阅读说明：本技术 纳米八木天线阵列结构 (Nano yagi antenna array structure ) 是由 匡登峰 林宇 杨卓 马晓威 耿雪 郭蓉 李钰琛 于 2018-06-08 设计创作，主要内容包括：一种优化海豚形元胞圆阵列超表面产生的局域复合偏振光场的片上定向纳米八木天线阵列,由五根纳米金属棒组成构成一组,一共N组(N≥3且N为正整数),各组棒状结构沿径向指向圆心,等角度旋转排布构成圆形阵列。纳米八木天线结构对于海豚形元胞圆阵列超表面透射场能量强度的维持有一定的积极作用,优化透射光场z方向分量E<Sub>z</Sub>的强度占比,使优化程度随距离增加而增强,对透射场E<Sub>z</Sub>分量相位分布无明显消极作用。本结构具有良好的定向场增强、辐射的作用,能够显著增强涡旋光束E<Sub>z</Sub>的强度占比,这对于涡旋光束的检测有重要意义。本发明结构简单,促进光学器件的微型化和集成化,提高光通信的稳定度、灵敏度,对宽带光通信、光学成像、纳米操控等领域有重要的应用价值。(An on-chip directional nano yagi antenna array for optimizing a local composite polarized light field generated on the super surface of a dolphin-shaped cellular circular array is composed of a group consisting of five nano metal rods, wherein N groups (N is more than or equal to 3 and is a positive integer) are formed, and each group of rod-shaped structures point to the center of a circle along the radial direction and are arranged in an equiangular rotation mode to form the circular array. The nano yagi antenna structure has a certain positive effect on maintaining the energy intensity of the super-surface transmission field of the dolphin-shaped cellular circular array, and optimizes the component E of the transmission light field in the z direction z Such that the degree of optimization increases with distance, for the transmission field E z The component phase distribution has no significant negative effect. The structure has good functions of directional field enhancement and radiation, and can remarkably enhance vortex beam E z Is important for the detection of vortex beams. The invention has simple structure, promotes the miniaturization and integration of optical devices, improves the stability and sensitivity of optical communication, and has important application value in the fields of broadband optical communication, optical imaging, nano control and the like.)

1. An on-chip oriented nano yagi antenna array structure for optimizing a local composite polarized light field generated on the super surface of a dolphin-shaped cellular circular array is characterized in that five metal rod-shaped structures form a group, N groups are provided in total, (N is more than or equal to 3 and N is a positive integer), each group of rod-shaped structures points to the circle center along the radial direction, and the rod-shaped structures are arranged in an equiangular rotation mode to form the circular array. The distance between the antenna and the axis of the structure is R, and the included angle alpha between the two adjacent groups of antennas about the axis is 360 degrees/N. The antenna array is arranged above the super surface of the dolphin-shaped cellular circular array d₀To (3).

2. The structure of the nano yagi antenna array on the directional plate as claimed in claim 1, wherein the basic unit is a nanorod-like structure, each nano metal rod is composed of a cylinder and two hemispheres with the same radius as the cylinder at two ends, and the surface is smooth and integrated without connecting gaps.

3. The on-chip directional nano-yagi antenna array structure of claim 1 or 2, wherein: the longer metal rod is called reflector, the second longer metal rod is called main vibrator, and the shorter three equal length metal rods are called director. In a group of antenna structures, the radiator is spaced from the main oscillator by a distance a_rAfter that, the main oscillator is spaced from the director by the same distance, which is a_d＝λ/4。

4. The on-chip oriented nano-yagi antenna array structure of claim 1, 2 or 3, wherein the length of the main element L is_f2r + L, where L λ/4(λ is the wavelength of the incident light), reflector length L_r＝1.25L_fLength L of the guide_d＝0.9L_f。

5. The structure of the array of nano-yagi antenna on a directional chip as claimed in claim 1, 2, 3, 4 or 5, wherein the structure can optimize the local composite polarized light generated by the super surface of the dolphin-shaped circular array of unit cellsA field. Has certain positive effect on maintaining the energy intensity of the super-surface transmission field of the dolphin-shaped cellular circular array, and can optimize the component E of the transmission light field in the z direction_zSuch that the degree of optimization increases with distance, for the transmission field E_zThe component phase distribution has no significant negative effect.

Technical Field

The invention belongs to the field of nano antennas, relates to light field polarization modulation, nano control and surface plasma excitation, and particularly relates to an on-chip directional nano yagi antenna array for optimizing a local composite polarization light field generated on the super surface of a dolphin-shaped cellular circular array.

Background

At present, many kinds of optical devices with sub-wavelength scales are used for regulating and controlling the spin angular momentum and the orbital angular momentum of an optical field. In recent years, the application of using orbital angular momentum to improve information carrying capacity has been widely focused, and how to improve the propagation efficiency of light beams containing Orbital Angular Momentum (OAM) is gradually called one of the research hotspots.

In 2011, OAM beams are generated by fiber couplers, and the mode purity of the OAM beams can reach over 96.4%. But due to the poor waveguide dispersion of the fiber coupler, the higher-order OAM modes are sensitive to wavelength variations, resulting in mode instability. In the traditional OAM wave beam generation methods, such as the spiral phase plate method and the computational holography method, the OAM wave attenuation is severe due to the additional modulation optical path.

The miniaturization and integration of optical devices are important issues in current optical field research, but the traditional optical devices have the defects of large size, difficulty in integration and the like. In 2016, a structure in which a circular hole is engraved in a silver film was proposed, so that a device can suppress phase noise while achieving high integration. It does not improve single direction beam strength.

The invention improves E in OAM wave beam through a group of nano yagi antenna arrays_zThe strength ratio improves the detection performance of OAM. Since the nano-antenna array is miniature and light, the size of the device is reduced as much as possible.

Disclosure of Invention

The invention provides an enhanced vortex beam E_zYagi antenna array with intensity proportional to the intensity of the total light field E. The antenna array is composed ofThe antenna comprises N groups of nano-structured yagi antenna units, and each antenna unit comprises five nano-metal rods. Each nano metal rod consists of two hemispheres with the radius of r and a cylinder with the radius of r. Among them, the longer metal rod is called a reflector, the second longest metal rod is called a main vibrator, and the shorter three metal rods are called directors. Length L of main oscillator_f2r + L, where L λ/4(λ is the wavelength of the incident light), reflector length L_r＝1.25L_fLength L of the guide_d＝0.9L_f. And the radii of the three are the same. Distance a between reflector and main oscillator_rλ/4.4, the distance a between the director and the main oscillator_dλ/4. The distance between the N groups of antennas and the axis of the structure is R, and the included angle alpha between the two adjacent groups of antennas and the axis is 360 degrees/N.

The antenna array structure has good functions of directional field enhancement and radiation, and can remarkably enhance vortex beam E_zIs important for the detection of vortex beams.

The invention has the advantages and positive effects that:

The dolphin-shaped metal cells tie incident light energy to the surface of the structure, convert incident linearly polarized light into spiral phase light beams, generate local composite polarized light fields and transmit the nano yagi antenna array on the orientation sheet, and the nano yagi antenna array enables a component E in the z direction of the transmitted light fields_zthe ratio of the intensity of (a) to the total optical field E intensity is significantly enhanced at the same propagation distance compared to a super-surface without the nano-yagi antenna array. Meanwhile, the antenna has no obvious influence on the phase helix effect of the original super surface in the composite optical field. The structure has good functions of directional field enhancement and radiation, and can remarkably enhance vortex beam E_zIs important for the detection of vortex beams. The nano yagi antenna structure has the advantages of good directivity, high gain, simple manufacture and convenience in integrating lumped components on the surface of the structure. The invention improves the stability and the sensitivity of optical communication, and has important application value in the fields of broadband optical communication, optical imaging, nano control and the like.

Drawings

Fig. 1 is a three-view of a nano-antenna array. Wherein: (a) the plane view is a front view and a side view of one group of metal rod-shaped structures, the radial direction of the yagi antenna array in the front view is an x axis, the vertical radial direction is a y axis (not shown), and the arrangement extending direction of one group of metal rod-shaped structures in the yagi antenna array is a z axis. (b) Is a top view of a nano yagi antenna array placed on the super surface of the dolphin-shaped cellular circular array.

Fig. 2 is a schematic diagram showing the comparison between the intensities of the transmission fields at different distances behind the super surface when linearly polarized light which propagates in the z direction and has the polarization direction of the x direction is incident on the super surface of the dolphin-shaped cellular circular array and the intensities of the transmission fields at different distances behind the super surface when the nano antenna array structure is used (taking N as an example, 8). Wherein: (a) the intensity distribution diagram of the transmission field at the position D-1000 nm behind the super surface of the dolphin-shaped cellular circle array is shown; (b) the intensity distribution diagram of the transmission field at the position D-1000 nm behind the super surface of the dolphin-shaped cellular circular array is shown after the nano yagi antenna array is used; (c) the intensity distribution diagram of the transmission field at the position D ═ 2000nm behind the super surface of the dolphin-shaped cellular circle array is shown; (d) the intensity distribution diagram of the transmission field at the position D equal to 2000nm behind the super surface of the dolphin-shaped cellular circular array is shown after the nano yagi antenna array is used; (e) the intensity distribution diagram of the transmission field at the position D (3000 nm) behind the super surface of the dolphin-shaped cellular circle array is shown; (f) the intensity distribution of the transmission field at the position D-3000 nm behind the super surface of the dolphin-shaped cellular circular array is schematically shown after the nano yagi antenna array is used.

FIG. 3 shows the z-component E of the light field at different distances behind the super-surface when linearly polarized light propagating along the z-direction and having the polarization direction of the x-direction is incident on the super-surface of the dolphin-shaped cellular circular array_zLight field intensity | E of_z|²Occupying the total light field intensity | E²The ratio of (A) to (B) is equal to the z-component E of the light field at different distances behind the rear super-surface after the nano yagi antenna array is used_zLight field intensity | E of_z|²Occupying the total light field intensity | E²A comparison of ratios of (a) to (b) at the same distance (taking N ═ 8 as an example). Wherein: (a) is a transmission field z minute at the position D-1000 nm behind the super surface of the dolphin-shaped cellular circle arrayQuantity E_zLight field intensity | E of_z|²The proportion of the total light field intensity; (b) the transmission field z component E at the position D-1000 nm behind the super surface of the dolphin-shaped cellular circular array is obtained by using a nano yagi antenna array_zLight field intensity | E of_z|²The proportion of the total light field intensity; (c) is a transmission field z component E at the position D ═ 2000nm behind the super surface of the dolphin-shaped cellular circle array_zlight field intensity | E of_z|²Occupying the total light field intensity | E²The ratio of (A) to (B); (d) the transmission field z component E at the position D ═ 2000nm behind the super surface of the dolphin-shaped cellular circular array after the nano yagi antenna array is used_zLight field intensity | E of_z|²The proportion of the total light field intensity; (e) is a transmission field z component E at the position D (3000 nm) behind the super surface of the dolphin-shaped cellular circle array_zLight field intensity | E of_z|²Occupying the total light field intensity | E²The ratio of (A) to (B); (f) the transmission field z component E of the dolphin-shaped cellular circular array at the position D of 3000nm behind the super surface is measured by using a nano yagi antenna array_zLight field intensity | E of_z|²The proportion of the total light field intensity.

FIG. 4 is a graph showing the light field E at different distances behind the super-surface when linearly polarized light propagating in the z direction and having the polarization direction in the x direction is incident on the super-surface of the dolphin-shaped cellular circular array_zThe phase distribution of the components and the light field E at different distances behind the rear super surface after the nano yagi antenna array is used_zThe phase distribution of the components is a comparative diagram at the same distance (taking N-8 as an example). Wherein: (a) e of transmission field at the position D1000 nm behind super surface of dolphin-shaped cellular circular array_za component phase distribution diagram; (b) is E of transmission field at the position D ═ 1000nm behind the super surface of dolphin-shaped cellular circular array after using nano yagi antenna array_zA component phase distribution diagram; (c) is E of transmission field at the position D ═ 2000nm behind the super surface of dolphin-shaped cellular circular array after using nano yagi antenna array_zA component phase distribution diagram; (d) is E of transmission field at the position D ═ 2000nm behind the super surface of dolphin-shaped cellular circular array after using nano yagi antenna array_zA component phase distribution diagram; (e) e of a transmission field at the position D (3000 nm) behind the super surface of the dolphin-shaped cellular circular array_zA component phase distribution diagram; (f) is E of transmission field at the position D of 3000nm behind super surface of dolphin-shaped cellular circular array after using nano yagi antenna array_zThe component phase distribution is shown schematically.

Detailed Description