A high-performance ferroelectric single crystal PIN-PMN-PT loaded electro-optic modulator and a preparation method thereof

Abstract

The application discloses a high-performance ferroelectric single crystal PIN-PMN-PT-based loaded electro-optic modulator and a preparation method thereof. The electro-optic modulator comprises a PIN-PMN-PT substrate, a straight waveguide layer covering an intermediate region on the PIN-PMN-PT substrate, and an upper cladding layer covering the PIN-PMN-PT substrate and the straight waveguide layer. Modulation electrodes are arranged on the upper cladding layer and located on both sides of the straight waveguide layer and parallel to the long side of the straight waveguide layer. The modulation electrodes are rectangular traveling wave electrodes. The new loaded electro-optic modulator is prepared by using PIN-PMN-PT single crystal with high linear electro-optic coefficient and amorphous silicon material. An external electric field is applied to the modulator to change the phase of the optical carrier and achieve the effect of optical wave modulation. The technical problems of high driving voltage and high integration difficulty of the existing electro-optic modulator are solved. The prepared loaded electro-optic modulator can reduce the driving voltage of the electro-optic modulator, improve the modulation efficiency, shorten the modulation length, and realize miniaturization and low power consumption.

Description

Technical Field

[0001] This invention relates to the field of optical fiber communication system technology, and in particular to a loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT and its fabrication method. Background Technology

[0002] Electro-optic modulators are key components in optical transceiver modules of fiber optic communication systems. They convert electrical signals into optical signals for long-distance transmission over fiber optic networks. Currently, with the exponential growth of data transmission rates in fiber optic communication systems, higher demands are being placed on the modulation bandwidth (3dB electro-optic bandwidth), modulation rate, and integrability of electro-optic modulators.

[0003] Currently, common commercial electro-optic modulators mainly include silicon-based electro-optic modulators, indium phosphide-based electro-optic modulators, and lithium niobate-based electro-optic modulators. Silicon-based modulators are mainly based on the plasma dispersion effect, thus limiting the modulation rate and resulting in low modulation linearity. Lithium niobate-based electro-optic modulators have high modulation rates, but their electro-optic coefficients are relatively low, leading to larger device size and power consumption. Both types of modulators require high drive voltages (half-wave voltages), making it difficult to achieve 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-optic response mechanism is the same as that of lithium niobate crystal, but its electro-optic coefficient can exceed 900 pm / V, which is 30 times that of lithium niobate crystal. Therefore, it can be applied to electro-optic modulators with low driving voltage, high modulation efficiency, and integrability.

[0005] In recent years, the excellent electro-optic 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, 2002, 139(2021).) at Qingdao University successfully fabricated a highly transparent Sm-doped PMN-PT electro-optic crystal with a transmittance of 70% and a secondary electro-optic coefficient of 35 × 10⁻⁶. -16 m 2 / V 2The half-wave voltage was 113V (d=L=1mm), verifying the application prospects of Sm-doped PMN-PT crystals in the field of electro-optic modulation. However, 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. (Liu X, Tan P, Ma X, Wang D, Jin X, Liu Y, Xu B, Qiao L, Qiu C, Wang B, Zhao W, Wei C, Song 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 synergistic design of crystal orientation and polarization techniques, ultra-high electro-optic performance was obtained in ternary PIN-PMN-PT crystals, and an electro-optic Q-switcher based on 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 that of previously reported binary PMN-PT single crystals. However, due to the limitations of the electro-optic Q-switcher fabrication technology, its half-wave voltage is as high as 200V, which does not reach the theoretical limit of the crystal. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide a loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT and its fabrication method. By employing PIN-PMN-PT single crystal with a high linear electro-optic coefficient and amorphous silicon material to fabricate a novel loaded electro-optic modulator, an external electric field is applied to the modulator to change the phase of the optical carrier, thereby achieving the effect of optical wave modulation. This solves the technical problems of high driving voltage and difficult integration in existing electro-optic modulators. The loaded electro-optic modulator prepared by the present invention can reduce the driving voltage of the electro-optic modulator, improve modulation efficiency, shorten the modulation length, and achieve miniaturization and low power consumption.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT includes a PIN-PMN-PT substrate 1, a straight waveguide layer 2 covering the middle region of the PIN-PMN-PT substrate 1, and an upper cladding layer 3 covering both the PIN-PMN-PT substrate 1 and the straight waveguide layer 2; modulation electrodes 4 are disposed on both sides of the straight waveguide layer 2 and parallel to the long side of the straight waveguide layer 2 on the upper cladding layer 3, 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 PIN-PMN-PT substrate 1 has a thickness H3 of 0.3-1 mm; the straight waveguide layer 2 has a thickness H4 of 0.3-1 μm; the straight waveguide layer 2 has a width W3 of 5-10 μm; the upper cladding layer 3 has a thickness H2 of 0.5-1 μm; the modulation electrode 4 has a thickness H1 of 0.5-1 μm, a width W1 of 30-80 μm, and a width W2 between two modulation electrodes 4 of 10-50 μm; the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3, and the modulation electrode 4 have the same length L, which is 5-10 mm.

[0011] The thickness H4 of the straight waveguide layer 2 is 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, or 1μm; the width W3 of the straight waveguide layer 2 is 5μm, 6μm, 7μm, 8μm, 9μm, or 10μm; the thickness H2 of the upper cladding layer 3 is 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, or 1μm; and the thickness H1 of the modulation electrode 4 is 0.5μm, 0.6μm, 0.7μm, or 0.8μm, or 0.9μm, or 1μm. The width W1 of the modulation electrode 4 is 30μm, 40μm, 50μm, 60μm, 70μm or 80μm, and 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, straight waveguide layer 2, upper cladding layer 3 and modulation electrode 4 is the same, which is 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 the light wave into the transmission waveguide through end-face coupling. That is, the incident light wave 5 is perpendicularly 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 fabricating a loaded electro-optic modulator based on a high-performance ferroelectric single-crystal PIN-PMN-PT includes the following steps:

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

[100] direction of the crystal, and cut 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 the required size.

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

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

[0018] Step 4: Amorphous Si is deposited on the surface of PIN-PMN-PT substrate 1 using chemical vapor deposition to form an amorphous Si thin film with a thickness of 0.3-1μm; then, a strip-shaped straight waveguide pattern is photolithographically etched on the amorphous Si thin film using deep ultraviolet lithography 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 step 4 using chemical vapor deposition to form a SiO2 thin film with a thickness of 0.5-1.5μm, namely the upper cladding layer 3;

[0020] Step 6: A gold film with a thickness of 0.5-1 μm is sputtered on the surface of the upper cladding 3 obtained in step 5 using magnetron sputtering. Then, a pair of gold electrode patterns located on both sides of the straight waveguide and parallel to the straight waveguide are photolithographically etched on the surface of the gold film to form two modulation electrodes 4. 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: A gold film with a thickness of 10-20 nm is sputtered on both sides of the crystal device after Step 6 along the incident direction of the light wave using a magnetron sputtering process. Then, a high-voltage polarizer is used for 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℃ and the holding time is 8-12h.

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

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

[0025] Compared with existing commercial electro-optic modulators, the advantages of this invention are as follows:

[0026] 1. This invention utilizes PIN-PMN-PT single crystal as a substrate. The half-wave voltage of the electro-optic modulator is inversely proportional to the length of the modulation region. PIN-PMN-PT single crystal possesses an ultra-high electro-optic coefficient (γ). 33 With a voltage of >400pm / V, this invention enables smaller electro-optic modulators that are easier to integrate and operate at low drive voltages.

[0027] 2. This invention uses PIN-PMN-PT single crystal as the substrate. Since its electro-optic coefficient can exceed 900 pm / 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 this invention has a low half-wave voltage. At the same time, since the PIN-PMN-PT single crystal has a high refractive index in the microwave band, the SiO2 cladding between the straight waveguide layer and the modulation electrode can reduce the overall microwave effective refractive index of the electro-optic modulator, which greatly improves the refractive index matching between microwaves and light waves.

[0028] 3. This invention employs a loaded amorphous silicon thin film straight waveguide. By optimizing the film thickness, a portion of the incident light wave passes through the amorphous silicon thin film, while a portion passes through the upper surface of the PIN-PMN-PT substrate. This confines the incident light to the straight waveguide layer, achieving a sufficient modulation effect.

[0029] 4. The SiO2 cladding used in this invention can 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 the metal electrode, the present invention places the modulation electrode on the SiO2 cladding, which reduces optical loss and increases the overlap rate of the optical field and the microwave electric field (increasing the electro-optic overlap factor).

[0031] In summary, compared with the prior art, this invention uses PIN-PMN-PT single crystal with a high linear electro-optic coefficient and amorphous silicon material to prepare a novel loaded electro-optic modulator. By applying an external electric field to the modulator, the phase of the optical carrier is changed, thereby achieving the effect of optical wave modulation. This solves the technical problems of high driving voltage and difficult integration of existing electro-optic modulators. The loaded electro-optic modulator prepared by this 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. Attached Figure Description

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

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

[0034] Figure 3 The diagram shows the electrical performance test results of the loaded electro-optic modulator based on 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 3, modulation electrode 4, incident light wave 5, light wave 6. Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to 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 includes a PIN-PMN-PT substrate 1, a straight waveguide layer 2 covering the middle region of the PIN-PMN-PT substrate 1, and an upper cladding layer 3 covering both the PIN-PMN-PT substrate 1 and the straight waveguide layer 2; modulation electrodes 4 are disposed on the upper cladding layer 3 on both sides of the straight waveguide layer 2 and parallel to the long side 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 high refractive index difference, which greatly enhances the light confinement 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; and the thickness H1 of the modulation electrode 4 is 0.5-1 μm. The length of the PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3, and the modulation electrode 4 is 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 the 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 is the same, which is 5-10mm, preferably 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm.

[0040] When a radio frequency signal is applied to the surface of the modulation electrode 4, the PIN-PMN-PT single crystal undergoes a linear electro-optic effect within the modulation region, causing the phase of the optical carrier transmitted in the crystal to change under the action of an external electric field, thereby achieving 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 perpendicularly incident from one end face in the direction 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 fabricating a loaded electro-optic modulator based on a high-performance ferroelectric single-crystal PIN-PMN-PT includes the following steps:

[0043] Step 1: Orient the PIN-PMN-PT single crystal rod using an XRD diffractometer, mark the

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

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

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

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

[0045] PIN-PMN-PT single-crystal rods were obtained through directional growth using the Bridgman crucible descent method. In this process, a PIN-PMN-PT ceramic block was placed inside a cylindrical crucible and then slowly descended at a controlled rate of 6 mm / day through a furnace with a precisely controlled temperature range of 1150℃-1400℃, slightly above the material's melting point. As the crucible traversed the heating zone, the internal material melted, forming a liquid state. With the crucible's continued and stable descent, the bottom of the crucible first exited the high-temperature zone, and the temperature dropped below the melting point, triggering the crystallization process. During this process, the crystal grew continuously as the crucible descended, eventually forming a PIN-PMN-PT single-crystal rod with a perovskite crystal structure.

[0046] Step 2: Perform high-temperature annealing on the PIN-PMN-PT single crystal wafer obtained in Step 1 to remove residual stress and replenish missing oxygen vacancies; the annealing temperature is 600-850℃ and the holding time is 8-12h.

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

[0048] Step 4: Amorphous Si is deposited on the surface of PIN-PMN-PT substrate 1 using chemical vapor deposition to form an amorphous Si thin film with a thickness of 0.3-1 μm. The deposition temperature is 80-120℃ and the deposition time is 6-14 min. Then, a strip-shaped straight waveguide pattern is photolithographically etched on the amorphous Si thin film using deep ultraviolet lithography to form a straight waveguide layer 2. The etching temperature is 100-140℃.

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

[0050] Step 6: A gold film with a thickness of 0.5-1 μm is sputtered onto the surface of the upper cladding 3 obtained in Step 5 using magnetron sputtering. Then, a pair of gold electrode patterns located on both sides of the straight waveguide and parallel to the straight waveguide are photolithographically etched on the surface of the gold film to form two modulation electrodes 4. 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℃.

[0051] Step 7: Using magnetron sputtering, a gold film with a thickness of 10-20 nm is sputtered on both sides of the crystal device after Step 6 along the incident direction of the light wave. Then, a high-voltage polarizer (model: Bailibo MPD) is used to perform high-temperature polarization treatment to give it piezoelectric and electro-optic properties. After cooling to room temperature, a loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT is obtained. The polarization temperature is 110-140℃, the polarization voltage is 50-110V, the voltage rise / fall time is 30-50s, the voltage rise / fall rate is 1-3V / s, and the cooling rate is 1-3℃ / min.

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

[0053] Example 1

[0054] A loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT is disclosed. The PIN-PMN-PT substrate 1 has a width of 70 μm; the straight waveguide layer 2 has a width W3 of 5 μm; and the modulation electrode 4 has a width W1 of 30 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 is the same, which is 5 mm.

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

[0056] Step 1: Orient the PIN-PMN-PT single crystal rod using an XRD diffractometer, mark the

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

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

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

[0057] Step 2: Anneal the PIN-PMN-PT single crystal obtained in Step 1 at 600℃ for 12 hours;

[0058] Step 3: The PIN-PMN-PT crystal after annealing in Step 2 is subjected to optical-grade surface polishing using a polishing machine to obtain a PIN-PMN-PT crystal with a surface roughness of 1nm, namely PIN-PMN-PT substrate 1; the thickness of PIN-PMN-PT substrate 1 after polishing is 0.3mm.

[0059] Step 4: Amorphous Si is deposited on the surface of PIN-PMN-PT substrate 1 using chemical vapor deposition to form an amorphous Si thin film with a thickness of 0.3 μm. The deposition temperature is 80℃ and the deposition time is 8 min. Then, a strip-shaped straight waveguide pattern is photolithographically etched on the amorphous Si thin film using deep ultraviolet lithography to form a straight waveguide layer 2 with a width of 5 μm. The etching temperature is 100℃.

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

[0061] Step 6: A gold film with a thickness of 0.5 μm is sputtered on the surface of the upper cladding 3 obtained in Step 5 using magnetron sputtering. 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 photolithographically etched on the surface of the gold film to form two modulation electrodes 4. The etching width between the two modulation electrodes 4 is 10 μm; the etching temperature is 85℃.

[0062] Step 7: Gold is sputtered onto both sides of the crystal device processed in Step 6 along the direction parallel to the incident light wave using magnetron sputtering to form a gold film with a thickness of 10 nm. Then, a high-voltage polarizer is used to perform high-temperature polarization treatment to give it piezoelectric and electro-optic properties. After cooling to room temperature, a loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT is obtained. The polarization temperature is 120℃, the polarization voltage is 50V, the voltage rise / fall time is 50s, the voltage rise / fall rate is 1V / s, and the cooling rate is 1℃ / 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 is disclosed. The PIN-PMN-PT substrate 1 has a width of 100 μm; the straight waveguide layer 2 has a width W3 of 6 μm; and the modulation electrode 4 has a width W1 of 40 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 is the same, which is 6 mm.

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

[0067] Step 1: Orient the PIN-PMN-PT single crystal rod using an XRD diffractometer, mark the

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

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

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

[0068] Step 2: Anneal the PIN-PMN-PT single crystal obtained in Step 1 at 700℃ for 11 hours;

[0069] Step 3: The PIN-PMN-PT crystal after annealing in Step 2 is subjected to optical-grade surface polishing using a polishing machine to obtain a PIN-PMN-PT crystal with a surface roughness of 0.9 nm, namely PIN-PMN-PT substrate 1; the thickness of PIN-PMN-PT substrate 1 after polishing is 0.55 mm.

[0070] Step 4: Amorphous Si is deposited on the surface of PIN-PMN-PT substrate 1 using chemical vapor deposition to form an amorphous Si thin film with a thickness of 0.5 μm. The deposition temperature is 90℃ and the deposition time is 6 min. Then, a strip-shaped straight waveguide pattern is photolithographically etched on the amorphous Si thin film using deep ultraviolet lithography to form a straight waveguide layer 2 with a width of 6 μm. The etching temperature is 110℃.

[0071] Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 after step 4 using chemical vapor deposition to form a SiO2 thin film with a thickness of 0.6 μm, namely the upper cladding layer 3; the deposition temperature is 330℃ 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 3 obtained in Step 5 using magnetron sputtering. 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 photolithographically etched on the surface of the gold film to form two modulation electrodes 4. The etching width between the two modulation electrodes 4 is 20 μm; the etching temperature is 90℃.

[0073] Step 7: Using magnetron sputtering, gold is sputtered onto both sides of the crystal device after Step 6 along the direction parallel to the incident light wave to form a gold film with a thickness of 20 nm. Then, a high-voltage polarizer is used to perform high-temperature polarization treatment to give it piezoelectric and electro-optic properties. After cooling to room temperature, a loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT is obtained. The polarization temperature is 125℃, the polarization voltage is 60V, the voltage rise / fall time is 30s, the voltage rise / fall rate is 2V / s, and the cooling rate is 2℃ / 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 is disclosed. The PIN-PMN-PT substrate 1 has a width of 130 μm; the straight waveguide layer 2 has a width W3 of 8 μm; and the modulation electrode 4 has a width W1 of 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 is the same, which is 7 mm.

[0077] Step 1: Orient the PIN-PMN-PT single crystal rod using an XRD diffractometer, mark the

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

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

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

[0078] Step 2: Anneal the PIN-PMN-PT single crystal obtained in Step 1 at 750℃ for 10 hours;

[0079] Step 3: The PIN-PMN-PT crystal after annealing in Step 2 is subjected to optical-grade surface polishing using a polishing machine to obtain a PIN-PMN-PT crystal with a surface roughness of 0.8 nm, namely PIN-PMN-PT substrate 1; the thickness of PIN-PMN-PT substrate 1 after polishing is 0.75 mm.

[0080] Step 4: Amorphous Si is deposited on the surface of PIN-PMN-PT substrate 1 using chemical vapor deposition to form an amorphous Si thin film with a thickness of 0.6 μm. The deposition temperature is 100℃ and the deposition time is 8 min. Then, a strip-shaped straight waveguide pattern is photolithographically etched on the amorphous Si thin film using deep ultraviolet lithography to form a straight waveguide layer 2 with a width of 7 μm. The etching temperature is 120℃.

[0081] Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 after step 4 using chemical vapor deposition to form a SiO2 thin film with a thickness of 0.8 μm, namely the upper cladding layer 3; the deposition temperature is 320℃ 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 3 obtained in Step 5 using magnetron sputtering. 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 photolithographically etched on the surface of the gold film to form two modulation electrodes 4. The etching width between the two modulation electrodes 4 is 30 μm; the etching temperature is 95 °C.

[0083] Step 7: A 10 nm thick gold film is sputtered onto both sides of the crystal device processed in Step 6 along the incident direction of the light wave using a magnetron sputtering process; then, a high-voltage polarizer is used to perform high-temperature polarization treatment to give it piezoelectric and electro-optic properties, and then cooled to room temperature to obtain a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT; the polarization temperature is 130℃, the polarization voltage is 65V, the voltage rise / fall time is 33s, the voltage rise / fall rate is 2V / s, and the cooling rate is 2℃ / 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 is disclosed. The PIN-PMN-PT substrate 1 has a width of 160 μm; the straight waveguide layer 2 has a width W3 of 9 μm; and the modulation electrode 4 has a width W1 of 60 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 is the same, which is 8 mm.

[0087] Step 1: Orient the PIN-PMN-PT single crystal rod using an XRD diffractometer, mark the

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

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

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

[0088] Step 2: Anneal the PIN-PMN-PT single crystal obtained in Step 1 at 800℃ for 9 hours;

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

[0090] Step 4: Amorphous Si is deposited on the surface of PIN-PMN-PT substrate 1 using chemical vapor deposition to form an amorphous Si thin film with a thickness of 0.9 μm. The deposition temperature is 110℃ and the deposition time is 12 min. Then, a strip-shaped straight waveguide pattern is photolithographically etched on the amorphous Si thin film using deep ultraviolet lithography to form a straight waveguide layer 2 with a width of 9 μm. The etching temperature is 130℃.

[0091] Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate 1 and the straight waveguide layer 2 after step 4 using chemical vapor deposition to form a SiO2 thin film with a thickness of 0.9 μm, namely the upper cladding layer 3; the deposition temperature is 310℃ and the deposition time is 4h.

[0092] Step 6: A gold film with a thickness of 0.9 μm is sputtered on the surface of the upper cladding 3 obtained in Step 5 using magnetron sputtering. 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 photolithographically etched on the surface of the gold film to form two modulation electrodes 4. The etching width between the two modulation electrodes 4 is 40 μm; the etching temperature is 100℃.

[0093] Step 7: A 10 nm thick gold film is sputtered onto both sides of the crystal device processed in Step 6 along the incident direction of the light wave using a magnetron sputtering process; then, a high-voltage polarizer is used to perform high-temperature polarization treatment to give it piezoelectric and electro-optic properties, and then cooled to room temperature to obtain a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT; the polarization temperature is 135℃, the polarization voltage is 80V, the voltage rise / fall time is 40s, the voltage rise / fall rate is 2V / s, and the cooling rate is 2℃ / 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 is disclosed. The PIN-PMN-PT substrate 1 has a width of 210 μm; the straight waveguide layer 2 has a width W3 of 10 μm; and the modulation electrode 4 has a width W1 of 80 μm. The PIN-PMN-PT substrate 1, the straight waveguide layer 2, the upper cladding layer 3, and the modulation electrode 4 all have the same length L, which is 10 mm.

[0097] Step 1: Orient the PIN-PMN-PT single crystal rod using an XRD diffractometer, mark the

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

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

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

[0098] Step 2: Anneal the PIN-PMN-PT single crystal obtained in Step 1 at 850℃ for 8 hours;

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

[0100] Step 4: Amorphous Si is deposited on the surface of PIN-PMN-PT substrate 1 using chemical vapor deposition to form an amorphous Si thin film with a thickness of 1 μm. The deposition temperature is 120℃ and the deposition time is 14 min. Then, a strip-shaped straight waveguide pattern is photolithographically etched on the amorphous Si thin film using deep ultraviolet lithography to form a straight waveguide layer 2 with a width of 10 μm. The etching temperature is 140℃.

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

[0102] Step 6: A gold film with a thickness of 1 μm is sputtered on the surface of the upper cladding 3 obtained in step 5 using magnetron sputtering. 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 photolithographically etched on the surface of the gold film to form two modulation electrodes 4. The etching width between the two modulation electrodes 4 is 50 μm; the etching temperature is 105℃.

[0103] Step 7: A 10nm thick gold film is sputtered onto both sides of the crystal device processed in Step 6 along the incident direction of the light wave using a magnetron sputtering process; then, a high-voltage polarizer is used to perform high-temperature polarization treatment to give it piezoelectric and electro-optic properties, and then cooled to room temperature to obtain a loaded electro-optic modulator based on a high-performance ferroelectric single crystal PIN-PMN-PT; the polarization temperature is 140℃, the polarization voltage is 110V, the voltage rise / fall time is 37s, the voltage rise / fall rate is 3V / s, and the cooling rate is 3℃ / 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, when the length of the modulation electrode 4 is 8 mm, the 6.41 dB electro-optic modulator based on PIN-PMN-PT single crystal can achieve a bandwidth of 16 GHz, consistent with the aforementioned 3 dB electro-optic bandwidth, and within the bandwidth range, S 11 All values ​​are less than -15dB, indicating that the modulator structure proposed in this invention has good wave velocity matching. Furthermore, the PIN-PMN-PT single crystal material used exhibits an extremely high electro-optic coefficient (γ) after polarization. 33With a half-wave voltage-length product of up to 1.15 V·cm and excellent electro-optic performance (>400 pm / V), the electro-optic modulator prepared by this invention has a high modulation capability.

[0106] The loaded electro-optic modulator based on high-performance ferroelectric single crystal PIN-PMN-PT and its fabrication method provided by this 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 a high-performance ferroelectric single-crystal PIN-PMN-PT, characterized in that: The system includes a PIN-PMN-PT substrate (1), the middle region of which is covered by a straight waveguide layer (2). Both the PIN-PMN-PT substrate (1) and the straight waveguide layer (2) are covered by 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 side of the straight waveguide layer (2). The modulation electrodes (4) are rectangular traveling wave electrodes. The PIN-PMN-PT substrate (1) is a PIN grown along [011]. -PMN-PT single crystal, 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); the electro-optic modulator couples the light wave into the transmission waveguide through end-face coupling, that is, the incident light wave (5) is perpendicularly 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.

2. 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 length L of the PIN-PMN-PT substrate (1), the straight waveguide layer (2), the upper cladding layer (3), and the modulation electrode (4) is the same, which is 5-10 mm.

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

4. A method for fabricating a loaded electro-optic modulator based on a high-performance ferroelectric single-crystal PIN-PMN-PT as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Orient the PIN-PMN-PT single crystal rod, mark the [100] direction of the crystal, and cut 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 the required size. Step 2: Perform high-temperature annealing on the PIN-PMN-PT single crystal wafer obtained in Step 1; Step 3: Perform optical-grade surface polishing on the PIN-PMN-PT crystal wafer after annealing in Step 2 to obtain a PIN-PMN-PT crystal wafer with a surface roughness of 0.6-1nm, i.e., PIN-PMN-PT substrate (1); the thickness of the polished PIN-PMN-PT substrate (1) is 0.3-1mm; Step 4: Amorphous Si is deposited on the surface of the PIN-PMN-PT substrate (1) by chemical vapor deposition to form an amorphous Si thin film with a thickness of 0.3-1μm; then, a strip straight waveguide pattern is photolithographically etched on the amorphous Si thin film by deep ultraviolet lithography to form a straight waveguide layer (2). Step 5: SiO2 is deposited on the surface of the PIN-PMN-PT substrate (1) and the straight waveguide layer (2) after step 4 by chemical vapor deposition to form a SiO2 thin film with a thickness of 0.5-1.5μm, namely the upper cladding layer (3). Step 6: A gold film with a thickness of 0.5-1 μm is sputtered on the surface of the upper cladding 3 obtained in step 5 using magnetron sputtering. Then, a pair of gold electrode patterns located on both sides of the straight waveguide and parallel to the straight waveguide are photolithographically etched on the surface of the gold film to form two modulation electrodes (4). 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: A gold film with a thickness of 10-20 nm is sputtered on both sides of the crystal device after Step 6 along the incident direction of the light wave using a magnetron sputtering process. Then, a high-voltage polarizer is used for 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.

5. The method for fabricating a loaded electro-optic modulator based on a high-performance ferroelectric single-crystal PIN-PMN-PT according to claim 4, characterized in that: In step 2, the annealing temperature is 600-850℃ and the holding time is 8-12h.

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

7. The method for fabricating a loaded electro-optic modulator based on a high-performance ferroelectric single-crystal PIN-PMN-PT according to claim 4, characterized in that: In step 7, the polarization temperature is 110-140℃, the polarization voltage is 50-110V, the voltage ramping time is 30-50s, the voltage ramping rate is 1-3V / s, and the cooling rate is 1-3℃ / min.

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