阅读说明：本技术 一种超薄无衬底颜色可调谐的表面等离子体滤波器 (Ultrathin substrate-free color tunable surface plasma filter ) 是由 肖功利 杨寓婷 杨宏艳 张开富 徐燕萍 欧泽涛 陈剑云 李海鸥 邓艳容 傅涛 李 于 2019-12-16 设计创作，主要内容包括：本发明涉及微纳集成光学器件技术领域,公开了一种超薄无衬底颜色可调谐的表面等离子体滤波器。所述滤波器结构包括：波导层,缓冲层和矩形金属纳米盘阵列。其中波导层上覆盖有缓冲层,缓冲层上刻蚀有均匀排布的矩形金属纳米盘阵列,矩形金属纳米盘阵列x方向周期为P<Sub>x</Sub>,y方向周期为P<Sub>y</Sub>。当x与y相等,通过改变x(y)方向周期,可实现对滤出颜色的静态调制,当x与y不相等,可通过改变周期以实现对滤出颜色的静态调制,改变光的偏振以实现对滤出颜色的动态调制。本专利有着体积小,传输效率高,结构设计简单,能够同时实现对颜色的静态调制以及动态调制,可固定TE(TM)偏振滤出颜色,单独调制TM(TE)偏振下滤出的颜色等优点。本发明在未来光电器件集成,超高分辨率成像,LCD液晶显示系统等领域都有重要的应用。(The invention relates to the technical field of micro-nano integrated optical devices, and discloses an ultrathin substrate-free color tunable surface plasma filter. The filter structure includes: waveguide layer, buffer layer and rectangular metal nanodisk array. Wherein the waveguide layer is covered with a buffer layer, the buffer layer is etched with rectangular metal nano-disk arrays which are uniformly distributed, and the x-direction period of the rectangular metal nano-disk arrays is P x With period in y direction of P y . When x and y are equal, static modulation of the filtered color can be realized by changing the period of the x (y) direction, and when x and y are not equal, static modulation of the filtered color can be realized by changing the period, and dynamic modulation of the filtered color can be realized by changing the polarization of light. The color filter has the advantages of small volume, high transmission efficiency and simple structural design, can simultaneously realize static modulation and dynamic modulation of colors, can fix TE (TM) polarization filtering color, and can separately modulate TM (TE) polarization filtering colorColor and the like. The invention has important application in the fields of future photoelectric device integration, ultrahigh resolution imaging, LCD liquid crystal display systems and the like.)

1. An ultrathin substrate-free surface plasma filter with tunable colors comprises a waveguide layer 1 and a buffer layer 2 covering the waveguide layer 1, wherein rectangular metal nano-discs 3 arrays which are uniformly distributed are etched on the buffer layer 2. Wherein the material of the waveguide layer 1 is Si₃N₄Thickness H of₁Fixed at 100nm, and MgF is selected as the material of the buffer layer 2₂Thickness H of₂Fixed at 25nm, the rectangular metal nanoplate 3 array metal material is Al, and the thickness H thereof₃Fixed at 40nm. The x-direction period of the rectangular metal nano disc 3 array is P_xWith period in y direction of P_yThe duty ratio of the x and y directions of the array of the fixed rectangular metal nanodisks 3 is 0.7.

2. The ultra-thin substrate-less color tunable surface plasmon filter of claim 1, wherein: the buffer layer 2 covers the waveguide layer 1, and rectangular metal nano-discs 3 arrays which are evenly distributed are etched on the buffer layer 2.

3. The ultra-thin substrate-less color tunable surface plasmon filter of claim 1, wherein: the waveguide layer 1 is made of Si₃N₄The buffer layer 2 is made of MgF₂The material of choice for the rectangular metal nanodisk 3 array is Al.

4. The ultra-thin substrate-less color tunable surface plasmon filter of claim 1, wherein: thickness H of waveguide layer 1₁Fixed at 100nm and buffer layer 2 thickness H₂Fixed at 25nm, rectangular metal nanodisk 3 array thickness H₃Fixed at 40nm.

5. The ultra-thin substrate-less color tunable surface plasmon filter of claim 1, wherein: a rectangular nano metal disk 3 array with a period of P in the x direction_xWith period P in the y direction_y。

6. The ultra-thin substrate-less color tunable surface plasmon filter of claim 1, wherein: the duty ratio of the x and y directions of the rectangular metal nanodisk 3 array is fixed to 0.7.

(I) technical field

The invention relates to the technical field of micro-nano integrated optical devices, in particular to an ultrathin substrate-free color tunable surface plasma filter.

(II) background of the invention

In nature, many substances have beautiful and rich colors. They diffract, reflect and scatter light to appear different colors by the special microstructure of their surface. The surface plasmon is cluster oscillation of metal free charges induced on the metal surface by illumination, and the excitation of the surface plasmon is controlled by changing the shape and size of a plasmon metal nano structure, so that the effect of visible light frequency selection is achieved.

With the development of micro-nano processing technology, in recent years, the artificial manufacture of micro-nano metal structures is a main source for generating structural colors. Compared with the traditional chemical coloring agent, the structural color has the characteristics of recyclability, easiness in manufacturing, good durability and the like, and in addition, the secondary diffraction local effect of the plasmon can break through the diffraction limit and improve the imaging resolution. These characteristics make surface plasmon structural colors play an important role in the fields of ultrahigh resolution imaging, LCD liquid crystal display systems, CMOS digital integrated circuits, light emitting diodes and the like.

With the deep research on plasmon structural colors and the demand of scientific and technological development, a great number of problems are provided, such as how to improve the oxidation resistance and the vulcanization resistance of the device to prolong the service life of the device and how to realize large-scale and large-batch production; the plasmon structural color on the surface can realize dynamic regulation and the like.

In order to solve the problem of dynamic regulation and control of the surface plasmon structure color, the invention provides a transmission type color tunable filter which is composed of a metal nano disc array, a buffer layer and a waveguide. The transmission efficiency of the proposed filter can reach more than 70%, static modulation of color can be realized by changing the structure size and the period, and dynamic modulation of color can be realized by changing light polarization.

Disclosure of the invention

In view of the above problems, it is an object of the present invention to provide an ultra-thin substrate-less color tunable surface plasmon filter, in which light enters the filter from a positive z-axis direction and filtered light exits from a negative z-axis direction. By controlling the period of the rectangular metal nano-disk array, the static modulation of the filtered color can be realized, the dynamic modulation of the filtered color can be realized by controlling the polarization of incident light, and the filter can realize the manipulation of light covering the whole visible spectrum.

In order to achieve the purpose, the invention adopts the following technical scheme:

the ultrathin substrate-free color tunable surface plasma filter consists of a waveguide layer, a buffer layer and rectangular metal nano disks, wherein the waveguide layer is covered with the buffer layer, and the buffer layer is etched with rectangular metal nano disk arrays which are uniformly distributed.

In the above-mentioned scheme, the first step of the method,the preferred waveguide layer material is Si₃N₄Its thickness H₁Fixed at 100nm, the buffer layer is MgF₂Thickness H₂Fixed at 25nm, the rectangular metal nano-disc is made of Al with a thickness H₃Fixed at 40nm.

P_xIs the period of the rectangular Al nanodisk in the x direction, P_yThe period of the rectangular Al disk in the y direction is the period of the rectangular Al disk, the duty ratio of the rectangular Al nano disk directly influences the transmission efficiency and the saturation of filtered colors, and the duty ratios of the rectangular Al nano disk in the x direction and the y direction are determined to be 0.7 by comprehensive consideration.

Due to the adoption of the technical scheme, the invention has the following advantages:

according to the ultrathin substrate-free color tunable surface plasma filter provided by the invention, Al is selected from metal materials, and compared with a common Ag material, the Al is universal and low in price, has lower band-to-band transition loss and better oxidation resistance, and has wider application in practice.

Compared with a common solid color-mixing color filter, the ultrathin substrate-free color-tunable surface plasma filter provided by the invention can realize solid color mixing by changing the period of the Al nanodisk, and can also change the polarization angle of incident light to realize dynamic color modulation.

The ultrathin substrate-free color tunable surface plasma filter provided by the invention has the polarization sensitivity, and can realize dynamic modulation on filtered colors by modulating the polarization angle of incident light. Compared with a filter for realizing dynamic color matching by using liquid crystal, the invention can overcome the defects of complex structure, difficult realization of large-area manufacturing, larger structure size, difficult photoelectric integration, difficult color regulation and control and the like of the liquid crystal color matching filter. Compared with a filter using polarization modulation color, the ultrathin surface plasma filter without the substrate and with the tunable color has the advantages that TE (TM) polarization color is fixed and unchanged, and color under TM (TE) polarization is singly regulated.

(IV) description of the drawings

Fig. 1 is a schematic diagram of an ultra-thin substrate-less color tunable surface plasmon filter.

FIG. 2(a) shows a period P_x＝P_yWhen is, P_x＝P_yThe transmission spectrum is changed from 300nm to 600nm in steps of 50nm, and fig. 2(b) is a CIE chromatogram corresponding to fig. 2 (a).

FIG. 3 shows a fixed x, y direction period P_x＝P_yTransmission spectrum at a light angle of incidence theta varying from 0 deg. to 30 deg. in 10 deg. steps at 400 nm.

FIG. 4(a) shows a fixed x-direction period P_x300nm, polarization angle phi 0 DEG, period P in y-direction_yTransmission spectrum when the step size of 50nm is changed from 300nm to 600nm, FIG. 4(b) is the fixed x-direction period P_x400nm, polarization angle phi 0 DEG, period P in y direction_yThe transmission spectrum when the step size of 50nm is changed from 300nm to 600nm, and fig. 4(c) is the CIE chromatograms corresponding to fig. 4(a) and 4 (b).

FIG. 5(a) shows P being fixed_x＝300nm，P_yTransmission spectrum when the polarization angle phi is changed from 0 deg. to 90 deg. in 22.5 deg. steps at 400nm, and fixed P in fig. 5(b)_x＝300nm，P_yThe transmission spectrum when the polarization angle phi is changed from 0 ° to 90 ° in 22.5 ° steps at 500nm, and fig. 5(c) is a CIE chromatogram corresponding to fig. 5(a) and 5 (b).

The reference numbers in the figures are: 1 waveguide layer, 2 buffer layer, 3 rectangular metal nano-disc

(V) detailed description of the preferred embodiments

The invention will now be described in more detail by way of example with reference to the accompanying drawings in which:

referring to fig. 1, the ultrathin substrate-free color tunable surface plasmon filter includes a waveguide layer, a buffer layer 2 covering the waveguide layer 1, and rectangular metal nanodisk arrays 3 uniformly arranged on the buffer layer 2 by etching.

The waveguide layer 1 is made of Si₃N₄The buffer layer 2 is made of MgF₂The rectangular metal nanodisk array material is Al, and compared with the metal Ag with the lowest loss in a visible spectrum, the Al is easy to obtain, low in price, low in band-to-band transition loss, and better in oxidation resistance and corrosion resistanceForce.

Wherein the thickness H of the waveguide layer₁Fixed at 100nm and the thickness H of the buffer layer₂Fixed at 25nm, rectangular metal nanodisk thickness H₃Fixed at 40nm, and the x-direction period of the rectangular metal nano-disc is P_xWith period in y direction of P_yThe duty ratio of the x and y directions of the nanodisk is fixed to 0.7.

And performing numerical simulation on the structure by adopting a three-dimensional Finite Difference Time Domain (FDTD) method, setting FDTD boundary conditions as a Perfect Matching Layer (PML) in the positive and negative directions of z, setting periodic boundary conditions in the positive and negative directions of x and y, and setting the grid size in the positive and negative directions of x, y and z as 5nm by 2nm after a convergence test. The transmission coefficient T is defined as T Pout/Pin where Pin and Pout are the input and output power, respectively.

FIG. 2(a) is a schematic diagram of an ultra-thin substrate-less color tunable surface plasmon filter with period P in the x, y directions_x＝P_yUnder the condition that the polarization angle phi is 0, enabling P to be_x(P_y) Transmission spectrum when transforming from 300nm to 600nm with 50nm as step size. Fig. 2(b) is a CIE chromatogram corresponding to the transmission spectrum of fig. 2 (a). It can be seen from FIG. 2(a) that the period P follows the x (y) direction_x(P_y) The transmission spectrum is red-shifted, i.e. the filtered color gradually changes from the blue band to the red band, and besides, it can be seen from fig. 2(a) that the transmission efficiency (wavelength at the highest transmittance) of the filter is more than 70%, which indicates that the transmission efficiency of the filter is very high, and the filtering effect is ensured. A more intuitive color change can be seen from fig. 2(b), and as can be seen from fig. 2(b), the filter can realize full light control in visible light.

FIG. 3 shows an ultra-thin substrate-less color tunable surface plasmon filter with a period P in the x and y directions_x＝P_yThe transmission spectrum of the angle of incidence theta is transformed from 0 deg. to 30 deg. in steps of 10 deg. under the condition that the polarization angle phi is 0 at 400 nm. As can be seen from fig. 3, the filter is very sensitive to the incident angle and has very little tolerance to the angle, so in the actual manufacturing process, in order to reduce the error, it is necessary to make the incident angle vertical incidence have no deviation.

As shown in FIG. 4(a), the ultra-thin substrate-less color tunable surface plasmon filter has a fixed x-direction period P_x300nm, polarization angle phi 0 °, period P in y-direction_yTransmission spectrum varying from 300nm to 600nm in 50nm steps with period P in y-direction_yThe peak value of the main peak of the transmission spectrum of fig. 4(a) does not change gradually, which shows that the filtering color does not change too much. FIG. 4(b) shows the period P in the fixed x-direction_x400nm, a period P in the y-direction at a polarization angle phi of 0 DEG_yTransmission spectrum varying from 300nm to 600nm in 50nm steps with period P in y-direction_yThe main peak value of the transmission spectrum of fig. 4(b) does not change gradually, which shows that the filtering color does not change too much. 4(c) is the CIE chromatograms corresponding to fig. 4(a) and 4(b), and it can be seen more intuitively from the drawings that the filtered colors are all concentrated in a small range, and the colors are basically unchanged. Thus, when the polarization angle of the filter is 0 DEG, the period P in the x direction mainly determines the filtered color_xAnd a period P in the y direction_yDoes not have much influence on the filtered color.

As shown in FIG. 5(a), an ultra-thin substrate-less color tunable surface plasmon filter with a fixed x-direction period P_x300nm, period P in y-direction_yWhen the polarization angle is increased from 0 degrees to 90 degrees in steps of 22.5 degrees, the peak value between 400nm and 500nm is gradually reduced, and a new peak value between 500nm and 600nm is appeared and gradually increased along with the increase of the polarization angle. In fig. 5(b), the period Px in the fixed x-direction is 300nm, and the period P in the y-direction is_yAt 500nm, the transmission spectrum at an increase in the polarization angle from 0 ° to 90 ° in 22.5 ° steps. As the polarization angle increases, the peak between 400nm and 500nm gradually decreases, and a transmission peak between 600nm and 700nm appears, and then increases. Fig. 5(c) is a CIE chromatogram corresponding to fig. 5(a) and 5(b), and the color change with the change of the polarization angle can be clearly seen.

The ultrathin substrate-free surface plasma filter with tunable colors can realize the manipulation of light covering the whole visible spectrum and realize static modulation by changing the periods of the x direction and the y direction. Because the invention is sensitive to polarization, changing the polarization angle can realize dynamic modulation of color when the periods in the x and y directions are different. The filter can reach more than 70 percent of transmissivity, has extremely small thickness, and can play a great role in high-resolution color display, integrated photoelectric devices and the like.

While the preferred embodiments of the present invention have been described in detail, it is to be understood that the invention is not limited thereto, and that various equivalent modifications and substitutions may be made by those skilled in the art without departing from the spirit of the present invention, and are intended to be included within the scope of the present application.