A micro-nanostructure for wavelength-dependent 3D optical switching

Abstract

The present invention relates to a micro-nano structure for a wavelength-dependent 3D optical switch, comprising: a substrate; two silicon nano-pillar chains arranged in parallel on the substrate; each silicon nano-pillar chain comprises ordinary pillars and defective pillars of the same height, the ordinary pillars and defective pillars are arranged in a row, the defective pillars are arranged at the first and third positions at the end of the silicon nano-pillar chain; the radius of the defective pillars is greater than the radius of the ordinary pillars. The present invention can perform switch modulation of a 3D optical link under different input light phases and exhibit opposite switch characteristics under different wavelengths.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano optical device design, and in particular to a micro-nano structure for a wavelength-dependent 3D optical switch. Background Art

[0002] Phase-controlled optical switches are devices that control the on and off of optical paths by modulating the phase in an optical link. In photonic integrated circuits, common optical switches such as Mach-Zehnder interferometers (MZIs) can achieve on and off of 2D links, but they usually do not have 3D link switching characteristics and cannot meet the needs of future multi-layer structure chips; if multi-layer MZIs are made to meet the 3D link switching characteristics, the process difficulty will be greatly increased, and the device size will be further increased. Therefore, it is necessary to design a micro-nano structure with simple structure, compact size, and wavelength multiplexing to manufacture 3D optical switches to meet the needs of 3D optical path on and off. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a micro-nano structure for a wavelength-dependent 3D optical switch, which performs switch modulation of a 3D optical link under different input light phases and exhibits opposite switch characteristics under different wavelengths.

[0004] The technical solution adopted by the present invention to solve the technical problem is: to provide a micro-nano structure for a wavelength-dependent 3D optical switch, comprising:

[0005] substrate;

[0006] Two silicon nano-pillar chains are arranged in parallel on the substrate; each silicon nano-pillar chain includes ordinary pillars and defective pillars of the same height, the ordinary pillars and defective pillars are arranged in a row, and the defective pillars are arranged at the first and third positions at the end of the silicon nano-pillar chain; the radius of the defective pillar is greater than the radius of the ordinary pillar.

[0007] The period of the pillars in the silicon nano-pillar chain is 400 nm.

[0008] The radius of the common column is 110 nm, and the radius of the defective column is 190 nm.

[0009] The center distance between the silicon nano-pillar sub-chains is 350nm, and the defective columns of the two silicon nano-pillar sub-chains have overlapping parts.

[0010] The heights of the common pillars and the defective pillars are both 810 nm.

[0011] The refractive index of the ordinary column and the defective column is 3.46

[0012] The substrate is a silicon dioxide substrate with a refractive index of 1.5.

[0013] Beneficial Effects

[0014] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: the present invention can perform switch modulation of 3D optical links under different input light phases and exhibit opposite switch characteristics under different wavelengths. The optical switch has more degrees of freedom to manipulate the on and off of the 3D optical path and can be used with other optical devices to build a more flexible 3D optical link. The optical switch has a compact size and a flexible structure, and has practical value in the device design of photonic integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural diagram of a micro-nano structure for a wavelength-dependent 3D optical switch according to an embodiment of the present invention;

[0016] Figure 2 is a schematic diagram of the emission efficiency of a micro-nanostructure used for a wavelength-dependent 3D optical switch at different wavelengths according to an embodiment of the present invention;

[0017] Figure 3 yes Figure 2 The launch site diagram of the midpoint A and point B;

[0018] Figure 4 is the electric field distribution diagram of the xoy plane at wavelengths of 1500nm and 1640nm;

[0019] Figure 5 is the scattering intensity map produced by defect pillars of different sizes;

[0020] Figure 6 It is a schematic diagram of the transmission efficiency in TM0 mode and TM1 mode when the embodiment of the present invention is connected to a multimode waveguide. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0022] Embodiments of the present invention relate to a micro-nanostructure for wavelength-dependent 3D optical switching, such as Figure 1 As shown, it includes: a substrate 1 and two silicon nano-pillar chains 2.

[0023] Among them, the length of the pillar chain 2 is L = 18μm, and the period of the pillar is p = 400nm. The pillar chain 2 is composed of ordinary pillars 21 and defective pillars 22, most of which are ordinary pillars 21 with a radius r0 = 110nm. The first pillar and the third pillar at the end of each pillar chain 2 are defective pillars 22 with a radius rd = 190nm. The center distance between the two pillar chains is s = 350nm, so there is a partial overlap between the defective pillars of the two pillar chains in this embodiment. The height of all pillars is h = 810nm. The refractive index of the pillar is n = 3.46, and the substrate is a silicon dioxide substrate with a refractive index of nsub = 1.5.

[0024] The emission of the optical switch is simulated using the 3D finite-difference time-domain method. A point light source with Ez polarization is set before each pillar chain. The light from the point source can be coupled into the column chain and scattered into free space at the defective column. A monitor is placed 3.5 μm above the defective column to record the upward scattered field and calculate the emission efficiency. This embodiment calculates and The emission efficiency at the operating wavelength of 1460-1650nm, such as Figure 2 As shown. It can be seen that when When , there is light emission at wavelengths greater than 1560nm, but no emission at wavelengths less than 1560nm. When the wavelength is less than 1560nm, there is obvious emission. Figure 2 The launch field at point A and point B is as follows Figure 3 As shown. When λ=1640nm, When λ=1500nm, the emission field presents a spot size of 3μm×5μm, and the emission efficiency is 30%. Its intensity mainly comes from the Ex field, which can be considered as the superposition of the emission fields of the two chains on the xoz plane. When , the emission field is in the shape of the letter "C", which is the superposition of Ex and Ey with comparable intensities. The Ex field is composed of two points symmetrical about the xoz plane, and Ey is a point on the xoz plane. Therefore, these three points form an emission field in the shape of the letter "C" with an emission efficiency of 10%.

[0025] Figure 4 The electric field distribution of the xoy plane at 1500nm and 1640nm wavelengths is shown. Obviously, the propagation of light in the column chain directly affects the emission efficiency. When λ = 1500nm, Or λ = 1640nm, When λ = 1640nm, light can propagate in the column chain and scatter into free space. Or λ = 1500nm, When the phase difference is , the light has difficulty propagating in the column chain, so the luminous efficiency is low. This is due to the superposition of modes in the double-row chain. For a better understanding, a point light source is placed at an asymmetric position of the structure to excite the modes of the double-row chain and calculate the electric field E(x,y). Therefore, when there is a phase difference of When there are two light sources, the total electric field can be calculated as follows:

[0026]

[0027] Where E(x, y) = E x (x,y)+E y (x,y)+E z (x, y). Figure 4 is the distribution of the electric field components in the double-row chain when there is only one point light source. It can be seen that when the wavelength is 1500nm, the Ex and Ez components are anti-symmetrically distributed relative to the xoz plane, while the Ey component is symmetrically distributed, that is:

[0028] E x (x, -y) = -E x (x, y)

[0029] E y (x, -y) = E y (x, y)

[0030] E z (x, -y) = -E z (x, y)

[0031] Then equation (1) can be written as:

[0032]

[0033]

[0034] The intensity of the Ez component is dominant, so when Time can travel within the column, but when The case of 1640nm is based on the same principle. However, the symmetry of the electric field component is just opposite to that at 1500nm. Therefore, the propagation state of light is also reversed.

[0035] The emission characteristics of the micro-nanostructure used for wavelength-dependent 3D optical switches in this embodiment are mainly due to the scattering of defective columns. The large size of defective columns will lead to mode mismatch. Part of the electric field can no longer be bound in the column chain and leaks along the z direction, forming a scattered field. Figure 5The scattering intensity generated by defective columns of different sizes was simulated. The scattering intensity reached a maximum value of 18% at r = 190nm. In this embodiment, two defective columns are set in each chain to form a 2×2 array, which can better constrain the emission field shape in the x and y directions.

[0036] Example: 3D optical switch connected to multimode waveguide

[0037] In the above simulation, a point light source is used as the input light. In this embodiment, a similar effect is achieved with a symmetric or antisymmetric incident field. A typical example is the mode input of a multimode waveguide. Figure 6 A silicon multimode waveguide with a height of 810 nm and a width of 650 nm is shown. By calculating the TM modes of this waveguide, it is found that TM0 is symmetric (see Figure 6 (a)), corresponding to the phase difference of the point light source , while TM1 is antisymmetric (see Figure 6 (b)), corresponding to the phase difference of the point light source The emission efficiency is calculated by using a waveguide mode source instead of a point light source. Figure 6 (c) Obviously, this result is consistent with the result of point light source input. By modulating the mode of the waveguide, the effect of 3D optical switching can be achieved.

Claims

1. A micro-nanostructure for wavelength-dependent 3D optical switching, characterized in that: include: substrate; Two silicon nano-pillar chains are arranged in parallel on the substrate; each silicon nano-pillar chain includes ordinary pillars and defective pillars of the same height, the ordinary pillars and defective pillars are arranged in a row, and the defective pillars are arranged at the first and third positions at the end of the silicon nano-pillar chain; the radius of the defective pillar is greater than the radius of the ordinary pillar.

2. The micro-nano structure for wavelength-dependent 3D optical switch according to claim 1, characterized in that: The period of the pillars in the silicon nano-pillar chain is 400 nm.

3. The micro-nano structure for wavelength-dependent 3D optical switch according to claim 1, characterized in that: The radius of the common column is 110 nm, and the radius of the defective column is 190 nm.

4. The micro-nano structure for wavelength-dependent 3D optical switch according to claim 3, characterized in that: The center distance between the two silicon nano-pillar chains is 350 nm, and there are overlapping parts of the defective pillars of the two silicon nano-pillar chains.

5. The micro-nano structure for wavelength-dependent 3D optical switch according to claim 1, characterized in that: The heights of the common pillars and the defective pillars are both 810 nm.

6. The micro-nano structure for wavelength-dependent 3D optical switch according to claim 1, characterized in that: The refractive indexes of the common columns and defective columns are both 3.

46.

7. The micro-nano structure for wavelength-dependent 3D optical switch according to claim 6, characterized in that: The substrate is a silicon dioxide substrate with a refractive index of 1.5.

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