal light passing through the two channel waveguides 4a1 and 4b1, the other signal light passes through the channel waveguide 4b1 of the first waveguide type optical element body, and then the phase is changed by the optical phase shifter 11a. And passes through the channel waveguide 4b2 of the second waveguide type optical element body and receives the 2 × 2 optical distributor 3a2.
To the output channel waveguide 2 by interfering with the signal light from the arrayed waveguide type optical multiplexer / demultiplexer 6a2.

Here, the phase is adjusted by adjusting the voltage applied to the electrode 10a formed on the channel waveguide 7a of each optical phase shifter 11a, the interference state changes for each wavelength, and various light Frequency characteristics can be realized.

Optical phase shifter 11a of the present waveguide type optical element
Does not use heat, but utilizes the change in the refractive index due to the electro-optic effect, so that the influence of one optical phase shifter 11a on another adjacent optical phase shifter 11a can be almost ignored. Specifically, it was confirmed that the effect on the adjacent optical phase shifters is negligibly small even if the distance between the optical phase shifters is reduced to at least about 100 μm.
Therefore, phase control is facilitated, and desired optical frequency characteristics can be easily obtained. Further, since the interval between the optical phase shifters can be remarkably narrowed, the waveguide type optical element can be downsized at the same time.

FIG. 2 is a plan view showing a second embodiment of the waveguide type optical device of the present invention.

The present waveguide type optical element is a transversal type variable gain equalizer, and like the waveguide type optical element shown in FIG. 1, first and second waveguide type optical elements using quartz as a substrate. It is composed of an optical element body (both sides of the figure) and an optical phase shifter (center of the figure) using LiNbO ₃ as a substrate, which is connected between the first and second waveguide type optical element bodies.

First waveguide type optical element body (left side in the figure)
Is an input channel waveguide 1 formed on the substrate 9a so that one end (the left end in the figure) is exposed on one end surface of the substrate 9a, and the input end is connected to the other end of the input channel waveguide 1 The 1 × N optical distributor 3c1 that distributes the generated signal light into a plurality of N (the number is not limited to 5 in the figure) and the input end is connected to the output end of the 1 × N optical distributor 3c1 and has a predetermined length. N channel waveguides 5c1 each having a different length, an input end connected to the other end of each channel waveguide 5c1, a 1 × 2 optical distributor 3d1 for dividing the input signal light into two, and an input end It is composed of 2N channel waveguides 5e1 formed on the substrate 9a so that the other ends thereof are connected to the output ends of the 1 × 2 optical distributor 3d1 and the other end is exposed at the other end face 22a of the substrate 9a.

Second waveguide type optical element body (right side of the figure)
Is a 2N channel waveguide 5e2 formed on the substrate 9b so that one end is exposed at one end face 22b of the substrate 9b.
And the input end is connected to the output end of the channel waveguide 5e2 and the 2 × 1 optical distributor for multiplexing the input signal light is formed (the input and output sides of the 1 × 2 optical distributor 3d1 are opposite to each other). .), The input end is connected to the output end of each 2 × 1 optical distributor 3d2, and the N channel waveguides 5c2 having different lengths by a predetermined length, and the input end to the output end of the channel waveguide 5c2. An N × 1 optical distributor (which is formed such that the input and output sides of the 1 × N optical distributor 3c1 are opposite to each other.) 3c2 that is connected and multiplexes N signal lights, and the input end is N × 1. The output channel waveguide 2 is connected to the output end of the optical distributor 3c2 and is formed on the substrate 9b so that the output end is exposed at the other end face (right end face in the figure) of the substrate 9b.

The vicinity of the input end face 22b of the channel waveguide 5e2 is perpendicular to the end face 22b of the substrate 9b, and the interval between the channel end faces 22b of the channel waveguide 5e2 is:
It is formed so as to have an interval equal to the interval at the waveguide end face 22a of the channel waveguide 5e1 of the first waveguide type optical element body.

The optical phase shifter 11b is formed on the substrate 9cb and on the substrate 9cb so as to be parallel to each other and at an interval equal to that of the other end face 22a of the channel waveguide 5e1 of the first waveguide type optical element body. Channel waveguide 7b,
Electrodes 10 respectively formed on the channel waveguides 7b
and b.

Optical distributors 3d1 and 3d2, channel waveguides 5e1 and 5e2, and two adjacent optical phase shifters 11
One zero-order operation Mach-Zehnder interferometer 21 is configured with b as one set.

Also in such a waveguide type optical element, as shown in FIG.
The same effect as the waveguide type optical element shown in FIG.

FIG. 3 is a plan view showing a third embodiment of the waveguide type optical element of the present invention.

This waveguide type optical element is a transversal type variable gain equalizer, and like the embodiment shown in FIG. 1, two first and second waveguides using quartz as substrates 9a and 9b are used. Type optical element body and a plurality of optical phase shifters 11c are formed on a substrate 9cc made of LiNbO ₃ , and the waveguide end face 22
They are connected by a and 22b.

First waveguide type optical element body (left side in the figure)
Is an input channel waveguide 1 (1a, 1b) formed on the substrate 9a so that the input end is exposed at one end face (left end face in the figure) of the substrate 9a, and the input channel waveguide 1 at the input end. The 2 × 2 optical distributor 3a1 to which the output end of is connected and the input end is connected to the output end of the 2 × 2 optical distributor and have different lengths so that the output end is exposed to the other end face 22a of the substrate 9a. Two channel waveguides 5g formed on the substrate 9a
And two channel waveguides 5i1 formed on the substrate 9a so that the input end is exposed on the other end face 22a of the substrate 9a.
And 2 × 2 whose input end is connected to the channel waveguide 5i1
The optical distributor 3a2 and the input end are connected to the output end of the 2 × 2 optical distributor 3a2, and the output end is the other end face 22a of the substrate 9a.
Is formed on the substrate 9b so as to be exposed to the outside, is folded back into a substantially mountain shape (upper side of the figure) and a substantially J shape (lower side of the figure), and is constituted by two channel waveguides 5h1 having different lengths. There is.

Second waveguide type optical element body (right side of the figure)
Is the two channel waveguides 5i2 formed on the substrate 9b so that the input end is exposed on one end face 22b of the substrate 9b.
And a 2 × 2 optical distributor 3a3 whose input end is connected to the output end of the channel waveguide 5i2, and an input end which is a 2 × 2 optical distributor 3
It is connected to the output end of a3, is formed on the substrate 9b so that the output end is exposed at one end surface 22b of the substrate 9b, and is folded back into a substantially J shape (upper side of the figure) and a substantially valley shape (lower side of the figure). The two channel waveguides 5h2 having different lengths, the two channel waveguides 5i3 formed on the substrate 9b so that the input ends are exposed on the one end face 22b of the substrate 9b, and the input ends are channel guides. 2 × 2 connected to the output end of the waveguide 5i3
The optical distributor 3a4 and two output channel conductors formed on the substrate 9b so that the input end is connected to the output end of the 2 × 2 optical distributor 3a4 and the other end is exposed at the other end face of the substrate 9b. The waveguide 2 (2a, 2b).

The spacing between the channel waveguides 5i2, 5h2, and 5i3 at the waveguide end face 22b is the same as the channel waveguide 5g at the waveguide end face 22 of the first waveguide type optical element body.
It is formed to be equal to the interval of 5i1 and 5h1.

The optical phase shifter 11c is composed of a substrate 9cc, a channel waveguide 7c formed on the substrate 9cc, and an electrode 10c formed on each channel waveguide 7c. The interval between the channel waveguides 7c is the same as the channel waveguides 5 on the waveguide end face 22a of the first waveguide type optical element body.
g, 5i1, and 5h1 are formed to be equal to each other.

Also in such a waveguide type optical element, FIG.
The same effect as the waveguide type optical element shown in FIG.

FIG. 4 is a plan view showing a fourth embodiment of the waveguide type optical element of the present invention.

The present waveguide type optical element is a Mach-Zehnder type variable gain equalizer and has a circuit configuration similar to that of the embodiment shown in FIG. 1, except that the channel waveguide 5j1 is formed at the waveguide end faces 22a and 22b. 5j2, 5k1, 5k2, 7
It is characterized in that d is inclined with respect to the waveguide end faces 22a and 22b.

That is, each channel waveguide 5j is formed at the end face of the connecting portion between the channel waveguide 7d formed with the optical phase shifter 11d and the first and second waveguide type optical element bodies.
1, 5j2, 5k1, 5k2, and 7d are obliquely connected to the connection portion end faces 22a and 22b in order to prevent reflected return light.

The channel waveguide 7d of the substrate 9cd made of LiNbO ₃ is inclined about 5 ° with respect to the normal to the waveguide end faces 22a, 22b, and the channel waveguides 5j1, 5j2, 5k1, 5k2 of the substrates 9a, 9b made of quartz are formed. Is the waveguide end face 2
It is inclined by about 7.5 ° with respect to the normal line of 2a and 22b.
Since the refractive indexes of LiNbO ₃ and quartz are greatly different (LiNbO ₃ is about 2.14 and quartz is about 1.45), Fresnel reflection occurs at the waveguide end faces 22a and 22b. Therefore, the channel waveguides 5j1, 5j2, 5k1,
If the angles of the end faces 22a and 22b of 5k2 and 7d with respect to the normal line are 0 °, that is, if they are perpendicular to the end faces 22a and 22b of the waveguides, the reflected light from the end faces 22a and 22b of the waveguides 5j1, 5j2, 5k1. 5 k2 is guided, and the reflected return light as an element becomes large.

Therefore, the channel waveguides 5j1 and 5j
2, 5k1, 5k2, and 7d are inclined with respect to the normal line of the end faces 22a and 22b, and the reflected light causes the channel waveguides 5j1 and
Reflected return light is prevented so as not to couple with the guided modes 5j2, 5k1, and 5k2.

Note that in such a waveguide type optical element, the same effect as that of the waveguide type optical element shown in FIG. 1 can be obtained. The invention according to the fourth embodiment is the second invention.
Also, the present invention can be applied to the waveguide type optical element shown in the third embodiment.

Here, the optical phase shifter is preferably made of a material having a large electro-optical effect. As a material, in addition to LiNbO ₃ described above, a ferroelectric crystal, In
Examples include P-based and GaAs-based compound semiconductors and polymers. Further, as the material of the optical phase shifter, in addition to the material having the electro-optical effect, the material having the photoelastic effect (for example, quartz, ZnO, etc.) and the material having the magneto-optical effect (for example, Y
IG (yttrium iron garnet) or the like may be used.

The waveguide type optical element of the present invention is used in an optical multiplex transmission system, such as a variable gain equalizer, a wavelength dispersion or polarization dispersion compensator, a variable optical filter, an optical wavelength multiplexer / demultiplexer, and an Add.
It can be used for a / Drop filter or the like.

[0065]

In summary, according to the present invention, it is possible to provide a waveguide type optical element in which phase control in an interferometer is easy and desired optical frequency characteristics can be easily obtained.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of a waveguide type optical element of the present invention.

FIG. 2 is a plan view showing a second embodiment of a waveguide type optical element of the present invention.

FIG. 3 is a plan view showing a third embodiment of the waveguide type optical element of the present invention.

FIG. 4 is a plan view showing a fourth embodiment of a waveguide type optical element of the present invention.

FIG. 5 is a plan view showing a conventional example of a Mach-Zehnder variable gain equalizer using a silica-based PLC, which is used for controlling frequency-loss characteristics.

FIG. 6 is a plan view showing a conventional example of a transversal variable gain equalizer.

FIG. 7 is a plan view showing a conventional example of a lattice type variable gain equalizer.

[Description of Reference Signs] 1 (1a, 1b) Input channel waveguide 2 (2a, 2b) Output channel waveguides 3a1, 3a2, 3b1-3b4 Optical distributors 4a1, 4a2, 5a1, 5a2, 7a Channel waveguide 6a1 , 6a2 Arrayed waveguide type optical multiplexer / demultiplexer 9a, 9b, 9ca Substrate 10a Electrode 11a Optical phase shifter

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/095 G02F 1/313 1/313 G02B 6/12 HJL (72) Inventor Takashi Chiba Tokyo 1-6-1, Otemachi, Chiyoda-ku, Nitatsu Electric Cable Co., Ltd. (72) Inventor Naoto Uezuka 1-6-1, Otemachi, Chiyoda-ku, Tokyo F-Term (Reference) 2H047 KA03 KA12 KB09 LA18 NA01 NA02 NA06 QA04 TA11 2H079 AA02 AA03 AA07 AA12 BA01 CA05 DA03 DA12 DA16 GA04 GA05 KA20 2K002 AA02 AB04 BA06 BA11 BA12 CA02 CA03 CA13 DA06 EA04 EA10 EA25 HA03 HA05 HA09

Claims (3)

[Claims] 1. A waveguide type optical element including an optical phase shifter in which a plurality of channel waveguides are arranged adjacent to each other at a predetermined interval, and electrodes are formed on the channel waveguides.
A waveguide type optical element, wherein the optical phase shifter is made of a substrate material having an electro-optical effect, a photoelastic effect or a magneto-optical effect. 2. The waveguide type optical element comprises a waveguide type optical element main body and the optical phase shifter as separate bodies, and a channel waveguide and the waveguide type optical element main body constituting the optical phase shifter. 2. The waveguide type optical element according to claim 1, wherein each channel waveguide is obliquely connected to the end face of the connection part at the end face of the connection part. 3. The waveguide type optical element according to claim 1, wherein the waveguide type optical element body is made of a silica material.