CN112859477B - A Mach-Zehnder Interferometer Based on Nanoantennas - Google Patents

Abstract

The invention discloses a Mach-Zehnder interferometer based on a nano antenna. The interferometer comprises a lower substrate (1), a modulator (2), a birefringent material (3) and an upper substrate (4); the modulator (2) is positioned on the lower substrate (1); the birefringent material (3) is filled between the lower substrate (1) and the upper substrate (4) and wraps the modulator (2); the phase shifter (2-1) of the modulator (2) is a sub-wavelength nano antenna (2-2) array; when light passes through the nano antenna (2-2), Mie resonance occurs, and phase retardation is obtained while high forward scattering rate is achieved, and the phase retardation is controlled by the refractive index of the birefringent material; the output intensity modulation of the interferometer is achieved by modulating the refractive index of the birefringent material. Compared with the traditional Mach-Zehnder interferometer, the Mach-Zehnder interferometer has the advantages of higher modulation efficiency, higher working speed, compatibility with a CMOS (complementary metal oxide semiconductor) process, contribution to integration of devices and cost saving.

Description

A Mach-Zehnder Interferometer Based on Nanoantennas

technical field

The invention relates to a Mach-Zehnder interferometer, in particular to a Mach-Zehnder interferometer based on a nano-antenna.

Background technique

In current photonic integrated circuits, the propagation of light is controlled by a network of 2×2 optical analog gates. As a basic component of programmable photonic integrated circuits, the most common on-chip implementation of a 2×2 optical gate is a Mach-Zehnder interferometer; meanwhile, the modulation of the light intensity is performed by a Mach-Zehnder interferometer derived from the Mach-Zehnder interferometer. Del Modulator is implemented. The phase modulation function of the current Mach-Zehnder interferometer is mostly realized by thermo-optic materials, that is, the refractive index of the material is changed by temperature change, and then the phase change of light passing through the material is changed.

However, Mach-Zehnder interferometers based on thermo-optic materials have certain drawbacks: on the one hand, the heating process requires more time; on the other hand, heating itself consumes more energy and introduces thermal crosstalk. Therefore, programmable photonic integrated circuits for optical computing and other fields require new materials and technologies to further improve their performance. Although electro-optic materials such as lithium niobate currently exist as new solutions, they still cannot meet the needs in terms of process compatibility and miniaturization.

Light can generate Mie resonance in nano-antennas with certain material and geometric parameter characteristics, which improves the forward scattering rate of light. Therefore, one-dimensional nanoparticle chains have the function of guiding light wave transmission. If the nano-antenna is wrapped with birefringent material such as liquid crystal, when the refractive index characteristics of the birefringent material change, the phase retardation caused by Mie resonance will also change. Therefore, by modulating the refractive index of the birefringent material by voltage and then controlling the Mie resonance, phase modulation can be achieved, and finally the output intensity modulation of the interferometer can be achieved. The Mach-Zehnder interferometer based on this principle can improve the performance of programmable photonic integrated circuits such as size, speed, and process compatibility.

SUMMARY OF THE INVENTION

Technical problem: The present invention provides a nano-antenna-based Mach-Zehnder interferometer for the problems existing in the prior art. Based on the Mie resonance phenomenon of light in the nano-antenna, the dynamic control of the optical phase is realized, thereby realizing A Mach-Zehnder interferometer for miniaturization of programmable photonic integrated circuits.

Technical solution: a nano-antenna-based Mach-Zehnder interferometer of the present invention includes a lower substrate (1), a modulator, a birefringent material, and an upper substrate; the modulator is located on the lower substrate; the birefringent material is filled with Between the lower substrate and the upper substrate, and wrapping the modulator; the phase shifter of the modulator is a subwavelength nano-antenna array; when the light passes through the nano-antenna, Mie resonance occurs, and it has a high forward scattering rate while obtaining The phase retardation is controlled by the refractive index of the birefringent material; by modulating the refractive index of the birefringent material, the output intensity modulation of the interferometer is realized.

The nano-antenna adopts various geometric shapes of nano-spheres, nano-bricks or nano-pillars.

The birefringent material adopts liquid crystal.

The liquid crystal can work in an electric driving mode or in an optical driving mode.

The lower substrate is a pixelated driving circuit.

The phase shifter has a hybrid tapered coupler, which reduces the loss of the waveguide structure during transmission.

The interferometer is used to modulate the intensity of the input light.

The interferometer implements a 2x2 optical gate.

The phase shifter has a hybrid tapered coupler, which reduces the loss of the waveguide structure during transmission.

Beneficial effects: Compared with the prior art, the present invention has the following remarkable features: First, the phase modulation method based on the Mie resonance principle has higher modulation efficiency, and the required phase can be obtained within a shorter modulation distance The modulation amount is conducive to the miniaturization of programmable photonic integrated circuits; second, the use of birefringent materials that respond quickly to external biases can greatly improve the working speed of the device compared to traditional thermo-optic materials; The fabrication of the antenna is compatible with the existing CMOS process, which is beneficial to reduce the fabrication cost.

Description of drawings

Figure 1 is a schematic diagram of a nanoantenna-based Mach-Zehnder interferometer.

FIG. 2 is a schematic top view of the structure of the modulator part of the nano-antenna-based Mach-Zehnder interferometer.

FIG. 3 is a schematic diagram of the geometric parameters of the modulator and the nano-antenna structure.

FIG. 4 is a schematic top view of the structure of the modulator part.

FIG. 5 is a schematic top view of the structure of the modulator part of the nano-antenna-based 2×2 optical gate.

FIG. 6 is a schematic top view of the structure of the modulator part of the nanopillar-based Mach-Zehnder interferometer.

FIG. 7 is a schematic diagram of the geometric parameters of the nanopillar phase shifter structure.

FIG. 8 is a schematic top view of a phase shifter incorporating a hybrid tapered coupler.

FIG. 9 is a schematic diagram of the working principle of the hexagonal optical gate network based on the present invention.

There are: a lower substrate 1, a modulator 2, a birefringent material 3, an upper substrate 4, a phase shifter 2-1, and a nano-antenna 2-2.

Detailed ways

The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

FIG. 1 is a schematic diagram of a Mach-Zehnder interferometer based on nanoantennas. It consists of an upper substrate 1 , a modulator 2 , a birefringent material 3 and a lower substrate 4 . The modulator is prepared on the lower substrate, and the birefringent material is filled between the upper and lower substrates and wraps the entire modulator structure.

Liquid crystal is used as the birefringent material. The liquid crystal can be driven by electric driving. The lower substrate is a pixelated liquid crystal driving circuit. The modulator can be fabricated using CMOS compatible 193nm photolithography and reactive ion etching methods. The upper substrate adopts total reflection metal material. The lower surface of the upper substrate is coated with an alignment layer for the alignment of liquid crystal molecules. Orientation can be rubbed orientation or photo-orientation.

The schematic top view of the structure of the modulator part is shown in FIG. 2 . The basic structure and interference principle of the well-known integrated waveguide Mach-Zehnder interferometer are the same. Monochromatic light is input into the waveguide from any coupling input port, passes through the 3dB directional coupler 1, and is divided into two paths of equal intensity light. The light is output and coupled out to the subsequent optical path. The intensity transmission coefficient of the two output lights is determined by the phase difference between the two lights after phase modulation.

The waveguide in the modulator is a strip-shaped waveguide made of silicon material, and the cross-section is shown in Figure 3(a). The rectangular silicon waveguide has a width W of 400 nm and a height H of 220 nm. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. As shown in Fig. 3(b), the nanoparticle and the waveguide have the same cross section, and the length L is 243 nm. The period p of the nanoparticle arrangement, that is, the distance between the center points of two adjacent nanoparticles, is 400 nm. The input light wavelength is 1650nm. Under this geometric parameter, light undergoes Mie resonance in the nanoparticle with high forward scattering rate, and the amount of phase retardation changes at the same time.

The working principle of the interferometer is as follows: when the device receives the control signal, a corresponding voltage is applied between the upper and lower substrates, and an electric field is formed inside the liquid crystal layer; under the action of the electric field, the director of the liquid crystal molecules changes, and the refractive index distribution changes accordingly. ; Changes in the external environment change the amount of phase delay produced by the Mie resonance. Therefore, the modulation of the optical phase can be realized by the external voltage bias, the phase difference between the two input lights can be controlled, and the power of the two output lights can be finally controlled.

Example 2

According to the Mach-Zehnder interferometer based on the nano-antenna proposed in the present invention, a Mach-Zehnder modulator is realized. Its basic structure is the same as that described in Embodiment 1, that is, it consists of an upper substrate, a modulator, a birefringent material and a lower substrate. The birefringent material is liquid crystal, and the lower substrate is a pixelated liquid crystal driving circuit. The modulator can be fabricated using CMOS compatible 193nm photolithography and reactive ion etching methods. The upper substrate adopts total reflection metal material. The lower surface of the upper substrate is coated with an alignment layer for the alignment of liquid crystal molecules. Orientation can be rubbed orientation or photo-orientation.

The schematic top view of the structure of the modulator part is shown in FIG. 4 . Monochromatic light is coupled into the waveguide from the input port, and after passing through the 3dB beam splitter, the light is divided into two paths of light with equal power, one of which is phase-modulated when passing through the phase shifter. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. Light undergoes Mie resonance in nanoparticles with high forward scattering rate, and the amount of phase retardation changes. The two paths of light pass through the 3dB beam combiner and interfere, and the power of the output light after the combined beam is determined by the phase difference of the two paths of light. Finally, the output light is output through the coupling output terminal.

The waveguide in the modulator is a strip-shaped waveguide made of silicon material, and the cross-section is shown in Figure 3(a). The rectangular silicon waveguide has a width W of 400 nm and a height H of 220 nm. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. As shown in Fig. 3(b), the nanoparticle and the waveguide have the same cross section, and the length L is 243 nm. The period p of the nanoparticle arrangement, that is, the distance between the center points of two adjacent nanoparticles, is 400 nm. The input light wavelength is 1650nm. Under this geometric parameter, light undergoes Mie resonance in the nanoparticle with high forward scattering rate, and the amount of phase retardation changes at the same time.

The working principle of the Mach-Zehnder modulator based on the present invention is as follows: when the device receives the control signal, a corresponding voltage is applied between the upper and lower substrates, and an electric field is formed inside the liquid crystal layer; under the action of the electric field, the director of the liquid crystal molecules changes. , its refractive index distribution changes accordingly; the change of the external environment changes the phase retardation generated by the Mie resonance in the phase shifter. Therefore, the modulation of the optical phase can be realized through the external voltage bias, so as to control the phase difference between the two paths of light after the beam splitter, and finally control the intensity of the coupled output light.

Example 3

According to the Mach-Zehnder interferometer based on nano-antenna proposed in the present invention, a 2×2 optical gate is realized. Its basic structure is the same as that described in Embodiment 1, that is, it consists of an upper substrate, a modulator, a birefringent material and a lower substrate. The birefringent material is liquid crystal, and the lower substrate is a pixelated liquid crystal driving circuit. The modulator can be fabricated using CMOS compatible 193nm photolithography and reactive ion etching methods. The upper substrate adopts total reflection metal material. The lower surface of the upper substrate is coated with an alignment layer for the alignment of liquid crystal molecules. Orientation can be rubbed orientation or photo-orientation.

The schematic top view of the structure of the modulator part is shown in FIG. 5 . Monochromatic light enters the waveguide from any coupling input port, passes through the 3dB directional coupler 1, and is divided into two paths of light of equal intensity. Each light needs to go through a direction shifter to modulate its phase. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. Light undergoes Mie resonance in nanoparticles with high forward scattering rate, and the amount of phase retardation changes. Then the two paths of light pass through the directional coupler 2 to obtain two paths of output light, which are coupled and output to the subsequent optical paths. The intensity transmission coefficient of the two output lights is determined by the phase difference between the two lights after phase modulation.

The waveguide in the modulator is a strip-shaped waveguide made of silicon material, and the cross-section is shown in Figure 3(a). The rectangular silicon waveguide has a width W of 400 nm and a height H of 220 nm. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. As shown in Fig. 3(b), the nanoparticle and the waveguide have the same cross section, and the length L is 243 nm. The period p of the nanoparticle arrangement, that is, the distance between the center points of two adjacent nanoparticles, is 400 nm. The input light wavelength is 1650nm. Under this geometric parameter, light undergoes Mie resonance in the nanoparticle with high forward scattering rate, and the amount of phase retardation changes at the same time.

The working principle of the 2×2 optical gate based on the present invention is as follows: after the device receives the control signal, a corresponding voltage is applied between the upper and lower substrates, and an electric field is formed inside the liquid crystal layer; under the action of the electric field, the director of the liquid crystal molecules changes, Its refractive index distribution changes accordingly; the change of the external environment changes the phase retardation caused by the Mie resonance in the phase shifter. The pixelated liquid crystal driving circuit of the lower substrate can realize pixelated voltage control, that is, different voltages can be applied to the two phase shifters in the modulator, so that the phase delays of the two phase shifters can be independently controlled. Therefore, the modulation of the two optical phases can be realized by external voltage bias. Since the phases of the two paths of light can be modulated, the light path has two degrees of freedom, which can ultimately control the intensity transmission coefficient and phase difference of the two paths of coupled output light. Based on the above principles, the intensity transmission coefficient can be designed, and then the input voltage can be controlled to fully couple the input light to any output to realize a 2×2 optical gate.

Example 4

FIG. 1 is a schematic diagram of a Mach-Zehnder interferometer based on nanoantennas. It consists of an upper substrate 1 , a modulator 2 , a birefringent material 3 and a lower substrate 4 . The modulator is prepared on the lower substrate, and the birefringent material is filled between the upper and lower substrates and wraps the entire modulator structure.

Liquid crystal is used as the birefringent material. The liquid crystal can be driven by electric driving. The lower substrate is a pixelated liquid crystal driving circuit. The modulator can be fabricated using CMOS compatible 193nm photolithography and reactive ion etching methods. The upper substrate adopts total reflection metal material. The lower surface of the upper substrate is coated with an alignment layer for the alignment of liquid crystal molecules. Orientation can be rubbed orientation or photo-orientation.

The schematic top view of the structure of the modulator part is shown in FIG. 6 . The basic structure and interference principle of the well-known integrated waveguide Mach-Zehnder interferometer are the same. Monochromatic light is input into the waveguide from any coupling input port, passes through the 3dB directional coupler 1, and is divided into two paths of equal intensity light. The light is output and coupled out to the subsequent optical path. The intensity transmission coefficient of the two output lights is determined by the phase difference between the two lights after phase modulation.

The waveguide in the modulator is a strip-shaped waveguide made of silicon material, and the cross-section is shown in Figure 3(a). The rectangular silicon waveguide has a width W of 400 nm and a height H of 220 nm. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. A schematic top view of the phase shifter is shown in FIG. 7 , the nanoparticles are nano-pillars, the diameter D is 340 nm, and the height is also H=220 nm. The period p of the arrangement of nanoparticles, that is, the distance between the center points of two adjacent nanoparticles is 510 nm. The input light wavelength is 1650nm. Under this geometric parameter, light undergoes Mie resonance in the nanoparticle with high forward scattering rate, and the amount of phase retardation changes at the same time.

The working principle of the interferometer is as follows: when the device receives the control signal, a corresponding voltage is applied between the upper and lower substrates, and an electric field is formed inside the liquid crystal layer; under the action of the electric field, the director of the liquid crystal molecules changes, and the refractive index distribution changes accordingly. ; Changes in the external environment change the amount of phase delay produced by the Mie resonance. Therefore, the modulation of the optical phase can be realized by the external voltage bias, the phase difference between the two input lights can be controlled, and the power of the two output lights can be finally controlled.

Example 5

FIG. 1 is a schematic diagram of a Mach-Zehnder interferometer based on nanoantennas. It consists of an upper substrate 1 , a modulator 2 , a birefringent material 3 and a lower substrate 4 . The modulator is prepared on the lower substrate, and the birefringent material is filled between the upper and lower substrates and wraps the entire modulator structure.

Liquid crystal is used as the birefringent material. The liquid crystal can be driven by electric driving. The lower substrate is a pixelated liquid crystal driving circuit. The modulator can be fabricated using CMOS compatible 193nm photolithography and reactive ion etching methods. The upper substrate adopts total reflection metal material. The lower surface of the upper substrate is coated with an alignment layer for the alignment of liquid crystal molecules. Orientation can be rubbed orientation or photo-orientation.

The schematic top view of the structure of the modulator part is shown in FIG. 6 . The basic structure and interference principle of the well-known integrated waveguide Mach-Zehnder interferometer are the same. Monochromatic light is input into the waveguide from any coupling input port, passes through the 3dB directional coupler 1, and is divided into two paths of equal intensity light. The light is output and coupled out to the subsequent optical path. The intensity transmission coefficient of the two output lights is determined by the phase difference between the two lights after phase modulation.

The waveguide in the modulator is a strip-shaped waveguide made of silicon material, and the cross-section is shown in Figure 3(a). The rectangular silicon waveguide has a width W of 400 nm and a height H of 220 nm. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. A schematic top view of the phase shifter is shown in FIG. 7 , the nanoparticles are nano-pillars, the diameter D is 340 nm, and the height is also H=220 nm. The period p of the arrangement of nanoparticles, that is, the distance between the center points of two adjacent nanoparticles is 510 nm. The input light wavelength is 1650nm. Under this geometric parameter, light undergoes Mie resonance in the nanoparticle with high forward scattering rate, and the amount of phase retardation changes at the same time.

In order to reduce the loss of light due to geometric abrupt changes or refractive index jumps, a hybrid tapered coupler is used to optimize the coupling efficiency. The schematic top view of the phase shifter with the hybrid conical coupler is shown in Figure 8.

The working principle of the interferometer is as follows: when the device receives the control signal, a corresponding voltage is applied between the upper and lower substrates, and an electric field is formed inside the liquid crystal layer; under the action of the electric field, the director of the liquid crystal molecules changes, and the refractive index distribution changes accordingly. ; Changes in the external environment change the amount of phase delay produced by the Mie resonance. Therefore, the modulation of the optical phase can be realized by the external voltage bias, the phase difference between the two input lights can be controlled, and the power of the two output lights can be finally controlled.

Example 6

FIG. 1 is a schematic diagram of a Mach-Zehnder interferometer based on nanoantennas. It consists of an upper substrate 1 , a modulator 2 , a birefringent material 3 and a lower substrate 4 . The modulator is prepared on the lower substrate, and the birefringent material is filled between the upper and lower substrates and wraps the entire modulator structure.

Liquid crystal is used as the birefringent material. The liquid crystal can be driven by light driving. The modulator can be fabricated using CMOS compatible 193nm photolithography and reactive ion etching methods. The upper substrate is made of glass material, so that the driving light can pass through. The lower surface of the upper substrate is coated with an alignment layer for the alignment of liquid crystal molecules. The orientation method can adopt the photo-alignment method, and the orientation agent adopts SD1 material.

The schematic top view of the structure of the modulator part is shown in FIG. 2 . The basic structure and interference principle of the well-known integrated waveguide Mach-Zehnder interferometer are the same. Monochromatic light is input into the waveguide from any coupling input port, passes through the 3dB directional coupler 1, and is divided into two paths of equal intensity light. The light is output and coupled out to the subsequent optical path. The intensity transmission coefficient of the two output lights is determined by the phase difference between the two lights after phase modulation.

The waveguide in the modulator is a strip-shaped waveguide made of silicon material, and the cross-section is shown in Figure 3(a). The rectangular silicon waveguide has a width W of 400 nm and a height H of 220 nm. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. As shown in Fig. 3(b), the nanoparticle and the waveguide have the same cross section, and the length L is 243 nm. The period p of the nanoparticle arrangement, that is, the distance between the center points of two adjacent nanoparticles, is 400 nm. The input light wavelength is 1650nm. Under this geometric parameter, light undergoes Mie resonance in the nanoparticle with high forward scattering rate, and the amount of phase retardation changes at the same time.

The working principle of the interferometer is as follows: ultraviolet polarized light is used as the driving light, and the driving light is incident from above the upper substrate and irradiated to the SD1 alignment layer. The orientation of the SD1 molecules is reoriented to be perpendicular to the driving light polarization direction. Under the action of SD1 molecule, the director of liquid crystal molecule changes with the orientation of SD1 molecule, and its refractive index distribution changes accordingly; the change of external environment changes the phase retardation generated by Mie resonance. Therefore, the modulation of the optical phase can be realized by the external voltage bias, the phase difference between the two input lights can be controlled, and the power of the two output lights can be finally controlled.

Example 7

According to the Mach-Zehnder interferometer based on the nano-antenna proposed in the present invention, various forms of optical gate networks such as polygon, ellipse and any irregular shape can be realized. The polygons may include triangles, quadrilaterals, hexagons, etc., and ellipses include circles and other shapes. The hexagonal optical gate network is taken as an example below, and its basic structure is the same as that described in Embodiment 1, that is, it consists of an upper substrate, a modulator, a birefringent material and a lower substrate. The birefringent material is liquid crystal, and the lower substrate is a pixelated liquid crystal driving circuit. The modulator can be fabricated using CMOS compatible 193nm photolithography and reactive ion etching methods. The upper substrate adopts total reflection metal material. The lower surface of the upper substrate is coated with an alignment layer for the alignment of liquid crystal molecules. The orientation method can be rubbed orientation or photo-orientation.

The basic unit of the hexagonal gate network is a 2×2 optical gate, and the schematic top view of the structure of the modulator part is shown in Figure 5. Monochromatic light enters the waveguide from any coupling input port, passes through the 3dB directional coupler 1, and is divided into two paths of light of equal intensity. Each light needs to go through a direction shifter to modulate its phase. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. Light undergoes Mie resonance in nanoparticles with high forward scattering rate, and the amount of phase retardation changes. Then the two paths of light pass through the directional coupler 2 to obtain two paths of output light, which are coupled and output to the subsequent optical paths. The intensity transmission coefficient of the two output lights is determined by the phase difference between the two lights after phase modulation.

The waveguide in the modulator is a strip-shaped waveguide made of silicon material, and the cross-section is shown in Figure 3(a). The rectangular silicon waveguide has a width W of 400 nm and a height H of 220 nm. The phase shifter in the modulator consists of a one-dimensional nanoparticle resonator chain. As shown in Fig. 3(b), the nanoparticle and the waveguide have the same cross section, and the length L is 243 nm. The period p of the nanoparticle arrangement, that is, the distance between the center points of two adjacent nanoparticles, is 400 nm. The input light wavelength is 1650nm. Under this geometric parameter, light undergoes Mie resonance in the nanoparticle with high forward scattering rate, and the amount of phase retardation changes at the same time.

The hexagonal optical gate network based on the present invention can use any port of it as an input or output port of light, and its working principle is shown in Figure 9, taking two transmission paths as an example. In Figure 9, the rectangles in the transport network represent 2x2 optical gate units. By controlling the liquid crystal in the form of pixels, different gate units in the network can have different coupling functions, which are distinguished by different colors in Figure 9, that is, the white gate unit controls the input and output on the same side, and the black gate unit controls the input light. coupled to the other side output. When the working state of the liquid crystal is changed, the coupling function of the gate unit changes accordingly, and the propagation path of light in the network is switched. According to the above principles, the programming of the optical gate network can be realized by controlling the liquid crystal, so that light can propagate in any path in the network, and any port can be used as an input or output port.

On the basis of the above-mentioned basic principles, researchers construct optical gate networks of any shape, which all belong to the protection scope of the present invention.

Claims (8)

1. A Mach-Zehnder interferometer based on a nano-antenna, characterized in that: the interferometer comprises a lower substrate (1), a modulator (2), a birefringent material (3), and an upper substrate (4); the The modulator (2) is located on the lower substrate (1); the birefringent material (3) is filled between the lower substrate (1) and the upper substrate (4), and wraps the modulator (2); the modulator ( 2) The phase shifter (2-1) is a subwavelength nano-antenna (2-2) array; when light passes through the nano-antenna (2-2), Mie resonance occurs, and the phase is obtained while having a high forward scattering rate The retardation amount is controlled by the refractive index of the birefringent material; the output intensity modulation of the interferometer is realized by modulating the refractive index of the birefringent material. 2. The nano-antenna-based Mach-Zehnder interferometer according to claim 1, wherein the nano-antenna (2-2) adopts nano-spheres, nano-bricks or nano-pillars. 3 . The nano-antenna-based Mach-Zehnder interferometer according to claim 1 , wherein the birefringent material ( 3 ) adopts liquid crystal. 4 . 4 . The nano-antenna-based Mach-Zehnder interferometer according to claim 3 , wherein the liquid crystal operates in an electric drive mode or an optical drive mode. 5 . 5 . The nano-antenna-based Mach-Zehnder interferometer according to claim 4 , wherein the lower substrate ( 1 ) is a pixelated driving circuit. 6 . 6. A nano-antenna-based Mach-Zehnder interferometer according to claim 1, characterized in that: the phase shifter (2-1) has a hybrid conical coupler, which reduces the loss during transmission. 7 . The nano-antenna-based Mach-Zehnder interferometer according to claim 1 , wherein the interferometer is used to modulate the intensity of the input light. 8 . 8 . The nano-antenna-based Mach-Zehnder interferometer according to claim 1 , wherein the interferometer implements a 2×2 optical gate. 9 .

Images