Loading type electro-optical modulator based on high-performance ferroelectric single crystal PIN-PMN-PT and preparation method of loading type electro-optical modulator

Abstract

The invention discloses a loading type electro-optical modulator based on high-performance ferroelectric single crystal PIN-PMN-PT and a preparation method of the loading type electro-optical modulator, the electro-optical modulator comprises a PIN-PMN-PT substrate, a straight waveguide layer covers a middle area on the PIN-PMN-PT substrate, upper cladding layers cover the PIN-PMN-PT substrate and the straight waveguide layer, and lower cladding layers cover the upper cladding layers. Modulation electrodes which are located on the two sides of the straight waveguide layer and are parallel to the long edge of the straight waveguide layer are arranged on the upper cladding, and the modulation electrodes are rectangular traveling wave electrodes; a PIN-PMN-PT single crystal with a high linear electro-optical coefficient and an amorphous silicon material are adopted to prepare the novel loading type electro-optical modulator, and an external electric field is applied to the modulator, so that the change of an optical carrier phase is realized, the effect of modulating an optical wave is achieved, and the technical problems that an existing electro-optical modulator is relatively high in driving voltage and high in integration difficulty are solved; according to the loading type electro-optical modulator prepared by the invention, the driving voltage of the electro-optical modulator can be reduced, the modulation efficiency is improved, the modulation length is shortened, and miniaturization and low power consumption are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber communication systems, and in particular to a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT and a preparation method thereof. Background Art

[0002] The electro-optic modulator is a key component of the optical transceiver module in the optical fiber communication system. It can convert electrical signals into optical signals for long-distance transmission and communication in the optical fiber network. Nowadays, as the data transmission rate of the optical fiber communication system increases exponentially, higher requirements are placed on the modulation bandwidth (3dB electro-optic bandwidth), modulation rate, and integration of the electro-optic modulator.

[0003] Currently, common commercial electro-optic modulators include silicon-based electro-optic modulators, indium phosphide-based electro-optic modulators, lithium niobate-based electro-optic modulators, etc. Silicon-based modulators are mainly based on the plasma dispersion effect, so the modulation rate is limited and the modulation linearity is low. The modulation rate of lithium niobate-based electro-optic modulators is high, but their electro-optic coefficients are relatively low, resulting in large device size and power consumption. Both of the above modulators require a high driving voltage (half-wave voltage), which makes it difficult to meet the requirements of miniaturization and easy integration.

[0004] Lead indium niobate-lead magnesium niobate-lead titanate (PIN-PMN-PT) single crystal is a high-performance ferroelectric single crystal material. Its electro-optical response mechanism is the same as that of lithium niobate crystal, but its electro-optic coefficient can reach up to 900pm / V, which is 30 times that of lithium niobate crystal. Therefore, it can be used in low driving voltage, high modulation efficiency, and integrated electro-optic modulators.

[0005] In recent years, the excellent electro-optical properties of PMN-PT crystals have been verified. In 2021, Zhang Yongcheng et al. (ZeFang, Xiaodong Jiang, Yongcheng Zhang*, et al. Ultra-transparent PMN-PT Electro-Optic Ceramics and its Application in Optical Communication, Advanced Optical Materials, 9, 2002139 (2021).) from Qingdao University successfully prepared highly transparent Sm-doped PMN-PT electro-optical crystals with a transmittance of 70% and a secondary electro-optic coefficient of 35×10 -16 m 2 / V 2, the half-wave voltage is 113V (d=L=1mm), which verifies the application prospect of Sm-doped PMN-PT crystal in the field of electro-optic modulation, but its half-wave voltage-length product of 11.3V·cm is much higher than that of other electro-optic crystal materials; Liu Xin et al. from Xi'an Jiaotong University (Liu X, Tan P, Ma X, Wang D, JinX, LiuY, Xu B, Qiao L, Qiu C, Wang B, Zhao W, Wei C, 7Song K, Guo H, Li X, Li S, Wei X, Chen LQ, Xu Z, Li F*, Tian Hao*, and Zhang S*. Ferroelectric crystals with giant electro-optic property enabling ultracompact Q-switches. Science, 376, 371-377 (2022).) Through the coordinated design of crystal orientation and polarization technology, ultra-high electro-optical performance was obtained in the ternary PIN-PMN-PT crystal, and an electro-optic Q-switched switch based on the PIN-PMN-PT single crystal was developed. The linear electro-optic coefficient of this crystal is more than 30 times that of conventional electro-optic crystals and higher than the previously reported binary PMN-PT single crystal. However, due to the processing technology limitations of the electro-optic Q-switched switch, its half-wave voltage is as high as 200V, which does not reach the theoretical limit of the crystal. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT and a preparation method thereof. A new loaded electro-optic modulator is prepared by using a PIN-PMN-PT single crystal with a high linear electro-optic coefficient and an amorphous silicon material. By applying an external electric field to the modulator, the phase of the optical carrier is changed, thereby achieving the effect of modulating the light wave, solving the technical problems of the existing electro-optic modulator having a high driving voltage and a high integration difficulty. The loaded electro-optic modulator prepared by the present invention can reduce the driving voltage of the electro-optic modulator, improve the modulation efficiency, shorten the modulation length, and achieve miniaturization and low power consumption.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT comprises a PIN-PMN-PT substrate 1, wherein the middle region of the PIN-PMN-PT substrate 1 is covered with a straight waveguide layer 2, and the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 are both covered with an upper cladding layer 3; the upper cladding layer 3 is provided with modulation electrodes 4 located on both sides of the straight waveguide layer 2 and parallel to the long sides of the straight waveguide layer 2, and the modulation electrodes 4 are rectangular traveling wave electrodes.

[0009] The PIN-PMN-PT substrate 1 is a PIN-PMN-PT single crystal grown along

[011] , the straight waveguide layer 2 is an amorphous Si thin film waveguide, the upper cladding layer 3 is a SiO2 thin film, and the two modulation electrodes 4 are symmetrical gold electrodes.

[0010] The thickness H3 of the PIN-PMN-PT substrate 1 is 0.3-1mm; the thickness H4 of the straight waveguide layer 2 is 0.3-1μm; the width W3 of the straight waveguide layer 2 is 5-10μm; the thickness H2 of the upper cladding layer 3 is 0.5-1μm; the thickness H1 of the modulation electrode 4 is 0.5-1um, the width W1 of the modulation electrode 4 is 30-80μm, and the width W2 between the two modulation electrodes 4 is 10-50μm; the lengths L of the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3 and the modulation electrode 4 are the same, all of which are 5-10mm.

[0011] The thickness H4 of the straight waveguide layer 2 is 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm, and the width W3 of the straight waveguide layer 2 is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm; the thickness H2 of the upper cladding layer 3 is 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm; the thickness H1 of the modulation electrode 4 is 0.5 μm, 0.6 μm, 0.7 μm m, 0.8μm, 0.9μm or 1μm, the width W1 of the modulation electrode 4 is 30μm, 40μm, 50μm, 60μm, 70μm or 80μm, the width W2 between two modulation electrodes 4 is 10μm, 20μm, 30μm, 40μm or 50μm; the length L of the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding 3 and the modulation electrode 4 are the same, which are 5mm, 6mm, 7mm, 8mm, 9mm or 10mm.

[0012] The refractive index n1 of the straight waveguide layer 2 is greater than the refractive index n2 of the PIN-PMN-PT substrate 1 .

[0013] The electro-optic modulator couples light waves into the transmission waveguide by end face coupling, that is, the incident light wave 5 is vertically incident from one end face of the short side of the straight waveguide layer 2, and the modulated light wave 6 is output from the other end face.

[0014] A method for preparing a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT comprises the following steps:

[0015] Step 1: Orient the PIN-PMN-PT single crystal ingot, mark the

[100] direction of the crystal, and cut it along the marked

[100] direction to obtain a PIN-PMN-PT single crystal wafer grown along

[011] ; then cut the PIN-PMN-PT single crystal wafer to obtain a PIN-PMN-PT single crystal wafer of a desired size;

[0016] Step 2: performing high temperature annealing treatment on the PIN-PMN-PT single crystal wafer obtained in step 1;

[0017] Step 3: performing optical-grade polishing on the PIN-PMN-PT crystal wafer annealed in step 2 to obtain a PIN-PMN-PT crystal wafer with a surface roughness of 0.6-1 nm, i.e., a PIN-PMN-PT substrate 1; the thickness of the polished PIN-PMN-PT substrate 1 is 0.3-1 mm;

[0018] Step 4: using chemical vapor deposition to deposit amorphous Si on the surface of the PIN-PMN-PT substrate 1 to form an amorphous Si film with a thickness of 0.3-1 μm; then using deep ultraviolet lithography to photoetch a strip straight waveguide pattern on the amorphous Si film to form a straight waveguide layer 2;

[0019] Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 after the treatment in step 4 by chemical vapor deposition to form a SiO2 film with a thickness of 0.5-1.5 μm, i.e., the upper cladding layer 3;

[0020] Step 6: sputter a gold film with a thickness of 0.5-1 μm on the surface of the upper cladding layer 3 obtained in step 5 by using a magnetron sputtering process, and then photoetch a pair of gold electrode patterns located on both sides of the straight waveguide and parallel to the straight waveguide on the surface of the gold film by using an ultraviolet photolithography process to form two modulation electrodes 4, wherein the etching width between the two modulation electrodes 4 is 10-50 μm, and the width of the modulation electrode 4 is 30-80 μm;

[0021] Step 7: Use magnetron sputtering technology to sputter a gold film with a thickness of 10-20nm along the two side surfaces parallel to the incident direction of the light wave on the crystal device processed in step 6, and then use a high-voltage polarizer to perform high-temperature polarization treatment. After cooling to room temperature, a loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT is obtained.

[0022] In step 2, the annealing temperature is 600-850° C., and the holding time is 8-12 hours.

[0023] In step 4, the deposition temperature is 80-120° C., and the deposition time is 6-14 min; in step 5, the deposition temperature is 300-350° C., and the deposition time is 3-4.5 h; in step 4, the etching temperature is 100-140° C., and in step 6, the etching temperature is 85-105° C.

[0024] In step 7, the polarization temperature is 110-140° C., the polarization voltage is 50-110 V, the voltage increase / decrease time is 30-50 s, the voltage increase / decrease rate is 1-3 V / s, and the cooling rate is 1-3° C. / min.

[0025] Compared with the existing commercial electro-optic modulator, the beneficial effects of the present invention are as follows:

[0026] 1. The present invention adopts PIN-PMN-PT single crystal as the substrate. The half-wave voltage of the electro-optic modulator is inversely proportional to the length of the modulation area. The PIN-PMN-PT single crystal has an ultra-high electro-optic coefficient (γ 33 >400pm / V), so the present invention can realize an electro-optic modulator with a smaller size, which is easier to integrate and works at a low driving voltage.

[0027] 2. The present invention adopts PIN-PMN-PT single crystal as the substrate. Since its electro-optic coefficient can be as high as more than 900pm / V, and the half-wave voltage of the electro-optic modulator is inversely proportional to the electro-optic coefficient, the loaded electro-optic modulator prepared by the present invention has a lower half-wave voltage. At the same time, since the refractive index of the PIN-PMN-PT single crystal in the microwave band is relatively high, the SiO2 cladding is filled between the straight waveguide layer and the modulation electrode, which can reduce the overall microwave effective refractive index of the electro-optic modulator, greatly improving the refractive index matching between microwaves and light waves.

[0028] 3. The present invention adopts a loaded amorphous silicon thin film straight waveguide. By optimizing the film thickness, part of the incident light wave passes through the amorphous silicon thin film, and part of the incident light wave passes through the upper surface of the PIN-PMN-PT substrate, so that the incident light is constrained to the straight waveguide layer, achieving a full modulation effect.

[0029] 4. The present invention uses SiO2 cladding to reduce the scattering effect in light wave transmission and increase the binding force on the light field.

[0030] 5. In order to reduce the absorption of light waves by metal electrodes, the present invention places the modulation electrode on the SiO2 cladding, which reduces light loss and increases the overlap rate of the light field and the microwave electric field (increases the electro-optical overlap factor).

[0031] In summary, compared with the prior art, the present invention adopts PIN-PMN-PT single crystal with high linear electro-optic coefficient and amorphous silicon material to prepare a new type of loaded electro-optic modulator, and realizes the change of the phase of the optical carrier by applying an external electric field to the modulator, thereby achieving the effect of modulating the light wave, and solves the technical problems of high driving voltage and high integration difficulty of the existing electro-optic modulator; the loaded electro-optic modulator prepared by the present invention can reduce the driving voltage of the electro-optic modulator, improve the modulation efficiency, shorten the modulation length, and achieve miniaturization and low power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of the loaded electro-optic modulator based on the high-performance ferroelectric single crystal PIN-PMN-PT of the present invention.

[0033] Figure 2 It is a schematic diagram of the cross-sectional two-dimensional structure of the loaded electro-optic modulator based on the high-performance ferroelectric single crystal PIN-PMN-PT of the present invention.

[0034] Figure 3 This is a test diagram of electrical performance of the loaded electro-optic modulator based on the high-performance ferroelectric single crystal PIN-PMN-PT of the present invention.

[0035] In the figure: PIN-PMN-PT substrate 1, straight waveguide layer 2, upper cladding layer 3, modulation electrode 4, incident light wave 5, light wave 6. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0037] like Figure 1 As shown, a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT comprises a PIN-PMN-PT substrate 1, wherein the middle area on the PIN-PMN-PT substrate 1 is covered with a straight waveguide layer 2, and the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 are both covered with an upper cladding layer 3; the upper cladding layer 3 is provided with modulation electrodes 4 located on both sides of the straight waveguide layer 2 and parallel to the long sides of the straight waveguide layer 2, and the modulation electrodes 4 are rectangular traveling wave electrodes.

[0038] The PIN-PMN-PT substrate 1 is a PIN-PMN-PT single crystal grown along

[011] , the straight waveguide layer 2 is an amorphous Si thin film waveguide, the upper cladding layer 3 is a SiO2 thin film, and the two modulation electrodes 4 are symmetrical gold electrodes; the refractive index n1 of the straight waveguide layer 2 is greater than the refractive index n2 of the PIN-PMN-PT substrate 1, and has a higher refractive index difference, which greatly enhances the light binding ability.

[0039] like Figure 2 As shown, the thickness H3 of the PIN-PMN-PT substrate 1 is 0.3-1 mm; the thickness H4 of the straight waveguide layer 2 is 0.3-1 μm, preferably 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm; the width W3 of the straight waveguide layer 2 is 5-10 μm, preferably 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm; the thickness H2 of the upper cladding layer 3 is 0.5-1 μm, preferably 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm; the thickness H1 of the modulation electrode 4 is 0.5-1 μm m, preferably 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm or 1μm, the width W1 of the modulation electrode 4 is 30-80μm, preferably 30μm, 40μm, 50μm, 60μm, 70μm or 80μm, the width W2 between two modulation electrodes 4 is 10-50μm, preferably 10μm, 20μm, 30μm, 40μm or 50μm; the length L of the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3 and the modulation electrode 4 are the same, all of which are 5-10mm, preferably 5mm, 6mm, 7mm, 8mm, 9mm or 10mm.

[0040] The radio frequency signal is applied to the surface of the modulation electrode 4. In the modulation area, the PIN-PMN-PT single crystal produces a linear electro-optical effect, so that the phase of the optical carrier transmitted in the crystal changes under the action of the external electric field, thereby realizing phase modulation of the optical field.

[0041] The present invention couples light waves into the transmission waveguide by end face coupling, that is, the incident light wave 5 is vertically incident from one end face of the short side of the straight waveguide layer 2, and the modulated light wave 6 is output from the other end face.

[0042] like Figure 3 As shown, a method for preparing a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT comprises the following steps:

[0043] Step 1: Orient the PIN-PMN-PT single crystal ingot by XRD diffractometer, mark the

[100] direction of the crystal, cut it along the marked

[100] direction by wire cutting machine, and obtain a PIN-PMN-PT single crystal wafer grown along

[011] ; then cut the PIN-PMN-PT single crystal wafer by dicing machine to obtain a PIN-PMN-PT single crystal wafer of required size;

[0044] The preparation process of the PIN-PMN-PT single crystal ingot is as follows:

[0045] The crucible descent method (Bridgman method) is used for directional growth to obtain a PIN-PMN-PT single crystal ingot, that is, during the experimental process of crystal growth, the PIN-PMN-PT ceramic block is placed inside a cylindrical crucible, and then undergoes a controlled slow descent process of 6 mm / day, and passes through a heating furnace with a certain temperature range of 1150°C-1400°C, and the furnace temperature is precisely controlled to a narrow range slightly higher than the melting point of the material; when the crucible passes through the heating area, the material inside it is heated and melted to form a liquid; as the crucible continues to steadily descend, the bottom of the crucible is the first to leave the high-temperature area, and the temperature drops below the melting point, thereby triggering the crystallization process; in this process, the crystal continues to grow as the crucible descends, until a PIN-PMN-PT single crystal ingot with a perovskite crystal structure is finally formed;

[0046] Step 2: performing high temperature annealing treatment on the PIN-PMN-PT single crystal wafer obtained in step 1 to remove residual stress and supplement missing oxygen vacancies; the annealing temperature is 600-850° C. and the holding time is 8-12 hours;

[0047] Step 3: using a grinding and polishing machine to perform optical-grade polishing on the surface of the PIN-PMN-PT crystal wafer annealed in step 2 to remove scratches and cuts on the crystal surface, thereby obtaining a PIN-PMN-PT crystal wafer with a surface roughness of 0.6-1 nm, i.e., a PIN-PMN-PT substrate 1; the thickness of the polished PIN-PMN-PT substrate 1 is 0.3-1 mm;

[0048] Step 4: using chemical vapor deposition to deposit amorphous Si on the surface of the PIN-PMN-PT substrate 1 to form an amorphous Si film with a thickness of 0.3-1 μm, the deposition temperature is 80-120° C., and the deposition time is 6-14 min; then using deep ultraviolet lithography to photoetch a strip straight waveguide pattern on the amorphous Si film to form a straight waveguide layer 2; the etching temperature is 100-140° C.;

[0049] Step 5: using chemical vapor deposition to deposit SiO2 on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 treated in step 4 to form a SiO2 film with a thickness of 0.5-1.5 μm, i.e., the upper cladding layer 3; the deposition temperature is 300-350° C., and the deposition time is 3-4.5 h;

[0050] Step 6: sputter a gold film with a thickness of 0.5-1 μm on the surface of the upper cladding layer 3 obtained in step 5 by using a magnetron sputtering process, and then photoetch a pair of gold electrode patterns located on both sides of the straight waveguide and parallel to the straight waveguide on the surface of the gold film by using an ultraviolet photolithography process to form two modulation electrodes 4, wherein the etching width between the two modulation electrodes 4 is 10-50 μm, and the width of the modulation electrode 4 is 30-80 μm; the etching temperature is 85-105° C.;

[0051] Step 7: Use a magnetron sputtering process to sputter a gold film with a thickness of 10-20nm on both sides of the crystal device processed in step 6 parallel to the incident direction of the light wave, and then use a high-voltage polarizer (model: Bailibo MPD) to perform high-temperature polarization treatment to make it have piezoelectric and electro-optical properties. Then, after cooling to room temperature, a loaded electro-optical modulator based on high-performance ferroelectric single crystal PIN-PMN-PT is obtained; the polarization temperature is 110-140°C, the polarization voltage is 50-110V, the step-up and step-down time is 30-50s, the step-up and step-down rate is 1-3V / s, and the cooling rate is 1-3°C / min.

[0052] The loaded electro-optic modulator based on the high-performance ferroelectric single crystal PIN-PMN-PT prepared by the present invention has the following performance effects: insertion loss <10dB, transmission loss <2.5dB, 3dB electro-optic bandwidth >10GHz, half-wave voltage <2V, modulation rate >40Gbps.

[0053] Example 1

[0054] A loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT, wherein the width of the PIN-PMN-PT substrate 1 is 70 μm; the width W3 of the straight waveguide layer 2 is 5 μm; the width W1 of the modulation electrode 4 is 30 μm, and the lengths L of the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3 and the modulation electrode 4 are the same, all being 5 mm.

[0055] A method for preparing a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT comprises the following steps:

[0056] Step 1: Orient the PIN-PMN-PT single crystal ingot by XRD diffractometer, mark the

[100] direction of the crystal, cut it along the marked

[100] direction by wire cutting machine, and obtain a PIN-PMN-PT single crystal wafer grown along

[011] ; then cut the PIN-PMN-PT single crystal wafer by dicing machine to obtain a PIN-PMN-PT single crystal wafer of required size;

[0057] Step 2: annealing the PIN-PMN-PT single crystal obtained in step 1 at 600°C for 12h;

[0058] Step 3: using a grinding and polishing machine to perform optical-grade polishing on the surface of the PIN-PMN-PT crystal annealed in step 2 to obtain a PIN-PMN-PT crystal with a surface roughness of 1 nm, i.e., a PIN-PMN-PT substrate 1; the thickness of the PIN-PMN-PT substrate 1 after polishing is 0.3 mm;

[0059] Step 4: using chemical vapor deposition to deposit amorphous Si on the surface of the PIN-PMN-PT substrate 1 to form an amorphous Si film with a thickness of 0.3 μm, the deposition temperature is 80°C, and the deposition time is 8 min; then using deep ultraviolet lithography to photoetch a strip straight waveguide pattern on the amorphous Si film to form a straight waveguide layer 2 with a width of 5 μm; the etching temperature is 100°C;

[0060] Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 after the treatment in step 4 by chemical vapor deposition to form a SiO2 film with a thickness of 0.5 μm, i.e., the upper cladding layer 3; the deposition temperature is 350° C., and the deposition time is 3 h;

[0061] Step 6: A gold film with a thickness of 0.5 μm is sputtered on the surface of the upper cladding layer 3 obtained in step 5 by using a magnetron sputtering process, and then a pair of gold electrode patterns located on both sides of the straight waveguide layer 2 and parallel to the straight waveguide layer 2 are photoetched on the surface of the gold film by using an ultraviolet photolithography process to form two modulation electrodes 4, and the etching width between the two modulation electrodes 4 is 10 μm; the etching temperature is 85° C.;

[0062] Step 7: Use a magnetron sputtering process to sputter gold along the two side surfaces parallel to the incident direction of the light wave on the crystal device processed in step 6 to form a gold film with a thickness of 10 nm, and then use a high-voltage polarizer to perform high-temperature polarization treatment to give it piezoelectric and electro-optical properties. Then, after cooling to room temperature, a loaded electro-optical modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT is obtained; the polarization temperature is 120°C, the polarization voltage is 50V, the step-up and step-down time is 50s, the step-up and step-down rate is 1V / s, and the cooling rate is 1°C / min.

[0063] The high-performance ferroelectric single crystal PIN-PMN-PT electro-optic modulator prepared in Example 1 of the present invention was tested at room temperature, and its insertion loss was 10dB, transmission loss was 2dB, 3dB electro-optic bandwidth was 21GHz, half-wave voltage was 1.98V, and modulation rate was 55Gbps.

[0064] Example 2

[0065] A loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT, wherein the width of the PIN-PMN-PT substrate 1 is 100 μm; the width W3 of the straight waveguide layer 2 is 6 μm; the width W1 of the modulation electrode 4 is 40 μm, and the lengths L of the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3 and the modulation electrode 4 are the same, all being 6 mm.

[0066] A method for preparing a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT comprises the following steps:

[0067] Step 1: Orient the PIN-PMN-PT single crystal ingot by XRD diffractometer, mark the

[100] direction of the crystal, cut it along the marked

[100] direction by wire cutting machine, and obtain a PIN-PMN-PT single crystal wafer grown along

[011] ; then cut the PIN-PMN-PT single crystal wafer by dicing machine to obtain a PIN-PMN-PT single crystal wafer of required size;

[0068] Step 2: annealing the PIN-PMN-PT single crystal obtained in step 1 at 700°C for 11h;

[0069] Step 3: using a grinding and polishing machine to perform optical-grade polishing on the surface of the PIN-PMN-PT crystal annealed in step 2 to obtain a PIN-PMN-PT crystal with a surface roughness of 0.9 nm, i.e., a PIN-PMN-PT substrate 1; the thickness of the PIN-PMN-PT substrate 1 after polishing is 0.55 mm;

[0070] Step 4: using chemical vapor deposition to deposit amorphous Si on the surface of the PIN-PMN-PT substrate 1 to form an amorphous Si film with a thickness of 0.5 μm, the deposition temperature is 90° C., and the deposition time is 6 min; then using deep ultraviolet lithography to photoetch a strip straight waveguide pattern on the amorphous Si film to form a straight waveguide layer 2 with a width of 6 μm, the etching temperature is 110° C.;

[0071] Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 after the treatment in step 4 by chemical vapor deposition to form a SiO2 film with a thickness of 0.6 μm, i.e., the upper cladding layer 3; the deposition temperature is 330° C., and the deposition time is 3.5 h;

[0072] Step 6: A gold film with a thickness of 0.9 μm is sputtered on the surface of the upper cladding layer 3 obtained in step 5 by using a magnetron sputtering process, and then a pair of gold electrode patterns located on both sides of the straight waveguide layer 2 and parallel to the straight waveguide layer 2 are photoetched on the surface of the gold film by using an ultraviolet photolithography process to form two modulation electrodes 4, and the etching width between the two modulation electrodes 4 is 20 μm; the etching temperature is 90° C.;

[0073] Step 7: Use a magnetron sputtering process to spray gold on the two side surfaces of the crystal device processed in step 6 parallel to the incident direction of the light wave to form a gold film with a thickness of 20nm, and then use a high-voltage polarizer to perform high-temperature polarization treatment to make it have piezoelectric and electro-optical properties. Then, after cooling to room temperature, a loaded electro-optical modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT is obtained; the polarization temperature is 125°C, the polarization voltage is 60V, the step-up and step-down time is 30s, the step-up and step-down rate is 2V / s, and the cooling rate is 2°C / min.

[0074] The high-performance ferroelectric single crystal PIN-PMN-PT electro-optic modulator prepared in Example 2 of the present invention was tested at room temperature, and its insertion loss was 9.2dB, transmission loss was 1.8dB, 3dB electro-optic bandwidth was 20GHz, half-wave voltage was 1.9V, and modulation rate was 48Gbps.

[0075] Example 3

[0076] A loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT, wherein the width of the PIN-PMN-PT substrate 1 is 130 μm; the width W3 of the straight waveguide layer 2 is 8 μm; the width W1 of the modulation electrode 4 is 50 μm, and the lengths L of the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3 and the modulation electrode 4 are the same, all being 7 mm.

[0077] Step 1: Orient the PIN-PMN-PT single crystal ingot by XRD diffractometer, mark the

[100] direction of the crystal, cut it along the marked

[100] direction by wire cutting machine, and obtain a PIN-PMN-PT single crystal wafer grown along

[011] ; then cut the PIN-PMN-PT single crystal wafer by dicing machine to obtain a PIN-PMN-PT single crystal wafer of required size;

[0078] Step 2: annealing the PIN-PMN-PT single crystal obtained in step 1 at 750°C for 10 hours;

[0079] Step 3: using a grinding and polishing machine to perform optical-grade polishing on the surface of the PIN-PMN-PT crystal annealed in step 2 to obtain a PIN-PMN-PT crystal with a surface roughness of 0.8 nm, i.e., a PIN-PMN-PT substrate 1; the thickness of the PIN-PMN-PT substrate 1 after polishing is 0.75 mm;

[0080] Step 4: using chemical vapor deposition to deposit amorphous Si on the surface of the PIN-PMN-PT substrate 1 to form an amorphous Si film with a thickness of 0.6 μm, the deposition temperature is 100° C., and the deposition time is 8 min; then using deep ultraviolet lithography to photoetch a strip straight waveguide pattern on the amorphous Si film to form a straight waveguide layer 2 with a width of 7 μm; the etching temperature is 120° C.;

[0081] Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 after the treatment in step 4 by chemical vapor deposition to form a SiO2 film with a thickness of 0.8 μm, i.e., the upper cladding layer 3; the deposition temperature is 320° C., and the deposition time is 3.5 h;

[0082] Step 6: A gold film with a thickness of 0.8 μm is sputtered on the surface of the upper cladding layer 3 obtained in step 5 by using a magnetron sputtering process, and then a pair of gold electrode patterns located on both sides of the straight waveguide layer 2 and parallel to the straight waveguide layer 2 are photoetched on the surface of the gold film by using an ultraviolet photolithography process to form two modulation electrodes 4, and the etching width between the two modulation electrodes 4 is 30 μm; the etching temperature is 95° C.;

[0083] Step 7: Use a magnetron sputtering process to sputter a gold film with a thickness of 10 nm on both sides of the crystal device processed in step 6 parallel to the incident direction of the light wave; then use a high-voltage polarizer to perform high-temperature polarization treatment to give it piezoelectric and electro-optical properties, and then cool it to room temperature to obtain a loaded electro-optical modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT; the polarization temperature is 130°C, the polarization voltage is 65V, the step-up and step-down time is 33s, the step-up and step-down rate is 2V / s, and the cooling rate is 2°C / min.

[0084] The high-performance ferroelectric single crystal PIN-PMN-PT electro-optic modulator prepared in Example 3 of the present invention was tested at room temperature, and its insertion loss was 9.3dB, transmission loss was 1.9dB, 3dB electro-optic bandwidth was 17GHz, half-wave voltage was 1.63V, and modulation rate was 48Gbps.

[0085] Example 4

[0086] A loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT, wherein the width of the PIN-PMN-PT substrate 1 is 160 μm; the width W3 of the straight waveguide layer 2 is 9 μm; the width W1 of the modulation electrode 4 is 60 μm, and the lengths L of the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3 and the modulation electrode 4 are the same, all being 8 mm.

[0087] Step 1: Orient the PIN-PMN-PT single crystal ingot by XRD diffractometer, mark the

[100] direction of the crystal, cut it along the marked

[100] direction by wire cutting machine, and obtain a PIN-PMN-PT single crystal wafer grown along

[011] ; then cut the PIN-PMN-PT single crystal wafer by dicing machine to obtain a PIN-PMN-PT single crystal wafer of required size;

[0088] Step 2: annealing the PIN-PMN-PT single crystal obtained in step 1 at 800°C for 9h;

[0089] Step 3: using a grinding and polishing machine to perform optical-grade polishing on the surface of the PIN-PMN-PT crystal annealed in step 2 to obtain a PIN-PMN-PT crystal with a surface roughness of 0.7 nm, i.e., a PIN-PMN-PT substrate 1; the thickness of the PIN-PMN-PT substrate 1 after polishing is 0.85 mm;

[0090] Step 4: using chemical vapor deposition to deposit amorphous Si on the surface of the PIN-PMN-PT substrate 1 to form an amorphous Si film with a thickness of 0.9 μm, the deposition temperature is 110° C., and the deposition time is 12 min; then using deep ultraviolet lithography to photoetch a strip straight waveguide pattern on the amorphous Si film to form a straight waveguide layer 2 with a width of 9 μm; the etching temperature is 130° C.;

[0091] Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 after the treatment in step 4 by chemical vapor deposition to form a SiO2 film with a thickness of 0.9 μm, i.e., the upper cladding layer 3; the deposition temperature is 310° C., and the deposition time is 4 hours;

[0092] Step 6: A gold film with a thickness of 0.9 μm is sputtered on the surface of the upper cladding layer 3 obtained in step 5 by using a magnetron sputtering process, and then a pair of gold electrode patterns located on both sides of the straight waveguide layer 2 and parallel to the straight waveguide layer 2 are photoetched on the surface of the gold film by using an ultraviolet photolithography process to form two modulation electrodes 4, and the etching width between the two modulation electrodes 4 is 40 μm; the etching temperature is 100° C.;

[0093] Step 7: Use a magnetron sputtering process to sputter a gold film with a thickness of 10 nm on both sides of the crystal device processed in step 6 parallel to the incident direction of the light wave; then use a high-voltage polarizer to perform high-temperature polarization treatment to give it piezoelectric and electro-optical properties, and then cool it to room temperature to obtain a loaded electro-optical modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT; the polarization temperature is 135°C, the polarization voltage is 80V, the step-up and step-down time is 40s, the step-up and step-down rate is 2V / s, and the cooling rate is 2°C / min.

[0094] The high-performance ferroelectric single crystal PIN-PMN-PT electro-optic modulator prepared in Example 4 of the present invention was tested at room temperature, and its insertion loss was 8.8dB, transmission loss was 1.7dB, 3dB electro-optic bandwidth was 16GHz, half-wave voltage was 1.43V, and modulation rate was 46Gbps.

[0095] Example 5

[0096] A loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT, wherein the width of the PIN-PMN-PT substrate 1 is 210 μm; the width W3 of the straight waveguide layer 2 is 10 μm; the width W1 of the modulation electrode 4 is 80 μm, and the lengths L of the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3 and the modulation electrode 4 are the same, all being 10 mm.

[0097] Step 1: Orient the PIN-PMN-PT single crystal ingot by XRD diffractometer, mark the

[100] direction of the crystal, cut it along the marked

[100] direction by wire cutting machine, and obtain a PIN-PMN-PT single crystal wafer grown along

[011] ; then cut the PIN-PMN-PT single crystal wafer by dicing machine to obtain a PIN-PMN-PT single crystal wafer of required size;

[0098] Step 2: annealing the PIN-PMN-PT single crystal obtained in step 1 at 850°C for 8h;

[0099] Step 3: using a grinding and polishing machine to perform optical-grade polishing on the surface of the PIN-PMN-PT crystal annealed in step 2 to obtain a PIN-PMN-PT crystal with a surface roughness of 0.6 nm, i.e., a PIN-PMN-PT substrate 1; the thickness of the PIN-PMN-PT substrate 1 after polishing is 1 mm;

[0100] Step 4: using chemical vapor deposition to deposit amorphous Si on the surface of the PIN-PMN-PT substrate 1 to form an amorphous Si film with a thickness of 1 μm, the deposition temperature is 120°C, and the deposition time is 14 min; then using deep ultraviolet lithography to photoetch a strip straight waveguide pattern on the amorphous Si film to form a straight waveguide layer 2, the straight waveguide width is 10 μm; the etching temperature is 140°C;

[0101] Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 after the treatment in step 4 by chemical vapor deposition to form a SiO2 film with a thickness of 1 μm, i.e., the upper cladding layer 3; the deposition temperature is 300° C., and the deposition time is 4.5 h;

[0102] Step 6: A gold film with a thickness of 1 μm is sputtered on the surface of the upper cladding layer 3 obtained in step 5 by using a magnetron sputtering process, and then a pair of gold electrode patterns located on both sides of the straight waveguide layer 2 and parallel to the straight waveguide layer 2 are photoetched on the surface of the gold film by using an ultraviolet photolithography process to form two modulation electrodes 4, and the etching width between the two modulation electrodes 4 is 50 μm; the etching temperature is 105° C.;

[0103] Step 7: Use a magnetron sputtering process to sputter a gold film with a thickness of 10 nm on both sides of the crystal device processed in step 6 parallel to the incident direction of the light wave; then use a high-voltage polarizer to perform high-temperature polarization treatment to give it piezoelectric and electro-optical properties, and then cool it to room temperature to obtain a loaded electro-optical modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT; the polarization temperature is 140°C, the polarization voltage is 110V, the step-up and step-down time is 37s, the step-up and step-down rate is 3V / s, and the cooling rate is 3°C / min.

[0104] The high-performance ferroelectric single crystal PIN-PMN-PT electro-optic modulator prepared in Example 5 of the present invention was tested at room temperature, and its insertion loss was 8.8dB, transmission loss was 1.7dB, 3dB electro-optic bandwidth was 12GHz, half-wave voltage was 1.15V, and modulation rate was 44Gbps.

[0105] like Figure 3 As shown in the figure, when the length of the modulation electrode 4 is 8 mm, the 6.41 dB electro-optical bandwidth of the prepared PIN-PMN-PT single crystal-based loaded electro-optical modulator can reach 16 GHz, which is consistent with the 3 dB electro-optical bandwidth mentioned above, and within the bandwidth range S 11 All are less than -15dB, indicating that the modulator structure proposed in the present invention has good wave velocity matching. In addition, since the PIN-PMN-PT single crystal material used has an ultra-high electro-optic coefficient (γ 33>400pm / V) and excellent electro-optical performance. The half-wave voltage-length product of the electro-optical modulator prepared by the present invention can reach up to 1.15V·cm, so it has a high modulation ability.

[0106] The loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT and the preparation method thereof provided by the present invention can be applied to optical communication systems with low half-wave voltage and easy integration.

Claims

1. A loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT, characterized in that: The invention comprises a PIN-PMN-PT substrate (1), wherein the middle area on the PIN-PMN-PT substrate (1) is covered with a straight waveguide layer (2), the PIN-PMN-PT substrate (1) and the straight waveguide layer (2) are both covered with an upper cladding layer (3), and the upper cladding layer (3) is provided with modulation electrodes (4) located on both sides of the straight waveguide layer (2) and parallel to the long sides of the straight waveguide layer (2), wherein the modulation electrodes (4) are rectangular traveling wave electrodes.

2. The loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT according to claim 1, characterized in that: The PIN-PMN-PT substrate (1) is a PIN-PMN-PT single crystal grown along [011], the straight waveguide layer (2) is an amorphous Si thin film waveguide, the upper cladding layer (3) is a SiO2 thin film, and the two modulation electrodes (4) are symmetrical gold electrodes.

3. The loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT according to claim 1, characterized in that: The thickness H3 of the PIN-PMN-PT substrate (1) is 0.3-1 mm; the thickness H4 of the straight waveguide layer (2) is 0.3-1 μm; the width W3 of the straight waveguide layer (2) is 5-10 μm; the thickness H2 of the upper cladding layer (3) is 0.5-1 μm; the thickness H1 of the modulation electrode (4) is 0.5-1 μm, the width W1 of the modulation electrode (4) is 30-80 μm, and the width W2 between the two modulation electrodes (4) is 10-50 μm; the lengths L of the PIN-PMN-PT substrate (1), the straight waveguide layer (2), the upper cladding layer (3) and the modulation electrode (4) are the same, all being 5-10 mm.

4. The loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT according to claim 3, characterized in that: The thickness H4 of the straight waveguide layer (2) is 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm, and the width W3 of the straight waveguide layer (2) is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm; the thickness H2 of the upper cladding layer (3) is 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm; the thickness H1 of the modulation electrode (4) is 0.5 μm, 0.6 μm, 0.7 μm, The thickness W1 of the modulation electrode (4) is 0.8 μm, 0.9 μm or 1 μm, the width W1 of the modulation electrode (4) is 30 μm, 40 μm, 50 μm, 60 μm, 70 μm or 80 μm, and the width W2 between two modulation electrodes (4) is 10 μm, 20 μm, 30 μm, 40 μm or 50 μm; the length L of the PIN-PMN-PT substrate (1), the straight waveguide layer (2), the upper cladding layer (3) and the modulation electrode (4) are the same, which are 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm.

5. The loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT according to claim 1, characterized in that: The refractive index n1 of the straight waveguide layer (2) is greater than the refractive index n2 of the PIN-PMN-PT substrate (1).

6. The loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT according to claim 1, characterized in that: The electro-optic modulator couples light waves into a transmission waveguide by end face coupling, that is, an incident light wave (5) is vertically incident from one end face of the short side of a straight waveguide layer (2), and a modulated light wave (6) is output from the other end face.

7. A method for preparing a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT as claimed in claims 1 to 6, characterized in that: The steps include: Step 1: Orient the PIN-PMN-PT single crystal ingot, mark the [100] direction of the crystal, and cut it along the marked [100] direction to obtain a PIN-PMN-PT single crystal wafer grown along [011]; then cut the PIN-PMN-PT single crystal wafer to obtain a PIN-PMN-PT single crystal wafer of a desired size; Step 2: performing high temperature annealing treatment on the PIN-PMN-PT single crystal wafer obtained in step 1; Step 3: performing optical-grade polishing on the surface of the PIN-PMN-PT crystal wafer annealed in step 2 to obtain a PIN-PMN-PT crystal wafer with a surface roughness of 0.6-1 nm, namely, a PIN-PMN-PT substrate (1); the thickness of the polished PIN-PMN-PT substrate (1) is 0.3-1 mm; Step 4: using chemical vapor deposition to deposit amorphous Si on the surface of the PIN-PMN-PT substrate (1) to form an amorphous Si film with a thickness of 0.3-1 μm; then using deep ultraviolet lithography to photoetch a stripe straight waveguide pattern on the amorphous Si film to form a straight waveguide layer (2); Step 5: using chemical vapor deposition to deposit SiO2 on the surface of the PIN-PMN-PT substrate (1) and the straight waveguide layer (2) treated in step 4, to form a SiO2 film with a thickness of 0.5-1.5 μm, i.e., the upper cladding layer (3); Step 6: sputtering a gold film with a thickness of 0.5-1 μm on the surface of the upper cladding layer 3 obtained in step 5 by using a magnetron sputtering process, and then photoetching a pair of gold electrode patterns located on both sides of the straight waveguide and parallel to the straight waveguide on the surface of the gold film by using an ultraviolet photolithography process to form two modulation electrodes (4), wherein the etching width between the two modulation electrodes (4) is 10-50 μm, and the width of the modulation electrode 4 is 30-80 μm; Step 7: Use magnetron sputtering technology to sputter a gold film with a thickness of 10-20nm along the two side surfaces parallel to the incident direction of the light wave on the crystal device processed in step 6, and then use a high-voltage polarizer to perform high-temperature polarization treatment. After cooling to room temperature, a loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT is obtained.

8. The method for preparing a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT according to claim 7, characterized in that: In step 2, the annealing temperature is 600-850° C., and the holding time is 8-12 hours.

9. The method for preparing a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT according to claim 7, characterized in that: In step 4, the deposition temperature is 80-120° C., and the deposition time is 6-14 min; in step 5, the deposition temperature is 300-350° C., and the deposition time is 3-4.5 h; in step 4, the etching temperature is 100-140° C., and in step 6, the etching temperature is 85-105° C.

10. The method for preparing a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT according to claim 7, characterized in that: In step 7, the polarization temperature is 110-140° C., the polarization voltage is 50-110 V, the voltage increase / decrease time is 30-50 s, the voltage increase / decrease rate is 1-3 V / s, and the cooling rate is 1-3° C. / min.

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