JP2000206476A - Temperature control type optical waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently heat a core part by a heating element. SOLUTION: This temperature control type optical waveguide includes a clad part 3 which is formed on a substrate 1, the core part 2 which is formed in the clad part 3, has a refractive index larger than the refractive index of the clad part 3 and is changed in the refractive index by temperature and the heating element 4 which is formed atop the clad part 3 so as to made to face part of the core part 2. The section of the clad part 3 which exist under the heating element 4 is formed with a thermal separating part 5 between the section, existing on the outer side thereof and the substrate 1. The heat from the heating element 4 can be transferred to the core part 2 without dissipation of heat. The core part 2 may thus be heated and operated efficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control type optical waveguide suitable for an optical switching element utilizing a thermo-optic effect used in an optical communication system or the like, and in particular, to enhance the heating efficiency of a core with a heating element. The present invention relates to a temperature-controlled optical waveguide.

[0002]

2. Description of the Related Art As one of optical components used in an optical communication system or the like, there is an optical switching element disposed between two optical waveguides and used for switching a path of an optical signal.

[0003] As such an optical switching element,
Some use a thermo-optic effect that causes a change in the refractive index of the core by heat, and a temperature-controlled optical waveguide is used. An example of an optical switching element using such a temperature-controlled optical waveguide is shown in a sectional view in FIG. 4 and a perspective view in FIG. FIGS. 4 and 5 show examples of a symmetric Mach-Zehnder type optical switching element using an optical switching element based on a temperature-controlled optical waveguide having a three-dimensional waveguide shape utilizing the thermo-optic effect.

In these figures, reference numeral 1 denotes a substrate and 2 and 3 denote a core portion and a clad portion of a three-dimensional waveguide optical waveguide formed on the substrate 1, respectively. Is formed. 4 is the core 2
Is a heating element formed on the cladding part 3 so as to cover a part of the core part 2 corresponding to a part of the optical switching element provided in a part of the optical switching element. Functions as a switching element.

According to the optical switching element using such a temperature control type optical waveguide, the light entering from the input 1 port to the core 2 is branched into two at the branch and propagated through the respective paths. Later, they interfere at the joint. At this time, if the phase difference is an even multiple of π in the two paths from the branch to the junction, the light that has interfered at the junction is guided only to the output 2 port. On the other hand, if the phase difference is an odd multiple of π in the two paths from the branch to the junction, the light that has interfered at the junction is guided only to the output 1 port.

Here, when the heating element 4 is not to be heated,
Core 2 at the bottom of heating element 4 and core 2 at the other path
And the phase difference is 0, the light is guided to the output 2 port.

When the heating element 4 generates heat, the refractive index of the core portion 2 and the cladding portion 3 of the optical waveguide below the heating element 4 can be changed by the thermo-optic effect, thereby causing a phase difference. If the phase difference is an odd multiple of π, the light that interferes at the junction is guided to the output 1 port. With such an operation principle, a light switching operation can be obtained.

[0008]

However, in the conventional temperature control type optical waveguide as shown in FIGS. 4 and 5, heat from the heating element 4 is conducted while radiating inside the clad portion 3, and the heat is transmitted to the substrate. Therefore, only the core portion 2 and the cladding portion 3 of the optical waveguide below the heating element 4 cannot be efficiently heated, and the heating efficiency of the heating element 4 to the core section 2 is poor. There was a problem.

The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to dissipate heat from a heating element when changing the refractive index of a core portion using a thermo-optic effect. An object of the present invention is to provide a temperature-controlled optical waveguide that can efficiently conduct heat to a core portion without causing the core portion and the clad portion of the optical waveguide located below the heating element to be efficiently heated. .

[0010]

According to the temperature control type optical waveguide of the present invention, a clad formed on a substrate and a refractive index formed in the clad are larger than the clad and change with temperature. A core portion, and a heating element formed on the upper surface of the cladding portion so as to face a part of the core portion, and a portion of the cladding portion located below the heating element is positioned outside the heating element. A thermal isolation portion is formed between the portion and the substrate.

Further, in the temperature control type optical waveguide according to the present invention, in the above structure, the thermal isolation portion is a gap.

According to the temperature control type optical waveguide of the present invention, the temperature of the optical waveguide consisting of the clad part and the core part formed in the clad part and the heating element formed on the upper surface thereof so as to face the core part. In the control-type optical waveguide, a thermal isolation portion is formed between a portion of the clad portion located below the heating element and a portion of the cladding portion located outside the substrate and a portion of the substrate located below the heating element. It has been
The side surface and the bottom surface of the clad portion of the optical waveguide at the portion where the heating element is formed are thermally separated from the surrounding clad portion and the substrate. As a result, since the heat from the heating element has a property of propagating in a medium having good heat conduction, the heat propagates in the clad portion having higher heat conductivity than the thermal separation portion, and is different from a conventional temperature control type optical waveguide. In addition, there is no possibility that heat from the heating element diverges and conducts widely in the clad portion along the lateral direction of the substrate, or conducts to the substrate. Therefore,
Since the heat from the heating element does not radiate outward from the side or bottom surface of the cladding located thereunder, and is confined only to the optical waveguide below the heating element, the core located below the heating element The part can be efficiently heated.

Further, when the thermal isolation portion is formed by a gap, the thermal isolation portion can be easily formed, the temperature control type optical waveguide can be easily manufactured, and the effect of thermal isolation is extremely large. As a result, the core located below the heating element can be heated very efficiently, and a temperature-controlled optical waveguide having extremely good responsiveness can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a temperature-controlled optical waveguide according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a temperature-controlled optical waveguide according to the present invention. In FIG. 1, 1
Denotes a substrate, 2 and 3 denote a core portion and a clad portion of the optical waveguide, respectively, and 4 denotes a heating element formed on the upper surface of the clad portion 3. The clad part 3 is formed on the substrate 1,
The core portion 2 formed in the cladding portion 3 is formed of a medium having a refractive index larger than that of the cladding portion 3 and having a refractive index that changes with temperature.

The heating element 4 is formed to face a part of the core in the direction in which the guided light is propagated by the core 2. The core portion 2 located below such a heating element 4
Is preferably formed as a single core portion 2 in the cladding portion 3 and 5 is a portion of the cladding portion 3 located outside the heating element 4 with respect to a portion located below the heating element 4. Is a thermal separation part formed between the clad part 3 and the substrate 1 located below the heating element 4. In this example, the heating element 4 of the cladding 3 is used as the thermal separation section 5.
An example is shown in which a gap is formed between a portion located under the heating element 4 and a portion outside the same, and between the clad portion 3 located below the heating element 4 and the substrate 1. Thereby, the side surface and the bottom surface of the clad portion 3 of the optical waveguide in the portion where the heating element 4 is formed are thermally separated from the surrounding clad portion 3 and the substrate 1.

With such a configuration, the heat from the heating element 4 is confined in the portion of the optical waveguide located thereunder,
Since there is no conduction and divergence from the side surfaces and the bottom surface of the clad portion 3 where the thermal isolation portion 5 is formed, the core portion 2 located below the heating element 4 can be efficiently heated, By controlling the temperature of the core section 2 by the heat from the heating element 4 to change the refractive index, it is possible to operate the core section 2 with high efficiency as a temperature-controlled waveguide suitable for, for example, an optical switching element. Become.

In the temperature-controlled optical waveguide of the present invention, the substrate 1 is made of various substrates used as substrates for handling optical signals, such as an optical integrated circuit substrate and a substrate mixed with photoelectrons, such as a silicon substrate, an alumina ceramic substrate, and a glass ceramic. Substrates and multilayer ceramic wiring boards can be used.

The optical waveguide formed on the substrate 1 is an optical waveguide having a three-dimensional waveguide shape in which a core 2 is formed in a cladding portion 3.
An inorganic optical material such as lithium niobate / GaAs, or a polyimide / fluorine resin / fluorinated polyimide / siloxane polymer / PMMA (polymethyl methacrylate) / olefin resin may be used. Above all, organic materials such as polyimide, fluororesin, fluorinated polyimide, siloxane-based polymer, PMMA, and olefin-based resin have a large thermo-optic effect because of their larger thermal expansion coefficient than inorganic materials such as silica. This is preferable in that power consumption for driving the temperature-controlled optical waveguide can be reduced.

As the heating element 4, Al.Cu.Ta.A
A metal resistor made of u, Ag, W, Ti, Cr, Ni, or the like can be used. In order to form the heating element 4 on the upper surface of the clad portion 3, these metal resistor films are formed on a predetermined upper surface of the clad portion 3 by, for example, a sputtering method or a CVD method, and then a known thin film fine processing technique is used. May be used to form the heating element 4 having a desired shape.

As the thickness of the clad portion 3 between the heating element 4 and the upper surface of the core section 2 increases, the heat from the heating element 4 diverges and propagates. Since the clad portion 3 cannot be efficiently heated, it is preferable to make the clad portion 3 as thin as possible.

However, when the thickness of the cladding 3 is not sufficient and the electromagnetic field component of the propagating light is applied to the heating element 4, the light is absorbed by the heating element 4 made of metal or the like. Since a loss of an optical signal occurs, it is necessary to have a thickness such that an electromagnetic field component of light propagating through the core portion 2 and the cladding portion 3 near the core portion 2 becomes sufficiently small at the position of the heating element 4. is there.

In order to suppress such a loss to a negligible level, for example, in the case of a single mode optical waveguide, the thickness of the cladding portion 3 between the heating element 4 and the upper surface of the core portion 2 is determined as the thickness of the core portion 2. The thickness may be about 1.5 times the thickness of the sheet (vertical height). In practice, the necessary thickness may be obtained by performing calculations, experiments, and the like based on the well-known optical waveguide theory.

On the other hand, the thickness of the cladding portions 3 on both sides of the core portion 2 in the optical waveguide located below the heating element 4, that is, the thickness of the cladding portion 3 from the side surface of the core portion 2 to the thermal isolation portion 5 is As the thickness increases, the heat from the heating element 4 increases
Since the core portion 2 and the clad portion 3 near the core portion 2 cannot be efficiently heated due to diverging and conducting inside, the thinner the better, the better.

For example, in the case of a single mode optical waveguide, if the thickness of the cladding portion 3 is about 1.5 times the width of the core portion 2, almost all of the electromagnetic field components of light propagating through the optical waveguide will be in the cladding portion 3. Therefore, even if the thickness of the clad portion 3 is about 1.5 times the width of the core portion 2, there is no particular change in the characteristics of the propagating light. Since the heat from the body 4 is radiated and propagated, it is preferable that the width is set to about 1.5 times or less the width of the core portion 2. Even if the thickness of the clad portions 3 on both sides of the core portion 2 is smaller than this, the desired optical waveguide structure can be formed by the three portions of the core portion 2 / the clad portion 3 / the thermal isolation portion 5. There is no particular problem because it can be designed. The same applies to the thickness of the clad portion 3 between the bottom surface of the core portion 2 located below the heating element 4 and the bottom surface of the clad portion 3 therebelow.

The thermal separation part 5 is for thermally separating the part of the clad part 3 located below the heating element 4 from the part outside the clad part 3 and the substrate 1. It is also formed of a medium having a low thermal conductivity and a poor thermal conductivity so as to surround the core portion 2 and the cladding portion 3 to be temperature-controlled from the side and the bottom. As a material used for such a thermal isolation portion 5, it can be formed into a desired shape, size, or the like in a process of forming an optical waveguide.
Moreover, as long as it does not adversely affect the characteristics of the optical waveguide,
For example, polyimide, fluorine resin, low-density olefin resin such as polypropylene or polyethylene, acrylic resin, or the like can be used.

When the thermal separation part 5 is formed as a gap, even if it is filled with a gas such as the atmosphere, the heat conductivity of the gas is small and the heat capacity is small, so that a sufficiently large heat insulating effect can be obtained. Then, a higher heat insulating effect can be obtained. Moreover, since it is not necessary to particularly fill the gap with a material for heat insulation, the thermal isolation portion 5 can be easily formed.

The thickness of the thermal isolation portion 5 (the width of the void if it is a void) is determined by the thermal conductivity of the cladding portion 3, the thickness of the cladding portion 3, the calorific value of the heating element 4, In consideration of the thermal conductivity and the like of the thermal separation section 5, the thickness of the thermal separation section 5 at which a desired heat insulating effect can be obtained may be obtained from, for example, a thermal analysis by a finite element method or an experiment.

In order to form the thermal isolation portion 5, for example, after forming the optical waveguide, the cladding portions 3 on both sides of the heating element 4 are first removed in a groove shape up to the surface of the substrate 1, and then both grooves are formed. What is necessary is just to remove the board | substrate 1 between them so that it may connect with the bottom face of the clad part 3. As a method for removing the clad portion 3 up to the surface of the substrate 1, for example, a method using dicing, a method using reactive dry etching using a mask, a method using excimer laser etching, or the like may be used. Also,
As a method of removing the substrate 1, the substrate 1 is etched by wet etching, plasma dry etching, or the like from portions where the clad portion 3 is removed in a groove shape on both sides of the heating element 4, and undercut by isotropic etching is performed. By utilizing this, the corresponding portion of the substrate 1 may be removed.

As shown in FIG. 2 as a cross-sectional view similar to FIG. 1, a method in which an intermediate layer 6 is formed between the substrate 1 and the clad portion 3 and this is used can also be used.

FIG. 2 is a sectional view showing another example of the embodiment of the temperature control type optical waveguide according to the present invention.
The same parts as in are denoted by the same reference numerals. In this example, an intermediate layer 6 is formed between the substrate 1 and the clad portion 3, and the intermediate layer 6 is used to form the thermal isolation portion 5. Such an intermediate layer 6 hardly erodes the clad portion 3 or the substrate 1 and can be etched using an etchant that can etch substantially only the intermediate layer 6. It is sufficient to use a material that does not adversely affect the quality. When the intermediate layer 6 is formed as described above, the clad portions 3 on both sides of the heating element 4 are removed in a groove shape up to the surface of the substrate 1, and then the cladding portions 3 are removed in a groove shape on both sides of the heating element 4. It is possible to use a method in which the intermediate layer 6 is etched from a portion by, for example, wet etching or plasma dry etching, and the corresponding portion of the intermediate layer 6 is removed using undercut by isotropic etching.

As such an intermediate layer 6, for example, Al
-Metals such as Cu, Ti, Nb, Cr, and Mo can be used. For example, when Ti is used for the intermediate layer 6,
If hydrochloric acid is used as an etchant, only the intermediate layer 6 made of Ti can be easily etched without eroding the clad portion 3 of the inorganic or resin optical waveguide,
The thermal isolation part 5 having a sectional shape as shown in FIG. 2 can be formed.

When the desired material is filled without leaving a space in the thermal separation part 5, for example, a filling resin material solution dissolved by heating or a filling resin material dissolved in an organic solvent may be used. The solution may be formed by injecting the solution from the opening of the thermal separation unit 5 and filling the inside of the thermal separation unit 5. At this time, the thermal separation unit 5 can be easily filled by utilizing the capillary phenomenon or performing the filling step under reduced pressure.

Even if the thickness of the thermal separation part 5 (the thickness of the gap when the thermal separation part 5 is a gap) is narrow, the thickness of the clad parts 3 or the clad part 3 and the substrate 1 can be reduced. As long as it is thermally separated as described above, if the width of the opening of the groove-shaped portion formed by removing the cladding portions 3 on both sides of the heating element 4 is narrow, the heating element 4 is placed under the heating element 4. When the portion of the substrate 1 or the intermediate layer 6 located is removed by etching, the etchant sufficiently penetrates through the opening to make it difficult to etch the substrate 1 or the intermediate layer 6, and it is difficult to remove them satisfactorily. Becomes From such a viewpoint, it is preferable that the width of the opening of the groove portion is 1 μm or more.

As an example of an optical switching element using such a temperature-controlled optical waveguide of the present invention, an example of a symmetric Mach-Zehnder optical switching element is shown in FIG. 3 in a perspective view similar to FIG. 3, the same parts as those in FIGS. 1, 2 and 5 are denoted by the same reference numerals. Reference numeral 4 denotes a core unit 2 corresponding to an optical switching element provided in a part of the core unit 2.
Is a heating element formed on the cladding part 3 so as to cover a part of the heating element 4. The heating element 5 is located between the cladding part 3 located below and corresponding to the heating element 4 and the outside part thereof and the substrate 1. It is a thermal separation part formed in. A temperature control type optical waveguide is formed in this portion to function as an optical switching element.

According to the temperature control type optical waveguide of the present invention, the heat from the heating element 4 can be effectively confined to the portion of the optical waveguide located therebelow by forming the thermal isolation portion 5. However, it is possible to heat the portion efficiently, but on the other hand, the heat radiation property is deteriorated as compared with the conventional one, and the cooling time after stopping the heating may be prolonged.

However, as a heat radiation path after heating, there are a direction in which the light is transmitted in the direction along the light propagation direction of the optical waveguide, and a path in which the heat is transmitted and discharged through the electric wiring for supplying power from the heat generating element 4 to the heat generating element 4. With these, a sufficient heat radiation path can be secured, and operation can be performed without particularly deteriorating the responsiveness of temperature control.

[0038]

Next, a specific example of the temperature control type optical waveguide of the present invention will be described.

Example 1 As a temperature-controlled optical waveguide of the present invention having the structure shown in FIG. 1, a cladding portion 3 is made of a siloxane polymer and a core portion 2 is made of a titanium-containing siloxane polymer on a substrate 1 made of silicon. A step index optical waveguide was formed. At this time, the refractive index of the core portion 2 and the cladding portion 3 are 1.444 and 1.440, respectively, the core portion 2 is 8 μm in width × 8 μm in height, and the thickness of the cladding portion 3 between the upper surface of the core portion 2 and the heating element 4. 12μm
The thickness of the cladding 3 between the substrate 1 and the core 2 is 12 μm
And

Next, this was subjected to RIE (Reactive Ion Etc
(hing: reactive ion etching) to remove a part of the clad 3 around the core 2 in a groove shape. At this time, the thickness of the clad portion 3 between the side surface of the core portion 2 and the side surface of the surrounding clad portion 3 was 12 μm, and the depth was 12 μm.

Thereafter, the surface of the silicon substrate 1 exposed by removing a part of the clad portion 3 was etched with a KOH aqueous solution to remove the substrate 1 below the optical waveguide.

As a result, a thermal separation portion 5 composed of a void was formed.

Next, after a tungsten thin film was formed on the upper surface of the clad portion 3 where the thermal isolation portion 5 was formed by a sputtering method, photolithography and etching were performed to form a heating element 4 made of tungsten.

Thus, a temperature-controlled optical waveguide of the present invention having the structure shown in FIG. 1 was manufactured.

Example 2 Next, a symmetric Mach-Zehnder optical switch as shown in FIG. 3 using the temperature-controlled optical waveguide of the present invention of Example 1 was manufactured.

In the same manner as in [Example 1], on a substrate 1 made of silicon, a core portion 2 has a refractive index of 1.444 and a width of 8 μm × a height of 8 μm.
The cladding 3 is made of a siloxane polymer having a refractive index of 1.440, the thickness of the cladding 3 on the upper surface of the core 2 is set to 12 μm, and the cladding between the substrate 1 and the core 2 is formed. Assuming that the thickness of 3 is 12 μm,
A Mach-Zehnder type optical circuit was formed by forming a step index type optical waveguide having no heating element on the upper surface.

Next, the Mach-Zehnder optical circuit 2
One clad 3 of the two arms was etched by RIE to remove a part of the clad 3 around the core 2 in a groove shape. At this time, the thickness of the cladding 3 between the side of the core 2 and the side of the surrounding cladding 3 is
The thickness was 12 μm, the depth was 12 μm, and the length was 1 cm.

Thereafter, the surface of the silicon substrate 1 exposed by removing a part of the clad portion 3 was etched with a KOH aqueous solution to remove the substrate 1 below the optical waveguide.

As a result, a thermal separation portion 5 consisting of a void was formed.

Next, after a tungsten thin film was formed on the upper surface of the clad portion 3 where the thermal isolation portion 5 was formed by sputtering, photolithography and etching were performed to form a heating element 4 made of tungsten. Thus, a symmetric Mach-Zehnder optical circuit optical switch having the temperature-controlled optical waveguide of the present invention in a part of the arm as shown in FIG. 3 was produced.

In order to evaluate the characteristics of the optical switch using the temperature control type optical waveguide of the present invention thus manufactured, an LD (laser diode) light is incident on one of the input ports and the heating element 4 When the change in the intensity of the output light from the output port with respect to the power consumption was measured, the minimum power required for ON-OFF switching of the output light was about 200 W. This was a result showing that the power consumption was reduced to 1/3 or less as compared with the conventional structure described later.

Further, as shown in FIG.
A similar symmetric Mach-Zehnder optical switch was fabricated and evaluated using the temperature-controlled optical waveguide of the present invention in which an intermediate layer 6 of μm Al was formed and the thermal isolation portion 5 was formed in the same manner as described above. , Also compared to the conventional structure
The result is that the power consumption is reduced to / 3 or less.

Example 3 For comparison with the optical switch using the temperature controlled optical waveguide of the present invention shown in [Example 2], a similar optical switch using the temperature controlled optical waveguide having the conventional structure was used. Produced.

First, a step index type optical waveguide in which a cladding portion 3 is made of siloxane polymer and a core portion 2 is made of titanium-containing siloxane polymer is formed on a substrate 1 made of silicon, and a Mach-Zehnder having a structure shown in FIGS. A shaped optical circuit was formed. At this time, the refractive indices of the core part 2 and the clad part 3 are 1.444 and 1.440, respectively, and
The core 2 has a width of 8 μm × height 8 μm, the thickness of the cladding between the upper surface of the core 2 and the heating element 4 is 12 μm,
The thickness of the cladding 3 between the core and the core 2 was 12 μm.

Next, after a tungsten thin film was formed by a sputtering method, photolithography and etching were performed to form a heating element 4 made of tungsten.

In order to evaluate the characteristics of the optical switch using the temperature control type optical waveguide of the conventional structure manufactured as described above, LD light is made incident on one of the input ports and electricity is supplied to the heating element to generate heat. When the change in the intensity of the emitted light from the output side port with respect to the power consumption is measured, the minimum power required for ON-OFF switching of the emitted light is 650 W
Met. The power consumption is more than three times that of the optical switch using the temperature controlled optical waveguide of the present invention shown in [Example 2]. Thus, it was confirmed that the core portion could be efficiently heated, and the power consumption could be reduced.

As described above, according to the temperature control type optical waveguide of the present invention, the heat from the heating element is confined in the clad portion where the heating element is in contact and propagated, and is efficiently transmitted to the core located below the heating element. Can be conducted, and the heat radiation from the substrate can be suppressed, so that it was confirmed that an optical switching element with higher efficiency and lower power consumption can be obtained as compared with the temperature control type optical waveguide having the conventional structure. .

It should be noted that the above is only an example of the embodiment of the present invention, and the present invention is not limited to the embodiment. Various modifications and improvements may be made without departing from the gist of the present invention. No problem.

[0059]

As described above, according to the temperature control type optical waveguide of the present invention, the optical waveguide composed of the clad and the core formed in the clad and the upper surface thereof are formed so as to face the core. In the temperature control type optical waveguide comprising the heating element, the portion of the cladding portion located under the heating element is located between the cladding portion located outside thereof and the substrate located under the heating element. Since the thermal isolation portion is formed in the optical waveguide, the side and bottom surfaces of the cladding portion of the optical waveguide in the portion where the heating element is formed are thermally separated from the surrounding cladding portion and the substrate, and the conventional temperature controlled optical waveguide is formed. As in the case of the wave path, the heat from the heating element does not diverge and conduct in the clad portion along the lateral direction of the substrate, and does not conduct to the substrate. Therefore, the heat from the heating element does not radiate outward from the side or bottom surface of the cladding located therebelow, and is confined only to the optical waveguide below the heating element. The core portion to be heated can be efficiently heated.

Further, when the thermal isolation portion is formed by a gap, it is easy to form the thermal isolation portion, that is, to fabricate the temperature control type optical waveguide, and the effect of thermal isolation becomes extremely large. The core portion located below the heating element can be heated very efficiently, and the temperature controlled optical waveguide has extremely good responsiveness.

As described above, according to the present invention, when the refractive index of the core portion is changed using the thermo-optic effect, the heat from the heating element can be efficiently conducted to the core portion without dissipating. As a result, a temperature-controlled optical waveguide capable of efficiently heating the core portion and the clad portion of the optical waveguide located below the heating element could be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a temperature-controlled optical waveguide according to an embodiment of the present invention.

FIG. 2 is a sectional view showing another example of the embodiment of the temperature control type optical waveguide of the present invention.

FIG. 3 is a perspective view showing an example of an optical switch using the temperature control type optical waveguide of the present invention.

FIG. 4 is a cross-sectional view showing an example of a conventional temperature-controlled optical waveguide.

FIG. 5 is a perspective view showing an example of a conventional optical switch using a temperature-controlled optical waveguide.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Core part of optical waveguide 3 ... Cladding part of optical waveguide 4 ... Heating element 5 ... Thermal separation part

Claims (2)

[Claims] A cladding portion formed on a substrate, a core portion formed in the cladding portion having a refractive index larger than that of the cladding portion and changing with temperature, and a core portion formed on an upper surface of the cladding portion. A heating element formed so as to face a part thereof, wherein a portion of the cladding portion located under the heating element has a thermal isolation portion between the portion located outside thereof and the substrate. A temperature-controlled optical waveguide, which is formed. 2. The temperature controlled optical waveguide according to claim 1, wherein said thermal isolation portion is a gap.