JP2011033963A - Waveguide optical gate switch and multistage waveguide optical gate switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultra-miniature waveguide optical gate switch that is not affected by an error on manufacture, concerning the waveguide optical gate switch and multistage waveguide optical gate switch. <P>SOLUTION: The waveguide optical gate switch changes an amount of transmission of light by changing a complex index of refraction for part of an optical waveguide. The optical waveguide includes: a pair of core layers facing each other in an optical axis direction; a phase change material part arranged between the pair of core layers; and a cladding layer covering the pair of core layers and the phase change material part. Also, the optical waveguide includes a phase change means for changing a phase of the phase change material part in the phase change material part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a waveguide-type optical gate switch and a multi-stage waveguide-type optical gate switch. For example, the transmission amount of an optical signal propagating through an optical waveguide is controlled at a small size and at a high speed without being affected by manufacturing errors. It is related with the structure for doing.

  In recent years, with the progress of optical communication systems, the capacity of optical communication networks has been increased, and optical devices having various functions have been developed accordingly. In particular, an optical switch that controls the transmission amount of an optical signal propagating through an optical waveguide is a key device.

  For example, in an InGaAsP / InP directional coupled optical switch, a current is injected into a waveguide portion, and the refractive index of the core layer is changed by the plasma effect of the injected carriers. As a result, the coupling length of the directional coupling section changes and the output port is switched.

  However, in such an InGaAsP / InP directional coupling type optical switch, it is necessary to make the length of the directional coupling portion 100 μm or more in order to switch the output, so that it is difficult to reduce the size. There's a problem. There is also a problem that the switch speed for switching is not so fast.

  Therefore, in such an optical switch, a phase change optical switch that performs ON / OFF of an optical signal using a phase change material from the viewpoint of downsizing or increasing the switch speed has attracted attention (for example, Patent Document 1). reference).

  The present inventor has also proposed several optical switches using phase change materials (see, for example, Patent Document 2 or Patent Document 3). For example, in a directional coupler type optical switch using a phase change material, a phase change material portion is provided between a pair of core layers extending in parallel with each other in the directional coupling portion.

  In this configuration, a phase change between a crystalline state and an amorphous state is performed by applying a current pulse to the phase change material portion. As a result, the complex refractive index (mainly the real part) at the operating wavelength of the phase change material is changed, and the optical coupling amount of the pair of waveguides is changed to switch the output port, thereby operating as an optical switch. If attention is paid to one of the input / output waveguides, it is an optical gate switch.

  As described above, by providing the phase change material portion in the directional coupling portion, the coupling length of the directional coupling portion can be reduced to about several μm. Therefore, the InGaAsP / InP directional coupler type optical switch can be used. Compared to this, a significant reduction in size is possible.

JP 2004-117448 A JP 2006-184345 A JP 2009-128718 A

  However, in the case of the optical switch using the above-described phase change material, the coupling state between the waveguides is changed only by slightly shifting the position of the phase change material portion or slightly deviating the composition of the phase change material from the design value. Will change. Therefore, there is a problem that the extinction characteristic of the optical switch is deteriorated due to a manufacturing error.

  Further, when a directional coupler type optical switch using a phase change material is viewed as an optical gate switch, there is a problem that the size is still large.

  Therefore, an object of the present invention is to realize an ultra-compact waveguide type optical gate switch that is not affected by manufacturing errors.

To solve the above problem,
(1) The present invention is a waveguide-type optical gate switch that changes the amount of transmitted light by changing the complex refractive index of a part of the optical waveguide, and the optical waveguide is a pair facing each other in the optical axis direction. The core layer, a phase change material portion disposed between the pair of core layers, a clad layer covering the pair of core layers and the phase change material portion, and the phase change material portion includes It has the phase change means which changes the phase of a phase change material part, It is characterized by the above-mentioned.

  Thus, by disposing the phase change material portion between the pair of core layers, the change in the complex refractive index of the phase change material portion can be mainly used as the change in the imaginary part. Since the change in the imaginary part becomes a change in the light absorption rate, it becomes possible to control the amount of transmitted light with a very small size.

  (2) Further, in the above (1), the present invention provides, as the phase change means, a current application means for supplying a pulse current to the phase change material section, or a direct or insulating film on the phase change material section. It is characterized by including at least one of the laminated heat generating members.

  As the phase change means, either a current applying means for applying a pulse current to the phase change material portion, a heat generating member laminated directly or via an insulating film on the phase change material portion, or both may be used. May be used.

  Whichever configuration is used, the amorphous state has a small light absorption coefficient due to melting and rapid cooling due to a sudden rise in temperature, and the crystalline state with a large light absorption coefficient due to relatively slow temperature rise and slow cooling that does not melt. It becomes.

  (3) Further, in the above (2), the present invention is characterized by having a thermal diffusion film that covers the phase change material portion in a projective manner.

  Since the phase change, that is, the change between the amorphous state and the crystalline state is due to a thermal action, the effect of heating can be rapidly removed by providing a thermal diffusion film that covers the phase change material portion in a projective manner. Can do.

  (4) Further, according to the present invention, in any one of the above (1) to (3), the pair of core layers is a core layer as it approaches the phase change material portion at a portion facing the phase change material portion. It has the taper part which the width | variety expands, It is characterized by the above-mentioned.

  As described above, by making the optical waveguide a tapered waveguide in the vicinity of the phase change material portion, it is possible to reduce the radiation loss of light in the phase change material portion.

(5) In the present invention, in any one of the above (1) to (4), the phase change material portion may be amorphous silicon, amorphous germanium, amorphous gallium antimony, amorphous gallium arsenide, tetrahedral material, Ge-Sb. It is characterized by being made of any one of -Te chalcogenide material, Sb-Te chalcogenite material, arsenic glass chalcogenide material, NiO, HfO ₂ , ZrO ₂ , or ZnO.

  As the phase change material constituting the phase change material portion, the above-mentioned materials that have a proven record in phase change optical disks and the like and have a large change in complex refractive index accompanying the phase change are suitable.

  (6) In the present invention according to any one of the above (1) to (5), the core layer is formed of silicon, silicon nitride, silicon nitride oxide, silicon germanium, indium phosphide, gallium arsenide, indium gallium arsenide phosphorus, It is characterized by being made of any one of indium aluminum arsenide, indium gallium arsenide, gallium nitride, or arsenic gallium nitride.

  As the material constituting the core layer, the above-mentioned materials having a proven record in semiconductor optical integrated circuit devices including semiconductor lasers or dielectric optical waveguides are suitable, and if a material having a small absorption loss is selected according to the wavelength used. good.

  (7) Further, according to the present invention, in the multistage waveguide type optical gate switch, the waveguide type optical gate switch of any one of the above (1) to (6) is connected in multiple stages along the optical axis of the optical waveguide. It is characterized by.

  In this way, by connecting a single waveguide type optical gate switch in multiple stages along the optical axis of the optical waveguide, the extinction ratio can be remarkably increased, and a highly reliable optical gate switch is obtained. Can do.

  According to the disclosed waveguide type optical gate switch or multistage waveguide type optical gate switch, it is ultra-compact with a size of several μm and is capable of optical transmission at an ultra-high speed of several tens of nanoseconds without being affected by manufacturing errors. It is possible to control ON / OFF of an optical signal guided through the waveguide.

It is a notional block diagram of the waveguide type optical gate switch of an embodiment of the invention. It is explanatory drawing of the phase change material part length d dependence of an extinction ratio. It is a schematic plan view of the waveguide type optical gate switch of Example 1 of the present invention. It is a schematic sectional drawing of the waveguide type optical gate switch of Example 1 of the present invention. It is explanatory drawing of the manufacturing process to the middle of the waveguide type optical gate switch of Example 1 of this invention. It is explanatory drawing of the manufacturing process until the middle of FIG. 5 or subsequent of the waveguide type optical gate switch of Example 1 of this invention. It is explanatory drawing of the manufacturing process to the middle after FIG. 6 of the waveguide type optical gate switch of Example 1 of this invention. It is explanatory drawing of the manufacturing process to the middle after FIG. 7 of the waveguide type optical gate switch of Example 1 of this invention. It is explanatory drawing of the manufacturing process after FIG. 8 of the waveguide type optical gate switch of Example 1 of this invention. It is a schematic plan view of the waveguide type optical gate switch of Example 2 of the present invention. It is a schematic sectional drawing of the waveguide type optical gate switch of Example 2 of this invention. It is a schematic plan view of the waveguide type optical gate switch of Example 3 of the present invention. It is a schematic sectional drawing of the waveguide type optical gate switch of Example 3 of this invention. It is a schematic plan view of the waveguide type optical gate switch of Example 4 of the present invention. It is a schematic plan view of the waveguide type optical gate switch of Example 5 of the present invention.

  Here, with reference to FIG.1 and FIG.2, embodiment of this invention is described. FIG. 1 is a conceptual configuration diagram of a waveguide type optical gate switch according to an embodiment of the present invention, FIG. 1 (a) is a schematic plan view, and FIG. 1 (b) is a diagram of FIG. It is sectional drawing along the dashed-dotted line which connects AA 'in FIG.

  As shown in FIG. 1, an optical waveguide is formed by providing a striped core layer 3 between a lower cladding layer 2 and an upper cladding layer 4 provided on a substrate 1, and a part of the core layer 3 undergoes phase change. It replaces with the material part 5 and comprises an optical gate part. The phase change material portion 5 is provided with phase change means 6.

  By changing the complex refractive index of the phase change material portion 5 by the phase change means 6, the phase of the phase change material portion 5 is changed. At this time, the extinction ratio of the optical signal propagating through the core layer 3 due to the change of the light absorption coefficient mainly due to the change of the complex refractive index mainly due to the change of the imaginary part is not high speed. To control.

  In this case, the core layer 3 constituting the optical waveguide includes a semiconductor optical integrated circuit device including a semiconductor laser such as Si, SiN, SiON, SiGe, InP, GaAs, InGaAsP, InAlAs, InGaAs, GaN, and GaNAs, and a dielectric waveguide. It is desirable to use materials that have been proven in waveguides. In selecting the material, it is necessary to select a material having a low absorption rate in the wavelength band of the optical signal. For example, Si or InGaAsP is desirable in the 1.3 μm to 1.55 μm band.

  Further, as the substrate structure constituting the optical waveguide, it is desirable to use an SOI (Semiconductor on Insulator) substrate formed by a substrate bonding technique or a lateral seeding method in order to constitute the core layer 3 with a single crystal.

Further, the phase change material portion 5 includes tetrahedral materials such as α-Si, α-Ge, α-GaSb, α-GaAs, α-Se, Ge-Sb-Te chalcogenide materials, and Sb-Te chalcogenite materials. A material having a proven record in a phase change optical disk such as a chalcogenide material such as AsSe ₃ or AsS ₃ , a transition metal oxide material such as NiO, HfO ₂ , ZrO ₂ , or ZnO is desirable. In particular, the change in the optical absorption due to the phase change large _Ge 2 _-Sb 2 -Te ₅ or _{Ge 6 -Sb 2 -Te 9 Ge-} Sb-Te chalcogenide based materials and the like are desirable.

  In selecting the material in this case, it is necessary to select a material having a low absorption factor in the wavelength band of the optical signal in the amorphous state, and a material having a refractive index matching the refractive index of the core layer is desirable.

  The phase change means 6 may be a current application means for applying a pulse current to the phase change material section 5 or a heat generating member laminated on the phase change material section 5 directly or via an insulating film. good. In any case, the thermal action by the current from the phase change means 6 or the phase change by heating by the heat generating material is utilized. Note that Au, Cu, Al, W, Mo, Ta, or TiN may be used as an electrode material in the case of passing a current, and W, Mo, Ta, or TiN that are high melting point materials are particularly desirable.

  Regardless of which configuration is used, the amorphous state has a small light absorption coefficient due to melting and rapid cooling due to a rapid rise in temperature, and a crystalline state with a large light absorption coefficient due to relatively slow temperature rise and slow cooling that does not melt. It becomes.

  Further, in order to rapidly switch the phase change by such a thermal reaction, it is necessary to rapidly discharge the temperature in the phase change material portion 5, so heat is dissipated so as to cover the phase change material portion 5 in a projected manner. It is desirable to provide a body. Au or Al may be used as the heat radiating body, but it is desirable to use Al which has a proven record in heat sinks and is inexpensive.

  Further, the core layer 3 may be formed in a tapered waveguide shape in the vicinity of the phase change material portion 5, and the phase change material portion 5 can reduce the radiation loss in the transmission state.

In addition, as a material of the cladding layer, in particular, the upper cladding layer that also serves as the buried layer, a material that prevents diffusion (migration) of the material constituting the phase change material portion 5 is desirable. For example, in the case of a Ge-Sb-Te-based material may _SiO 2 -ZnS addition of ZnS to SiO _2. In order to ensure the extinction of the optical gate switch, the optical gate switch may be connected in multiple stages along the optical axis of the optical waveguide to form a multistage waveguide structure.

Figure 2 is an explanatory view of a phase change material portion length d dependence of the extinction ratio, _where, using a Ge ₂ -Sb 2 -Te ₅ as a phase change material, width 1.00 .mu.m, a height of 0.33μm The results of simulating the transmittance and extinction ratio when the phase change material portion 5 having a cross section and transmitting an optical signal having a wavelength of 1.55 μm are shown. Note that the complex refractive index in the crystalline state of Ge ₂ —Sb ₂ —Te ₅ is 5.1 + 0.5i, and the complex refractive index in the amorphous state is 3.6 + 0.01i.

  As shown in the figure, the transmittance [dB] decreases as the phase change material portion length d increases. On the other hand, the extinction ratio [dB] decreases as the phase change material part length d increases until d = 1.0 μm, and becomes saturated when exceeding 1.0 μm. However, although the reason for the saturation state is unknown, it is considered to be due to the simulation setting conditions. In any case, it can be seen that by setting d = 1.0 μm or more, the extinction ratio can be made −30 dB or less.

  Based on the above, the waveguide type optical gate switch according to the first embodiment of the present invention will be described next with reference to FIGS. FIG. 3 is a schematic cross-sectional view of the waveguide type optical gate switch according to the first embodiment of the present invention, and FIG. 4A is a schematic plan view along the alternate long and short dash line connecting AA ′ in FIG. FIG. 4B is a schematic cross-sectional view taken along the alternate long and short dash line connecting BB ′ in FIG. 3.

As shown in the figure, a single crystal silicon core is formed between a SiO ₂ lower cladding layer 12 having a thickness of 150 to 200 nm and a SiO ₂ upper cladding layer 23 having a thickness of 150 to 200 nm on a polycrystalline silicon substrate 11. the layers 14 and 15 is provided, between the single-crystal silicon core layer 14 monocrystalline silicon core layer _14, providing a Ge ₂ -Sb 2 -Te of _five phase change material portion 18.

  In this case, the cross sections of the single crystal silicon core layers 14 and 15 have a width of 350 to 400 nm and a height of about 220 nm. In addition, the phase change material portion 18 has a thickness of about 220 nm, a width of 700 to 1000 nm, and a length d of 1.0 μm to 1.5 μm. Further, the interval between the single crystal silicon core layers 14 and 15 and the phase change material portion 18 is set to about 50 nm, and the constituent elements of the phase change material portion 18 are prevented from directly migrating to the single crystal silicon core layers 14 and 15. To do.

4B, the phase change material portion 18 is provided with a pair of TiN electrodes 21 and 22, and the phase change material portion 18 and the single crystal silicon core are covered so as to cover the TiN electrodes 21 and 22. A SiO ₂ upper clad layer 23 that also serves as a buried layer and an upper clad layer filling the gap between the layers 14 and 15 is formed. Further, the SiO ₂ upper cladding layer 23 is provided with electrode lead portions 24 and 25 for exposing a part of the TiN electrodes 21 and 22, and a pulse current is passed through the TiN electrodes 21 and 22 from the phase change material portion 18. To be applied.

Further, an Al radiator 28 having a thickness of, for example, about 200 nm to 300 nm is provided on the SiO ₂ upper cladding layer 23 so as to cover the phase change material portion 18, and heat generation in the phase change material portion 18 is generated. The heat is rapidly dissipated by the Al radiator 28.

  For example, in order to make the phase change material portion 18 in an amorphous state and in a light transmission state, depending on the size of the phase change material portion 18, for example, a pulse voltage of a short voltage of about 10 nanoseconds is applied to generate a current. The phase change material portion 18 is rapidly heated and melted with an energy of several mW, and then rapidly cooled to an amorphous state.

  On the other hand, when the phase change material portion 18 is in a single crystal state, a voltage having a small amplitude is applied for about 100 nanoseconds when the phase change material portion 18 is in an amorphous state, and the temperature is relatively slow so as not to melt the phase change material portion 18. After raising the temperature, it should be gradually cooled.

  Next, with reference to FIGS. 5 to 9, a manufacturing process of the waveguide type optical gate switch according to the first embodiment of the present invention will be described. In addition, the upper figure in each figure is a schematic plan view, and the lower figure is a schematic cross-sectional view along an alternate long and short dash line connecting AA 'and BB' in the upper figure.

First, as shown in FIG. 5A, a SiO ₂ film having a thickness of, for example, 200 nm and a single crystal having a thickness of, for example, 220 nm are formed on the single crystal silicon substrate 11 to form the SiO ₂ lower cladding layer 12. An SOI substrate in which silicon layers 13 are sequentially stacked is prepared.

  Next, as shown in FIG. 5B, the single crystal silicon layer 13 is etched in a stripe shape so as to have a width of, for example, 400 nm, and a gap for forming a phase change material portion is formed. A pair of single crystal silicon core layers 14 and 15 are formed.

Then, as shown in FIG. 6, after forming the resist pattern 16 was opening a gap for forming a phase change material portion, for example, a sputtering _method, Ge ₂ -Sb ₂ -Te ₅ Composition of GST film 17 For example to a thickness of 220 nm. Next, the phase change material portion 18 is formed by removing the GST film 17 on the resist pattern 16 together with the resist pattern 16 by lift-off.

  Next, as shown in FIG. 7, after forming a resist pattern 19 having an electrode pattern whose one end is applied to the phase change material portion 18 as an opening, a TiN film 20 having a thickness of, for example, 200 nm is deposited by sputtering. . Next, a pair of TiN electrodes 21 and 22 are formed by removing the TiN film 20 on the resist pattern 19 together with the resist pattern 19 by lift-off.

Next, as shown in FIG. 8, after depositing a SiO ₂ film on the entire surface, the single crystal silicon core layers 14 and 15 are flattened by CMP (Chemical Mechanical Polishing) so as to have a thickness of, for example, 200 nm. Turn into. Next, electrode lead portions 24 and 25 for the TiN electrodes 21 and 22 are formed by etching.

  Next, as shown in FIG. 9, a resist pattern 26 having an opening of, for example, 50 μm × 100 μm is formed so as to cover the phase change material portion 18, and an Al film 27 having a thickness of, for example, 300 nm is deposited by sputtering. Let

  Finally, together with the resist pattern 26, the Al film 27 on the resist pattern 26 is removed by lift-off to form an Al radiator 28, whereby the basic structure of the waveguide type optical gate switch shown in FIGS. Complete.

  As described above, in the first embodiment of the present invention, since the change of the light absorption coefficient due to the change of the imaginary part mainly in the complex refractive index of the phase change material part is utilized, the size of the optical gate switch is set to 1 μm to several It can be made ultra-small with a size of μm.

  Further, since it is a gate type optical switch, the coupling length is not a problem as in the case of a directional coupling type optical switch, so that it is possible to construct an optical switch with high tolerance for manufacturing errors and high reliability. .

  In addition, since the phase does not change unless energy is applied to the phase change material portion, it has a memory property, and power is consumed only at the time of switching, so that the power can be reduced. Therefore, it is not necessary to provide a Peltier effect element or the like for temperature control.

  Next, a waveguide type optical gate switch according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a schematic plan view of the waveguide type optical gate switch according to the second embodiment of the present invention, and FIG. 11A is a schematic cross-sectional view taken along the alternate long and short dash line connecting AA ′ in FIG. FIG. 11B is a schematic cross-sectional view taken along the alternate long and short dash line connecting BB ′ in FIG. 10. In the second embodiment of the present invention, the configuration and the basic manufacturing process are the same as those in the first embodiment except that a heating element for assisting the phase change of the phase change material portion 18 is provided. .

  In the waveguide type optical gate switch of the second embodiment, a heating element 31 made of, for example, a TiN film is provided immediately above the phase change material portion 18 by a lift-off method. Therefore, after first forming W electrodes 29 and 30 using refractory metal W as a pair of electrodes for passing a current to the phase change material portion 18, the phase change material portion 18 and the heating element 31 are formed by using a lift-off method. Are sequentially formed. In the figure, the phase change material portion 18 and the heating element 31 are formed by two lift-off processes. However, the phase change material portion 18 and the heating element 31 may be formed by a single process. Are the same planar shape.

  In this case, since the current flowing through the phase change material portion 18 flows in parallel in the heating element 31, the heating element 31 made of TiN having a resistance value higher than that of W or the like generates heat due to Joule heat, and the phase change material portion. 18 is heated uniformly to assist the phase change.

  Next, a waveguide type optical gate switch according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a schematic plan view of a waveguide type optical gate switch according to a third embodiment of the present invention, and FIG. 13A is a schematic cross-sectional view along the alternate long and short dash line connecting AA ′ in FIG. FIG. 13B is a schematic cross-sectional view along the alternate long and short dash line connecting BB ′ in FIG. In the third embodiment of the present invention, the configuration and the basic manufacturing process are the same as those in the first embodiment except that only the heating element 31 is used as the phase change means.

In the waveguide type optical gate switch of the third embodiment, a TiN film is formed on the phase change material portion 18 by a lift-off method through an auxiliary cladding layer 32 made of SiO ₂ which also serves as a buried layer and an insulating layer. A radiator 31 is formed, and a pair of W electrodes 29 and 30 for the radiator 31 are provided.

  In this case, Joule heat is generated by flowing current from the W electrodes 29 and 30 to the heating element 31, and the phase change material portion 18 is uniformly heated by the heat to cause a phase change. Since the heater member such as the TiN film has less change in electric resistance than the phase change material, switching control is facilitated.

  Next, a waveguide type optical gate switch according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a schematic plan view of a waveguide type optical gate switch according to Example 4 of the present invention. In the fourth embodiment of the present invention, the configuration and basic manufacturing process are the same as those in the first embodiment except that the single crystal silicon core layers 14 and 15 are tapered in the vicinity of the phase change material portion 18. Only the figure is shown.

  In the fourth embodiment, in the step of forming the single crystal silicon core layers 14 and 15 shown in FIG. 5B described above, the side facing the phase change material portion 18 is the tapered waveguide portions 33 and 34. is there. In this case, the taper angles of the tapered waveguides 33 and 34 are, for example, about 1 ° to 2 °, and the widths of the end portions of the tapered waveguide portions 33 and 34 facing the phase change material portion 18 are set to the single crystal silicon core layers 14 and 14. The core width is 15 to 2 times to 3 times. Therefore, the lengths of the tapered waveguide portions 33 and 34 are about 10 μm although they depend on the taper angle and the like.

  As described above, in the fourth embodiment of the present invention, since the vicinity of the phase change material portion 18 is the tapered waveguide portions 33 and 34, the phase change material portion 18 can reduce the radiation loss of light in the transmission state. it can.

  Next, a waveguide type optical gate switch according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 15 is a schematic plan view of a waveguide type optical gate switch according to the fifth embodiment of the present invention. The waveguide type optical gates 40 to 42 shown in the first to fourth embodiments are replaced with the core layer 43. It is arranged in multiple stages along the optical axis direction. In addition, the pitch which arrange | positions each waveguide type optical gate 40-42 is 100 micrometers, for example.

  In the fifth embodiment, since the waveguide type optical gates 40 to 42 are multistaged, even if the extinction ratio in one waveguide type optical gate 40 to 42 is insufficient, the extinction ratio can be increased by using multiple stages. Therefore, a highly reliable waveguide type optical gate switch can be realized.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the conditions and configurations shown in the embodiments. For example, the tapered waveguide shown in the fourth embodiment is also applied to the second or third embodiment.

Further, when the heating element is provided as in the second or third embodiment, the vertical positional relationship with the phase change material portion may be reversed. However, it is necessary to devise a manufacturing process such as forming a recess in the SiO ₂ lower cladding layer so that the optical axis of the phase change material portion and the optical axis of the single crystal silicon core layers 14 and 15 coincide.

  In the fourth embodiment, the tapered waveguide portion and the phase change material portion are directly coupled. However, as shown in the first embodiment, a gap may be provided therebetween. Conversely, also in the first to third embodiments, as in the fourth embodiment, the single crystal silicon core layer and the phase change material portion may be directly coupled.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower clad layer 3 Core layer 4 Upper clad layer 5 Phase change material part 6 Phase change means 11 Silicon substrate 12 SiO ₂ Lower clad layer 13 Single crystal silicon layers 14 and 15 Single crystal silicon core layers 16, 19 and 26 Resist Pattern 17 GST film 18 Phase change material part 20 TiN film 21, 22 TiN electrode 23 SiO ₂ upper cladding layer 24, 25 Electrode extraction part 27 Al film 28 Al heat radiator 29, 30 W electrode 31 Heating element 32 Auxiliary cladding layer 40 ~ 42 waveguide type optical gate 43 core layer 44 upper clad layer

Claims (7)

A waveguide-type optical gate switch that changes a light transmission amount by changing a complex refractive index of a part of an optical waveguide,
The optical waveguide includes a pair of core layers facing each other in the optical axis direction, a phase change material portion disposed between the pair of core layers, and a clad layer covering the pair of core layers and the phase change material portion And having
The phase change material section is a waveguide type optical gate switch having phase change means for changing the phase of the phase change material section.   2. The phase change means includes at least one of current application means for applying a pulse current to the phase change material portion, or a heat generating member laminated directly or via an insulating film on the phase change material portion. A waveguide type optical gate switch described in 1.   The waveguide-type optical gate switch according to claim 2, further comprising a thermal diffusion film that projects the phase change material portion.   4. The pair of core layers according to claim 1, wherein the pair of core layers has a tapered portion in which a width of the core layer increases as the phase change material portion approaches the phase change material portion. Waveguide type optical gate switch. The phase change material portion includes amorphous silicon, amorphous germanium, amorphous gallium antimony, amorphous gallium arsenide, tetrahedral material, Ge—Sb—Te chalcogenide material, Sb—Te chalcogenite material, arsenic glass chalcogenide material, NiO, The waveguide-type optical gate switch according to any one of claims 1 to 4, wherein the waveguide-type optical gate switch is made of any one of HfO ₂ , ZrO ₂ , and ZnO.   The core layer is made of silicon, silicon nitride, silicon nitride oxide, silicon germanium, indium phosphide, gallium arsenide, indium gallium arsenide phosphorus, indium aluminum arsenide, indium gallium arsenide, gallium nitride, or gallium arsenide nitride. The waveguide type optical gate switch according to claim 1.   A multistage waveguide type optical gate switch in which the waveguide type optical gate switch according to any one of claims 1 to 6 is connected in multiple stages along the optical axis of the optical waveguide.

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