Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/35—Non-linear optics
  • G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/35—Non-linear optics
  • G02F1/3501—Constructional details or arrangements of non-linear optical devices, e.g. shape of non-linear crystals
  • G02F1/3509—Shape, e.g. shape of end face
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/35—Non-linear optics
  • G02F1/355—Non-linear optics characterised by the materials used
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/35—Non-linear optics
  • G02F1/37—Non-linear optics for second-harmonic generation
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/35—Non-linear optics
  • G02F1/37—Non-linear optics for second-harmonic generation
  • G02F1/377—Non-linear optics for second-harmonic generation in an optical waveguide structure
  • G02F1/3775—Non-linear optics for second-harmonic generation in an optical waveguide structure with a periodic structure, e.g. domain inversion, for quasi-phase-matching [QPM]

Definitions

• the present invention relates to a wavelength conversion element having a periodic polarization inversion structure and a method for manufacturing the same.
• a known light source for producing blue or green laser light for example, is one that combines a laser that oscillates with red light as the fundamental wave with a wavelength conversion element that functions as a second harmonic generator.
• wavelength conversion is performed by a QPM (Quasi-Phase Matching) structure that is realized using a periodic polarization inversion structure in which polarization inversion sections and non-polarization inversion sections are periodically alternated.
• Patent Document 1 describes a wavelength conversion element in which a periodic polarization inversion structure formed in an optical waveguide has first and second polarization inversion sections with different design widths arranged alternately, the difference between the design width of the first polarization inversion section and the design width of the second polarization inversion section is an odd multiple of the accuracy of the mask used to form the electrodes, and the design width of the non-polarization inversion section is approximately constant.
• the substrate surface is etched to observe the formation of periodic steps in the polarization inversion parts, thereby confirming that the periodic polarization inversion structure is correctly formed in the substrate.
• a bonding layer such as SiO2
• the bonding layer is formed on the steps formed by etching, so similar steps also occur on the surface of the bonding layer.
• a wavelength conversion element is produced by bonding the substrate to the support substrate via the bonding layer, a gap is formed between the bonding layer and the support substrate due to the steps on the bonding layer surface. Air bubbles can get caught in this gap and become trapped inside the wavelength conversion element, which can cause problems such as poor appearance.
• the present invention was made in consideration of the above, and its main objective is to realize a wavelength conversion element and a manufacturing method thereof that can prevent air bubbles from being trapped inside, even when the formation of a periodic polarization inversion structure is confirmed by etching.
• the manufacturing method of a wavelength conversion element according to the present invention is a manufacturing method of a wavelength conversion element having a periodic polarization inversion structure, and includes the steps of forming the periodic polarization inversion structure by alternately forming polarization inversion sections and non-polarization inversion sections on a ferroelectric substrate, etching the surface of the ferroelectric substrate on which the periodic polarization inversion structure is formed to form a step between the polarization inversion sections and the non-polarization inversion sections, forming a bonding layer with a first thickness on the ferroelectric substrate on which the step is formed, polishing the surface of the bonding layer so that the thickness of the bonding layer becomes a second thickness, and bonding a support substrate to the polished surface of the bonding layer.
• the wavelength conversion element according to the present invention has a periodic polarization inversion structure, in which polarization inversion sections and non-polarization inversion sections are alternately provided on a ferroelectric substrate, the periodic polarization inversion structure having a step between the polarization inversion sections and the non-polarization inversion sections, a bonding layer provided on the ferroelectric substrate having the step, and a support substrate bonded onto the bonding layer, the step being 10 to 40 nm, and the surface roughness of the bonding layer on the side of the support substrate being 2 nm or less.
• the present invention makes it possible to realize a wavelength conversion element and a manufacturing method thereof that can prevent air bubbles from being trapped inside, even when the formation of a periodic polarization inversion structure is confirmed by etching.
• FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a wavelength conversion element according to an embodiment of the present invention.
• 11A to 11C are diagrams illustrating a process for forming a periodically poled structure, among the processes for manufacturing a wavelength conversion element according to a comparative example.
• 11A to 11C are diagrams illustrating an etching process in the manufacturing process of a wavelength conversion element according to a comparative example.
• 11A and 11B are diagrams illustrating a bonding layer forming process in the manufacturing process of a wavelength conversion element according to a comparative example.
• 11A to 11C are diagrams illustrating a bonding process of a support substrate in the manufacturing process of a wavelength conversion element according to a comparative example.
• 4A to 4C are diagrams illustrating a process for forming a periodically poled structure, among the processes for manufacturing a wavelength conversion element according to an embodiment of the present invention.
• 4A to 4C are diagrams illustrating an etching process in the manufacturing process of a wavelength conversion element according to one embodiment of the present invention.
• 4A to 4C are diagrams illustrating a step of forming a bonding layer in the manufacturing process of a wavelength conversion element according to one embodiment of the present invention.
• 5A to 5C are diagrams illustrating a polishing step of a bonding layer in the manufacturing process of a wavelength conversion element according to an embodiment of the present invention.
• 5A to 5C are diagrams illustrating a bonding step of a support substrate in a manufacturing process of a wavelength conversion element according to an embodiment of the present invention.
• 1A to 1C are diagrams showing the observation results of the bonding layer surface before, during and after a polishing step.
• 13 is an image of a bonding layer of a wavelength conversion element according to a comparative example, observed with a dark-field microscope.
• 1 is an image of a bonding layer of a wavelength conversion element according to an embodiment of the present invention, observed with a dark-field microscope.
• (Structure of Wavelength Conversion Element) 1 is a schematic cross-sectional view showing a schematic configuration of a wavelength conversion element according to an embodiment of the present invention.
• the wavelength conversion element 100 has a structure in which a ferroelectric substrate 10 is bonded to a support substrate 40 via a bonding layer 20 and an adhesive layer 30.
• the ferroelectric substrate 10 is a substrate made of a ferroelectric material.
• the ferroelectric material constituting the ferroelectric substrate 10 may be, for example, MgO:LN (lithium niobate with MgO added) or MgO:LT (lithium tantalate with MgO added).
• the ferroelectric substrate 10 has polarization inversion sections 11 formed with a polarization direction opposite to that of other sections, which are periodically arranged at regular intervals. In other words, the ferroelectric substrate 10 has polarization inversion sections 11 and other sections (non-polarization inversion sections) periodically and alternately formed. This forms a periodic polarization inversion structure in the ferroelectric substrate 10.
• the bonding layer 20 is used to form a bonding surface when bonding the ferroelectric substrate 10 to the support substrate 40.
• a bonding surface suitable for bonding is formed on the bonding layer 20, and the ferroelectric substrate 10 can be firmly bonded to the support substrate 40.
• the periodic polarization inversion structure formed on the ferroelectric substrate 10 can be bonded to the support substrate 40 via the bonding layer 20 rather than directly to the support substrate 40, the periodic polarization inversion structure can also be protected.
• the bonding layer 20 is made of an amorphous material such as SiO2.
• an amorphous material such as SiO2.
• the bonding layer 20 can be formed by any suitable method. For example, it can be formed by physical vapor deposition such as sputtering, vacuum deposition, or ion beam assisted deposition (IAD), chemical vapor deposition, or atomic layer deposition (ALD).
• the bonding layer 20 can be formed at, for example, room temperature (25°C) to 300°C.
• the adhesive layer 30 bonds the ferroelectric substrate 10 to the support substrate 40 via the bonding layer 20.
• the adhesive layer 30 is made of, for example, a resin, and is interposed between the bonding layer 20 and the support substrate 40 to bond them together. That is, in the wavelength conversion element 100, the surface of the bonding layer 20 and the support substrate 40 are bonded via the adhesive layer 30.
• the support substrate 40 supports the ferroelectric substrate 10. Any suitable substrate may be used as the support substrate 40.
• the support substrate 40 may be made of a single crystal or a polycrystalline material. It may also be made of a metal.
• the material constituting the support substrate 40 is preferably selected from the group consisting of silicon, sialon, sapphire, cordierite, mullite, glass, quartz, crystal, alumina, SUS, iron-nickel alloy (42 alloy), LN (LiNbO3: lithium niobate), LT (LiTaO3: lithium tantalate), and brass. Any suitable thickness may be adopted as the thickness of the support substrate 40.
• the silicon may be single crystal silicon, polycrystalline silicon, or high resistance silicon.
• the support substrate 40 may be SOI (Silicon on Insulator).
• the above-mentioned sialon is a ceramic obtained by sintering a mixture of silicon nitride and alumina, and has a composition represented by, for example, Si6-wAlwOwN8-w.
• sialon has a composition in which alumina is mixed into silicon nitride, and w in the formula indicates the mixing ratio of alumina.
• w is preferably 0.5 or more and 4.0 or less.
• the sapphire is a single crystal having the composition Al2O3
• the alumina is a polycrystalline body having the composition Al2O3.
• the alumina is preferably translucent alumina.
• the cordierite is a ceramic with a composition of 2MgO.2Al2O3.5SiO2
• the mullite is a ceramic with a composition in the range of 3Al2O3.2SiO2 to 2Al2O3.SiO2.
• the wavelength conversion element 100 described above is used as a second harmonic generating element for converting the wavelength of red laser light, for example, to obtain blue or green laser light.
• the wavelength conversion element 100 may further have any layer. The type, function, number, combination, arrangement, etc. of such layers can be appropriately set according to the purpose.
• the wavelength conversion element 100 can be manufactured in any suitable shape. Furthermore, the size of the wavelength conversion element 100 can be appropriately set depending on the purpose.
• FIG. 2A shows the process of forming a periodic polarization inversion structure in the manufacturing process of a wavelength conversion element 110 according to a comparative example.
• a predetermined voltage is applied to the polarization inversion section 11 and other sections of a ferroelectric substrate 10 made of MgO:LN or MgO:LT, thereby forming the polarization inversion section 11 and non-polarization inversion sections alternately and periodically.
• FIG. 2B shows an etching process in the manufacturing process of the wavelength conversion element 110 according to the comparative example.
• a mixture of hydrofluoric acid and nitric acid is applied to the surface of the ferroelectric substrate 10 on which the periodic polarization inversion structure was formed in the manufacturing process of FIG. 2A, and etching is performed.
• the polarization inversion portion 11 and the non-polarization inversion portion are different, the polarization inversion portion 11 is eroded deeper than the non-polarization inversion portion, and a step 12 is formed between the polarization inversion portion 11 and the non-polarization inversion portion on the surface of the ferroelectric substrate 10.
• this step 12 it can be confirmed that a periodic polarization inversion structure has been formed in the ferroelectric substrate 10.
• FIG. 2C shows the bonding layer deposition process in the manufacturing process of the wavelength conversion element 110 according to the comparative example.
• a bonding layer 20 is formed by depositing an amorphous material such as SiO2 on the ferroelectric substrate 10 on which the steps 12 were formed in the etching process of FIG. 2B.
• various deposition methods can be used to form the bonding layer 20 so that the thickness from the surface of the ferroelectric substrate 10 is a predetermined thickness according to the deposition time. Therefore, steps 21 are formed on the surface of the bonding layer 20 in correspondence with the steps 12 on the surface of the ferroelectric substrate 10.
• FIG. 2D shows the bonding process of the support substrate in the manufacturing process of the wavelength conversion element 110 according to the comparative example.
• an adhesive layer 30 is formed by applying a resin or the like to the surface of the bonding layer 20 formed in the film formation process of FIG. 2C, and the support substrate 40 is placed on this adhesive layer 30.
• the bonding layer 20 and the support substrate 40 are bonded by the adhesive layer 30, and the ferroelectric substrate 10 and the support substrate 40 are bonded via the bonding layer 20 and the adhesive layer 30.
• the wavelength conversion element 110 of the comparative example is manufactured by carrying out the steps described above in FIG. 2A to FIG. 2D in order.
• a gap 31 is formed between the adhesive layer 30 and the support substrate 40.
• This gap 31 is formed because the adhesive layer 30 is formed along the step 21 on the surface of the bonding layer 20 in the bonding process of FIG. 2D, and the bonding layer 20 and the support substrate 40 are bonded through the adhesive layer 30 in this state. That is, in the manufacturing method of the wavelength conversion element according to the comparative example described in FIG. 2A to FIG. 2D, a step 12 is formed on the surface of the ferroelectric substrate 10 in the etching process of FIG. 2B, and a step 21 corresponding to the step 12 is formed on the surface of the bonding layer 20 formed in the subsequent film formation process of FIG. 2C, so that a gap 31 is formed between the adhesive layer 30 and the support substrate 40. In the bonding process of FIG. 2D, if air bubbles are caught in this gap 31, the wavelength conversion element 110 is manufactured with the air bubbles trapped inside.
• the wavelength conversion element 110 is constructed using at least a portion of a transparent material, since it is necessary to transmit the laser light that performs the wavelength conversion. Air bubbles trapped inside the wavelength conversion element 110 can be seen from the outside through this transparent portion, which may cause poor appearance. In addition, the expansion and contraction of air bubbles due to temperature changes may lead to defects such as poor bonding. In other words, in the wavelength conversion element 110 according to the comparative example, a gap 31 is formed between the adhesive layer 30 and the support substrate 40, which may cause these problems.
• Figure 3A shows the process of forming a periodic polarization inversion structure in the manufacturing process of a wavelength conversion element 100 according to one embodiment of the present invention.
• a periodic polarization inversion structure is formed in the ferroelectric substrate 10 by periodically and alternately forming polarization inversion parts 11 and non-polarization inversion parts in the ferroelectric substrate 10 using a method similar to that of the process of forming a periodic polarization inversion structure in the comparative example described in Figure 2A.
• FIG. 3B shows an etching process in the manufacturing process of a wavelength conversion element 100 according to one embodiment of the present invention.
• a step 12 is formed between the polarization inversion portion 11 and the non-polarization inversion portion by etching the surface of the ferroelectric substrate 10 on which a periodic polarization inversion structure was formed in the manufacturing process of FIG. 3A.
• the height of the step 12 is, for example, 10 to 40 nm.
• FIG. 3C shows the bonding layer deposition process in the manufacturing process of the wavelength conversion element 100 according to one embodiment of the present invention.
• a bonding layer 20 is deposited on the ferroelectric substrate 10 on which the step 12 was formed in the etching process in FIG. 3B.
• a step 21 is formed on the surface of the bonding layer 20 in correspondence with the step 12 on the surface of the ferroelectric substrate 10.
• the first thickness is, for example, 480 to 700 nm.
• FIG. 3D shows a polishing step of the bonding layer in the manufacturing process of the wavelength conversion element 100 according to one embodiment of the present invention.
• the bonding layer 20 formed in the film formation step of FIG. 3C is subjected to processing such as grinding and polishing until the thickness of the bonding layer 20 reaches a predetermined thickness (second thickness).
• second thickness a predetermined thickness
• the step 21 that existed on the surface of the bonding layer 20 at the end of the film formation step of FIG. 3C is eliminated, and for example, the unevenness of the surface of the bonding layer 20 (the surface that is bonded to the support substrate 40) is reduced to 2 nm or less, so that a flat surface is formed.
• the difference in thickness of the bonding layer 20 before and after polishing can be, for example, 5 to 15 times the height of the step 12 (step 21), and more preferably, 5 to 10 times. Within this range, it is possible to sufficiently flatten the surface of the bonding layer 20 while maintaining the necessary thickness of the bonding layer 20 after polishing.
• the second thickness is, for example, 380 to 500 nm.
• Figure 3E shows the bonding process of the support substrate in the manufacturing process of the wavelength conversion element 100 according to one embodiment of the present invention.
• an adhesive layer 30 is formed by applying a resin or the like to the surface of the bonding layer 20 polished in the polishing process of Figure 2D, similar to the bonding process in the comparative example described in Figure 2D, and the support substrate 40 is placed on this adhesive layer 30.
• the bonding layer 20 and the support substrate 40 are bonded by the adhesive layer 30, and the ferroelectric substrate 10 and the support substrate 40 are bonded via the bonding layer 20 and the adhesive layer 30.
• the wavelength conversion element 100 of this embodiment is manufactured by carrying out the steps described above in Figures 3A to 3E in order.
• the wavelength conversion element 100 of this embodiment can solve the problems that occur in the wavelength conversion element 110 of the comparative example described above. Specifically, since the step 21 is removed from the surface of the bonding layer 20 in the polishing step of FIG. 3D, when the adhesive layer 30 is formed in the subsequent bonding step of FIG. 3E, the gap 31 as shown in FIG. 2D is not formed between the adhesive layer 30 and the support substrate 40. Therefore, the wavelength conversion element 100 can prevent air bubbles from being trapped inside, and it is possible to avoid problems such as poor appearance and poor bonding caused by air bubbles.
• cleaning methods include wet cleaning, dry cleaning, and scrub cleaning.
• scrub cleaning is preferable because it is simple and efficient.
• a specific example of scrub cleaning is a method in which a cleaning agent (e.g., Sun Wash series manufactured by Lion Corporation) is used, followed by cleaning with a scrub cleaner using a solvent (e.g., a mixed solution of acetone and isopropyl alcohol (IPA)).
• a cleaning agent e.g., Sun Wash series manufactured by Lion Corporation
• IPA isopropyl alcohol
• a ferroelectric substrate 10 was prepared using MgO:LN, a 4 inch diameter x 0.3 mm thick lithium niobate single crystal doped with 5% magnesium. Multiple electrodes were placed at regular intervals on this ferroelectric substrate 10 and connected to a power source. A pulsed voltage of 1.4 kV (pulse width 20 msec, 25 Hz, 4 pulses, upper limit of applied current 2 mA) was generated from the power source, and the periodic polarization inversion structure formation process of FIG. 3A was carried out, forming a periodic polarization inversion structure.
• the etching process of FIG. 3B was performed by etching the surface of the ferroelectric substrate 10 using a mixed solution of hydrofluoric acid (aqueous solution of hydrogen fluoride) and nitric acid, and a step 12 was formed between the polarization inversion portion 11 and the non-polarization inversion portion.
• the etching process of FIG. 3B may be performed using an aqueous solution of hydrogen fluoride with a concentration of 50 wt % instead of the mixed solution of hydrofluoric acid and nitric acid.
• a SiO2 film with a thickness of 540 nm was formed by sputtering on the surface of the ferroelectric substrate 10 on which the step 12 was formed, thereby carrying out the film formation process shown in FIG. 3C, and a bonding layer 20 was formed on the ferroelectric substrate 10.
• a predetermined area of the surface of this bonding layer 20 was then observed with an atomic force microscope (AFM), and it was confirmed that a step 21 had been formed.
• Figure 4(a) shows the observation results of the surface of the bonding layer 20 after the film formation process (before the polishing process is carried out). In this state, it was confirmed that a step 21 with a height of about 13 nm was formed on the surface of the bonding layer 20.
• polishing process of FIG. 3D was carried out by polishing the surface of the bonding layer 20 by chemical mechanical polishing (CMP).
• CMP chemical mechanical polishing
• the surface of the bonding layer 20 was polished by about 100 nm until the thickness of the bonding layer 20 became 440 nm from 540 nm, so that the surface of the bonding layer 20 became uniform.
• AFM atomic force microscope
• Figure 4(b) shows the observation result of the surface of the bonding layer 20 during the polishing process.
• Figure 4(b) shows the observation result after the surface of the bonding layer 20 has been polished by 50 nm. In this state, the height of the step 21 has been reduced to about 3 nm, but it was confirmed that the step 21 has not yet been completely removed.
• Figure 4(c) shows the observation results of the surface of the bonding layer 20 after the polishing process.
• Figure 4(c) shows the observation results after the surface of the bonding layer 20 has been polished by 100 nm. In this state, it was confirmed that the step 21 has almost completely disappeared (less than 2 nm) and the surface of the bonding layer 20 has become flat.
• a resin e.g., epoxy resin
• the support substrate 40 was placed on the adhesive layer 30 and the adhesive layer 30 was dried, thereby carrying out the bonding process shown in FIG. 3E.
• a wavelength conversion element 100 having the structure shown in FIG. 1 was obtained.
• the air bubbles trapped inside the wavelength conversion element 110 appear brighter than other parts. This shows that a large number of air bubbles are trapped inside the wavelength conversion element 110.
• FIG. 5B it can be seen that there are no air bubbles inside the wavelength conversion element 100, and that the trapping of air bubbles inside has been suppressed.
• the manufacturing method of the wavelength conversion element 100 having a periodic polarization inversion structure includes forming a periodic polarization inversion structure by alternately forming polarization inversion parts 11 and non-polarization inversion parts on the ferroelectric substrate 10 (FIG. 3A: forming process of periodic polarization inversion structure), etching the surface of the ferroelectric substrate 10 on which the periodic polarization inversion structure is formed to form a step 12 between the polarization inversion parts 11 and the non-polarization inversion parts (FIG. 3B: etching process), forming a bonding layer 20 with a first thickness on the ferroelectric substrate 10 on which the step 12 is formed (FIG.
• FIG. 3A forming process of periodic polarization inversion structure
• FIG. 3B etching process
• FIG. 3C forming process of bonding layer
• FIG. 3D polishing process of bonding layer
• FIG. 3E bonding process of supporting substrate
• the difference between the first thickness and the second thickness of the bonding layer 20 is 5 to 15 times the height of the step 12. In this way, the thickness of the bonding layer 20 after polishing can be maintained while the surface of the bonding layer 20 can be sufficiently flattened.
• This adhesive layer 30 is made of, for example, a resin. In this way, the surface of the bonding layer 20 and the support substrate 40 can be bonded easily and firmly.
• the ferroelectric substrate 10 can be made of either MgO:LN or MgO:LT. In this way, the ferroelectric substrate 10 can be made of any material depending on the application.

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• Optics & Photonics (AREA)
• Chemical & Material Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

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Citations (5)

• 2023
  • 2023-10-19 JP JP2024565630A patent/JP7825740B2/ja active Active
  • 2023-10-19 WO PCT/JP2023/037937 patent/WO2024135076A1/ja not_active Ceased
• 2025
  • 2025-06-11 US US19/234,352 patent/US20250306429A1/en active Pending

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