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CN-224216907-U - Dual-channel optical filter based on three rectangular cavity side coupling waveguides

CN224216907UCN 224216907 UCN224216907 UCN 224216907UCN-224216907-U

Abstract

The utility model relates to a dual-channel optical filter based on three-rectangular-cavity side coupling waveguides, which comprises a silicon substrate, a sapphire layer, a graphene nano strip waveguide, a first graphene rectangular resonant cavity, a second graphene rectangular resonant cavity and a third graphene rectangular resonant cavity, wherein the sapphire layer is arranged above the silicon substrate, the graphene nano strip waveguide, the first graphene rectangular resonant cavity, the second graphene rectangular resonant cavity and the third graphene rectangular resonant cavity are arranged on the upper surface of the sapphire layer, the first graphene rectangular resonant cavity and the third graphene rectangular resonant cavity are arranged on one side of the graphene nano strip waveguide in series, and the second graphene rectangular resonant cavity is arranged on the other side of the graphene nano strip waveguide. The dual-channel optical filter solves the problems of narrow bandwidth and poor filtering effect of the graphene structure optical filter, and realizes the dual-channel optical filter which has small size, wide bandwidth, excellent filtering effect, dynamic tunability and easy integration in the infrared band.

Inventors

  • WANG BOYUN
  • YU HUAQING
  • He Wuguang

Assignees

  • 湖北工程学院

Dates

Publication Date
20260508
Application Date
20250718

Claims (9)

  1. 1. A dual-channel optical filter based on three-rectangular-cavity-side coupling waveguides is characterized by comprising a silicon substrate (1), a sapphire layer (2), graphene nano strip waveguides (3), a first graphene rectangular resonant cavity (4), a second graphene rectangular resonant cavity (5) and a third graphene rectangular resonant cavity (6), wherein: The sapphire layer (2) is arranged above the silicon substrate (1), the graphene nano strip waveguide (3), the first graphene rectangular resonant cavity (4), the second graphene rectangular resonant cavity (5) and the third graphene rectangular resonant cavity (6) are arranged on the upper surface of the sapphire layer (2), the first graphene rectangular resonant cavity (4) and the third graphene rectangular resonant cavity (6) are connected in series and arranged on one side of the graphene nano strip waveguide (3), the second graphene rectangular resonant cavity (5) is arranged on the other side of the graphene nano strip waveguide (3), the first graphene rectangular resonant cavity (4) and the second graphene rectangular resonant cavity (5) generate a coupling destructive interference effect, a single PIT effect is generated, and the second graphene rectangular resonant cavity (5) and the third graphene rectangular resonant cavity (6) generate a coupling destructive interference effect, and a single PIT effect is generated.
  2. 2. The dual-channel optical filter based on the three-rectangular cavity-side coupling waveguide according to claim 1, wherein the thickness of the silicon substrate (1) is 300 nm and the thickness of the sapphire layer (2) is 200 nm.
  3. 3. The dual-channel optical filter based on the three-rectangular cavity-side coupling waveguide according to claim 2, wherein the width of the graphene nano-strip waveguide (3) is 10 nm.
  4. 4. The dual-channel optical filter based on the three-rectangular-cavity-side coupling waveguide of claim 3, wherein the lengths of the first graphene rectangular resonant cavity (4), the second graphene rectangular resonant cavity (5) and the third graphene rectangular resonant cavity (6) are 140 nm, and the widths are 20 nm.
  5. 5. The dual-channel optical filter based on the three-rectangular-cavity-side coupling waveguide of claim 4, wherein the coupling distances between the first graphene rectangular resonant cavity (4), the second graphene rectangular resonant cavity (5), the third graphene rectangular resonant cavity (6) and the graphene nano-strip waveguide (3) are all 15 nm.
  6. 6. The dual-channel optical filter based on the three-rectangular cavity side coupling waveguide according to claim 5, wherein a distance between a center of the first graphene rectangular resonant cavity (4) and a center of the third graphene rectangular resonant cavity (6) in a front-rear direction is 50nm, and a distance between centers of the two second graphene rectangular resonant cavities (5) in the front-rear direction is 50nm.
  7. 7. The dual-channel optical filter based on the three-rectangular-cavity side-coupling waveguide of claim 6, wherein the thickness of single-layer graphene adopted by the optical filter is 0.2 nm, the distances between dipoles of the slow light device excited SPPs and the centers of the first graphene rectangular resonant cavity (4), the second graphene rectangular resonant cavity (5) and the third graphene rectangular resonant cavity (6) are fixed to be 150 nm, and the distances between the centers of the first graphene rectangular resonant cavity (4), the second graphene rectangular resonant cavity (5) and the third graphene rectangular resonant cavity (6) and a detector are 150 nm.
  8. 8. The dual-channel optical filter based on the three-rectangular cavity-side coupling waveguide according to claim 7, wherein the fermi level of the graphene nano-strip waveguide (3) is 0.40 eV, the fermi level of the first graphene rectangular resonant cavity (4) is 0.42eV, the fermi level of the second graphene rectangular resonant cavity (5) is 0.43eV, and the fermi level of the third graphene rectangular resonant cavity is 0.44eV.
  9. 9. The dual-channel optical filter based on three rectangular cavity-side coupling waveguides of claim 8, wherein the size of the optical filter is less than 0.05 μm 2 .

Description

Dual-channel optical filter based on three rectangular cavity side coupling waveguides Technical Field The utility model relates to the technical field of optical communication, in particular to a dual-channel optical filter based on a three-rectangular cavity-side coupling waveguide. Background The optical filter can realize wavelength selection functions of wavelength division multiplexing, bandpass or bandstop, and is an important device in the optical communication technology. With the development of large-scale integrated all-optical devices, the requirements of small-size and dynamic tunability of the multi-channel optical filter of the infrared band are more and more obvious, so that the realization of the dynamically tunable multi-channel optical filter with a novel working mechanism of dynamic tunability, small-size and easy integration is very important. Surface plasmons (Surface Plasmon Polaritons, SPPs for short) are a type of surface electromagnetic evanescent wave that propagates along a metal-dielectric interface and decays exponentially in the direction perpendicular to the metal surface. SPPs have the characteristics of breaking through the traditional optical diffraction limit and enhancing the strong local optical field, so that the guidance and the control of light in the sub-wavelength level can be realized. SPPs can be used as a carrier of energy and information, and have important application value in high-density integrated photon circuits. Currently, many SPPs-based photonic devices have emerged, such as bandpass filters, bandstop filters, multiplexers (demultiplexers), mach-Zehnder interferometers (MZIs), optical switches, sensors, logic gates, and the like. Because SPPs bandpass or bandstop filters have the characteristics of small loss, good out-of-band rejection and the like, and SPPs-based optical filters are important links in high-density integrated photon loops, a plurality of SPPs optical filters with optical resonant cavity side-coupled waveguide structures appear. Thus, it is a trend in the future to realize SPPs optical filters with compact device size, multiple channels, wide bandwidth, dynamic tunability, and ease of integration. Currently, SPPs optical filters based on the plasmon-induced transparency (Plasmon Induced Transparency, abbreviated as PIT) effect are attracting more and more attention. The generation of the PIT phenomenon is similar to the electromagnetic induction transparent (Electromagnetically Induced Transparency, EIT) effect in atomic gas, but compared with the EIT phenomenon in atomic gas, which is determined by the absorption characteristics of materials, the EIT-like phenomenon generated by the geometric structure of the resonant cavity coupled plasma waveguide system has a wider application prospect due to the characteristics of being capable of operating at room temperature, chip integration compatibility, transmission band tunability, bandwidth controllability and the like. The PIT effect is suitable for application in optical filters because of the transparent peaks generated in the transmission spectrum of the PIT effect. In recent years, graphene, a two-dimensional material with a single carbon atom layer, provides a novel and low-loss way for limiting and controlling SPPs, and is widely applied to the design of SPPs devices. Considering the unique properties of graphene, graphene-based micro-nano structures can generate very strong local SPPs from the near infrared region to the terahertz band. The PIT effect is generated in the graphene structure, and the PIT effect optical filter can be dynamically tuned by changing the Fermi level of the graphene. The defects of the prior art are as follows: 1. Because the traditional SPPs waveguide system generates a single PIT effect, only a single-channel optical filter can be realized, and the filtering channel is single. 2. Because conventional SPPs optical filters are typically static and not tunable, they suffer from poor flexibility and difficulty in adapting to dynamic scenes. 3. The traditional filter based on the MZI and the fiber bragg grating has the defects of large size, unfavorable large-scale integration of devices, narrow bandwidth, poor out-of-band rejection and the like, and is unfavorable for the application development of the optical filter in a broadband high-speed optical communication network. Disclosure of utility model The utility model aims to solve the problems that the bandwidth of a graphene structure optical filter is narrow and the filtering effect is poor, the dual-channel optical filter which is small in size, wide in bandwidth, excellent in filtering effect, dynamically tunable and easy to integrate is realized in an infrared band, the ultra-compact graphene optical filter can be realized, the size of the graphene optical filter is greatly reduced, and the problem that the graphene optical filter is not easy to integrate in an on-chip plasmon optical path is solved. In