JPS6289936A - Lightguide element - Google Patents

Abstract

PURPOSE:To improve the use efficiency of heating energy for changing the refractive index by forming a lightguide layer and its adjacent layer of a laminated body with thermooptical materials having specific temperature coefficients of refractive index respectively and providing a heating means on the surface of the adjacent layer and providing diffraction gratings at the position to be heated on the surface of the adjacent layer. CONSTITUTION:A laminated body 13 consisting of a lightguide layer 11 and an adjacent layer 12 brought into intimate contact with this layer 11 is provided on a substrate 10. The lightguide layer 11 consists of thermooptical materials whose temperature coefficient of refractive index is zero or negative, on the other hand the adjacent layer 12 consists of thermooptical materials whose temperature coefficient of refractive index is positive. The lightguide layer 11, the adjacent layer 12, and the substrate 10 consist of materials satisfying n2>n1, n3, when n3 is the refractive index of the substrate 10 and n1 and n2 are refractive indexes of the adjacent layer 12 and the optical waveguide layer 11 in non-heating state respectively, so as to the light advances in the lightguide layer 11. Diffraction gratings G1-Gn formed with transparent electrothermal materials are provided in a row on the surface of the adjacent layer 12. When the current from a heating power source is flowed to these gratings through a driver 15, the adjacent layer 12 and the lightguide layer 11 are heated, and the refractive index of the adjacent layer 12 is made higher and that of the optical waveguide layer 11 is made lower.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to an optical waveguide element, and more particularly, an optical waveguide element comprising an optical waveguide layer (path) made of a thermo-optical material that changes the optical refractive index according to temperature changes. This invention relates to an optical waveguide element that allows guided light inside the layer to be emitted to the outside of the layer so that it can be used for optical scanning, optical modulation, etc.

(Prior Art) As is well known, various types of optical scanning recording devices and reading devices have been provided. Conventionally, as an optical scanning device that scans recording light or reading light one-dimensionally in such an apparatus, the light beam is deflected and scanned using a mechanical optical deflector, such as a galvanometer mirror, one-gon mirror, or a rotating polygon mirror. - Devices that deflect and scan light beams using optical deflectors using solid-state optical deflection elements such as EOD (electro-optical deflector) and AOD (acoustic optical deflector); ■ Liquid crystal element arrays and P
A shutter array such as an LZT array and a line light source are combined, a drive circuit is individually connected to each shutter element of the shutter array, and 0N10FF is selected and listened to simultaneously according to the image signal to perform line sequential scanning. In general, a large number of light emitting elements such as LEDs are arranged in rows, and a drive circuit is individually connected to each light emitting element, and the 0
It is known to perform line-sequential scanning by selecting N10FF and emitting light at the same time.

However, the mechanical optical deflector described in ■ above is weak against photography.
Further, FjM has the disadvantage that mechanical durability is low and adjustment is troublesome. The optical system becomes large because the light beam is roughly swung and deflected, which leads to the problem of increasing the size of the recording device and reading device.

In addition, even in optical scanning devices using EODs and AODs (2), the problem arises that the device tends to be large because the light beam is deflected by swinging it in the same way as described above. The above EO
Since the Dya AOD cannot have a large optical deflection angle, the optical system tends to be much larger than when using a mechanical optical deflector (2).

On the other hand, in the optical scanning device using the shutter array (2), since it is necessary to use two polarizing plates, there is a problem that the light utilization efficiency of the light source is extremely low.

In addition, in the optical scanning device (2) using a large number of light emitting elements arranged in parallel, there is a problem that the light emitting intensity of each light emitting element varies, making it unsuitable for precision scanning.

In view of the above circumstances, the present applicant has developed an optical scanning device that has excellent durability and dynamic resistance, is easy to adjust, has high light utilization efficiency, is capable of precision scanning, and can be made compact. (Patent Application No. 74061/1982). This optical scanning device uses an optical waveguide element, at least one of which is made of a material that changes the diffraction index of light by adding energy, and an optical waveguide layer that is closely attached to each other and a light beam that is usually smaller than the optical waveguide layer. a laminate of adjacent layers exhibiting a diffraction index; a plurality of energy adding means provided on the optical waveguide layer and/or the adjacent layer along the optical path of the guided light traveling within the optical waveguide; A diffraction grating provided in the upper portion corresponding to at least the energy adding point by the energy adding means and the plurality of energy adding means are sequentially and selectively set to a predetermined energy adding state, and the energy adding point is set to a predetermined energy adding state. and a drive circuit that changes the optical refractive index of the optical waveguide layer and/or the adjacent layer so that the guided light is emitted outside the laminated body by the delta effect of the optical waveguide layer with the diffraction grating. light, diffraction index (nz) a5 and/or adjacent,
Change the optical refractive index (nl, which has the relationship nz > nl in the normal state, that is, the state where no energy key is added) so that the difference (nz n+) becomes small, or so that n2 ≦ n1. The field A5 of the guided light confined in the optical waveguide layer is changed, the guided light is taken out from the stack of the optical waveguide layer and the adjacent layer by interaction with the diffraction grating, and is scanned. It is designed to be used as light.

To explain in more detail, for example, as shown in FIG. 1, this optical scanning device includes an optical waveguide 11 on a substrate 10 and an adjacent layer 12 (formed from a temperature optical material) having a diffraction grating G on its surface. ), and between the optical refractive index n3 of the substrate 10, the optical refractive index n2 of the optical waveguide layer 11 when unheated, and the optical refractive index n of the adjacent layer 12, which is also unheated, nz ＞
It is assumed that the relationship between nl and n3 holds true.

In the case of the configuration shown in FIG. 1, the dispersion curve when the adjacent @12 is not heated by h0 is expressed as shown in FIG. 2(a).

In FIG. 2 (a), the vertical axis represents the effective refractive index of light, and the horizontal axis represents the thickness of the optical waveguide layer 11. If the thickness of the optical waveguide layer 11 is T, then the effective refractive index of the optical waveguide layer 11 is n.ff
It is. At this time, assuming the TEo mode, the field distribution (electric field distribution) of the guided light 14 is expressed as shown in FIG. 3(a). FIG. Although it seeps out slightly, it does not interact with the diffraction grating G, and the guided light 14 is shown to be traveling through the optical waveguide layer 11 without leaking to the outside.

Next, a portion P1. which faces the diffraction grating G provided on the surface of the adjacent layer 12. : The adjacent layer 12 is heated to a predetermined temperature to increase its optical refractive index from nl to nl +Δn. At this time, the dispersion curve is represented by the dashed line in Fig. 2(b),
The effective refractive index neff of the optical waveguide layer 11 increases to n'. At this time, the electric field force ff distribution of the guided light changes as shown in FIG. 3(b), and the amount of light leaking out of the guided light into the adjacent layer 12 increases so as to sufficiently interact with the diffraction grating G. As a result, the leaked light in the shaded area in the figure is directed upwards in the figure (downward or both above and below depending on the type of diffraction grating G).
The guided light propagates while being radiated to the outside, and eventually most of the guided light is taken out to the outside.

Furthermore, in the configuration shown in FIG. 1, when the optical refractive index of the adjacent layer 12 is changed from nl to n1+Δn'', this n
When the value of l+Δn11 becomes large enough to be equal to the effective refractive index n'' of the optical waveguide layer 11, which changes with the change in the optical refractive index of the adjacent layer 12, the dispersion curve ff becomes as shown in FIG. 2(C). It will look like a dashed line,
The guided light converts from the guided mode to the radiating mode, and the light migrates to the adjacent layer 12. The electric field distribution of the guided light at this time is the third
The waveguide light changes as shown in Figure (C), and a large amount of guided light leaks into the adjacent layer 12, interacts with the diffraction grating G, travels upward (and/or downward) in the figure, and is quickly released to the outside. taken out. Further, by changing the optical refractive index n1 of the adjacent @12 so that it is approximately equal to the optical refractive index n2 of the optical waveguide layer 11 or larger than nl, the total reflection condition of the guided light in the optical waveguide layer 11 is changed. The guided light can be moved into the adjacent layer 12 by changing the wavelength, and can be extracted to the outside through interaction with the diffraction grating G. In this way, the guided light can be extracted to the outside at the heated location, so a plurality of the above-mentioned diffraction gratings G are provided extending in one row, and the portions P facing each diffraction grating G are sequentially selected. When heated all at once, light is emitted from the adjacent layer 12 while changing its emitting position, and optical scanning is performed.

Since the optical scanning device with the above configuration uses a single light source, there is no problem of variations in the light emission intensity of the light source seen in the above-mentioned LED arrays, etc., and precision scanning is possible, and the light utilization efficiency of the light source is also increased. It will be done.

This optical scanning device also has excellent durability and vibration resistance because it does not have any mechanically operating parts, and is easy to adjust, and it is possible to scan without shaking the light beam roughly. , to avoid increasing the size of the optical scanning system and to use an optical scanning recording device or reading bag@? It can be formed into a small size.

The aforementioned materials that change the optical refractive index by adding energy include electro-optic materials that change the optical refractive index by an electric field, thermo-optic materials that change the optical refractive index by temperature, acousto-optic materials that change the optical refractive index by ultrasonic waves, and materials that change the optical refractive index by a magnetic field. Magneto-optical materials that change the optical refractive index are available. When using thermo-optical materials, it is necessary to efficiently change the optical refractive index of the optical waveguide layer and the adjacent layer with low heating energy consumption, that is, the efficiency of heating energy use for changing the optical surface refractive index is high. This is practically desirable.

(Objective of the Invention) Therefore, the present invention provides an optical waveguide element in which an optical waveguide layer and an adjacent layer are formed of a thermo-optic material, and which can constitute an optical scanning device as described above. The purpose of the present invention is to provide an optical waveguide element with high heating energy utilization efficiency.

(Structure of the Invention) The optical waveguide element of the present invention is characterized in that the optical waveguide layer and the adjacent layer of the laminate described in (a) above are formed so that the temperature coefficient of the optical refractive index is zero or negative (that is, the optical refractive index does not change upon heating, or and a humidity optical material having a positive temperature coefficient (that is, the optical refractive index increases with heating) and exhibiting a smaller optical refractive index than the optical waveguide layer when not heated,
A heating means is provided on the surface of the adjacent layer so as to heat a predetermined location along the optical path of the guided light traveling within the optical waveguide layer, and a diffraction grating is provided on the surface of the adjacent layer at the heating location. be.

In the optical waveguide device having the above configuration, a plurality of heating means are provided so as to heat each of the plurality of zero force points arranged in one row, and these heating means are sequentially and selectively set to a predetermined heating state. By combining these drive circuits, an optical scanning device is formed.

Furthermore, in the optical waveguide element having the above configuration, an optical modulator can be formed by providing only one heating means and combining this heating means with a drive circuit that sets the heating means to a predetermined heating state based on an image signal or the like. .

(Function) When the adjacent layer is heated by the above-mentioned heating means, the temperature of the optical waveguide layer also rises, and the relationship between the optical refractive index n2 of the optical waveguide layer and the optical refractive index n1 of the adjacent layer is normally changed to B\f( In this case, from the relationship nz > nl (when not heated), it is possible to change the difference (nz nx) so that it becomes smaller, or so that n2≦n1, and the guided light can be taken out of the laminate. . In the optical waveguide device of the present invention, the temperature-optical material constituting the optical waveguide layer has a temperature coefficient of optical refraction of zero or an angle, while the temperature-optical material constituting the adjacent layer has a temperature coefficient of optical refraction index of zero or an angle. Since a positive value is used, the difference (n2 nx) can be made sufficiently small as described above, or n2≦n1, without heating the adjacent layer or optical waveguide layer very much. .

(Embodiments) Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Figure 4 is one of the fruits of this invention W! 2 shows an optical scanning device 20 formed using an optical waveguide element according to an embodiment. On the substrate 10, there is provided a laminate 13 consisting of an optical waveguide @11 and an adjacent layer 12 in close contact with the optical waveguide layer 11.

The optical waveguide layer 11 is formed of a humidity optical material having a zero or negative temperature coefficient of optical refractive index, while the adjacent layer 12 is formed of a temperature optical material having a positive temperature coefficient of optical refractive index. Then, as described above, the optical waveguide @11
, the adjacent layer 12, and the substrate 10 are each made of a material that satisfies the relationship n, >nl·nl. As mentioned above, n
l is the optical refractive index of the substrate 10, and nl and n2 are the optical refractive indexes of the adjacent optical waveguide layer 11, @12, and when not heated, respectively.

As a rough combination of materials for the adjacent layer 12, the optical waveguide layer 11, and the substrate 10, for example, He-
Schott Co., Ltd., whose optical refractive indexes n1, n2, and nl for the Ne laser are 1.52.1.54.1°46, respectively.
(West Germany) optical glass KF9 (absolute temperature coefficient Δn/Δd at +20 to +40'C is +2, 9 x 10'
/°C: Same as below iX), same BAK2 (-〇, 1x
10'/'C), same FK3 (-2,0X10"6/°
C); Or optical glass PK2 (+1.4x10″
6/°C), same KF1 (-0,4x10°6°7°C)
, same FK3: Furthermore, optical crow BK7 (+1.2
X10-6/°C), same BAK2 (-0,1x10'
/'C), FK3: Optical glass KF9 (+2.
9x10°"/'C), same BAK2 (0,0x10'
/'C), FK3, etc. In addition to the above-mentioned optical glasses, crystals, plastics, etc. can also be used as temperature optical materials as long as the conditions for temperature change in refractive index and m-refractive index are satisfied. Regarding optical waveguides, for example, see the book edited by T. Tamir [Integrated Optics (1ntegrated
0ptics)” (Topics in Applied
Physics (Topics in Applie)
d Physics) Volume 7) Springer Fair Laser (Springer-VerlaQ)
Published (1975): Nishihara, Haruna, Suhara co-author "Optical integrated circuit"
There are detailed descriptions in published works such as Ohmsha (1985).

In addition, the optical waveguide layer 11, the adjacent layer 12, and the substrate 10 each have a thickness of 0.5 to]0 μm, 1 to 50 μm, and 1 μm, respectively, as examples.
Although formed as described above, it is not limited to this.

On the surface of the adjacent layer 12, diffraction gratings G1, G2, G3, . . . , Gn made of a transparent electrothermal material are arranged in a row. Examples of the above-mentioned transparent electrothermal materials include In2O3
and 5 nOz. The size of the diffraction gratings G1 to Qn is, for example, 10×10 μm to 0.0 μm.
The size is about 2×5M, and the interval between each diffraction grating 01 to Gn is set to about 100 to 200 μm. Each diffraction grating 01
A plurality of grating elements constituting ~Qn are electrically connected to each other at both ends, and each diffraction grating G1~Qn is connected to a driver 1 formed on a substrate 10.
5. Note that this driver 15
It may be provided independently from 0.

- A waveguide lens 16 is formed on the optical waveguide layer 11 in an extension of the direction in which the diffraction gratings G1 to Qn are arranged, and a waveguide lens 16 is formed on the substrate 10 toward the waveguide lens 16 in the optical waveguide layer 11. A semiconductor laser 17 is attached which emits a laser beam (radiation beam) 14'.

FIG. 5 shows the drive circuit 21 of the optical scanning device 20. The operation of the optical scanning device 20 will be described below with reference also to FIG. First, the aforementioned semiconductor laser 17 is driven, and a laser beam 14' is emitted into the optical waveguide layer 11. This laser beam 14' is converted into parallel light 14 by a waveguide lens 16, and this light 14 travels in the optical waveguide layer 11 in a waveguide mode in the direction in which the diffraction gratings G1 to G3n are arranged (see FIG. 4). And for the diffraction gratings 01 to Gn,
The current (2) from the heating power source 22 is passed through the driver 15. This driver 15 is a tarokku signal QCL.
Diffraction gratings G1 to i3n that operate in response to the output of the shift register 23 that operates in synchronization with K and supply current
The current is supplied by selecting the jl primary one by one. In other words, initially only the first diffraction grating G1 among the diffraction gratings 01 to Gn of nflMl, then only the second diffraction grating G2,
. . . and the current I is supplied. In this way, when the current I is sequentially passed through the diffraction gratings G1 to Qn, each of the diffraction gratings G1 to
Gn sequentially generates heat, and the adjacent layer 12 and the optical waveguide layer 11 in the portion facing the heated diffraction grating are heated, and the optical refractive index of the adjacent layer 12 increases, and conversely, the optical refractive index of the optical waveguide layer 11 increases. becomes lower. Then, as described above, the light (waveguide light) 14 is emitted from the optical waveguide layer 11 to the adjacent layer 12 side in the portion where the optical refractive index has changed, and is reflected in the diffraction gratings G1 to Gn.
The light is emitted to the outside of the adjacent layer 12 due to the diffraction effect. In other words, the emission position of the light 14 changes sequentially, first from the diffraction grating G1, then from the diffraction grating G2, then after the diffraction grating Gn, and then back from the diffraction grating G1. The light 14 causes scanning in the direction of the arrow X in FIG.
・・・-・Gn-+G (n-1) →G (n-2)
- The current supply to the diffraction gratings G1 to Gn may be controlled so as to change as follows. When main scanning is performed as described above and sub-scanning is performed by moving the scanned object 18 in the direction of arrow Y in FIG. 4 in synchronization with the main scanning using the clock signal CLK, the scanned object 18 will be scanned two-dimensionally.

Note that since the adjacent layer 12 and the optical waveguide layer 11 are respectively formed of a temperature optical material with a positive temperature coefficient of optical refractive index, and a temperature optical material with a zero or negative temperature coefficient, both layers 11.
Light 14 may exit from adjacent layer 12 without significantly heating 12.

In this embodiment, the diffraction gratings G1 to Gn provided on the surface of the adjacent layer 12 are formed as condensing diffraction gratings, and the light 14 emitted from the diffraction gratings 01 to On is focused at one point on the object to be scanned 18. It is now focused on This condensing diffraction grating has a quadratic curved grating pattern (grid pattern) in the traveling direction of the guided light 14 in the optical waveguide layer 11.
The curvature of each pattern and the pitch between the patterns are varied, thereby providing the above-mentioned focusing effect. Note that such a condensing diffraction grating is described in detail, for example, on pages 47 to 54 of Technical Research Report 0QC83-84 of the Institute of Electronics and Communication Engineers.

Alternatively, the semiconductor laser 17 may not be directly coupled to the optical waveguide layer 11, but the light may be incident on the optical waveguide layer 11 through a lens, a coupler prism, a grating coupler, or the like. Furthermore, when forming the optical waveguide layer, the semiconductor laser 17
It may be made integrally with this.

The light source that generates the scanning light is not limited to the semiconductor laser 17 in (a) above, but other sources such as a gas laser or a solid-state laser may also be used.

Further, in order to focus the light 14 emitted from the adjacent layer 12 to one point, as described above, it is necessary to use the diffraction gratings 01 to Gn as a focusing diffraction grating, and as shown in FIG. A lens array 30 made of, for example, a SELFOC lens array may be interposed between the scanning body 18 and the scanning body 18.

Further, as shown in FIG. 7, a lens L1 is placed on the adjacent layer 12 at a position facing each of the diffraction gratings G1, G2, G3 to Gn.
A lens array layer 31 having lenses L2, L3 to Ln may be provided. In this case, the lens L1~In
may be in the shape of a normal convex lens as shown in FIG. 7, or may be a gradient index lens in which the refractive index of the array 1@ material is distributed. In general, the light 14 may be focused by both the lens array 30 or lens array 31 as described above and the focusing diffraction grating. However, if only the above-mentioned condensing diffraction grating is used, the lens array 30 and the lens array layer 31 are unnecessary, and the structure of the optical scanning device becomes simple, which is preferable. Also, the adjacent layer 1
It is not always necessary to focus the light 14 emitted from the light source 2 as described above, and depending on the case, the object 18 to be scanned may be scanned with parallel light, or diffused light.

In the embodiment described above, the laminate 13 of the optical waveguide layer 11 and the adjacent figure 12 is provided on the substrate 10, but such a substrate 10 is not used, and the optical waveguide layer 11 is directly exposed to the air. Even if they are in contact with each other, there is no groove, and in general, by laminating the adjacent layers 12 on both surfaces of the optical waveguide layer 11, scanning light is emitted to both the upper and lower sides of the optical waveguide layer 11, and the two surfaces to be scanned are simultaneously scanned. It is also possible to scan.

Roughly speaking, in the above embodiment, the optical waveguide layer 11 and the adjacent @12 are heated by the diffraction gratings 01 to Qn made of electrothermal material, but the predetermined heating point is sandwiched from the left and right or surrounded from all sides. It is also possible to heat a predetermined location by arranging a heating means in this way.

Further, the optical scanning device using the optical waveguide element of the present invention may be formed so that a plurality of rows of diffraction gratings G1 to Gn are lined up in the scanning light extraction portion, so that a plurality of scanning lights can be extracted simultaneously. can.

Although the embodiments formed so as to constitute an optical scanning device have been described above, the optical waveguide element of the present invention can also be formed so as to constitute an optical modulator. Hereinafter, an embodiment formed in this way will be described with reference to FIG. Note that in FIG. 8, elements equivalent to those in FIG. 4 are given the same numbers, and explanations thereof will be omitted unless particularly necessary. In the stacked body 13 constituting this optical modulator 50, only one relatively large diffraction grating G is provided on the adjacent layer 12. Even in this configuration, if the diffraction grating G is heated, the guided light 14
is emitted to the outside of the stacked body 13. Therefore, if the heating of the diffraction grating G, that is, the supply of heating current to the diffraction grating G, is controlled based on the image signal etc., the light 1
4 is modulated in accordance with the image signal and the like. In this case, the light emitted outside the laminate 13 as described above may be used as modulated light, or the light passing through the diffraction grating G and proceeding within the optical waveguide @ 11 may be used, for example, through a coupler prism or the like. The light may be taken out of the optical waveguide layer 11 by using the above method, and the taken out light may be used as modulated light. In other words, in the latter case, the light extracted as described above is modulated in accordance with the image signal etc. since the amount of light is reduced by that amount when the guided light 14 is emitted from the diffraction grating G.

(Effects of the Invention) As described above in detail, when the optical waveguide element of the present invention is applied to an optical scanning device, the optical scanning device can be configured to use a single light source, so the LED array, etc. There is no problem of variations in the light emission intensity of the light source, which is seen in the above, and precision scanning is possible, and the light utilization efficiency of the light source is improved.Also, since the optical waveguide element of the present invention does not have any mechanically operating parts, it is durable and photo-resistant. This optical waveguide element has excellent mobility, is easy to adjust, and can scan without shaking the light beam roughly. Accordingly, this optical waveguide element avoids increasing the size of the optical scanning system and is suitable for optical scanning and recording devices. The reading device can be made compact.

Furthermore, since the optical waveguide element of the present invention can efficiently extract guided light to the outside of the optical waveguide layer using the diffraction grating, when applied to an optical modulator, it has the effect of sufficiently increasing its extinction ratio.

Furthermore, in the optical waveguide element of the present invention, since the adjacent layer and the optical waveguide layer are formed of a temperature optical material with a positive temperature coefficient of optical refractive index and a temperature optical material with a zero or negative temperature coefficient, there is a relatively small difference between these layers. If a temperature change is given, light will be emitted outside the adjacent diagram, and the consumption of 7JD heat energy can be kept low.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram explaining the mechanism of guided light extraction of the device of the present invention, Fig. 2 is a graph showing the dispersion curve of the configuration of Fig. 1, and Fig. 3 is an electric field valve of the guided light in the configuration of Fig. 1. FIG. 4 is a perspective view showing an optical scanning device configured using an optical waveguide element according to the first embodiment of the present invention, and FIG. 5 is a block diagram showing an electric circuit of the optical scanning device. 6 and 7 are side views showing another example of an optical scanning device formed using the optical waveguide element of the present invention, and FIG. 8 is a second embodiment of the present invention! FIG. 2 is a perspective view showing an optical modulator configured using an optical waveguide element according to an embodiment. 10... group (anti-11... optical waveguide diagram 12
... Adjacent layer 13 ... Laminated body 14 ... Light 15 ... Driver 16 ... Waveguide lens 17 ... Semiconductor laser 20 ... Optical scanning device 21 ... Drive circuit 22 ...・Heating power supply
23...Shift register 50...Optical modulator

Claims (1)

[Claims] (1) An optical waveguide layer made of a temperature optical material with a temperature coefficient of optical refractive index of zero or negative, and a temperature at which the temperature coefficient of optical refractive index is positive and exhibits an optical refractive index smaller than that of the optical waveguide layer when not heated. a laminate of adjacent layers made of an optical material; a heating means provided on the surface of the adjacent layer so as to heat a predetermined location along the optical path of the guided light traveling within the optical waveguide layer; An optical waveguide element consisting of a diffraction grating provided on the surface of an adjacent layer. (2) The optical waveguide element according to claim 1, wherein a plurality of the heating means are provided so as to respectively heat a plurality of heating points arranged in a row.