CN210775899U

CN210775899U - Multiband optical filter

Info

Publication number: CN210775899U
Application number: CN201921515853.3U
Authority: CN
Inventors: 曹笈; 朱滨; 孙英豪; 刘文朋; 刘钢; 谷雨
Original assignee: Jiangsu Jitri Intelligent Sensor Research Institute Co ltd
Current assignee: Jiangsu Jitri Intelligent Sensor Research Institute Co ltd
Priority date: 2019-09-12
Filing date: 2019-09-12
Publication date: 2020-06-16
Anticipated expiration: 2029-09-12

Abstract

The utility model discloses a multiband optical filter, which comprises a transparent substrate layer, wherein a photosensitive device layer is arranged on the substrate layer, a light filtering structure layer is arranged on the photosensitive device layer, and a focusing structure layer is arranged on the light filtering structure layer; the light filtering structure layer is composed of a nano disc array, the nano disc array comprises a plurality of sub arrays, each sub array comprises a plurality of nano discs, the nano discs in each sub array have the same diameter, height and period, and the diameters, heights and periods of the nano discs in different sub arrays are different. The utility model discloses a focus and the filtering function of multiband to replace traditional focus optical system and light filter, realize multiband imaging device's miniaturization and portableization, preparation simple process, focus structural layer and light filtering structural layer are all gone on same basement circuit layer, and are with low costs, realize batch production easily.

Description

Multiband optical filter

Technical Field

The utility model relates to a multiband sensing technology field specifically is a multiband light filter.

Background

In order to realize the detection of various spectrums, the traditional multiband imaging device needs to use different optical filters and then realizes the filtering of multiband by the control of a rotating wheel, thereby causing larger volume and inconvenient use; on the other hand, in order to realize multiband focusing and reduce aberration, multiband imaging also needs a large and complex optical component for continuously reducing aberration, and the traditional multiband imaging device has a large volume and a complex imaging system and is inconvenient to use. Therefore, how to realize miniaturization and portability of the multiband imaging system still remains a problem to be solved urgently.

SUMMERY OF THE UTILITY MODEL

Utility model purpose: in order to overcome the defects existing in the prior art, the utility model provides a multiband optical filter.

The technical scheme is as follows: in order to solve the above technical problem, the multiband optical filter of the present invention comprises a transparent substrate layer, wherein a filter structure layer is disposed on the substrate layer, and a focusing structure layer is disposed on the filter structure layer; the light filtering structure layer is composed of a nano disc array, the nano disc array comprises a plurality of sub arrays, each sub array comprises a plurality of nano discs, the nano discs in each sub array have the same diameter and period, and the diameters, the heights and the periods of the nano discs in different sub arrays are different.

Preferably, the aspect ratio of the nanodisk array is 1:10-1:1, the height of the nanodisk is 50-200nm, and the period is 100-400 nm.

Preferably, the light filtering structure layer is an amorphous silicon nanodisk, an aluminum nanodisk array or a silver nanodisk array.

Preferably, the focusing structure layer comprises a plurality of periodically arranged nano-pillars, and the plurality of nano-pillars can generate a phase shift of 0-2 pi in a visible light range.

Preferably, the thickness of the focusing structure layer is equal to the wavelength, and the period is equal to 0.7 times the wavelength.

Preferably, each of the nano-pillars has a cylindrical shape or an elliptic cylindrical shape.

Preferably, the nano-pillars are arranged in a plurality of concentric circles, the diameters of the nano-pillars in the same circle are the same, and the nano-pillars between different circles are gradually increased from outside to inside.

Preferably, the nano-pillars are silicon nitride nano-pillars, gold nano-pillars or gallium nitride nano-pillars.

Preferably, the nanodisk array comprises at least four subarrays.

Has the advantages that: the utility model discloses following beneficial effect has:

1. the multi-band focusing and filtering functions are realized, so that the traditional focusing optical system and the traditional optical filter are replaced, and the miniaturization and the portability of the multi-band imaging device are realized.

2. The preparation process is simple, the focusing structure layer and the filtering structure layer are both carried out on the same substrate circuit layer, the cost is low, and the batch production is easy to realize.

Drawings

Fig. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic diagram of a nanodisk array structure of a filter structure layer;

fig. 3 is a schematic structural diagram of the filter structure layer.

Detailed Description

The present invention will be further described with reference to the accompanying drawings.

As shown in fig. 1 and fig. 2, a multiband optical filter of the present invention includes a transparent substrate layer 1, a filter structure layer 2 disposed on the substrate layer 1, and a focusing structure layer 4 disposed on the filter structure layer 2; the filtering structure layer 2 is composed of a nano-disc array, the nano-disc array comprises at least four sub-arrays 21, each sub-array 21 comprises a plurality of nano-discs, the nano-discs in each sub-array 21 have the same diameter, height and period, and the diameters, heights and periods of the nano-discs in different sub-arrays 21 are different. The height of the nano-disc is 50-200nm, the period is 100-400nm, and the aspect ratio of the nano-disc array is 1:10-1: 1. The light filtering structure layer 2 is an amorphous silicon nanodisk, the focusing structure layer 4 comprises a plurality of periodically arranged nano-pillars 41, the nano-pillars 41 can generate a phase shift of 0-2 pi in a visible light range, and the flat layer 3 is arranged between the light filtering structure layer 2 and the focusing structure layer 4.

As shown in fig. 3, the thickness of the focusing structure layer 4 is equal to the wavelength, the period is equal to 0.7 times the wavelength, and each of the nano-pillars 41 is cylindrical. The nano-pillars 41 are arranged in a plurality of concentric circles, the diameter of the nano-pillars 41 in the same circle is the same, and the diameter of the nano-pillars 41 between different circles is gradually increased from outside to inside.

In particular, the substrate layer 1 of the present invention is a transparent material, which may be glass or a transparent polymer material. The light filtering structure layer 2 is arranged above the substrate layer 1 and consists of a nano disc array, and the heights of the nano discs are consistent and are between 50nm and 200 nm; the nanodisk array comprises a plurality of subarrays 21, each subarray 21 comprises a plurality of nanodisks, the nanodisks in each subarray 21 have the same diameter and period, each subarray 21 can be selected to be transparent to one wavelength, and simultaneously, pixels of the photosensitive device layer on the corresponding CMOS can detect light with the corresponding wavelength, as an example, as shown in fig. 2, one nanodisk array may comprise nine subarrays 21, the diameters and periods of the nanodisks are different between different subarrays 21, and by setting different diameters and periods, light with different nine wavelengths can be selected to be transparent. The height of the nano-disc in the utility model is between 50-200nm, the period is between 100-400nm, and the aspect ratio of the nano-disc is between 1:10-1: 1. The utility model discloses well optical filtering structure layer 2 is amorphous silicon nanodisk, preferably hydrogenation amorphous silicon, and its relative amorphous silicon internal defect is less, can reduce the absorption of photon, improves the transmissivity of light. The amorphous silicon film can grow on different substrates at low temperature, a required structure can be formed through one-time photoetching, meanwhile, the aspect ratio of the amorphous silicon film relative to the nanowire structure is small, the stability in the preparation process is high, the process is simple, and the method is compatible with a CMOS (complementary metal oxide semiconductor) process. Amorphous silicon nanodisk has the high absorption in the visible light region, the characteristics that the transmissivity is low, and the utility model provides an amorphous silicon nanodisk essence is an ultra-thin dielectric hypersurface, nanodisk structure scattering sectional area is big, when the cycle is less than the wavelength of required transmission, utilize the nanodisk structure of array type can produce electric dipole and the resonance of magnetic dipole that arouses by the mie scattering, the scattering section through array type nanodisk structure induces resonance enhancement specific wavelength, can strengthen the incident light transmission of specific wavelength, and the incident light of nonspecific wavelength wave band can't transmit, can control resonance condition through changing nanodisk cycle and diameter, change the incident light center wavelength that can strengthen the transmission, thereby realize the filtering characteristic. In another embodiment of the present application, the light filtering structure layer may also be an aluminum nanodisk or a silver nanodisk, wherein the aluminum nanodisk is not easily oxidized and can filter light in the visible light range; the silver nanodisk has good wavelength selectivity and good color saturation.

The gaps between the nano-disc arrays in the utility model can be filled with polymer materials to form a flat layer 3, and the polymer materials can be used as a refractive index matching layer, so that a uniform optical environment is established for the nano-discs, which is beneficial to improving the transmission of light; and after filling, a relatively flat surface can be provided, thereby being beneficial to the integration of other devices in the follow-up process. The polymer material may be PMMA or other transparent material. In another embodiment, the silicon dioxide film can be used for filling, the silicon dioxide film with the thickness higher than that of the nano disc is deposited and then is ground to realize planarization, the silicon dioxide is used as the planarization layer 3 to be beneficial to the subsequent process, the adhesion between the silicon dioxide and the silicon nitride is stronger, and the phenomenon of film falling is not easy to occur.

The utility model discloses a focusing structure layer 4 is transparent low refracting index material, has great transmittance to the wavelength in the visible light scope, can be transparent conductive oxide, organic polymer, silicon nitride etc, the utility model discloses well focusing structure layer 4 is including having a plurality of silicon nitride nano columns of periodic arrangement, and the nano column period is the same in the same ring. By changing the diameters of the silicon nitride nano-columns 51 in different rings, phase shift of 0 to 2 pi can be generated for incident light waves in a visible light range, a required random phase profile can be obtained, meanwhile, a large transmission amplitude is kept, phase shift required according to different positions in a lens surface is realized, and the corresponding diameter of the nano-columns is designed, so that constant focal length can be realized in a specific waveband in the visible light range of 400nm to 700 nm. The utility model discloses well silicon nitride nanometer post's shape is cylindrical or elliptic cylinder shape, and the cycle p, diameter (d) and thickness (t) of nanometer post all influence the focusing effect. The period and the thickness can influence the transmission amplitude, different resonances can occur in different thicknesses and periods, wide resonance generated by resonance can result in strongly-changed transmission amplitude, when t is 1.2 lambda and p is 0.4 lambda (lambda is a design wavelength), the phase delay and the transmission amplitude are continuous for all simulated column diameters, the transmission amplitude has only small change, but the aspect ratio is large at the moment, and the manufacturing is not suitable; in ensuring a proper manufacturing aspect ratio while maintaining an approximate transmission amplitude over the entire phase range, the preferred parameters t λ and p 0.7 λ for the present application, design wavelength 633nm, can achieve the required phase profile by varying the nanopillar diameter, which in the present application corresponds to six different nanopillar diameters of 192nm,242nm, 292nm,342nm, 392nm, 442nm, respectively, in order to achieve a phase shift of 0 to 2 π. In another embodiment of the present application, the focusing structure layer is a gold nanorod or a gallium arsenide nanorod, wherein the gold nanorod utilizes metal plasmon resonance, thereby having higher transmission efficiency. The focusing structure layer 4 in the application has a simple structure, can replace a traditional complex optical device, and realizes the focusing of all wavelengths in a visible spectrum range.

While conventional optical elements rely primarily on refraction to control light propagation, which relies heavily on surface precision curvature to achieve gradual phase accumulation, silicon nitride nanorods in this application are planar lenses that do not rely on light propagation to gradually accumulate phase, but rather produce discrete abrupt changes in the phase of the incident light, thereby replacing existing complex optical components in a flat and compact manner. Meanwhile, the filtering structure layer 2 adopts an amorphous silicon nano disc structure, and filtering of specific wavelength can be realized through resonance of electric dipoles and magnetic dipoles generated by Mie scattering; the multiband optical filter is integrated with the optical filter structure layer 2 and the focusing structure layer 4, the optical filter structure layer and the focusing structure layer are arranged on the same substrate circuit layer, the thickness of the whole optical filter is between 100um and 150um, and the miniaturization and integration of the multiband optical filter are achieved.

The utility model discloses the following step preparation of accessible:

s1: depositing a light filtering structure layer film on the substrate layer 1;

s2: carrying out primary photoetching and etching on the film of the light filtering structure layer to form a nano-disk array to form a light filtering structure layer 2;

s3: depositing a flat layer 3 on the nanodisk array to flatten the surface;

s4: depositing a focusing structure layer film on the flat layer 3;

s5: and photoetching and etching the focusing structure layer film for one time to form periodically arranged nano columns to form a focusing structure layer 4.

Claims

1. A multiband optical filter, comprising: the optical filter comprises a transparent substrate layer (1), wherein a light filtering structure layer (2) is arranged on the substrate layer (1), and a focusing structure layer (4) is arranged on the light filtering structure layer (2); the light filtering structure layer (2) is composed of a nano-disc array, the nano-disc array comprises a plurality of sub-arrays (21), each sub-array (21) comprises a plurality of nano-discs, the nano-discs in each sub-array (21) have the same diameter, height and period, and the diameters and periods of the nano-discs in different sub-arrays (21) are different.

2. The multiband optical filter of claim 1, wherein: the aspect ratio of the nano-disc array is 1:10-1:1, the height of the nano-disc is 50-200nm, and the period is 100-400 nm.

3. The multiband optical filter of claim 1, wherein: the light filtering structure layer (2) is an amorphous silicon nano disc, an aluminum nano disc array or a silver nano disc array.

4. The multiband optical filter of claim 1, wherein: the focusing structure layer (4) comprises a plurality of nano-pillars (41) which are periodically arranged, and the nano-pillars (41) can generate a phase shift of 0-2 pi in a visible light range.

5. The multiband optical filter of claim 4, wherein: the thickness of the focusing structure layer (4) is equal to the wavelength, and the period is equal to 0.7 times of the wavelength.

6. The multiband optical filter of claim 4, wherein: each nano-pillar (41) is cylindrical or elliptic cylindrical.

7. The multiband optical filter of claim 4, wherein: the nano columns (41) are arranged into a plurality of concentric circles, the diameters of the nano columns (41) in the same circle are the same, and the nano columns (41) between different circles are gradually increased from outside to inside.

8. The multiband optical filter of any one of claims 4 to 7, wherein the nano-pillars are silicon nitride nano-pillars, gold nano-pillars, or gallium nitride nano-pillars.

9. The multiband optical filter of claim 1, wherein: the nanodisk array comprises at least four subarrays (21).