阅读说明：本技术 一种表面等离激元窄带梳状滤波器 (Surface plasmon narrow-band comb filter ) 是由 赵洪霞 程培红 丁志群 于 2021-07-13 设计创作，主要内容包括：本发明公开了一种表面等离激元窄带梳状滤波器,其包括下层硅膜层、上层石墨烯层、顶层二氧化硅层,下层硅膜层的宽度方向上的中间区域上开设有贯穿其上下表面的单缝,被单缝分成左侧硅膜层和右侧硅膜层,单缝内自下而上依次填充有石墨烯和二氧化硅,形成在下面的石墨烯填充层和在上面的二氧化硅填充层,石墨烯填充层的上表面与二氧化硅填充层的下表面之间不存在空隙,上层石墨烯层贴合设于左侧硅膜层的上表面、二氧化硅填充层的上表面及右侧硅膜层的上表面上,顶层二氧化硅层贴合设于上层石墨烯层的上表面上,且顶层二氧化硅层的宽度方向的中心位置与上层石墨烯层的的宽度方向的中心位置对齐；优点是单信道带宽窄,且结构简单,易于片上集成。(The invention discloses a surface plasmon narrow-band comb filter, which comprises a lower silicon film layer, an upper graphene layer and a top silicon dioxide layer, wherein a single slit penetrating through the upper surface and the lower surface of the lower silicon film layer is arranged in the middle area in the width direction of the lower silicon film layer and is divided into a left silicon film layer and a right silicon film layer by the single slit, graphene and silicon dioxide are sequentially filled in the single slit from bottom to top, the lower graphene filling layer and the upper silicon dioxide filling layer are formed, no gap exists between the upper surface of the graphene filling layer and the lower surface of the silicon dioxide filling layer, the upper graphene layer is adhered to the upper surface of the left silicon film layer, the upper surface of the silicon dioxide filling layer and the upper surface of the right silicon film layer, the top silicon dioxide layer is adhered to the upper surface of the upper graphene layer, the center position of the top silicon dioxide layer in the width direction is aligned with the center position of the upper graphene layer in the width direction; the advantages are narrow single channel bandwidth, simple structure and easy on-chip integration.)

1. A surface plasmon narrow-band comb filter, characterized in that: the graphene-silicon composite material comprises a lower silicon film layer, an upper graphene layer and a top silicon dioxide layer, wherein a single slit penetrating through the upper surface and the lower surface of the lower silicon film layer is formed in a middle area in the width direction of the lower silicon film layer, the lower silicon film layer is divided into a left silicon film layer and a right silicon film layer by the single slit, graphene and silicon dioxide are sequentially filled in the single slit from bottom to top to form a lower graphene filling layer and an upper silicon dioxide filling layer, no gap exists between the upper surface of the graphene filling layer and the lower surface of the silicon dioxide filling layer, the upper graphene layer is arranged on the upper surface of the left silicon film layer, the upper surface of the silicon dioxide filling layer and the upper surface of the right silicon film layer in a bonding manner, and the top silicon dioxide layer is arranged on the upper surface of the upper graphene layer in a bonding manner, and the central position of the top silicon dioxide layer in the width direction is aligned with the central position of the upper graphene layer in the width direction.

2. A surface plasmon narrowband comb filter according to claim 1, wherein: the width ratio of the left silicon film layer, the single slit and the right silicon film layer is (5-15): 1 (5-15), the width of the upper graphene layer is consistent with the sum of the widths of the left silicon film layer, the single slit and the right silicon film layer, and the width ratio of the top silicon dioxide layer to the upper graphene layer is 1 (0.6-32).

3. A surface plasmon narrowband comb filter according to claim 2, wherein: the width of left side silicon membranous layer with the width of right side silicon membranous layer be 200 ~ 300 nanometers, the width of single gap be 20 ~ 40 nanometers, the width on upper graphene layer be 420 ~ 640 nanometers, the width on top layer silica layer be 20 ~ 640 nanometers.

4. A surface plasmon narrowband comb filter according to claim 1, wherein: the thickness ratio of the lower silicon film layer to the graphene filling layer to the silicon dioxide filling layer is (10-25): (9.5-23): 1.

5. A surface plasmon narrowband comb filter according to claim 4, wherein: the thickness of the graphene filling layer is 76-92 nanometers, the thickness of the silicon dioxide filling layer is 4-8 nanometers, and the thickness of the lower silicon film layer is 80-100 nanometers.

6. A surface plasmon narrowband comb filter according to claim 1, wherein: the thickness of the upper graphene layer is 0.68-1.7 nanometers.

7. A surface plasmon narrowband comb filter according to claim 1, wherein: the thickness of the top silicon dioxide layer is 3-20 nanometers.

Technical Field

The invention relates to a filter, in particular to a surface plasmon narrow-band comb filter, which consists of a plurality of pass bands and stop bands which are arranged at certain frequency intervals in the same way, and only allows signals in certain specific frequency ranges to pass through.

Background

Surface plasmons (SPPs for short) are a special form of electromagnetic field localized at the metal-dielectric interface, propagating along the metal surface and decaying exponentially perpendicular to the interface to both sides. Due to the unique surface propagation characteristic, the surface plasmon polariton photonic device can overcome the traditional optical diffraction limit, guides and manipulates light at the sub-wavelength level, greatly reduces the space size of the photonic device and the interaction distance of an electromagnetic field, and enables optical integration in the micro-nano range to be possible.

At present, the functional structure based on the surface plasmon mainly focuses on an absorber, a detector, a modulator, a filter and the like, wherein the infrared filter has wider application, such as being applied to the fields of infrared band frequency selection, communication and the like, but most of research focuses on single-channel filtering, and research and reports about multi-channel comb filtering are less. The research on the multichannel comb filtering is mainly as follows: a multi-channel filter based on a quasi-periodic sequence grating structure of MIM waveguide designed by y.gong et al, which obtains 10 reflection channels in a wavelength range of 1.2-1.8 μm, but has single channel bandwidths of more than 30 nm (see Gong, Yongkang; Liu, Xueming; Wang, lean. high-channel-count planar filter with the metal-insulator-metal-sequence grating optical filters, 2010, vol.35, No.3,285-287. (yuankang, liuxue, wane. metal-insulator-metal-wave sequence grating high-channel counting plasma filter 2010, 285-287)); for example, Luoxin et al insert N periodic structures composed of two insulating media with different refractive indexes between two metal interlayers to obtain 14 channels within a wavelength range of 1-2 microns, and although the number of channels is increased and the isolation is also increased to 0.2dB, the bandwidth of a single channel still reaches more than 7 nm (see Roxin, Xihua, Wenkun Hua, et al. two-section MIM structure surface plasma narrowband optical filter. optical science, 2013,33(11): 1123003). The multi-channel comb filter based on the surface plasmon still has the defect of large single-channel bandwidth, and becomes a key obstacle for restricting the practicability and the full utilization of limited bandwidth resources, so that the practical requirement is met, the limited bandwidth resources are fully utilized, and further improvement and optimized design are needed.

Disclosure of Invention

The invention aims to solve the technical problem of providing a surface plasmon narrow-band comb filter which is narrow in single-channel bandwidth, simple in structure and easy to integrate on a chip.

The technical scheme adopted by the invention for solving the technical problems is as follows: a surface plasmon narrow-band comb filter, characterized in that: the graphene-silicon composite material comprises a lower silicon film layer, an upper graphene layer and a top silicon dioxide layer, wherein a single slit penetrating through the upper surface and the lower surface of the lower silicon film layer is formed in a middle area in the width direction of the lower silicon film layer, the lower silicon film layer is divided into a left silicon film layer and a right silicon film layer by the single slit, graphene and silicon dioxide are sequentially filled in the single slit from bottom to top to form a lower graphene filling layer and an upper silicon dioxide filling layer, no gap exists between the upper surface of the graphene filling layer and the lower surface of the silicon dioxide filling layer, the upper graphene layer is arranged on the upper surface of the left silicon film layer, the upper surface of the silicon dioxide filling layer and the upper surface of the right silicon film layer in a bonding manner, and the top silicon dioxide layer is arranged on the upper surface of the upper graphene layer in a bonding manner, and the central position of the top silicon dioxide layer in the width direction is aligned with the central position of the upper graphene layer in the width direction.

The width ratio of the left silicon film layer, the single slit and the right silicon film layer is (5-15): 1 (5-15), the width of the upper graphene layer is consistent with the sum of the widths of the left silicon film layer, the single slit and the right silicon film layer, and the width ratio of the top silicon dioxide layer to the upper graphene layer is 1 (0.6-32).

The width of left side silicon membranous layer with the width of right side silicon membranous layer be 200 ~ 300 nanometers, the width of single gap be 20 ~ 40 nanometers, the width on upper graphene layer be 420 ~ 640 nanometers, the width on top layer silica layer be 20 ~ 640 nanometers.

The thickness ratio of the lower silicon film layer to the graphene filling layer to the silicon dioxide filling layer is (10-25): (9.5-23): 1.

The thickness of the graphene filling layer is 76-92 nanometers, the thickness of the silicon dioxide filling layer is 4-8 nanometers, and the thickness of the lower silicon film layer is 80-100 nanometers.

The thickness of the upper graphene layer is 0.68-1.7 nanometers.

The thickness of the top silicon dioxide layer is 3-20 nanometers.

Compared with the prior art, the invention has the advantages that:

1) set up the single seam that runs through the upper and lower surface of lower floor's silicon membrane layer on the intermediate region on the width direction of lower floor's silicon membrane layer, and the laminating sets up upper graphene layer on the upper surface of lower floor's silicon membrane layer, graphite alkene has been introduced on silicon membrane single seam structure surface promptly, surface plasmon has been excited, the local reinforcing of surface mode has been realized, and then surface plasmon has been excited again on the surface that upper graphene layer and lower floor's silicon membrane layer contacted by the local light field in both ends about the single seam border, the surface plasmon of twice excitation satisfies that constructive interference has just produced pectination transmission spectrum.

2) A silicon dioxide filling layer is arranged in the single slit, a top layer silicon dioxide layer is attached to a middle area in the width direction of the upper surface of the upper layer graphene layer, namely, silicon dioxide medium layers are arranged on the upper surface and the lower surface of an area corresponding to the single slit of the upper layer graphene layer, and the reflection enhanced transmittance of incident light waves is strongly inhibited.

3) The single-slit-based multi-channel comb filter has the advantages that the graphene filling layer is arranged in the single slit, the graphene filling layer and the upper graphene layer form a passband microcavity, the secondary interference effect of surface plasmons excited by a local optical field on the upper surface of the lower silicon film layer and the left and right ends of the edge of the single slit can be induced, the single-channel bandwidth (which can be narrowed to 2.88 nanometers and is narrowed by more than 2.5 times compared with the existing surface plasmon-based multi-channel comb filter) in a transmission spectrum can be greatly narrowed, the number of channels is increased, and meanwhile, the passband transmittance is improved.

4) The requirement selection of adjacent channel spacing, single channel bandwidth and channel number can be realized by regulating and controlling the width of the top silicon dioxide layer.

5) Because the vertical absorption rate of the single-layer graphene to light is only 2.3 percent and the single-layer graphene is almost completely transparent, the single slit is filled with the graphene, the inherent absorption of the material is small, and the passband transmittance of the comb filter is high.

6) The comb channel is generated by the self-coupling resonance of the material of the comb filter, and no special graphic structural unit design or complex superposition is needed, so that the comb filter has a simpler structure, is easier to integrate on a chip, is compatible with a silicon processing process, and can play an irreplaceable role in the aspect of photonic devices.

Drawings

FIG. 1 is a schematic diagram of a two-dimensional planar structure of a comb filter according to the present invention;

FIG. 2 is a schematic diagram of a comb transmission spectrum of a comb filter according to the first embodiment;

FIG. 3 is a schematic diagram of the comb transmission spectrum of the comb filter according to the second embodiment;

FIG. 4 is a schematic diagram of the comb transmission spectrum of the comb filter of the third embodiment;

FIG. 5 is a schematic diagram of a comb transmission spectrum of a comb filter of a comparative example;

FIG. 6 is a schematic diagram of a comb transmission spectrum of a comb filter of a comparative example;

FIG. 7 is a schematic diagram of the comb transmission spectrum of a comb filter of a comparative example three;

fig. 8 is a schematic diagram of the comb transmission spectrum of the comb filter of comparative example four.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

The first embodiment is as follows:

the surface plasmon narrowband comb filter provided in this embodiment includes, as shown in fig. 1, a lower silicon film layer 1, an upper graphene layer 2, and a top silicon dioxide layer 3, a single slit 11 penetrating through upper and lower surfaces of the lower silicon film layer 1 is formed in a middle region of the lower silicon film layer 1 in a width direction, the lower silicon film layer 1 is divided into a left silicon film layer 12 and a right silicon film layer 13 by the single slit 11, the single slit 11 is filled with graphene and silicon dioxide from bottom to top, a lower graphene filling layer 4 and an upper silicon dioxide filling layer 5 are formed, a gap does not exist between an upper surface of the graphene filling layer 4 and a lower surface of the silicon dioxide filling layer 5, the upper graphene layer 2 is attached to and disposed on an upper surface of the left silicon film layer 12, an upper surface of the silicon dioxide filling layer 5, and an upper surface of the right silicon film layer 13, the top silicon dioxide layer 3 is attached to and disposed on an upper surface of the upper graphene layer 2, and the center position of the top layer silicon dioxide layer 3 in the width direction is aligned with the center position of the upper graphene layer 2 in the width direction.

In this embodiment, the width of the lower silicon film layer 1 is 450 nm, the width of the single slit 11 is 21 nm, the width of the left silicon film layer 12 and the width of the right silicon film layer 13 are both 214.5 nm, the width of the upper graphene layer 2 is 450 nm, the width of the top silicon dioxide layer 3 is 40 nm, the thickness of the lower silicon film layer 1 is 90 nm, the thickness of the graphene filling layer 4 is 85.556 nm, the thickness of the silicon dioxide filling layer 5 is 4.444 nm, the thickness of the upper graphene layer 2 is 1.7 nm, and the thickness of the top silicon dioxide layer 3 is 11.4 nm.

In the present embodiment, the upper graphene layer 2 may be formed by stacking 5 graphene monolayers 21, and the thickness of the graphene monolayer is 0.34 nm. The upper graphene layer 2 in practical design may be formed by stacking 2 to 5 graphene monolayers 21.

In order to obtain the comb transmission spectrum of the comb filter and detect the performance index of the comb filter, the characteristics of the transmission spectrum after the interaction of incident plane electromagnetic waves and the comb filter structure are studied under the incidence of a Transverse Magnetic (TM) polarized light field, namely when light waves vertically enter the comb filter from one side of the top silicon dioxide layer 3. Fig. 2 shows a schematic diagram of the comb transmission spectrum of the comb filter of the present embodiment. Analyzing the graph 2, it can be seen from the graph 2 that the filtering pass band is concentrated in the range of 1-1.25 micrometers, the filtering pass band is in the near infrared band, the number of channels is up to 19, the distances between adjacent channels are equal and are all 11.5 nanometers, the bandwidth of a single channel (the width of a transmission peak when the height of the peak is reduced to a half) can reach 2.88 nanometers, and the bandwidth value is far superior to that of the existing multi-channel comb filter based on the surface plasmon.

Example two:

the structure of the surface plasmon narrowband comb filter provided in this embodiment is the same as that of the comb filter in the first embodiment, and on the basis of the first embodiment, in order to determine the influence of the difference in the width of the top silicon dioxide layer 3 on the comb transmission spectrum of the comb filter, the width of the top silicon dioxide layer 3 is changed, and the width of the top silicon dioxide layer 3 is designed to be 300 nm, while other parameters are kept unchanged.

Fig. 3 shows a schematic diagram of the comb transmission spectrum of the comb filter of the present embodiment. Analyzing fig. 3, it can be seen from fig. 3 that the filter pass band range is unchanged and still concentrates in the range of 1-1.25 μm, but the number of channels is reduced to 14, the distance between adjacent channels is increased to 18.35 nm, and the bandwidth of a single channel is increased to 5.98 nm.

Example three:

the structure of the surface plasmon narrowband comb filter provided in this embodiment is the same as that of the comb filter in the first embodiment, and on the basis of the first embodiment, in order to further determine the influence of the difference in the width of the top silicon dioxide layer 3 on the comb transmission spectrum of the comb filter, the width of the top silicon dioxide layer 3 is changed again, and the width of the top silicon dioxide layer 3 is designed to be 450 nm, while other parameters are kept unchanged.

Fig. 4 shows a schematic diagram of the comb transmission spectrum of the comb filter of the present embodiment. Analyzing fig. 4, it can be seen from fig. 4 that the filter passband range is unchanged and still concentrates on the range of 1-1.25 micrometers, but the number of channels is reduced to 11, the distance between adjacent channels is obviously increased to 25.2 nanometers, and meanwhile, the bandwidth of a single channel is increased to 6.78 nanometers.

Comparing fig. 2, fig. 3 and fig. 4, it can be clearly found that: as the width of the top silicon dioxide layer 3 is increased from 40 nm to 450 nm, the number of channels of the comb filter is reduced from 19 to 11 due to the increase of the area of the surface plasmon mode local area and the enhancement of the whole structure loss; the interval between adjacent channels is increased from 11.5 nanometers to 25.2 nanometers, and the bandwidth of a single channel is increased from 2.88 nanometers to 6.78 nanometers, but is still lower than the bandwidth value of the single channel of the existing multi-channel comb filter based on the surface plasmon. Therefore, by using the design structure of the comb filter, not only can a comb transmission spectrum with narrower single-channel bandwidth be obtained, but also the number of channels, the distance between adjacent channels and the single-channel bandwidth of the comb filter can be flexibly adjusted by changing the width value of the top silicon dioxide layer 3.

Comparative example one:

the structure of the surface plasmon narrowband comb filter provided by the comparative example is the same as that of the comb filter of the first embodiment, the width ratio of the left silicon film layer 12, the single slit 11 and the right silicon film layer 13 is changed only on the basis of the first embodiment, and the design is 8.5:1:8.5, specifically: the width of lower silicon film layer 1 is 540 nanometers, the width of single slit 11 is 30 nanometers, the width of left side silicon film layer 12 and the width of right side silicon film layer 13 are 255 nanometers, the width of upper graphene layer 2 is 540 nanometers, the width of top layer silicon dioxide layer 3 is 40 nanometers, the thickness of lower silicon film layer 1 is 90 nanometers, the thickness of graphene filling layer 4 is 85.556 nanometers, the thickness of silicon dioxide filling layer 5 is 4.444 nanometers, the thickness of upper graphene layer 2 is 1.7 nanometers, and the thickness of top layer silicon dioxide layer 3 is 11.4 nanometers.

The comb transmission spectrum of the comb filter of this comparative example is shown in fig. 5. As can be seen from fig. 5, the transmittance of the comb filter is substantially unchanged compared to the first embodiment, except that the number of channels is reduced from 19 to 14, the adjacent channel spacing is increased to 13.21 nm, and the single-channel bandwidth is increased to 4.26 nm.

Comparative example two:

the structure of the surface plasmon narrowband comb filter provided by the comparative example is the same as that of the comb filter of the first embodiment, the width ratio of the left silicon film layer 12, the single slit 11 and the right silicon film layer 13 is changed only on the basis of the first embodiment, the design is 13:1.5:13, and specifically: the width of lower silicon film layer 1 is 440 nanometers, the width of single slit 11 is 24 nanometers, the width of left silicon film layer 12 and the width of right silicon film layer 13 are both 208 nanometers, the width of upper graphene layer 2 is 440 nanometers, the width of top silicon dioxide layer 3 is 40 nanometers, the thickness of lower silicon film layer 1 is 90 nanometers, the thickness of graphene filling layer 4 is 85.556 nanometers, the thickness of silicon dioxide filling layer 5 is 4.444 nanometers, the thickness of upper graphene layer 2 is 1.7 nanometers, and the thickness of top silicon dioxide layer 3 is 11.4 nanometers.

The comb transmission spectrum of the comb filter of this comparative example is shown in fig. 6. As can be seen from fig. 6, the transmittance of each channel of the comb filter is slightly decreased, the number of channels is reduced to 16, the adjacent channel spacing is increased to 13 nm, and the single-channel bandwidth is increased to 4.13 nm as compared with the first embodiment.

Comparative example three:

the structure of the surface plasmon narrowband comb filter provided by the comparative example is the same as that of the comb filter of the first embodiment, the thickness of the graphene filling layer 4, the thickness of the silica filling layer 5, the thickness of the upper graphene layer 2 and the thickness ratio of the top silica layer 3 are changed only on the basis of the first embodiment, the design is 45:2.5:0.68:6, and the specific steps are as follows: the width of lower floor's silicon membrane layer 1 is 450 nanometers, the width of single gap 11 is 21 nanometers, the width of left side silicon membrane layer 12 and the width of right side silicon membrane layer 13 are 214.5 nanometers, the width of upper graphene layer 2 is 450 nanometers, the width of top layer silica layer 3 is 40 nanometers, the thickness of lower floor's silicon membrane layer 1 is 95 nanometers, the thickness of graphite alkene filling layer 4 is 90 nanometers, the thickness of silica filling layer 5 is 5 nanometers, the thickness of upper graphene layer 2 is 1.36 nanometers, the thickness of top layer silica layer 3 is 12 nanometers.

The comb transmission spectrum of the comb filter of this comparative example is shown in fig. 7. As can be seen from fig. 7, compared with the first embodiment, the overall filter passband of the comb filter is shifted to the right, the transmittance of each channel decreases approximately linearly from the long wavelength, the number of channels increases to 22, the adjacent channel spacing increases to 12.55 nm, and the single channel bandwidth increases to 3.76 nm.

Comparative example four:

the structure of the surface plasmon narrowband comb filter provided by the comparative example is the same as that of the comb filter of the first embodiment, the thickness of the graphene filling layer 4, the thickness of the silica filling layer 5, the thickness of the upper graphene layer 2 and the thickness ratio of the top silica layer 3 are changed only on the basis of the first embodiment, the design is 83:5:1.02:15, and the specific steps are as follows: the width of lower silicon film layer 1 is 450 nanometers, the width of single slit 11 is 21 nanometers, the width of left silicon film layer 12 and the width of right silicon film layer 13 are both 214.5 nanometers, the width of upper graphene layer 2 is 450 nanometers, the width of top silicon dioxide layer 3 is 40 nanometers, the thickness of lower silicon film layer 1 is 88 nanometers, the thickness of graphene filling layer 4 is 83 nanometers, the thickness of silicon dioxide filling layer 5 is 5 nanometers, the thickness of upper graphene layer 2 is 1.02 nanometers, and the thickness of top silicon dioxide layer 3 is 15 nanometers.

The comb transmission spectrum of the comb filter of this comparative example is shown in fig. 8. As can be seen from fig. 8, compared with the first embodiment, the filtering passband of the comb filter is shifted to the right as a whole, except for the left side frequency, the transmittance of each channel is decreased almost linearly from the long wavelength side, the number of channels is increased to 20, the interval between adjacent channels is increased to 11.94 nm, and the bandwidth of a single channel is increased to 4.15 nm.

As can be seen from fig. 5, 6, 7, and 8, if the width and thickness of each component of the comb filter are within the above selectable value range, and the width ratio and thickness ratio of each component of the comb filter are changed, the transmission spectrum of the comb filter only changes significantly in transmittance, but the single-channel bandwidth is less than 7 nm, and is lower than the single-channel bandwidth of the conventional surface plasmon-based multi-channel comb filter.

In summary, the invention adopts surface plasmon interference to excite the comb-shaped transmission spectrum, the silicon dioxide dielectric layers are simultaneously arranged on the upper surface and the lower surface of the upper graphene layer 2 (namely, the top silicon dioxide layer 3 is arranged on the upper surface, and the silicon dioxide filling layer 5 is arranged on the lower surface), and the graphene microcavity is constructed by the graphene filling layer 4 and the upper graphene layer 2, so that the narrowing of the bandwidth of each channel of the comb-shaped transmission spectrum can be realized, and simultaneously, the number of channels, the distance between adjacent channels and the bandwidth of a single channel of the comb-shaped filter can be flexibly adjusted by changing the width value of the top silicon dioxide layer 3 or the proportion of other structural parameters.

In each of the above examples and comparative examples, the material of the lower silicon film layer 1 is silicon, germanium or gold may be selected in practical implementation, and since the absorption coefficient of the dielectric silicon in the near-infrared band is the smallest, the dielectric silicon is selected for the examples and comparative examples; the upper graphene layer 2 and the graphene filling layer 4 are made of graphene; the material of the top silicon dioxide layer 3 and the silicon dioxide filling layer 5 is silicon dioxide.