An all-solid-state tunable polarization controller based on phase change material

Abstract

The present application relates to the field of nano-optics and optoelectronic integration, and particularly relates to a full solid-state tunable polarization controller based on phase change material. The present application comprises a transparent substrate, a bottom transparent electrode and a polarization control unit. The present application realizes electric control of the refractive index of the phase change material by applying voltage to the bottom transparent (such as ITO) electrode, realizes continuous control of the birefringent phase of the orthogonal polarized incident light through the polarization control unit of the elliptical column structure of the phase change material, and further changes the polarization state of the outgoing light. The present application has the advantages of planarization and full solid state, and can effectively solve the problems of large volume, heavy weight and difficulty in full solid state integration of the existing polarization controller; it is suitable for polarization light generation and control, polarization imaging and encryption, and has important application prospect and significance.

Description

Technical Field

[0001] This invention relates to the field of nano-optics and optoelectronic integration, specifically to an all-solid-state tunable polarization controller based on phase change materials. Background Technology

[0002] Polarization is a fundamental property of light, playing a crucial role in both classical and quantum optics. Dynamically generating arbitrary polarization states has numerous important applications in integrated optics, such as generating circularly polarized light for chiral drug molecule sensing, polarization-sensitive digital holography, polarization imaging, and polarization encryption. Traditional methods typically employ polarizers, waveplates, and phase retarders to control arbitrary polarization states, which suffers from large size, heavy weight, and slow control speed, making it difficult to meet the requirements of integrated optical systems.

[0003] Compared to traditional polarization control elements, optical metasurfaces are ultrathin planar devices composed of artificial microstructures. They can control the polarization state of light on a single planar structure, offering advantages such as small size and light weight. Furthermore, combining them with tunable functional structures enables continuous polarization state control. Currently, tunable polarization metasurfaces mainly utilize liquid crystal materials and microelectromechanical systems (MEMS), which present challenges due to liquids and moving parts, making it difficult to achieve fully solid-state continuous tunable polarization control and limiting their application in extreme environments (low temperature, high speed). Summary of the Invention

[0004] To address the aforementioned problems or shortcomings and to solve the issue that existing tunable polarization controllers cannot achieve full solid-state integration, this invention provides a full solid-state tunable polarization controller based on phase change materials.

[0005] The technical solution of this invention is as follows:

[0006] A fully solid-state tunable polarization controller based on phase change materials includes a transparent substrate, a bottom transparent electrode, and a polarization control unit.

[0007] The bottom transparent electrode is covered on a transparent substrate, with a transmittance of ≥70% in visible and near-infrared wavelengths and a resistivity of <10. -3 Ω·cm, used as a heating device.

[0008] The polarization control units are periodically arranged on the bottom transparent electrode and are made of phase change material to form a phase change material metasurface. By applying an external pulse voltage to the electrode, the crystallinity of the phase change material is changed, the birefringence phase is controlled, and thus the polarization state of the emitted light is changed.

[0009] The bottom transparent electrode is gold-plated where the polarization control unit is not placed to reduce the voltage drop on the circuit, so that the voltage drop is concentrated at the location where the polarization control unit is placed, and at the same time, it serves as a contact electrode with the external pulse voltage source.

[0010] Furthermore, the polarization control unit is also covered with a protective layer that is transparent in visible and near-infrared wavelengths, and the material is silicon dioxide or aluminum oxide.

[0011] Furthermore, the transparent substrate is a visible light or near-infrared transparent substrate, such as silicon dioxide, aluminum oxide, or magnesium oxide.

[0012] Furthermore, the bottom transparent electrode is an ITO conductive film.

[0013] Furthermore, the polarization control unit is a periodically arranged elliptical cylinder fabricated on a bottom transparent electrode using phase change material; the structural parameters of the elliptical cylinder satisfy the Huygens resonance condition in one polarization direction, and there is no resonance in the polarization direction orthogonal to it, so that two orthogonally polarized incident lights can generate a large birefringence phase difference; therefore, the phase of the polarization direction that satisfies the Huygens resonance condition changes greatly with the refractive index of the phase change material, while the phase of the polarization direction without resonance remains basically unchanged, thereby realizing continuous control of the birefringence phase.

[0014] Furthermore, the phase change process of the phase change material depends on temperature. A low-voltage pulse at the microsecond level can induce a phase change, causing it to transition from an amorphous state to a crystalline state. Different voltage amplitudes cause the crystallinity of the phase change material to transition continuously from amorphous to fully crystalline, thereby producing a continuous phase modulation effect. A high-voltage pulse at the nanosecond level can cause the phase change material to return to the amorphous state, thereby realizing the reconfigurability of the metasurface.

[0015] Furthermore, the phase change material is antimony trisulfide (Sb₂S₃) or antimony triselenide (Sb₂Se₃).

[0016] Furthermore, the periodically arranged elliptical cylinders have the following characteristics: height H = 100nm - 1μm, major semi-axis D1 = 100nm - 1μm, minor semi-axis D2 = D1 / 2; the arrangement period of the elliptical cylinders is P = 200nm - 5μm, where P refers to the distance between the center points of adjacent elliptical cylinders.

[0017] In summary, this invention proposes an all-solid-state tunable polarization controller based on phase change materials, which can achieve continuous control of the polarization state of electromagnetic waves. It has the advantages of being all-solid-state and is expected to be applied in fields such as polarization imaging and chiral drug sensing. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention;

[0019] Figure 2 This example illustrates the relationship between transmittance of the sample under x / y orthogonal polarization incident light and the crystallinity of the phase change material.

[0020] Figure 3This example illustrates the relationship between phase variation and crystallinity of the phase transition material under orthogonally polarized incident x / y conditions.

[0021] Figure 4 The polarization state of transmitted light under different crystallinities of the phase change material in the example samples. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0023] The thickness of the transparent electrode is 80 nm;

[0024] The periodically arranged elliptical cylinder has a height of 155nm, a major semi-axis of 200nm and a minor semi-axis of 100nm, and a period of 600nm.

[0025] This embodiment designs an all-solid-state tunable polarization controller based on phase change materials (structure as follows). Figure 1 (As shown). On a 10mm × 10mm quartz substrate, an ITO electrode with a thickness of 80nm, a width of 60μm, and a length of 10mm is constructed from bottom to top. On top of this, a periodically arranged elliptical cylinder of Sb₂Se₃ phase change material is constructed: period P = 600nm, height H = 155nm, major semi-axis D₁ = 200nm, and minor semi-axis D₂ = 100nm. A gold layer is plated at the non-polarization modulation unit structure of the ITO electrode to reduce the voltage drop of the circuit, and wires are connected to the external control circuit at the ends. By applying external power, the crystallinity of the elliptical cylinder of the phase change material can be continuously changed, achieving anisotropic modulation of the intensity and phase of transmitted light.

[0026] Figure 2 To illustrate the relationship between the transmittance of polarized light along the major and minor axes and the crystallinity of the phase change material, the incident light wavelength is 1040 nm. Due to the inconsistency between the major and minor axes, the Huygens resonance condition is satisfied along the major axis, but not along the minor axis, resulting in a large transmittance contrast.

[0027] Figure 3 To illustrate the relationship between the phase of polarized light along the major and minor axes and the crystallinity of the phase change material, the incident light wavelength is 1040 nm. Similarly, the transmission phase difference in the two directions varies significantly with crystallinity, enabling dynamic control of the polarization state of the transmitted light, with a maximum phase difference of 250°. For example... Figure 4 As shown, the polarization state of its transmitted light varies considerably with the crystallinity of the phase change material.

[0028] As can be seen from the above embodiments, this invention designs an all-solid-state tunable polarization controller based on phase change materials. Combining the advantages of phase change materials—high speed, low loss, all-solid-state nature, and easy integration—it achieves electrical modulation of the refractive index of the phase change material by applying voltage to a bottom transparent electrode (such as ITO). The polarization modulation unit of the phase change material, with its elliptical cylindrical structure, enables continuous modulation of the birefringence phase of orthogonally polarized incident light, thereby changing the polarization state of the outgoing light. This invention has the advantages of planar design and all-solid-state nature, effectively solving the problems of large size, heavy weight, and difficulty in all-solid-state integration of existing polarization controllers. It is suitable for polarized light generation and modulation, polarization imaging and encryption, and has significant application prospects and importance.

Claims

1. A fully solid-state tunable polarization controller based on phase change materials, characterized in that: Includes a transparent substrate, a bottom transparent electrode, and a polarization control unit; The bottom transparent electrode is covered on a transparent substrate and has a transmittance of ≥70% in visible and near-infrared wavelengths and a resistivity of <10. -3 Ω∙cm, as a heating device; The polarization control units are periodically arranged on the bottom transparent electrode and are made of phase change material to form a phase change material metasurface. By applying an external pulse voltage to the electrode, the crystallinity of the phase change material is changed, the birefringence phase is controlled, and thus the polarization state of the emitted light is changed. The polarization control unit is a periodically arranged elliptical cylinder; The parameters of the elliptical cylinder structure satisfy the Huygens resonance condition in one polarization direction, and no resonance is generated in the polarization direction orthogonal to it. Thus, two orthogonally polarized incident lights can generate a large birefringence phase difference, realizing continuous control of the birefringence phase. The bottom transparent electrode is gold-plated where the polarization control unit is not placed to reduce the voltage drop on the circuit, so that the voltage drop is concentrated at the location where the polarization control unit is placed, and at the same time, it serves as a contact electrode with the external pulse voltage source.

2. The all-solid-state tunable polarization controller based on phase change materials as described in claim 1, characterized in that: The polarization control unit is also covered with a protective layer that is transparent in visible and near-infrared wavelengths, and the material is silicon dioxide or aluminum oxide.

3. The all-solid-state tunable polarization controller based on phase change materials as described in claim 1, characterized in that: The transparent substrate is a visible light and near-infrared transparent substrate.

4. The all-solid-state tunable polarization controller based on phase change materials as described in claim 1, characterized in that: The bottom transparent electrode is an ITO conductive film.

5. The all-solid-state tunable polarization controller based on phase change materials as described in claim 1, characterized in that: The transparent substrate is silicon dioxide, aluminum oxide, or magnesium oxide.

6. The all-solid-state tunable polarization controller based on phase change materials as described in claim 1, characterized in that: The phase change material can undergo a phase transition with a low-voltage pulse at the microsecond level, causing it to transition from an amorphous state to a crystalline state. Different voltage amplitudes cause the crystallinity of the phase change material to transition continuously from amorphous to fully crystalline, thereby producing a continuous phase modulation effect. A high-voltage pulse at the nanosecond level can cause the phase change material to return to the amorphous state, thus realizing the reconfigurability of the metasurface.

7. The all-solid-state tunable polarization controller based on phase change materials as described in claim 1, characterized in that: The phase change material is antimony trisulfide (Sb2S3) or antimony triselenide (Sb2Se3).

8. The all-solid-state tunable polarization controller based on phase change materials as described in claim 1, characterized in that: The periodically arranged elliptical cylinders have the following characteristics: height H = 100nm - 1μm, major semi-axis D1 = 100nm - 1μm, minor semi-axis D2 = D1 / 2; the arrangement period of the elliptical cylinders is P = 200nm - 5μm, where P refers to the distance between the center points of adjacent elliptical cylinders.

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