JP4634102B2 - Light control element - Google Patents

Description

  The present invention relates to a light control element that controls light by applying an electric field to an optical waveguide formed with a photonic crystal structure.

  A photonic crystal that is artificially formed in a dielectric with a periodic structure with a refractive index that is different one-dimensionally, two-dimensionally, or three-dimensionally at the wavelength of light is a band structure for photons that is similar to the band structure for electrons in semiconductor devices. Some periodic structures have a light forbidden body called photonic band gap. Photonic crystals have the effect of controlling light, such as a powerful light confinement effect and anomalous dispersion effect, so that they can realize various functions that are impossible with other optical functional elements. It is expected to be able to form important optical devices such as photonic ICs with dramatically reduced thickness.

  Three-dimensional photonic crystals, which have a large effect of controlling light, are difficult to manufacture, while two-dimensional photonic crystals are easily produced using microfabrication technologies such as lithography and etching, which are semiconductor chip process technologies. Can be formed. In a two-dimensional photonic crystal, for example, by forming a line-defect optical waveguide from which a part of the array is removed, light can be confined and propagated locally and a sharp bend can be realized. In addition, since the propagation speed of light of a certain wavelength propagating through a line defect waveguide is extremely slow, a large light interaction can be obtained at a short distance. Therefore, an optical control element such as an optical switch that modulates and controls light is provided. Can be miniaturized.

  In order for the photonic crystal to function as a light control element, the refractive index is controlled by forming a photonic crystal of an electro-optic material and applying a voltage.

  In Patent Document 1, an electrode is stacked on a planar substrate having a two-dimensional photonic crystal array and exhibiting an electro-optic effect along a path for guiding light, and a voltage is applied between the electrode and the counter electrode. An optical device has been proposed in which an optical waveguide is formed by changing the refractive index of a substrate immediately below the stacking direction of the electrodes by applying a voltage. In the optical device of Patent Document 1, light that has oozed from the optical waveguide to the electrode is easily absorbed by the electrode, and thus the light propagation loss is large.

  In Patent Document 2, an electrode is stacked along a line defect waveguide on a planar substrate having a line defect waveguide in a two-dimensional photonic crystal array, and a voltage is applied between the electrode facing the electrode. There has been proposed an optical switch that changes the refractive index of a line defect waveguide immediately below the stacking direction of the electrodes. In the optical device of Patent Document 1, light that has oozed from the line defect waveguide to the electrode is easily absorbed by the electrode, so that the light propagation loss is large.

JP 2002-131715 A JP 2002-303836 A

  An object of the present invention is to provide a light control element capable of confining light in an optical waveguide configured with a photonic crystal array with high efficiency and controlling light propagating through the optical waveguide.

The light control element of the present invention includes a propagation layer and an electrode pair. The propagation layer is formed of a material having an electro-optic effect, and includes a forbidden band region and an optical waveguide. The forbidden band region has two-dimensional periodic photonic crystal structures with different refractive indexes and prohibits two-dimensional propagation of light of a specific wavelength, and the optical waveguide linearizes the periodicity of the photonic crystal structure. The light of the wavelength prohibited to propagate in the forbidden band region is propagated. The electrode pair is embedded in a part of the propagation layer and is sandwiched from both sides without overlapping the optical waveguide in the direction orthogonal to the two-dimensional arrangement of the photonic crystal structure, and is identical to the photonic crystal structure in the forbidden band region These structures are integrally formed, and a light is controlled by applying a voltage to the electrode pair, generating an electric field in the optical waveguide, and changing the dielectric constant of the propagation layer .

Moreover , it is good to provide the voltage source which applies a voltage to an electrode pair.

According to the light control element of the first aspect, it is possible to control light while guiding light with high efficiency by preventing light absorption by the electrode when an electric field is generated in the optical waveguide.

According to the light control device according to claim 2, capable of controlling the light while guiding light with high efficiency by preventing absorption of light by the electrode when an electric field is generated in the optical waveguide.

  As shown in the plan view of FIG. 1A and the A1-A2 cross-sectional view of FIG. 1B, the light control element 1 of the first embodiment has a propagation layer 10, a first reflection layer 11, and a second reflection. The layer 12, the first electrode 13, the second electrode 14, the third electrode 15, the fourth electrode 16, and the silicon substrate 17 are provided, and the first reflective layer 11 and the second reflective layer 12 are provided so as to sandwich the propagation layer 10 from both sides. The first electrode 13 and the second electrode 14 are provided on the surface of the first reflective layer 11 opposite to the propagation layer 10, and the third electrode is provided on the surface of the second reflective layer 12 opposite to the propagation layer 10. An electrode 15 and a fourth electrode 16 are provided.

The propagation layer 10 is formed of a material having an electro-optic effect such as a Pockels effect or a Kerr effect that changes a refractive index depending on an applied electric field, for example, lithium niobate (LiNbO ₃ ), as shown in FIG. As shown in the plan view and the B1-B2 sectional view of FIG. 2B, it has a photonic crystal structure having a forbidden band region 100 and an optical waveguide 101.

  In the forbidden band region 100, the same cylindrical holes 102 are regularly arranged two-dimensionally with a period of about the wavelength of light, and each hole 102 has a straight line group 103 in parallel and equally spaced, and the straight line group 103 having the same interval. It is formed in a triangular arrangement with the intersection with the straight line group 104 rotated 60 degrees as it is. In the forbidden band region 100, a portion where lithium niobate is present and a region where the hole 102 is formed and the lithium niobate is not present are periodically arranged, so that the light propagating in the plane of the propagation layer 10 Propagation of light of a specific wavelength is prohibited. The forbidden band region 100 may be formed in an array such as a square array or a honeycomb array in addition to a triangular array. In addition to being filled with air, hole 102 may be filled with another substance having a refractive index different from that of lithium niobate, and any refractive index of lithium niobate and the substance in hole 102 may be large.

  The optical waveguide 101 is formed as a line defect structure by disturbing the two-dimensional regularity of the holes 102 in the forbidden band region 100 and not forming the holes 102 linearly. Since the regularity of the holes 102 is disturbed in the optical waveguide 101, it is possible to guide light having a wavelength prohibited to propagate in the forbidden band region 100, and the light incident on the optical waveguide 101 is two-dimensionally transmitted. It is confined in the optical waveguide 101. As long as light propagates, the line defect structure of the optical waveguide 101 may not form the holes 102 continuously in a linear manner, but may not form the holes 102 by jumping.

  The first reflective layer 11 and the second reflective layer 12 are formed so as to cover at least both sides in the stacking direction of the optical waveguide 101 with a material having a refractive index lower than that of lithium niobate forming the propagation layer 10, for example, silicon dioxide. Light incident on the waveguide 101 cannot propagate in the stacking direction. That is, light incident on the optical waveguide 101 parallel to the propagation layer 10 is confined in the optical waveguide 101 by the photonic crystal arrangement in the plane of the propagation layer 10, and the first reflective layer 11 and the second reflection layer 11 in the stacking direction. By being confined in the optical waveguide 101 by the reflective layer 12, it is confined in the optical waveguide 101 three-dimensionally and travels along the optical waveguide 101. For ease of manufacture, etc., holes 102 are formed in the first reflective layer 11 and the second reflective layer 12 as shown in the plan view of FIG. 3A and the C1-C2 cross-sectional view of FIG. It may be penetrated.

  The first electrode 13, the second electrode 14, the third electrode 15, and the fourth electrode 16 overlap only the forbidden band region 100 in the stacking direction orthogonal to the two-dimensional arrangement of the photonic crystal structure, and overlap the optical waveguide 101. It is formed along the optical waveguide 101 so as not to become. The distance between the first electrode 13 and the second electrode 14 and the distance between the third electrode 15 and the fourth electrode 16 are equal to the width of the optical waveguide 101. The first electrode 13 and the third electrode 15 constitute a pair of electrodes and are formed in the same shape so as to face each other in the stacking direction, and the second electrode 14 and the fourth electrode 16 are another pair of electrodes. The pair is formed in the same shape so as to face each other in the stacking direction. For ease of manufacture, etc., the first electrode 13, the second electrode 14, the third electrode 15 and the first electrode 13, as shown in the plan view of FIG. 4A and the D1-D2 cross-sectional view of FIG. The hole 102 may be passed through the fourth electrode 16.

  The light control element 1 having the same photonic crystal structure formed on the propagation layer 10, the first reflection layer 11, the second reflection layer 12, the first electrode 13, the second electrode 14, the third electrode 15, and the fourth electrode 16. The production method will be described. First, a positive resist is applied to the base silicon substrate 17, the silicon substrate 17 is etched to the shape of the third electrode 15 and the fourth electrode 16 by lithography, and the electrode material is deposited with a thickness of 200 nm on the whole to lift off. The third electrode 15 and the fourth electrode 16 are formed by removing the gold on the resist not etched by the method. A lead line is also formed at the same time so that a voltage can be applied to the third electrode 15 and the fourth electrode 16. Next, 2 μm of silicon dioxide is formed by sputtering or CVD so as to cover the silicon substrate 17, the third electrode 15, and the fourth electrode 16, thereby forming the second reflective layer 12. Next, a lithium niobate substrate is joined to the second reflective layer 12, the lithium niobate substrate is polished to a thickness of 0.5 μm, optically polished to suppress the surface roughness to 10 nm or less, and the polished surface is thermally oxidized The propagation layer 10 is formed by depositing 2 μm of silicon. Next, a positive resist is applied to the propagation layer 10, the silicon substrate 17 is etched to the shape of the first electrode 13 and the second electrode 14 by lithography, and gold of electrode material is deposited to a thickness of 200 nm on the whole and lift-off is used. The first electrode 13 and the second electrode 14 are formed by removing the gold on the resist that has not been etched. A lead line is also formed at the same time so that a voltage can be applied to the first electrode 13 and the second electrode 14. Next, nickel is deposited to a thickness of 100 nm so as to cover the second reflective layer 12, the first electrode 13, and the second electrode 14, a positive resist is applied, and a diameter of 280 nm at 400 nm intervals is applied by lithography using electron beam drawing. A metal mask having a photonic crystal structure having a plurality of holes 102 is formed. In addition to lithography using electron beam drawing, a metal mask may be formed by photolithography, laser processing, or the like. Using a metal mask, the second electrode 14 layer, the second reflective layer 12, the propagation layer 10, the first reflective layer 11, and the first electrode 13 layer are stacked in the stacking direction using argon-based dry etching and Freon-based dry etching. Etching forms holes 102 with a photonic crystal structure. Etching may be dry etching using plasma etching, wet etching using chemicals, or the like.

  If the propagation layer 10 is a material having an electro-optic effect such as a Pockels effect or a Kerr effect that changes the refractive index depending on an applied electric field, an inorganic crystal such as titanium niobate and KTP in addition to lithium niobate. Further, ceramics such as PZT and PZLT, organic molecules or organic crystals such as azo dyes, stilbenzene dyes and dusts, and semiconductor crystals having a quantum well structure may be used.

The propagation layer 10 includes ADP (NH ₄ H ₂ PO ₄ ), KDP (KH ₂ PO ₄ ), DKDP (KD ₂ PO ₄ ), RDP (RbH ₂ PO ₄ ), RDA (RbH ₂ AsO ₄ ), LN, LT , KN, KT, BNN, SBN, LI, BBO, LBO, BSO, GaAs, GaP, InP, ZnTe, ZnSe, ZnS, ZnO, CdTe, CdS, CdSe, Te, Se, Ag ₃ AsS ₃ , Ag ₃ SbS ₃ , AgGaS ₂ , AgGaSe ₂ , ZnGeP ₂ , GdGeAs ₂ , Bi ₁₂ SiO ₂₀ , Bi ₁₂ GeO ₂₀ , Bi ₁₂ TiO ₂₀ , KTiOAsO ₄ , KTiOPO ₄ , BaTiO ₃ , SrTiO ₃ , KTaO ₃ , KTa _0.65 Nb _0.35 O ₃ , Cd ₂ Nb ₂ O ₇ , LaBGeO ₅ and PZT, PLZT and other ceramics, Ga, In, Al, As, P, N, Sb, Zn, Se III-V and II-VI group semiconductor mixed crystals You may form with inorganic optical materials, such as a semiconductor quantum well structure.

  The propagation layer 10 is composed of azo dye, stilbenzene dye, dust, polydiacetylene, mNA, MNA, MAP, POM, DAN, DIVA, NPP, COANP, MNBA, MMONS, MBANP, TC-28, DNBB, DMNP, MNA, Organic optics such as MNP, MMNA, PCNB, ECNB, IPMPU, ECPMDA, p-NMDA, MNPMDA, 4NpNa, host-guest materials, polymer side complexes or modified materials with chemically bonded NLO groups to the main complex, and cross-linked materials You may form with a material.

Host polymers for organic optical materials such as LCP, PMMA, POE, Poly (Vp-co-St), PVP, PRO, PCL, PBSSe, PBDG, etc., and DANS, DANS ₃₃ , DR1, DCV, TCV , P-NMDA, p-NA, p-DMNP, CPABMCA, a combination with guest dyes such as MNA can be used.

  For modified materials in which NLO groups are chemically bonded to the polymer side complex or main complex, Poly (St-DR1), Poly (St-DASP), Poly (St-NPP), Poly (MMA-HNS) are used as NLO polymers. , Poly (MMA-co-MMA-DCV), Poly (St-co-MAAB), Poly (St-co-MABA), Poly (St-co-MA-CM), Poly (MMA-co-MMA-DR1 ), Poly (organopho-sphazene-ANS), PPNA, Poly (VA-co-Vat-NA), Poly (VAc-co-Vat-NA), Poly (ST-NA), Poly (MMA-NA), Poly (MMA-co-MMA-2R), Poly (MMS-co-MMA-3R), P6CS / MMA, polyallylamine, pNA-EG, PMMA / MNA, pNA-PVA, Poly (VDCN-co-VAc), MSMA And (Bis-A, NPDA), (Bis-A, ANT), (NNDN, NAN), (DGE + PS ( O), NPP), (PVCN, CNNB-R), etc. can be used, and DCAMP, FA6, PO86, AODA, TMSC, Poly (HEA-co-A-ASB), PtBM, etc. are used as LB film materials Polydiacetylene (PTS, TCDU, DC) HDFMP, BTFP, mBCMU), polyacetylene derivatives, polyphenylacetylene derivatives, polyarylene vinylenes (PPV, PTV, MO-PPV, PFV), polythiophenes, annulenes, phthalocyanines, fullerenes, and the like can be used.

The first reflective layer 11 and the second reflective layer 12 may be formed of a medium having a refractive index smaller than that of the propagation layer 10. The refractive indexes of the first reflective layer 11 and the second reflective layer 12 and the propagation layer 10 The larger the difference from the refractive index, the better. For example, when lithium niobate having a refractive index of about 2.2 is used for the propagation layer 10, the first reflective layer 11 and the second reflective layer 12 include thermally oxidized silicon having a refractive index of about 1.45 and magnesium fluoride (refractive index of about 1.3). MgF ₂ ), a crystal having a refractive index of about 1.5 or the like can be used, and thermally oxidized silicon, magnesium fluoride, and crystal can be formed relatively easily using a sputtering apparatus or the like.

The first reflective layer 11 and the second reflective layer 12 are each formed as a single layer, and if a high reflectance can be ensured, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ , ZnO, Ta ₂ O 5, TiO ₂ , multilayer film or a combination of dielectric material such as _{nb 2 O 2, Si, GaAs} , may be formed of a multilayer film of a combination of a semiconductor such as InP. By configuring the first reflective layer 11 and the second reflective layer 12 with a multilayer film, the difference from the refractive index of the propagation layer 10 can be easily increased. The dielectric multilayer film can be formed into 100 or more layers by, for example, sputtering, electron beam evaporation, or ion plating. The semiconductor multilayer film can be formed by, for example, molecular beam epitaxy (MBE) method or metal organic vapor phase growth. Films with different materials, that is, refractive indexes can be formed by the (MOCVD) method.

  When a voltage is applied to the first electrode 13 and the third electrode 15 constituting one electrode pair, and a voltage is applied to the second electrode 14 and the fourth electrode 16 constituting the other electrode pair, a forbidden band is obtained. An electric field is applied to the region 100 and an electric field spreads in the optical waveguide 101 as indicated by an arrow, and an electric field generated between the first electrode 13 and the third electrode 15, and the second electrode 14 and the fourth electrode. And the electric field generated between the optical waveguide 101 and the optical waveguide 101 are in the same direction.

  When the electric field is applied and the dielectric constants of the forbidden band region 100 and the optical waveguide 101 change, the wavelength of light that is prohibited to propagate in the forbidden band region 100 and allowed to propagate in the optical waveguide 101 changes, and the optical waveguide 101 Since the intensity, phase, polarization direction, etc. of propagating light can be modulated, optical control such as an optical switch for switching the wavelength of light propagating through the optical waveguide 101 by applying a voltage or switching between transmission and blocking of light It can function as an element.

  According to this light control element 1, since each electrode pair does not overlap the optical waveguide in the direction orthogonal to the two-dimensional arrangement of the photonic crystal structure, the light oozing out from the optical waveguide to the reflection layer is absorbed by the electrode. Therefore, the light can be modulated while propagating light with high efficiency, and the distance between the opposing electrode pairs can be reduced.

  As shown in the plan view of FIG. 5A and the E1-E2 cross-sectional view of FIG. 5B, the light control element 2 of the second embodiment is the same as the light control element 1 of the first embodiment. The first electrode 13 and the second electrode 14 having a configuration in which the three electrodes 15 and the fourth electrode 16 are not provided and are disposed across the optical waveguide 101 on one surface side of the propagation layer 10. Since the electric field generated by the voltage applied between them also extends to the optical waveguide 101 as indicated by the arrow, the electric field parallel to the two-dimensional arrangement of the photonic crystal structure and crossing the optical waveguide 101 To be applied. Since the distance between the first electrode 13 and the second electrode 14 is about the same as the width of the optical waveguide 101, that is, about the wavelength of light, a large electric field can be obtained with a small applied voltage. Note that the interval between the first electrode 13 and the second electrode 14 is about 1 to 10 μm depending on the thickness of the first reflective layer 11 and the second reflective layer 12 so that the voltage applied to the optical waveguide 101 is uniform. It is desirable to optimize with. Further, the third electrode 15 and the fourth electrode 16 in the first embodiment are used as another pair of electrodes, and an electric field that is parallel to the two-dimensional arrangement of the photonic crystal structure and crosses the optical waveguide 101 is guided. You may make it apply to the waveguide 101. FIG.

  When the electric field is applied and the dielectric constants of the forbidden band region 100 and the optical waveguide 101 change, the wavelength of light that is prohibited to propagate in the forbidden band region 100 and allowed to propagate in the optical waveguide 101 changes, and the optical waveguide 101 Since the intensity, phase, polarization direction, etc. of propagating light can be modulated, optical control such as an optical switch for switching the wavelength of light propagating through the optical waveguide 101 by applying a voltage or switching between transmission and blocking of light It can function as an element.

  According to this light control element 2, since each electrode pair does not overlap the optical waveguide in the direction orthogonal to the two-dimensional arrangement of the photonic crystal structure, the light oozing out from the optical waveguide to the reflection layer is absorbed by the electrode. Therefore, the light can be modulated while propagating light with high efficiency, and the distance between the opposing electrode pairs can be reduced.

  For ease of manufacture, the holes 102 may be passed through the first reflective layer 11 and the second reflective layer 12, and the first electrode 13, the second electrode 14, the third electrode 15 and the fourth electrode The hole 16 may be passed through the electrode 16. The third electrode 15 and the fourth electrode 16 are provided, and the same direction as the electric field generated by the first electrode 11 and the second electrode 12 due to the voltage applied between the third electrode 15 and the fourth electrode 16 is provided. This electric field may be generated in the optical waveguide 101.

  As shown in the plan view of FIG. 6A and the F1-F2 cross-sectional view of FIG. 6B, the light control element 3 of the third embodiment is provided in the light control element 2 of the second embodiment. Instead of the first electrode 13 and the second electrode 14, a first electrode 33 and a second electrode 34 having a photonic crystal structure and constituting a pair of electrodes are provided. The photonic crystal structure of the first electrode 33 and the second electrode 34 has a configuration in which the holes 302 are regularly arranged in the same manner as the forbidden band region 100 of the propagation layer 10. The period and diameter of the hole 302 are determined so as to prohibit the propagation of the wavelength of the electromagnetic wave generated by the voltage applied between the first electrode 33 and the second electrode 34. The first electrode 33 and the second electrode 34 are arranged with an interval at which electromagnetic waves generated by a voltage applied between the first electrode 33 and the second electrode 34 can resonate. The electromagnetic wave generated between the first electrode 33 and the second electrode 34 is amplified by confining the electromagnetic wave in a region overlapping the optical waveguide 100 in the stacking direction orthogonal to the two-dimensional arrangement of the photonic crystal structure. Generate a wave.

  According to the light control element 3, in addition to the effects of the light control element 2, light propagating through the optical waveguide can be efficiently modulated and high-speed modulation can be performed. In the first embodiment, a photonic crystal structure is formed on the first electrode 13 and the third electrode 15 constituting one pair of electrodes, and the first electrode 13 The third electrode 15 is disposed, a photonic crystal structure is formed on the second electrode 14 and the fourth electrode 16 constituting another electrode pair, and the second electrode 14 The fourth electrode 16 may be disposed, and a standing wave amplified by confining electromagnetic waves in the propagation layer 10 may be generated.

  As shown in the plan view of FIG. 7A and the G1-G2 cross-sectional view of FIG. 7B, the light control element 4 of the fourth embodiment includes the propagation layer 40, the first reflection layer 11, and the second reflection. The layer 12, the first electrode 43, the second electrode 44, and the silicon substrate 17 are provided. Similar to the light control element 1 of the first embodiment, the first reflective layer 11 and the second reflective layer 11 are sandwiched between both surfaces of the propagation layer 40. 2 reflective layers 12 are provided, and the second reflective layer 12 side is laminated on the silicon substrate 17. The propagation layer 40 has a configuration similar to that of the propagation layer 10 of the first embodiment, and has a configuration in which the first electrode 43 and the second electrode 44 are partially embedded.

  The first electrode 43 and the second electrode 44 constitute a pair of electrodes and are arranged with the optical waveguide 401 sandwiched from both sides in the plane of the forbidden band region 400 in which a two-dimensional array of photonic crystal structures is formed. Has been. The first electrode 43 and the second electrode 44 are integrally formed with the same structure as the photonic crystal structure of the forbidden band region 400. By forming a photonic crystal array on the first electrode 43 and the second electrode 44, light propagating through the optical waveguide 401 can be confined with high efficiency. In order to increase the efficiency of light confinement by the photonic crystal structure, it is preferable that the refractive indexes of the first electrode 43 and the second electrode 44 be the same as the refractive index of the propagation layer 40. By making the refractive indexes of the first electrode 43 and the second electrode 44 the same as the refractive index of the propagation layer 40, the distance between the first electrode 43 and the second electrode 44 can be reduced.

  When the electric field is applied and the dielectric constants of the forbidden band region 400 and the optical waveguide 401 change, the wavelength of light that is prohibited to propagate in the forbidden band region 400 and allowed to propagate in the optical waveguide 401 changes, and the optical waveguide 401 Since the intensity, phase, polarization direction, etc. of propagating light can be modulated, optical control such as an optical switch that switches the wavelength of light propagating through the optical waveguide 401 by applying a voltage, or switches between transmission and blocking of light It can function as an element.

  According to this light control element 4, since each electrode pair does not overlap the optical waveguide in the direction orthogonal to the two-dimensional arrangement of the photonic crystal structure, the light oozing out from the optical waveguide to the reflection layer is absorbed by the electrode. It can be modulated while propagating light with high efficiency, and the distance between the opposing electrode pairs can be reduced. Furthermore, by providing electrodes in the same plane as the optical waveguide, a uniform electric field parallel to the propagation layer can be transmitted. Can be applied to the waveguide.

  For ease of manufacture, the first electrode 43 and the second electrode 44 may penetrate part or all of the first reflective layer 11 and the second reflective layer 12. 11 and the second reflective layer 12 may penetrate the hole 102. Similarly to the third embodiment, a photonic crystal structure is formed on the first electrode 43 and the second electrode 44 constituting a pair of electrodes, and the first electrode is provided with an interval at which the generated electromagnetic wave can resonate. 43 and the second electrode 44 may be arranged, and a standing wave amplified by confining electromagnetic waves in the propagation layer 40 may be generated.

It is the top view and sectional drawing of the light control element of 1st Embodiment. It is the top view and sectional drawing of a propagation layer. It is the top view and sectional drawing of another light control element. It is the top view and sectional drawing of another light control element. It is the top view and sectional drawing of the light control element of 2nd Embodiment. It is the top view and sectional drawing of the light control element of 3rd Embodiment. It is the top view and sectional drawing of the light control element of 4th Embodiment.

Explanation of symbols

1; light control element, 2; light control element, 3; light control element, 4; light control element, 10; propagation layer,
11; First reflective layer, 12; Second reflective layer, 13; First electrode, 14; Second electrode,
15; third electrode, 16; fourth electrode, 17; silicon substrate, 33; first electrode,
34; second electrode, 40; propagation layer, 43; first electrode, 44; second electrode,
100; forbidden band region, 101; optical waveguide, 102; hole, 103;
104; straight line group; 302; hole; 400; forbidden band region; 401;

Claims (2)

A propagation layer and an electrode pair;
The propagation layer is made of a material having an electro-optic effect, and includes a forbidden band region and an optical waveguide, and the forbidden band region has a photonic crystal structure having a different refractive index periodically in two dimensions. Prohibiting two-dimensional propagation of light of the wavelength of the light, the optical waveguide perturbs the periodicity of the photonic crystal structure linearly, and propagates light of the wavelength prohibited to propagate in the forbidden band region ,
The electrode pair is embedded in a part of the propagation layer, and sandwiched from both sides without overlapping the optical waveguide in a direction perpendicular to the two-dimensional arrangement of the photonic crystal structure, and the photo of the forbidden band region The same structure as the nick crystal structure is formed integrally,
A light control element that performs light control by applying a voltage to the electrode pair, generating an electric field in the optical waveguide, and changing a dielectric constant of the propagation layer . Light control element according to claim 1, further comprising a voltage source for applying a voltage before Symbol electrode pair.

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