JP5303430B2 - Optical cantilever - Google Patents

Description

  The present invention relates to an optical cantilever, and more particularly to an optical cantilever including a photonic crystal resonator.

  Conventionally, in the field of MEMS (Micro Electromechanical System), various applications have been performed using the motion of cantilever elements. For example, a scanning probe microscope (SPM) in which a cantilever is driven using a piezoelectric element is a typical example. The cantilever manufactured in micron size has a one-sided support structure, and the other side can move freely, so that even a small external force causes displacement and it is easy to vibrate.

  Utilizing the mechanical properties of this cantilever support, its application to devices in the micron range has been extensively studied. For example, an application to an RF (Radio Frequency) -MEMS switch using static electricity as a driving force (for example, see Non-Patent Document 1), an application to a trace detection sensor (for example, see Non-Patent Document 2), and the like are known. .

N. Nishijima, J.-J. Hung, and GM Rebeiz, "A low-voltage high contact force RF-MEMS switch," Proc. IEEE MTT-S Int. Microw. Symp. Dig., 2004, pp. 577- 580. Nickolay V. Lavrik and Panos G. Datskosa, "Femtogram mass detection using photothermally actuated nanomechanical resonators", Appl. Phys. Lett. 82, 2697 (2003)

  However, in the driving of cantilevers, in the conventional driving methods such as static electricity and electric heating, the displacement of the cantilever tends to be limited to movement in one direction, and the installation of the drive electrode is not easy. There was no problem.

  In particular, when configuring a switching element (for example, a relay element) between two states that switches between two states, it is necessary to displace the cantilever in both directions, for example, in the vertical direction or the horizontal direction. However, in the conventional method, in order to realize such a drive that can be displaced in both directions, there is a problem that the structure becomes very complicated and actual processing is difficult.

  Accordingly, an object of the present invention is to provide a cantilever that can be displaced in both directions while having a simple configuration that does not require electrode installation.

In order to achieve the above object, an optical cantilever according to a first invention includes two slabs each including a different photonic crystal resonator,
A connecting portion for connecting and supporting the two slabs facing each other,
One of the two slabs is selectively thermally expanded by light irradiation to generate a displacement in a direction perpendicular to the slab surface.

  As a result, the displacement in both directions perpendicular to the slab surface can be generated by selectively driving one of the two slabs in a simple configuration in which the two slabs are opposed to each other and integrally supported. .

2nd invention is the optical cantilever which concerns on 1st invention,
The different photonic crystal oscillators have different resonance wavelengths.

  Thereby, it is possible to select which slab to resonate by irradiating light of the resonance wavelength of any photonic crystal oscillator or a wavelength close to this, and the direction of displacement of the cantilever can be determined by the wavelength of the light. Can be controlled.

3rd invention is the optical cantilever which concerns on 1st or 2nd invention,
The different photonic crystal oscillators have different absorption wavelengths.

  As a result, it is possible to select which slab is caused to generate thermal expansion by irradiating light of an absorption wavelength of one of the photonic crystal oscillators or a wavelength close to this, and the displacement of the cantilever can be selected. It is possible to control with higher accuracy using the wavelength.

A fourth invention is an optical cantilever according to any one of the first to third inventions,
The connecting portion is a heat insulating material provided by being sandwiched between the two slabs.

  Thereby, since two slabs are joined via the heat insulating material, the heat of thermal expansion generated in one slab is blocked by the heat insulating material, and displacement can be generated efficiently.

A fifth invention is an optical cantilever according to any one of the first to third inventions,
The connecting portion is provided between the two slabs so as to sandwich the photonic crystal oscillator from both sides in a plane, and forms a space between the facing photonic crystal oscillators.

  Thereby, an air space can be formed between the two slabs, and a cantilever that is displaced in both directions with a small amount of material can be simply configured.

A sixth invention is an optical cantilever according to any one of the first to fifth inventions,
The photonic crystal oscillator has two-dimensionally arranged holes.

  Accordingly, a photonic crystal oscillator can be configured using a two-dimensional photonic crystal, and the degree of freedom in design can be increased.

A seventh invention is the optical cantilever according to any one of the first to fifth inventions,
The photonic crystal resonator has a diffraction grating slit.

  Thereby, a photonic crystal oscillator using a one-dimensional photonic crystal can also be used, and the degree of design freedom can be further increased.

An eighth invention is the optical cantilever according to any one of the first to seventh inventions,
The different photonic crystal resonators have different compositions.

  Accordingly, different photonic crystal resonators can be configured using the composition, and selective driving can be performed using two slabs having the same shape.

A ninth invention is an optical cantilever according to the sixth invention,
The different photonic crystal resonators have different hole diameters.

  Thus, two different photonic crystal resonators can be configured according to the hole diameter, and various optical cantilevers having various characteristics can be configured by adjusting the hole diameter.

A tenth invention is an optical cantilever according to any one of the first to seventh inventions,
The different photonic crystal resonators have different thicknesses.

  Accordingly, two different photonic crystal resonators can be formed depending on the thickness, and the optical cantilever can be easily adjusted without requiring a complicated design.

  According to the present invention, a cantilever in a minute region can be displaced in both directions with a simple configuration.

FIG. 1 is an explanatory diagram of an optical cantilever according to Embodiment 1 of the present invention. FIG. 1A is a cross-sectional view illustrating the basic structure of the optical cantilever according to the first embodiment. FIG. 1B is a diagram showing a change in shape of an optical cantilever in which the photonic crystal resonator on the lower surface is excited and heated. FIG. 1C is a diagram showing a change in the shape of the optical cantilever when the photonic crystal resonator on the upper surface is heated by excitation. 6 is an explanatory diagram of an optical cantilever according to Embodiment 2. FIG. FIG. 2A is a cross-sectional configuration diagram of an optical cantilever according to the second embodiment. FIG. 2B is a plan configuration diagram of the optical cantilever according to the second embodiment. FIG. 2C is a diagram showing a change in the shape of the optical cantilever in which the photonic crystal resonator on the lower surface is excited and heated. FIG. 2D is a diagram showing a change in shape of an optical cantilever in which the photonic crystal resonator on the upper surface is excited and heated. FIG. 2E is a diagram illustrating an example of the base mode. FIG. 2F illustrates another example of the base mode. 6 is a view showing a method for manufacturing an optical cantilever according to Embodiment 2. FIG. FIG. 3A is a diagram showing a substrate preparation process. FIG. 3B is a diagram showing a pattern transfer process. FIG. 3C shows a sacrificial layer removal step. FIG. 10 is an explanatory diagram of an optical cantilever according to a fourth embodiment. FIG. 4A is a cross-sectional configuration diagram of an optical cantilever according to the fourth embodiment. FIG. 4B is a relationship characteristic diagram between the refractive index and the resonance wavelength of the optical cantilever according to the fourth embodiment. 10 is an explanatory diagram of an optical cantilever according to Embodiment 5. FIG. FIG. 5A is a cross-sectional configuration diagram of an optical cantilever according to the fifth embodiment. FIG. 5B is a relationship characteristic diagram between the hole radius and the resonance wavelength of the optical cantilever according to the fifth embodiment. 10 is an explanatory diagram of an optical cantilever according to Embodiment 6. FIG. FIG. 6A is a cross-sectional configuration diagram of an optical cantilever according to the sixth embodiment. FIG. 6B is a relationship characteristic diagram between the thickness of the optical cantilever and the resonance wavelength according to the sixth embodiment. FIG. 10 is a configuration diagram of an optical cantilever according to a seventh embodiment. FIG. 7A is a cross-sectional configuration diagram of an optical cantilever according to the seventh embodiment. FIG. 7B is a plan configuration diagram of the optical cantilever according to the seventh embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram for explaining an optical cantilever according to a first embodiment of the present invention. FIG. 1A is a cross-sectional view illustrating the basic structure of the optical cantilever according to the first embodiment. In FIG. 1A, the optical cantilever according to the first embodiment includes a first photonic crystal resonator 10, a second photonic crystal resonator 20, and a connecting portion 70. Both the first photonic crystal resonator 10 and the second photonic crystal resonator 20 are configured as plate-like slabs. Therefore, the first photonic crystal resonator 10 may be referred to as the first slab 10, and the second photonic crystal resonator 20 may be referred to as the second slab 20. Thereafter, in all of the embodiments, when it is not necessary to individually distinguish the first photonic crystal resonator 10 and the second photonic crystal resonator 20, the photonic crystal resonators 10, 20 are used. It shall be expressed as

  The first photonic crystal resonator 10 and the second photonic crystal resonator 20 are joined and integrated on both surfaces of a connecting portion 70 formed in a plate shape, and constitute an optical cantilever as a whole. Yes. That is, the connecting portion 70 is provided so as to be sandwiched between the first photonic crystal resonator 10 and the second photonic crystal resonator 20 facing each other, and supports both of them.

  Both the first photonic crystal resonator 10 and the second photonic crystal resonator 20 function to confine light of a specific wavelength for a certain period and function as a resonator. That is, heat is generated by the energy of light by confining light of a specific wavelength for a certain period. On the other hand, the connection part 70 is comprised with the heat insulating material. Therefore, the connecting unit 70 joins and integrates the first photonic crystal resonator 10 and the second photonic crystal resonator 20, and also connects the first photonic crystal resonator 10 or the second photonic crystal. One of the crystal resonators 20 has a function of blocking heat generated.

  The first photonic crystal resonator 10 and the second photonic crystal resonator 20 have resonance wavelengths λ1 and λ2 that are different from each other. In addition, both the first photonic crystal resonator 10 and the second photonic crystal resonator 20 are configured such that linear absorption does not occur at the operating wavelength and only nonlinear absorption such as two-photon absorption occurs. . Thereby, when the wavelength of the input light is equal to or close to the resonance wavelength of any of the photonic crystal resonators 10 and 20, the photonic crystal having the resonance wavelength equal to or close to the wavelength of the input light. Within the resonators 10 and 20, the light intensity increases and nonlinear light absorption occurs. Heat is generated by this nonlinear light absorption and heats one of the two photonic crystal resonators 10 and 20. When one of the photonic crystal resonators 10 and 20 is excited, the excited side generates heat and the temperature rises and expands. In other words, the length of the photonic crystal resonators 10 and 20 that are heated by excitation increases due to thermal expansion, but the other photonic crystal resonators 10 and 20 that are not heated serve as a connecting portion of a heat insulating material. Since it is insulated by 70 and it is difficult for heat to be transmitted, the length does not increase relatively. The first photonic crystal resonator 10 and the second photonic crystal resonator 20 are joined to the connecting portion 70, and when one slab expands, the entire photolithographic crystal resonator 10 and the second photonic crystal resonator 20 in a direction perpendicular to the slab surface, like a bimetal. A shape change that warps the structure occurs. Then, in an optical cantilever having a one-side support structure, the unsupported side generates a displacement on the side of the unswelled slab.

  FIG. 1B is a diagram illustrating a change in shape of the optical cantilever when the slab of the second photonic crystal resonator 20 on the lower surface is excited and heated, and FIG. It is the figure which showed the shape change of the optical cantilever at the time of exciting and heating the slab of the photonic crystal resonator 10. FIG.

  In FIG. 1B, when the second photonic crystal resonator (slab) 20 on the lower surface is excited and heated, the slab on the lower surface expands due to thermal expansion, the lower surface protrudes and warps, and the shape changes to bend upward. Occurs. In FIG. 1 (B), since the left side constitutes an optical cantilever supported, the right non-supporting side is displaced upward in the direction of the slab which is not extended.

  On the other hand, in FIG. 1C, the first photonic crystal resonator 10 on the upper surface is heated by excitation. In this case, the first photonic crystal resonator (slab) 10 disposed on the upper surface expands due to thermal expansion, the upper surface protrudes and warps, and the entire optical cantilever changes in shape to bend downward. In this case, in the optical cantilever in which the left side is cantilevered, the upper surface is extended to bend toward the lower surface, and the optical cantilever is displaced toward the lower surface.

  Thus, by selectively exciting the first photonic crystal resonator 10 and the second photonic crystal resonator 20, the optical cantilever is displaced in both the upward and downward directions perpendicular to the slab surface. It becomes possible. That is, when it is desired to displace the optical cantilever upward, the optical cantilever is irradiated with light having a resonance wavelength of the second photonic crystal resonator 20 on the lower surface or a wavelength close thereto, and the second photonic crystal resonance is performed. The vessel 20 may be excited and heated to extend the slab on the lower surface. Conversely, when it is desired to displace the optical cantilever downward, the optical cantilever is irradiated with light having a wavelength at or near the wavelength of the first photonic crystal resonator 10 on the upper surface, and the first photonic crystal is irradiated. The resonator 10 may be heated by exciting the slab on the upper surface. In the optical cantilever according to the present embodiment, heat is generated by nonlinear absorption, so that the same operation can be performed regardless of which photonic crystal resonator 10 or 20 receives light.

  In the first embodiment, the specific surface shapes of the first photonic crystal resonator 10 and the second photonic crystal resonator 20 are not shown, but the photonic crystal resonator 10 having various defect structures is shown. 20 can be applied.

  FIG. 2 is a diagram for explaining the configuration and function of the optical cantilever according to the second embodiment of the present invention. FIG. 2A is a diagram illustrating an example of a cross-sectional configuration of the optical cantilever according to the second embodiment. FIG. 2B is a diagram illustrating an example of a planar configuration of the optical cantilever according to the second embodiment. is there.

  As shown in FIG. 2A, the optical cantilever according to the second embodiment includes a first photonic crystal resonator 11 on the upper surface, a second photonic crystal resonator 21 on the lower surface, and a first photonic crystal. A hole 31 formed in the crystal resonator 11, a hole 41 formed in the second photonic crystal resonator 21, a first slab 50 including the first photonic crystal resonator 11, a second It has the 2nd slab 60 containing the photonic crystal resonator 21, and the connection part 71 which connects and supports the 1st slab 50 and the 2nd slab 60. FIG.

  In the following embodiments, the first slab 50 and the second slab 60 are also referred to as slabs 50 and 60 when there is no need to distinguish them separately, like the photonic crystal resonators 11 and 21. It may be possible.

  In the optical cantilever according to the first embodiment, the first photonic crystal resonator 10 and the second photonic crystal resonator 20 which are disposed to face each other have a connecting portion 70 formed of a heat insulating material therebetween. And it was joined to both surfaces of the connection part 70, and was integrally supported. On the other hand, in the optical cantilever according to the second embodiment, the first photonic crystal resonator 11 and the second photonic crystal resonance are provided between the two first slabs 50 and the second slab 60 facing each other. A connecting portion 71 is provided so as to sandwich the container 21 from both the left and right sides in a plane. In other words, in the optical cantilever according to the second embodiment, the connecting portion 71 is provided like a spacer between the first slab 50 and the second slab 60, and the first photonic crystal resonator 11 and the second slab 60 are connected to each other. The photonic crystal resonator 21 is different from the optical cantilever according to the first embodiment in that a space communicating with air is formed.

  As described above, the connecting portion 71 may be provided in such a configuration as to sandwich the photonic crystal resonators 11 and 21 from both sides in a plane. Even in this case, since the two slabs 50 and 60 are integrally connected and supported via the connecting portion 71, when thermal expansion occurs in one of the photonic crystal resonators 11 and 21, The degree of extension can be made different between the upper side and the lower side of the connecting part 71 in the portions of the photonic crystal resonators 11 and 21 sandwiched between the connecting parts 71, and deformation in the vertical direction can be caused. In the optical cantilever according to the second embodiment, the connecting portion 71 has a configuration in which the photonic crystal resonators 10 and 20 are planarly sandwiched from both sides in the longitudinal direction of the slabs 50 and 60. The deformation of one slab 50, 60 due to thermal expansion may be variously arranged as long as it can change the shape in relation to the other slab 50, 60 and generate a displacement perpendicular to the slab surface. For example, it is possible to arrange the slabs 50 and 60 so as to be sandwiched from both sides in the short direction, or to be sandwiched from both sides of the diagonal line.

  The photonic crystal resonators 11 and 21 are configured by applying a photonic crystal to the resonator. The photonic crystal has a structure in which the refractive index is periodically distributed. The photonic crystal is applied to the production of the photonic crystal resonators 11 and 21 by controlling the light transmission and controlling the light locally by using the light dispersion characteristic control and the forbidden band by the periodicity.

  As shown in FIGS. 2A and 2B, the photonic crystal resonators 11 and 21 have holes 31 and 41. The holes 31 and 41 are periodically provided in the photonic crystal resonators 11 and 21 to realize a structure in which the refractive index is periodically distributed. As shown in FIG. 2B, the holes 31 and 41 of the photonic crystal resonators 11 and 21 may be arranged in an arrangement having a two-dimensional period. FIG. 2B shows an example in which holes 31 are arranged in a lattice pattern in the first photonic crystal resonator 11. In addition, as shown in FIG. 2B, the optical cantilever according to the second embodiment may include a frame 80. The frame 80 is a member for supporting the main body including the optical cantilever slabs 50, 60 from the outside, and may be provided in connection with the slabs 50, 60. In FIG. 2A, the frame 80 is not shown.

  In FIGS. 2A and 2B, it goes without saying that the arrangement and number of the holes 31 and 41 may be arbitrarily set according to the application.

  2 (C) and 2 (D) configure the photonic crystal resonators 11 and 21 having a confinement structure using the light dispersion characteristic control based on the periodicity as described above, and the photonic crystal resonators 11 and 21 are formed. The displacement of the optical cantilever when selectively excited is shown.

  FIG. 2C is a diagram illustrating an example of the displacement of the optical cantilever when the second photonic crystal resonator 21 on the lower surface of the optical cantilever according to the second embodiment is excited and heated. As shown in FIG. 2C, when the second photonic crystal resonator 21 on the lower surface is excited and heated, the second photonic crystal resonator 21 expands due to thermal expansion, and the upper photon does not cause thermal expansion. There is a difference between the left and right lengths with the first photonic crystal resonator 11. Then, the second slab 60 on the lower surface inside the connecting portion 71 extends to the left and right, and the length of the first slab 50 on the upper surface inside the connecting portion 71 hardly changes. The optical cantilever is deformed so as to bend downward, and the end portion is displaced upward. This is the same as the modification of the optical cantilever according to the first embodiment shown in FIG.

  FIG. 2D is a diagram illustrating an example of the displacement of the optical cantilever when the first photonic crystal resonator 11 on the upper surface of the optical cantilever according to the second embodiment is excited and heated. As shown in FIG. 2D, when the first photonic crystal resonator 11 on the upper surface is excited and heated, the first photonic crystal resonator 11 expands by thermal expansion and does not cause thermal expansion. A difference occurs in the length in the longitudinal direction (left and right) with respect to the second photonic crystal resonator 21. Then, the first slab 50 on the upper surface inside the connecting portion 71 extends in the longitudinal direction (left and right), and the length of the second slab 60 on the lower surface inside the connecting portion 71 hardly changes. Is tilted to fall outward, the optical cantilever is deformed to warp upward, and the end portion is displaced downward. This is also the same as the modification of the optical cantilever according to the first embodiment shown in FIG.

  In light dispersion in photonic crystals, there are several gamma point modes (that is, the wave number component in the in-plane direction is 0), and among them, there are modes with symmetry that do not couple with external light. To do. This means that light inside the photonic crystal can be completely confined and does not leak outside, but light cannot be input into the photonic crystal.

  However, the discussion of the mode having symmetry that does not couple with external light is effective in the photonic crystal resonators 11 and 21 having an infinite size under the most ideal conditions. Such conditions are broken. That is, since the photonic crystal resonators 11 and 21 have a finite size, the light confined in the slabs 50 and 60 is coupled to the outside and has a finite Q value as a whole. Are easily coupled, and light can be easily input to the photonic crystal resonators 11 and 21 by external light irradiation.

  2E and 2F are diagrams showing two examples of the fundamental mode. 2E shows an example of the mode 1 base mode, and FIG. 2F shows an example of the mode 2 base mode. These modes may be selected as appropriate arbitrary modes depending on the settings of the photonic crystal resonators 11 and 21.

  In Example 3, a method for manufacturing an optical cantilever will be described. FIG. 3 is a diagram illustrating an example of a method of manufacturing an optical cantilever according to the second embodiment.

  FIG. 3A is a diagram illustrating an example of a substrate preparation process. In the substrate preparation step, a substrate for manufacturing an optical cantilever is prepared. As shown in FIG. 3A, the prepared substrate includes, for example, a first core layer 12 and a second core layer 22 processed as photonic crystal resonators 11 and 21, and the core layer 12, The substrate may include the first sacrificial layer 72 between the first sacrificial layer 72 and the second sacrificial layer 90 below the second core layer 22. The sacrificial layers 72 and 90 are preferably made of a material that can be selectively etched with the core layers 12 and 22.

  The substrate may be a substrate made of various materials. For example, the substrate may be a substrate in which the core layers 12 and 22 are formed of a semiconductor and the sacrificial layers 72 and 90 are formed of an oxide film. For example, silicon (Si), gallium arsenide (GaAs), or the like may be used as the semiconductor, and SiO or the like may be used as the oxide film. For example, an SOI (Silicon on Insulator) substrate may be prepared as the substrate, and a substrate on which SiO is further formed as the second sacrificial layer 90 may be used. By using such a semiconductor substrate used in the semiconductor manufacturing process, the semiconductor manufacturing process can be used as it is.

  FIG. 3B is a diagram showing an example of a pattern transfer process. In the pattern transfer process, holes 32 having a periodic pattern similar to the periodic patterns of the holes 31 and 41 formed in the photonic crystal resonators 11 and 21 are transferred by drawing. The periodic pattern defined in the drawing process is transferred to the bottom using a dry etching process, and the periodic pattern is also transferred to the second core layer 22.

  FIG. 3C shows an example of the sacrificial layer removal process. In the sacrificial layer removal step, the sacrificial layers 72 and 90 are removed by wet etching or dry etching. At this time, all of the second sacrificial layer 90 may be removed by etching. However, if the first sacrificial layer 72 is left without being removed, the connecting portion 72 can be formed. it can.

  In the case of wet etching, it is better to use an etchant having a dependence on the crystal plane, but even with an isotropic etchant, if the distance between the photonic crystal and the connecting portion 72 is secured while suppressing the reaction rate, processing is performed. Is possible.

  Thus, when manufacturing the optical cantilever according to the second embodiment from the semiconductor substrate, the optical cantilever can be easily manufactured using the semiconductor manufacturing process. 3 illustrates an example of manufacturing the optical cantilever according to the second embodiment. In FIG. 3C, all the first sacrificial layers 72 are also removed by etching and two photonic crystal resonances are produced. The optical cantilever according to the first embodiment can be easily manufactured by manufacturing the containers 10 and 20 and then joining them so as to sandwich the connecting portion 70 of the heat insulating material from both sides.

  The method for manufacturing an optical cantilever according to the third embodiment can also be used for manufacturing an optical cantilever according to an embodiment described below.

  FIG. 4 is a diagram for explaining an optical cantilever according to a fourth embodiment of the present invention. FIG. 4A is a diagram illustrating a cross-sectional configuration of the optical cantilever according to the fourth embodiment, and FIG. 4B is a relationship between the refractive index of the optical cantilever according to the fourth embodiment and the resonance wavelength or the absorption wavelength. It is the figure which showed the characteristic.

  As shown in FIG. 4A, the optical cantilever according to the fourth embodiment has an air layer between the first slab 51 and the second slab 61 in the same manner as the optical cantilever according to the second embodiment. Have. Further, the first slab 51 includes the first photonic crystal resonator 13, and the second slab 61 includes the second photonic crystal resonator 23. The first photonic crystal resonator 13 is provided with a hole 33 having a periodic pattern, and the second photonic crystal resonator 23 is similarly provided with a hole 43 having a periodic pattern. Further, both end portions of the first slab 51 and the second slab 61 are connected and supported by a connecting portion 73, and the first slab 51 and the second slab 61 are integrated.

  Since this configuration is almost the same as that of the optical cantilever according to the second embodiment, the first slab 51 and the second slab 61 are also deformed and displaced in the vertical direction as shown in FIG. , (D) performs the same operation. That is, when the first photonic crystal resonator 13 is selectively excited and heated, the optical cantilever is displaced downward, and when the second photonic crystal resonator 23 is excited and heated, The optical cantilever is displaced. The detailed contents are the same as those described in FIGS. 2C and 2D of the second embodiment, and thus the description thereof is omitted.

  In the optical cantilever according to the fourth embodiment, the compositions of the first photonic crystal resonator 13 and the second photonic crystal resonator 23 are different from each other. The first photonic crystal resonator 13 and the second photonic crystal resonator 23 can have different refractive indexes n1 and n2 by making the compositions different. Then, the resonance wavelength and / or the absorption wavelength of the photonic crystal resonators 13 and 23 can be tuned by changing the refractive indexes n1 and n2 accompanying the change in composition.

  The composition of the photonic crystal resonators 13 and 23 is the same as that of the two core layers 21 and 22 in the manufacturing method described in the third embodiment in a material system capable of epitaxial growth, such as a compound semiconductor such as gallium arsenide. It is possible to change the composition of each other. For example, by applying such a manufacturing method, the composition of the first photonic crystal resonator 13 and the second photonic crystal resonator 23 can be easily made different, whereby the refractive index n1. , N2 can be adjusted.

  FIG. 4B shows changes in the resonance wavelengths of modes 1 and 2 depending on the refractive indexes n1 and n2 of the slab constituent materials when the slabs 51 and 61 have a square lattice having a thickness of 400 nm and a period of 750 nm. Note that modes 1 and 2 correspond to modes 1 and 2 shown in FIGS.

  In FIG. 4B, since the effective refractive index of the slabs 51 and 61 as a whole increases, the resonance wavelength is shifted to a long wavelength, and the amount of movement is 10% of the change in the refractive indices n1 and n2. Shows a linear change of about 10%. In other words, in order to obtain tuning of the resonance wavelength of about 15 nm, a change of the refractive indexes n1 and n2 of only 0.03 is sufficient, and this change amount is an amount that can be sufficiently realized in the compound semiconductor system.

  In FIG. 4B, since the resonance wavelengths of mode 1 and mode 2 are different, for example, one mode of mode 1 or mode 2 is set in the first photonic crystal resonator 13, and the second The other mode may be set in the photonic crystal resonator 23. On the other hand, in the characteristics of only mode 1, the resonance wavelength ranges from about 1.63 nm to about 1.77 nm depending on the refractive index. Therefore, the setting of the resonance wavelength of photonic crystal resonators 13 and 23 can be performed only in mode 1. May be performed.

  As described above, the resonance wavelengths may be set in different modes or in the same mode as long as the wavelengths are different from each other with a certain difference. In FIG. 4B, the resonance wavelength is described as an example. However, the absorption wavelength is made different between the first photonic crystal resonator 13 and the second photonic crystal resonator 23. May be set.

  FIG. 5 is a diagram for explaining an optical cantilever according to a fifth embodiment of the present invention. FIG. 5A is a diagram illustrating an example of a cross-sectional configuration of the optical cantilever according to the fifth embodiment. FIG. 5B is a diagram illustrating the relationship between the hole radius and the resonance wavelength of the optical cantilever according to the fifth embodiment. It is the figure which showed an example.

  As described in Example 4, when a compound semiconductor is used, the refractive indices n1 and n2 of the two photonic crystal resonators 13 and 23 can be changed relatively easily. Then, it is difficult to adjust the refractive index n1. In such a case, the same operation can be performed by making the structures of the two opposing photonic crystals different.

  In the method of manufacturing the optical cantilever in Example 3, when silicon is used as the substrate, the two photonic crystal resonator structures by the core layers 21 and 22 can be manufactured by a wafer bonding technique or the like. , 22 is made of silicon oxide or the like.

  FIG. 5A shows an example of an optical cantilever according to the fifth embodiment manufactured by such a manufacturing method described above. As shown in FIG. 5A, in the optical cantilever according to Example 5, the hole diameters of the photonic crystal resonators 14 and 24 included in the two opposing slabs 52 and 62 having the same refractive index n1 are different from each other. It has a configuration. That is, the hole diameter of the hole 34 of the upper first photonic crystal resonator 14 is larger than the hole diameter of the hole 44 of the lower second photonic crystal resonator 24. Thus, the resonance wavelength or the absorption wavelength may be adjusted by making the diameters of the holes 34 and 44 of the two photonic crystal resonators 14 and 24 facing each other different. The point that the two slabs 52 and 62 are integrated and supported by the connecting portion 74 is the same as in the second and fourth embodiments. Further, since the relationship between the vertical displacement operation of the optical cantilever and the photonic crystal resonators 14 and 24 selectively excited and heated is the same as in the second and fourth embodiments, the description thereof is omitted.

  As described with reference to FIG. 3C of the third embodiment, the dry etching process is usually optimized for anisotropic etching, that is, vertical etching shape. That is, when it is desired to form uniform holes 32 in both the upper and lower core layers 12 and 22, a dry etching process is suitable.

  In the optical cantilever according to the fifth embodiment, the optimum conditions are shifted, the holes 32 are processed so as to have a tapered structure, and the diameters of the holes 34 and 44 of the photonic crystal resonators 14 and 24 on the upper and lower surfaces are realized. To do.

  FIG. 5B shows the relationship between the radius of the holes 34 and 44 of the photonic crystal resonators 14 and 24 having a square lattice periodic pattern with a thickness of 400 nm and a period of 750 nm, and the resonance wavelength. In FIG. 5B, when the hole diameter is expanded, the effective refractive index of the photonic crystal resonators 14 and 24 is lowered, and the resonance wavelength is shifted to a short wavelength. The amount of movement changes almost linearly, and the resonance wavelength changes by about 7% with respect to a change of 10% in radius. For example, when a change with a radius of 5 nm is given, the resonance wavelength moves about 12 nm. This amount of change is an amount that can be realized without significantly deviating from the optimization conditions for anisotropic etching.

  In FIG. 5B, an example of the relationship between the hole diameter and the resonance wavelength is given, but it goes without saying that the absorption wavelength can be adjusted by the hole diameter. Further, the two photonic crystal resonators 14 and 24 facing each other can use both different modes or the same mode as in the description in the fourth embodiment.

  FIG. 6 is a diagram for explaining an optical cantilever according to a sixth embodiment of the present invention. FIG. 6A is a diagram illustrating an example of a cross-sectional configuration of the optical cantilever according to the sixth embodiment, and FIG. 6B is an example of a relationship between the thickness of the optical cantilever according to the sixth embodiment and the resonance wavelength. FIG.

  Tuning of the resonance wavelength similar to that in the fifth embodiment can be realized by changing the thicknesses of the upper and lower slabs 53 and 63 facing each other. In the optical cantilever according to the sixth embodiment, the resonance wavelength is adjusted by adjusting the thickness of the slabs 53 and 63 including the photonic crystal resonators 15 and 25. As shown in FIG. 6A, the optical cantilever according to the sixth embodiment has the diameter of the hole 35 of the first photonic crystal resonator 15 on the upper surface and the hole of the second photonic crystal resonator 25 on the lower surface. The diameter of 45 is equal and the refractive index is also equal to n1, but the thickness of the first slab 53 including the first photonic crystal resonator 15 and the second including the second photonic crystal resonator 25 are the same. The thickness of the slab 63 is different. Note that the first slab 53 and the second slab 63 are integrated and supported by the connecting portion 75 in the same manner as in the second, fourth, and fifth embodiments. In addition, the vertical displacement operation of the optical cantilever by excitation heating is the same as in the second, fourth, and fifth embodiments, and a description thereof will be omitted.

  FIG. 6B shows a change in resonance wavelength depending on the thickness of the slabs 53 and 63 in the photonic crystal resonators 15 and 25 having a period of 750 nm, a hole diameter of 300 nm, and a refractive index of 3.19. As shown in FIG. 6B, when the thickness of the photonic crystal resonators 15 and 25 is increased while the period, hole diameter, and refractive index n1 are kept constant, the outside of the photonic crystal resonators 15 and 25, that is, Since the distribution of light existing in the air decreases, the effective refractive index increases, and the resonance wavelength shifts to a long wavelength.

  Thus, the resonance wavelength can also be adjusted by adjusting the thickness of the slabs 53 and 63 including the photonic crystal resonators 15 and 25. In addition, the absorption wavelength can be adjusted in the same manner as in the fourth and fifth embodiments. The two photonic crystal resonators 15 and 25 may use the same mode or different modes. Are the same as those in the fourth and fifth embodiments.

  Further, the optical cantilevers according to the fifth and sixth embodiments can be applied not only when the optical cantilever is configured by a single semiconductor such as silicon, but also when the optical cantilever is configured by a compound semiconductor system by epitaxial growth.

  FIG. 7 is a diagram illustrating an example of the configuration of the optical cantilever according to the seventh embodiment of the present invention. FIG. 7A is a diagram illustrating an example of a cross-sectional configuration of the optical cantilever according to the seventh embodiment, and FIG. 7B is a diagram illustrating an example of a planar configuration of the optical cantilever according to the seventh embodiment. is there.

  In FIG. 7A, the optical cantilever according to the seventh embodiment includes a first slab 54 including a first photonic crystal resonator 16 and a second slab 64 including a second photonic crystal resonator 26. And a connecting portion 76 that connects and integrates the first slab 54 and the second slab 64. These configurations are the same as those in the second to fifth embodiments. Further, when the first photonic crystal resonator 16 is excited and heated, it is displaced downward, and the second photonic crystal resonator 26 is excited and heated. Since the point of displacement upward is the same as in the second to fifth embodiments, the description thereof is omitted.

  As shown in FIG. 7B, in the optical cantilever according to the seventh embodiment, the first photonic crystal resonator 16 is not a circular two-dimensionally arranged holes 31 to 35, but a diffraction grating slit. This embodiment is different from the second to sixth embodiments in that 36 is provided. Thus, the optical cantilever according to the present embodiment forms the first photonic crystal resonator 16 by the diffraction grating-shaped slits 36.

  As shown in FIG. 7A, the second photonic crystal resonator 26 also includes a diffraction grating-like slit 46 as in the first photonic crystal resonator 16.

  In the optical cantilever according to the seventh embodiment, the two photonic crystal resonators 16 and 26 having the slits 36 and 46 arranged in the form of a diffraction grating stripe are made different from each other in resonance wavelength or absorption wavelength. Realize displacement in both directions. Since the photonic crystal resonators 16 and 26 can also be formed by forming the periodic diffraction grating slits 36 and 46 shown in FIGS. 3 thru | or Example 6 can be applied similarly. That is, also in the optical cantilever according to the seventh embodiment, as described in the first embodiment, it is possible to configure the optical cantilever as a structure joined so as to sandwich the connecting portion 70 of the heat insulating material. Further, as described in the fourth embodiment, the first photonic crystal resonator 16 and the second photonic crystal resonator 26 of the optical cantilever according to the seventh embodiment are formed of compound semiconductors, and the compositions thereof are different. It is also possible to Further, as described in the fifth embodiment, the opening widths of the slits 36 and 46 of the first photonic crystal resonator 16 and the second photonic crystal resonator 26 are different, or as described in the sixth embodiment. Furthermore, by making the thickness of the photonic crystal resonators 16 and 26 different, the effective refractive index of the photonic crystal resonators 16 and 26 can be made different, and the resonance wavelength and the absorption wavelength can be adjusted. Further, the manufacturing method of the optical cantilever according to the seventh embodiment can be applied as it is when the pattern to be transferred is formed into a slit shape, as described in the third embodiment.

  As described above, according to the optical cantilever according to the seventh embodiment, the photonic crystal resonators 16 and 26 in which the diffraction grating slits 36 and 46 having a one-dimensional periodic pattern are formed are used in both directions with a simple configuration. A cantilever that displaces to the position can be realized.

  In addition to the examples described in the first to seventh embodiments, the light of a specific wavelength can be absorbed by only one slab by changing the band gap of the material constituting the upper and lower photonic crystal resonators. Can also be set.

  Furthermore, in the first to seventh embodiments, the example in which linear absorption does not occur at the operating wavelength and only nonlinear absorption is used has been described. However, a photonic crystal resonator is configured with a material that causes linear absorption at the operating wavelength. However, basically the same effect occurs. However, in this case, the influence of linear absorption always occurs for both photonic crystal resonators, so it is necessary to select the light input direction so that it is possible only for one photonic crystal resonator. is there.

  As described above, according to the optical cantilever according to the present embodiment, the photonic crystal resonator is selectively heated and expanded using light, so that it is not necessary to install an electrode that is indispensable for conventional electric drive. The structure can be simplified. Further, the displacement control in both directions, which is very difficult for the conventional cantilever, can be realized by simply changing the excitation light wavelength, and the driving method can be facilitated.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  INDUSTRIAL APPLICABILITY The present invention can be widely used for devices in the field of optical control and optical MEMS that perform operation and control using cantilevers in the micron region and nano region.

10, 11, 13-16 First photonic crystal resonator 12, 22 Core layer 20, 21, 23-26 Second photonic crystal resonator 31-35, 41-45 hole 36 slit 50-54 first Slabs 60-64 second slabs 70, 71, 73-76 connecting portions 80, 81 frames 72, 90 sacrificial layers

Claims (10)

Two slabs each containing a different photonic crystal resonator;
A connecting portion for connecting and supporting the two slabs facing each other,
An optical cantilever characterized by selectively thermally expanding one of the two slabs by light irradiation to generate a displacement in a direction perpendicular to the slab surface.   The optical cantilever according to claim 1, wherein the different photonic crystal oscillators have different resonance wavelengths.   The optical cantilever according to claim 1 or 2, wherein the different photonic crystal oscillators have different absorption wavelengths.   The optical cantilever according to any one of claims 1 to 3, wherein the connecting portion is a heat insulating material provided by being sandwiched between the two slabs.   The connecting portion is provided between the two slabs so as to sandwich the photonic crystal oscillator in a plan view from both sides, and forms a space between the facing photonic crystal oscillators. Item 4. The optical cantilever according to any one of Items 1 to 3.   The optical cantilever according to any one of claims 1 to 5, wherein the photonic crystal oscillator has holes arranged two-dimensionally.   The optical cantilever according to any one of claims 1 to 5, wherein the photonic crystal resonator includes a diffraction grating slit.   The optical cantilever according to any one of claims 1 to 7, wherein the different photonic crystal resonators have different compositions.   The optical cantilever according to claim 6, wherein the different photonic crystal resonators have different hole diameters.   The optical cantilever according to claim 1, wherein the different photonic crystal resonators have different thicknesses.