JP2007240756A - Optical element and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which uses a photonic crystal and can be made compact, and a manufacturing method thereof. <P>SOLUTION: A clad 12 made of SiO<SB>2</SB>is provided on a Si substrate, and a linear core 11 is provided on the clad 12 to constitute a thin-line-shaped waveguide 14. A pair of pedestals 2 are stood on both sides of the clad 12 on the Si substrate by bonding at a normal temperature. A two-dimensional photonic crystal 3 has a periodical structure where holes 95 are formed like a triangular lattice and a defect waveguide part 95 is formed in a middle part of the triangular lattice. The two-dimensional photonic crystal 3 is so disposed that a space is formed between the photonic crystal 3 and an upper face of the core 11, and that the defect waveguide part 96 and the core 11 are parallel one over the other, and are bonded to upper faces of the pedestals 2 at a normal temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical element using photonic crystals and a method for manufacturing the same.

  A photonic crystal having a periodic refractive index distribution inside may have the function of a conventional optical device having a size of 1/100 to 1/1000. Realization of an ultra-compact optical integrated circuit in which a waver, an optical filter, a laser, an optical waveguide, a coupler and the like are integrated into one is expected. Application to electromagnetic waves other than light is also expected.

  There are three types of photonic crystals: a one-dimensional photonic crystal having a multilayer structure, a two-dimensional photonic crystal having a two-dimensional refractive index distribution, and a three-dimensional three-dimensional photonic crystal.

  The two-dimensional photonic crystal has an advantage that it is relatively easy to manufacture. Two-dimensional photonic crystals typically include two-dimensional photonic crystals that are asymmetrical on the top and bottom, such as those fabricated on SOI (Silicon On Insulator) substrates, and those that are fabricated by under-etching, etc. There are two-dimensional photonic crystals with an air bridge structure that is symmetrical in contact with the top and bottom.

As for conventional two-dimensional photonic crystals (optical devices) with an air bridge structure, for example, a tapered optical fiber is brought close to the defect waveguide of the two-dimensional photonic crystal slab in the wavelength order, and the optical power is evanescent. A technique for transferring to a photonic crystal with light and performing optical coupling is known (for example, see Non-Patent Document 1).
Applied Physics: Letters Vol 85, No. 1,5 July 2004

  However, according to the conventional optical element, a means for fixing the optical fiber with a taper to the two-dimensional photonic crystal having an air bridge structure is required, and it is inevitable to increase the size, and there are problems in practical use. Yes.

  Accordingly, an object of the present invention is to provide an optical element capable of reducing the size of an optical element using a photonic crystal and a method for manufacturing the same.

  In order to achieve the above object, one embodiment of the present invention provides the following optical element and method for manufacturing the same.

[1] Light comprising: a two-dimensional photonic crystal having a defect disturbing a periodic structure; and an external waveguide formed on a substrate and disposed opposite to each other with a gap provided in the slab waveguide portion element.

  According to the above configuration, the external waveguide can be formed on the substrate, and the two-dimensional photonic crystal can be disposed opposite to the external waveguide. Photonic crystals include a one-dimensional crystal, a two-dimensional crystal, and a three-dimensional crystal, but can be manufactured relatively easily by using a two-dimensional photonic crystal. In addition, by arranging the two-dimensional photonic crystal so as to face each other with a gap in the external waveguide, it is possible to obtain an air bridge structure in which the upper and lower surfaces are in contact with air, thereby increasing the light confinement effect. In addition, radiation mode to the substrate and mode conversion to orthogonal polarization can be suppressed, and high propagation efficiency can be obtained over a wide band.

  The periodic structure of the two-dimensional photonic crystal can be formed by periodically arranging substances having a low refractive index on a plate material (slab) having a high refractive index with a period of about the wavelength. The defective portion can be formed by changing the refractive index or disturbing the periodic arrangement. The low refractive index portion can be realized by arranging the concave portions in a triangular lattice or a square lattice. The recess may be filled with a low refractive index member, but by making it a hole, manufacturing is easy and a large refractive index difference is obtained. In the case of a two-dimensional photonic crystal slab, a triangular lattice structure is desirable for obtaining a band gap.

[2] The optical element according to [1], wherein light propagates through the external waveguide in a single mode. With this configuration, there is no optical communication failure due to the presence of light with different propagation speeds as in multimode. In addition, because of the single mode, the condition for phase matching with the defect waveguide can be found relatively easily.

[3] The optical element according to [1], wherein the substrate includes a pair of pedestals that support the two-dimensional photonic crystal on both sides of the external waveguide. Since the external waveguide formed on the substrate and the two-dimensional photonic crystal are opposed to each other, the substrate and the two-dimensional photonic crystal can be supported by a small pedestal.

[4] The external waveguide includes a clad formed on the substrate and a core formed on the clad, and the pedestal is erected on the exposed surface of the substrate. The optical device according to [3], which is characterized in that

[5] The external waveguide includes a clad formed on the substrate and a core formed on the clad, and the pedestal is erected on the clad. ] The optical element as described in.

[6] A photonic crystal substrate on which a two-dimensional photonic crystal having a defect portion that disturbs the periodic structure is formed, an external waveguide is formed on the substrate, and a pedestal having a predetermined height is provided on both sides of the external waveguide. A preparation step of preparing an external waveguide substrate provided on the substrate, contacting the photonic crystal substrate and the external waveguide substrate, and providing a gap between the slab waveguide portion and the external waveguide A bonding step of bonding the two-dimensional photonic crystal and the pedestal; and a separation step of separating the photonic crystal substrate and the external waveguide substrate to transfer the two-dimensional photonic crystal to the upper surface of the pedestal; The manufacturing method of the optical element characterized by the above-mentioned.

  According to the above configuration, the external waveguide and the two-dimensional photonic crystal are arranged to face each other via the pedestal provided on the external waveguide substrate, thereby enabling miniaturization. Moreover, it can be manufactured relatively easily by using a two-dimensional photonic crystal. In addition, since the two-dimensional photonic crystal can have an air bridge structure, it is possible to suppress the radiation mode to the substrate and the mode conversion to the orthogonal polarization, and high propagation efficiency can be obtained in a wide band.

[7] In the above [6], the preparation step includes a bonding step of bonding the pedestal provided on the donor substrate to the surface of the external waveguide substrate on both sides of the external waveguide. Manufacturing method of the optical element.

[8] A photonic crystal substrate in which a two-dimensional photonic crystal having a defect portion disturbing the periodic structure is formed and a pedestal having a predetermined height is provided outside the periodic structure portion, and an external surface on the substrate. A preparation step of preparing an external waveguide substrate on which a waveguide is formed, contacting the photonic crystal substrate and the external waveguide substrate, and providing a gap between the defect portion and the external waveguide A bonding step of bonding the pedestal and the external waveguide substrate, and separating the photonic crystal substrate and the external waveguide substrate to transfer the two-dimensional photonic crystal and the pedestal to the external waveguide substrate. A method for manufacturing an optical element, comprising: a separation step.

  According to the above configuration, the external waveguide and the two-dimensional photonic crystal are arranged to face each other via the pedestal provided on the photonic crystal substrate, thereby enabling miniaturization. Moreover, it can be manufactured relatively easily by using a two-dimensional photonic crystal. Further, since the two-dimensional photonic crystal can have an air bridge structure, it is possible to suppress the radiation mode to the substrate and the mode conversion to the orthogonal polarization, and high propagation efficiency can be obtained in a wide band.

[9] In the above [8], the preparation step includes a bonding step of bonding the pedestal provided on the donor substrate to the surface of the photonic crystal substrate outside the periodic structure portion. The manufacturing method of the optical element of description.

[10] The method for manufacturing an optical element according to any one of [6] to [9], wherein the bonding step is performed at room temperature bonding. According to the room temperature bonding, the two-dimensional photonic crystal and the pedestal are not thermally deformed, so that high shape accuracy can be obtained. Room temperature bonding refers to direct bonding of atoms at room temperature. Prior to bonding, it is preferable to clean the surface by irradiating the bonding surface with a neutral atom beam, ion beam or the like. By cleaning, the surface is activated and a strong bond is obtained.

  According to the present invention, an optical element using a photonic crystal can be reduced in size.

[First Embodiment]
(Configuration of optical element)
FIG. 1 shows an optical element according to a first embodiment of the present invention. This optical element 100 is erected on both sides of a Si substrate 1, a thin wire waveguide 14 formed as an external waveguide composed of a core 11 and a cladding 12, and a cladding 12 on the Si substrate 1. A long plate-like base 2 and a two-dimensional photonic crystal 3 fixed on the base 2 are provided.

  The two-dimensional photonic crystal 3 is provided with a strip-like or linear defect waveguide portion 96 arranged opposite to each other with a gap in the core 11 and a plurality of holes 95 adjacent to the defect waveguide portion 96 in a triangular lattice shape. And a periodic structure 97 having a periodic structure. Note that a portion constituting the defect waveguide portion 96 corresponds to a region where the hole 95 is not provided.

(Method for Manufacturing Optical Device According to First Embodiment)
Next, a method for manufacturing the optical element 100 will be described.

(1) Production of Core and Cladding FIGS. 2A and 2B show a production process of the core 11 and the clad 12. First, as shown in FIG. 2A, an SiO ₂ layer 13 is formed on an Si substrate 1 to prepare an SOI (Silicon On Insulator) substrate 5, and a core 11 made of Si fine wire is formed on the surface of the SiO ₂ layer 13. Form.

Next, as shown in FIGS. 2A and 2B, both sides of the SiO ₂ layer 13 are removed using a processing method such as wet etching so that the vicinity of the center of the SiO ₂ layer 13 remains, and a channel waveguide is obtained. The thin wire waveguide 14 is formed. The channel waveguide is a three-dimensional optical waveguide in which light is confined in two directions (x, y) (waveguide cross section) orthogonal to each other. As described above, the target substrate 6 as the external waveguide substrate composed of the Si substrate 1 and the thin wire waveguide 14 is completed.

(2) Production of Pedestal FIGS. 3A to 3D show a production process of the pedestal 2. First, as shown in FIG. 3A, a release layer 72 is formed on a Si substrate 71 by a spin coating method, and a Si layer 73 having a thickness of 450 nm, for example, is formed on the release layer 72. A first wafer 7 including a substrate 71, a release layer 72, and an Si layer 73 is produced.

  The release layer 72 has a role of appropriately maintaining the adhesion between the Si layer 73 and the Si substrate 71. As a material for such a role, polyimide, fluorinated polyimide, silicon oxide, or the like is known. In this case, a general polyimide film is formed on Si by a spin coating method as the release layer 72.

  The Si layer 73 can be deposited by sputtering, molecular beam epitaxy, chemical vapor deposition, vacuum vapor deposition, or the like, but sputtering is preferred in terms of obtaining good flatness.

  Next, as shown in FIG. 3B, the first wafer 7 is divided into a plurality of square cells 74, wet etching or the like is performed on the Si layer 73, and as shown in FIG. A pair of parallel pedestals 2 is formed in each cell 74. In the present embodiment, a pair of pedestals 2 is formed in one cell 74 for the sake of simplicity, but it is desirable in terms of productivity to form a plurality of pedestals in one cell 74. In this way, the donor substrate 8 composed of the Si substrate 71, the release layer 72, and the pair of bases 2 formed in each cell 74 is completed.

(3) Fabrication of two-dimensional photonic crystal FIGS. 4A to 4D show a fabrication process of the two-dimensional photonic crystal 3. First, as shown in FIG. 4A, a release layer 92 is formed on a Si substrate 91 by a spin coating method, and further, a slab (plate material) of a two-dimensional photonic crystal is formed on the release layer 92. A second wafer 9 is prepared by depositing the Si layer 93 to a thickness of 250 nm by, for example, sputtering.

  The release layer 92 has a role of appropriately maintaining the adhesion force between the Si layer 93 and the Si substrate 91, and known materials such as polyimide, fluorinated polyimide, and silicon oxide are used for such a role. In this case, a general polyimide film was formed on Si by a spin coating method as the release layer 92.

  The Si layer 93 can be deposited by sputtering, molecular beam epitaxy, chemical vapor deposition, vacuum evaporation, or the like, but sputtering is preferred.

  Next, as shown in FIG. 4B, the Si layer 93 is divided into a plurality of square cells 94, and each of them is subjected to EB (Electron Beam) exposure, dry etching, etc., as shown in FIG. A plurality of holes 95 are formed in the Si layer 93 of the cell 94, and the two-dimensional photonic crystal 3 including the periodic structure portion 97 including the plurality of holes 95 and the defect waveguide portion 96 is formed.

  In the present embodiment, a single two-dimensional photonic crystal defect waveguide portion 96 is formed in one cell 94 for simplicity, but a plurality of defect waveguide portions 96 are formed in one cell 94. It is desirable to form it from the point of productivity. In this way, the second wafer 9 made of the two-dimensional photonic crystal 3 having the Si substrate 71, the release layer 72, and the periodic structure portion 97 and the defect waveguide portion 96 formed in each cell 94 is completed.

(4) Fabrication of Optical Element FIGS. 5A (a) to (c) and FIGS. 5B (d) to (f) show fabrication steps of the optical element 100. FIG. In FIG. 5B, the first donor substrate 10 is shown in a cross-sectional view. First, the target substrate 6 shown in FIG. 2B, the second donor substrate 8 shown in FIG. 3D, and the first donor substrate 10 shown in FIG. 4D are placed in a vacuum chamber (not shown). Carry in.

  Next, as shown in FIG. 5A, the target substrate 6 is fixed to a lower stage (not shown), the second donor substrate 8 is fixed to an upper stage (not shown), and the second donor substrate 8 is fixed to the target substrate 6. The surfaces of the target substrate 6 and the second donor substrate 8 are cleaned by FAB (Fast Atom Beam) processing. The FAB process is a process in which a neutral atom beam, an ion beam, or the like is accelerated at a high voltage to irradiate a bonding surface to remove an oxide film, impurities, or the like on the bonding surface.

  Next, the target substrate 6 is lifted, and the lower end surface of the base 2 is brought into contact with the upper surface of the Si substrate 1 of the target substrate 6 with an appropriate load for a predetermined time as shown in FIG. Bonded to the upper surface of the Si substrate 1 at room temperature.

  Next, as shown in (c) of FIG. 5A, the target substrate 6 is lowered and separated from the second donor substrate 8. Thereby, the upper end surface of the base 2 is peeled off from the donor substrate 8, and the base 2 is transferred onto the target substrate 6. In this way, the target substrate 4 shown in FIG. 2 is manufactured.

  Next, as shown in (d) of FIG. 5B, the first donor substrate 10 is fixed to the upper stage instead of the second donor substrate 8, and the first donor substrate 10 is positioned above the target substrate 4. . At this time, alignment is performed so that the slab waveguide portion 96 of the two-dimensional photonic crystal 3 and the core 11 coincide with each other when seen from the plane, and the surfaces of the target substrate 4 and the first donor substrate 10 are cleaned by FAB.

  Next, the target substrate 4 is raised, and the lower surface of the two-dimensional photonic crystal 3 is brought into contact with the upper end surface of the pedestal 2 by applying an appropriate load for a predetermined time as shown in FIG. 5B (e). By this contact, the contact portion between the lower surface of the two-dimensional photonic crystal 3 and the upper surface of the base 2 is joined at room temperature.

  Next, as shown in FIG. 5B (f), when the target substrate 4 is lowered, since the lower surface of the two-dimensional photonic crystal 3 and the upper surface of the pedestal 2 are joined, the two-dimensional photonic crystal 3 becomes a donor. It peels from the release layer 92 of the substrate 10 and is transferred to the target substrate 4. Thus, the optical element 100 shown in FIG. 1 is completed.

(Operation of optical element)
FIG. 6 is a longitudinal sectional view for explaining the operation of the optical element 100. When the optical signal 200 of white light (light having a certain band including λc1) enters the core 11 from the left side of FIG. 6, the optical signal 200 propagates in the core 11 in the right direction. Of the white light of the optical signal 200, the waveguide mode of the defect waveguide section 96 of the two-dimensional photonic crystal 3 (which refers to the relationship between the frequency of the guided light and the wave number) and the waveguide mode of the core 11 are in phase. The matched light of wavelength λ1 is optically coupled to the defect waveguide section 96 as evanescent light, and the optical power is transferred from the core 11 to the defect waveguide section 96. At this time, the light coupled to the slab waveguide section 96 in the optical signal 200 propagates in the slab waveguide section 96 in the direction opposite to the direction in which the optical signal 200 is incident, and the slab waveguide section 96 serves as outgoing light 201. Emanates from the left side of the. As described above, the optical element 100 of the present embodiment functions as an optical coupling element.

  In FIG. 6, contrary to the above description, a configuration in which the optical signal 200 is incident on the defect waveguide portion 96 side and the emitted light 201 is emitted from the core 11 side is also possible.

FIG. 7 shows the relationship between the wavelength λ and the light transmittance (the level of the output light at the E portion in FIG. 6 / the level of the input light of the optical signal 200). g is a gap between the defect waveguide portion 96 and the core 11 and g ₁ <g ₂ <g ₃ (for example, g ₁ = 0.3 μm, g ₂ = 0.2 μm, g ₃ = 0.1 μm). It is. FIG. 8 shows the output light level of the output light 201 corresponding to the gap g at the wavelength λ1.

As is apparent from FIG. 7, at the wavelength λ ₁ where the waveguide mode of the defect waveguide section 96 of the two-dimensional photonic crystal slab and the waveguide mode of the core 11 are phase-matched, a dip may occur in the light transmittance. I understand. The light transmittance is worse as the gap g is smaller. In other words, the level of light coupled to the slab waveguide 96 is increased.

  As is clear from FIG. 8, the wavelength λ of the optical signal 200 is λ1, and the level of the outgoing light 201 is the highest at the smallest gap g1. Therefore, optical coupling can be controlled by a specific wavelength range.

(Effects of the first embodiment)
According to 1st Embodiment mentioned above, there exist the following effects.
(A) The target substrate 4 having the thin wire waveguide 14 and the donor substrate 10 having the two-dimensional photonic crystal 3 on which the defect waveguide portion 96 of the two-dimensional photonic crystal slab is formed are separately manufactured. By combining by room temperature bonding, the optical element 100 can be reduced in size.
(B) The two-dimensional photonic crystal 3 has an air bridge structure, can be vertically symmetrical, and can have a large difference in refractive index, so that a wide design margin can be obtained.
(C) The thin-line waveguide 14 is robust because it is formed on the Si substrate 1, and introduces light in a so-called single mode in which only one wave number of light exists for one frequency. Can do.

  In the above embodiment, in order to efficiently couple the thin wire waveguide 14 and the slab waveguide portion 96, the propagation constant of the thin wire waveguide 14 and the propagation constant of the two-dimensional photonic crystal 3 are designed to be matched. . In addition, the design is made so that the electromagnetic field profiles of the thin wire waveguide 14 and the slab waveguide portion 96 coincide as much as possible.

[Second Embodiment]
FIGS. 9A (a) to 9 (c) and FIGS. 9B (d) to (f) show the manufacturing steps of the optical element according to the second embodiment of the present invention. In the first embodiment, the pedestal 2 is joined to the target substrate 6 to produce the target substrate 4, and then the two-dimensional photonic crystal 3 is joined to the target substrate 4. In the present embodiment, the pedestal 2 is attached to the target substrate 4. After bonding to the first donor substrate 10, the two-dimensional photonic crystal 3 with the pedestal 2 is bonded to the target substrate 6.

  A method for manufacturing the optical element 100 according to the second embodiment will be described below.

(1) Production of Core and Cladding As described with reference to FIG. 2A, a thin-line waveguide 14 composed of the cladding 12 and the core 11 is formed on the Si substrate 1, and the target substrate 6 as an external waveguide substrate is formed. Is made.

(2) Fabrication of pedestal As described in FIGS. 3A to 3D, the release layer 72 is formed on the Si substrate 71, and the pedestal 2 is formed on the release layer 72. A donor substrate 8 is prepared.

(3) Fabrication of two-dimensional photonic crystal As described with reference to FIGS. 4A to 4D, the release layer 92 is formed on the Si substrate 91, and the two-dimensional photonic crystal slab is formed on the release layer 92. The two-dimensional photonic crystal 3 composed of the defect waveguide portion 96 and the periodic structure portion 97 is formed to produce the first donor substrate 10 as a photonic crystal substrate.

(4) Fabrication of optical element First, the target substrate 6 shown in FIG. 2B, the second donor substrate 8 shown in FIG. 3D, and the first donor substrate shown in FIG. 10 is carried into a vacuum chamber (not shown).

  Next, as shown in FIG. 9A, the first donor substrate 10 is fixed to a lower stage (not shown), the second donor substrate 8 is fixed to an upper stage (not shown), and the second donor substrate 8 is attached to the lower stage. Positioning above the first donor substrate 10, the surfaces of the first and second donor substrates 8, 10 are cleaned by FAB.

  Next, the second donor substrate 8 is lowered, and the lower end surface of the base 2 is brought into contact with the upper surface of the two-dimensional photonic crystal 3 of the first donor substrate 10 for a predetermined time as shown in FIG. 9A (b). The base 2 is bonded to the upper surface of the two-dimensional photonic crystal 3 at room temperature.

  Next, as shown in FIG. 9A (c), the second donor substrate 8 is raised and separated from the first donor substrate 10. As a result, the upper end surface of the pedestal 2 is peeled off from the second donor substrate 8, and the pedestal 2 is transferred onto the first donor substrate 10. In the present embodiment, since the release layers 92 and 72 are provided on both the first donor substrate 10 and the second donor substrate 8, the two-dimensional photonic crystal 2 of the first donor substrate 10 is provided. The bonding strength of the release layer 92 is adjusted to be larger than the bonding strength between the base 2 of the second donor substrate 8 and the release layer 72.

  Next, as shown in FIG. 9B (d), the first donor substrate 10 of FIG. 9A (c) is fixed to the upper stage in place of the second donor substrate 8, and the first donor substrate 10 is fixed to the target substrate. 6, the surfaces of the target substrate 4 and the first donor substrate 10 are cleaned by FAB processing.

  Next, the first donor substrate 10 is lowered, and the lower surface of the base 2 is brought into contact with the upper surface of the Si substrate 1 of the target substrate 6 for a predetermined time as shown in FIG. 9B (e). By this contact, the contact portion between the lower surface of the base 2 and the upper surface of the Si substrate 1 is bonded at room temperature.

  Next, as shown in FIG. 9B (f), when the Si substrate 91 is raised, the two-dimensional photonic crystal 3 and the pedestal 2 are separated from the release layer 92 of the first donor substrate 10 to form the target substrate 6. Transcribed. Thus, the optical element 100 shown in FIG. 1 is completed.

(Effect of the second embodiment)
According to the second embodiment described above, the optical element 100 can be reduced in size as in the first embodiment.

[Third Embodiment]
FIG. 10 shows an optical element according to the third embodiment of the present invention. In the first embodiment, as shown in FIG. 2, the SiO ₂ layer 13 is formed into a fine line by etching or the like to form the cladding 12, but in this embodiment, the SiO ₂ layer 13 is formed into a thin line. It was used as it is as a cladding. The present embodiment can be manufactured by a method similar to that of the first or second embodiment.

According to the third embodiment, the step of forming the SiO ₂ layer 13 into a thin line can be omitted, and the thickness of the Si layer 73 of the first wafer 7 for producing the pedestal 2 can be reduced. Can be thinned.

  Next, Example 1 of the present invention will be described. In Example 1, the periodic structure portion 97 of the two-dimensional photonic crystal 3 has a lattice constant a of 420 nm, a radius of the hole 95 of 122 nm, and a thickness of the slab waveguide portion 96 of 250 nm. The lattice constant a refers to the distance between adjacent ones of a combination of seven holes 95 including one hole 95 shown in FIG. 4C and six holes 95 surrounding it. The width of the core 11 constituting the thin wire waveguide 14 was 485 nm and the height was 250 nm. The gap g was set to 0.1 nm.

  Under the above conditions, it was found that when a white light optical signal 200 including 1.55 μm is incident on the core 11, 1.55 μm light can be obtained from the slab waveguide portion 96.

[Other embodiments]
The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  Further, a laser light emitting unit, other light emitting elements, light receiving elements, and the like can be built in or mounted in the optical element 100 of FIG.

  Moreover, you may comprise using a two-dimensional photonic crystal for a thin wire | line waveguide.

1 is a perspective view showing an optical element according to a first embodiment of the present invention. (A), (b) is a perspective view which shows the preparation processes of a core and a clad. (A)-(d) is a figure which shows the preparation process of a base. (A)-(d) is a figure which shows the preparation processes of a two-dimensional photonic crystal. (A)-(c) is a figure which shows the preparation processes of a target board | substrate. (D)-(f) is a figure which shows the manufacturing process of an optical element. It is a longitudinal direction sectional view for explaining operation of an optical element. FIG. 7 is a characteristic diagram showing a relationship between a wavelength λ and light transmittance (level of output light from part E in FIG. 6 / level of input light of optical signal 200). It is a characteristic view which shows the emitted light level of the emitted light according to the gap g. (A)-(c) is a figure which shows the preparation processes of the 1st donor substrate which concerns on the 2nd Embodiment of this invention. (D)-(f) is a figure which shows the manufacturing process of an optical element. It is sectional drawing of the optical element which concerns on the 3rd Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Base 3 Two-dimensional photonic crystal 4 Target substrate 5 SOI substrate 6 Target substrate 7 First wafer 8 Donor substrate 9 Second wafer 10 Donor substrate 11 Core 11 Target substrate 12 Cladding 13 SiO ₂ layer 14 Thin wire waveguide 71 Si substrate 72 Release layer 73 Si layer 74 Cell 91 Si substrate 92 Release layer 93 Si layer 94 Cell 95 Hole 96 Slab waveguide portion 97 Periodic structure portion 100 Optical element 200 Optical signal 201 Output light

Claims (10)

A two-dimensional photonic crystal having defects that disturb the periodic structure;
An optical element comprising: an external waveguide formed on a substrate and disposed opposite to each other with a gap provided in the defect portion.   The optical element according to claim 1, wherein the external waveguide propagates light in a single mode.   The optical element according to claim 1, wherein the substrate is provided with a pair of pedestals for supporting the two-dimensional photonic crystal on both sides of the external waveguide. The external waveguide includes a clad formed on the substrate and a core formed on the clad,
The optical element according to claim 3, wherein the pedestal is erected on an exposed surface of the substrate. The external waveguide includes a clad formed on the substrate and a core formed on the clad,
The optical element according to claim 3, wherein the pedestal is erected on the clad. A photonic crystal substrate on which a two-dimensional photonic crystal having a defect that disturbs the periodic structure is formed, an external waveguide is formed on the substrate, and a pedestal having a predetermined height is provided on both sides of the external waveguide. A preparation step of preparing an external waveguide substrate;
Joining the two-dimensional photonic crystal and the pedestal by bringing the photonic crystal substrate into contact with the external waveguide substrate and providing a gap between the slab waveguide portion and the external waveguide; ,
A method of manufacturing an optical element, comprising: a separation step of separating the photonic crystal substrate and the external waveguide substrate to transfer the two-dimensional photonic crystal to the upper surface of the pedestal.   The optical device according to claim 6, wherein the preparing step includes a bonding step of bonding the pedestal provided on the donor substrate to the surface of the external waveguide substrate on both sides of the external waveguide. Production method. A two-dimensional photonic crystal having a defect portion that disturbs the periodic structure is formed, and a photonic crystal substrate in which a pedestal having a predetermined height is provided outside the periodic structure portion, and an external waveguide is provided on the substrate. A preparation step of preparing the formed external waveguide substrate;
Joining the photonic crystal substrate and the external waveguide substrate, and joining the pedestal and the external waveguide substrate by providing a gap between the slab waveguide portion and the external waveguide;
A method for manufacturing an optical element, comprising: a separation step of separating the photonic crystal substrate and the external waveguide substrate to transfer the two-dimensional photonic crystal and the pedestal to the external waveguide substrate.   The optical device according to claim 8, wherein the preparation step includes a bonding step of bonding the pedestal provided on the donor substrate to a surface of the photonic crystal substrate outside the periodic structure portion. Manufacturing method.   The method for manufacturing an optical element according to claim 6, wherein the bonding step is performed at room temperature bonding.

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