An all-optical switch based on optical tamm state and a control method thereof

Abstract

The application provides an all-optical switch based on an optical Tamm state and a control method thereof, and the all-optical switch comprises a substrate layer and a noble metal film which are connected, the noble metal film is provided with a main waveguide and a branch waveguide, the main waveguide and the branch waveguide are MDM waveguides, a metal coupling layer is arranged between the main waveguide and the branch waveguide, a metal baffle is arranged in the main waveguide, the metal baffle is connected with the metal coupling layer, a photonic crystal is arranged in the branch waveguide, and the photonic crystal is composed of a plurality of high-refractive-index medium layers and low-refractive-index medium layers which are alternately arranged. In the application, signal light and pump light are transmitted in different waveguides, the influence between the signal light and the pump light is avoided, and the structure of the switch is simplified, meanwhile, by controlling the presence or absence of the pump light, the 'on' and 'off' state switching of the optical switch can be realized, the response speed of the optical switch is improved, the cost is low, and the optical switch is easy to prepare.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic information, and in particular to an all-optical switch based on optic Tamm states and a control method thereof. BACKGROUND

[0002] Optic Tamm states (OTS) is a kind of non-dissipative localized interface mode, which can be excited at the interface of different media, and the field strength is the maximum at the interface, and the field strength exponentially decays in the medium far away from the interface. In the planar structure, OTS can be excited by both TE polarized light and TM polarized light, that is, there is no need for specific incident angle or dispersion compensation element. In addition, OTS has different dispersion characteristics, and the dispersion curve will be parabolic blue-shifted with the increase of the incident angle. OTS exists in the photonic crystal heterojunction and metal-DBR structure, and has the characteristics of both cavity and exciton. Therefore, the theory of OTS has great advantages in the fields of optical switching, absorber, sensor, etc., especially in the field of optical switching, and has wide application prospects.

[0003] As a basic element, all-optical switch is used to process optical information, and has become a key device in current optical communication and optical computing technology. The essence of optical switch is to realize the on and off of optical path, that is, to change the refractive index of nonlinear optical material by adjusting the control pump light, so as to realize the control of light. According to the different functions of the switch, the optical switch can be divided into time-domain all-optical switch and space-domain all-optical switch. The former is the control of the "on / off" state of light in the time domain, and the switching of the state of all-optical switch is realized by controlling the optical signal, which is generally realized based on nonlinear effect. The latter is to switch the transmission path of light in space, and the control signal can be light or other electricity, heat, magnetism, mechanics, etc. At present, the most commonly used is the optical switch based on electricity, heat and mechanics. The performance requirements of the two types of all-optical switches are basically the same, except that the time-domain all-optical switch has higher requirements on the speed of the switch, and the switching time is usually required to be below nanosecond, while the space-domain all-optical switch mainly focuses on the fast switching of optical signals between different paths. As a basic unit of all-optical signal processing, all-optical switch has important application value in the information processing of optical communication network nodes. In addition, all-optical switch is also the cornerstone of the realization of photonic computer and quantum computer, and its performance often determines the upper limit of the performance of the whole system. Therefore, the research on all-optical switch will further promote the development of the fields of all-optical integration, optical communication and optical information processing. However, in the current all-optical switch, the signal light and the pump light are mostly transmitted along the same optical path, which has the problem of mutual interference. In order to filter out the pump light, an additional structure needs to be designed in the all-optical switch, which increases the complexity of the device. At the same time, the response speed of the all-optical switch also needs to be further improved. SUMMARY

[0004] The present application aims at overcoming the deficiencies in the prior art, and provides an all-optical switch based on optical Tamm state and a control method thereof, which solves the technical problems of mutual influence and complex structure caused by the transmission of pump light and signal light along the same light path in the prior art, and the technical problem of slow response speed of the all-optical switch.

[0005] To solve the problems in the prior art, the present application discloses an all-optical switch based on optical Tamm state, comprising a substrate layer and a noble metal film connected in sequence, wherein the noble metal film is provided with a main waveguide and a branch waveguide, the main waveguide and the branch waveguide are both MDM waveguides, a metal coupling layer is arranged between the main waveguide and the branch waveguide, a metal baffle is arranged in the main waveguide, the metal baffle is connected with the metal coupling layer, a photonic crystal is arranged in the branch waveguide, and the photonic crystal is composed of a plurality of high refractive index dielectric layers and low refractive index dielectric layers arranged alternately.

[0006] Further, the material of the low refractive index dielectric layer is aluminum oxide.

[0007] Further, the material of the high refractive index dielectric layer is gallium arsenide.

[0008] Further, the number of the high refractive index dielectric layers and the low refractive index dielectric layers is both 3.

[0009] Further, the thickness of the high refractive index dielectric layer is 130 nm, and the thickness of the low refractive index dielectric layer is 276 nm.

[0010] Further, the material of the metal baffle is silver, the thickness of the metal baffle is 10 nm, the material of the metal coupling layer is silver, and the thickness of the metal coupling layer is 15 nm.

[0011] Correspondingly, a control method of the all-optical switch based on optical Tamm state is provided, which is characterized in that:

[0012] The signal light of the all-optical switch is transmitted along the main waveguide, part of the light is reflected by the metal baffle, and the other part of the light is transmitted, and the transmitted light forms a continuous state;

[0013] When the signal light coupled into the branch waveguide satisfies the wave vector matching condition, the optical Tamm state on the interface between the coupling metal layer and the photonic crystal is excited, and a discrete state is formed;

[0014] The continuous state and the discrete state are coupled with each other, and an asymmetrically distributed Fano resonance type transmission spectrum is formed;

[0015] When there is no pump light in the branch waveguide, the signal light wavelength is located at the minimum of the transmission spectrum, and the all-optical switch is "off"; when the pump light is injected along the branch waveguide, the signal light wavelength is located at the maximum of the transmission spectrum, and the all-optical switch changes from "off" to "on"; by controlling the presence or absence of the pump light, the "on" and "off" states of the all-optical switch are switched.

[0016] Further, the product of the amplitude reflection coefficient r M of the signal light in the metal coupling layer and the amplitude reflection coefficient r phC of the signal light in the photonic crystal layer is 1, that is, r M r phC =1.

[0017] Further, the refractive index of each high refractive index medium layer in the photonic crystal is n L1 =n L +n K |E| 2 , the high refractive index medium layer adopts a third-order nonlinear material gallium arsenide, wherein n L is a linear part of the refractive index of the gallium arsenide material, n K is a Kerr coefficient, and E is an electric field intensity; the refractive index of each low refractive index medium layer in air is 1.63.

[0018] Further, the thickness of the high refractive index medium layer is λ / 4n L , and the thickness of the low refractive index medium layer is λ / 4n2; wherein λ is the center wavelength of the photonic crystal band gap, and n2 is the refractive index of the low refractive index medium layer.

[0019] The all-optical switch has the beneficial effects that:

[0020] In the all-optical switch, the signal light is transmitted along the main waveguide, most of the light is reflected by the metal baffle, and a small part of the light is transmitted to form a continuous state; when the signal light coupled into the branch waveguide satisfies the wave vector matching condition, the optical Tamm state on the interface between the coupling metal layer and the photonic crystal can be excited to form a discrete state; the continuous state and the discrete state are coupled with each other to form an asymmetrically distributed Fano resonance type transmission spectrum line. When there is no pump light in the branch waveguide, the signal light wavelength is located at the minimum of the transmission spectrum, and the all-optical switch is "off"; when the pump light is injected along the branch waveguide, due to the nonlinear effect, the refractive index of the gallium arsenide material changes, thereby changing the wave vector matching condition of the optical Tamm state, and the Fano resonance wavelength shifts, so that the signal light wavelength is located at the maximum of the transmission spectrum, and the all-optical switch changes from "off" to "on". By controlling the presence or absence of the pump light, the "on" and "off" states of the optical switch can be switched. In the all-optical switch, the signal light and the pump light are transmitted in different waveguides, which avoids the influence between them and simplifies the structure of the all-optical switch, and further improves the response speed of the optical switch. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the all-optical switch based on optical Tamm states provided in an embodiment of the present invention;

[0022] Figure 2 This is the transmission spectrum of the all-optical switch in an embodiment of the present invention with and without pump light;

[0023] Figure 3 This is a schematic diagram of the electric field intensity distribution in the all-optical switching device when the incident signal light wavelength is 1550nm and there is a pump light effect, according to an embodiment of the present invention. At this time, the optical switch is in the "on" state.

[0024] Figure 4 This is a schematic diagram of the electric field intensity distribution in the all-optical switching device when the incident signal light wavelength is 1550nm and there is no pump light, according to an embodiment of the present invention. At this time, the optical switch is in the "off" state.

[0025] Figure 5 This describes the relationship between the electric field intensity of the signal light pulse and the pump light pulse and time in an embodiment of the present invention.

[0026] In the figure: 1. Substrate layer; 2. Noble metal film; 3. Main waveguide; 31. Branch waveguide; 4. Metal baffle; 5. Photonic crystal; 6. Metal coupling layer; 51. High refractive index dielectric layer; 52. Low refractive index dielectric layer. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0028] like Figure 1 As shown, an all-optical switch based on optical Tamm states according to the present invention includes a substrate layer 1 and a noble metal film 2 connected together. The noble metal film 2 is characterized by having a main waveguide 31 and a branch waveguide 32, both of which are MDM waveguides. A metal coupling layer 6 is provided between the main waveguide 31 and the branch waveguide 32. A metal baffle 4 is provided in the main waveguide 31, and the metal baffle 4 is connected to the metal coupling layer 6. A photonic crystal 5 is provided in the branch waveguide 32, and the photonic crystal 5 is composed of several alternately arranged high-refractive-index dielectric layers 51 and low-refractive-index dielectric layers 52.

[0029] As an embodiment of the present invention, the material used for the low refractive index dielectric layer 52 is aluminum oxide (Al2O3); the material used for the high refractive index dielectric layer 51 is gallium arsenide (GaAs), a third-order nonlinear material; in addition, the material of the MDM waveguide core layer can be air or glass as required. In this embodiment of the present invention, the material of the MDM waveguide core layer is air with a refractive index of 1.

[0030] In one embodiment of the present invention, the thickness Dm of the metal baffle 2 in the waveguide core is 10 nm; the thickness L2 of each low-refractive-index dielectric layer 52 in the photonic crystal 5 is 276 nm, and the refractive index of aluminum oxide (Al2O3) in each low-refractive-index dielectric layer 52 in air is 1.63; the thickness L1 of each high-refractive-index dielectric layer 51 is 130 nm, and its refractive index is: n L1 =n L +n K |E| 2 , where n L For the linear portion of gallium arsenide (GaAs), a high-refractive-index third-order nonlinear material, n in this invention L =3.46, n K Let n be the Kerr coefficient. K =8.5944×10 -18 m 2 / V 2 E represents the electric field strength. When the incident light satisfies the phase-matching condition, an optical Tamm state can be excited at the interface between the metal coupling layer 6 and the photonic crystal 5. The phase-matching condition is the amplitude reflection coefficient r of the incident light at the metal coupling layer 6. M and the amplitude reflection coefficient r in photonic crystal layer 5 phC The product of r is 1, that is: M r phC =1, at which point the optical Tamm state can be excited at the interface between the metal coupling layer and the photonic crystal. The all-optical switch based on the optical Tamm state provided in this embodiment of the invention changes the refractive index of the GaAs material by controlling the presence or absence of pump light, thereby changing the excitation conditions of the optical Tamm at the interface between the photonic crystal and the coupling metal layer. This causes the resonance peak position of the Fano resonance transmission spectrum of the all-optical switch to shift, ultimately realizing the switching of the all-optical switch between the "on" and "off" states.

[0031] like Figure 2 As shown, the transmission spectra of the present invention are shown in the figure with and without pump light. It can be clearly seen from the figure that when pump light is present, the signal light wavelength of 1550nm is located at the peak of the transmission spectrum, and the optical switch is in the "on" state. When the pump light is off, the Fano resonance peak shifts, and the signal light wavelength of 1550nm is located at the valley of the transmission spectrum, and the optical switch is in the "off" state.

[0032] like Figure 3 The diagram shows the electric field intensity distribution in the all-optical switch device under the condition that the incident signal light wavelength is 1550 nm and there is a pump light effect, according to an embodiment of the present invention. Most of the light is reflected by the metal baffle 4, and a small portion is transmitted. The transmitted light is continuous. When the signal light coupled into the branch waveguide satisfies the wave vector matching condition, it can excite the optical Tamm state at the interface between the coupling metal layer 6 and the photonic crystal 5. This state is discrete, and the continuous and discrete states couple with each other to form an asymmetric Fano resonance transmission spectrum. The signal light wavelength is the resonance wavelength, and at this time, the all-optical switch is in the "on" state. It can be seen that the field intensity is localized at the interface between the metal coupling layer 6 and the photonic crystal 5. The electric field intensity of the excited optical Tamm state decays rapidly within the metal coupling layer 6 and oscillates and decays within the photonic crystal 5, exhibiting good optical field localization performance.

[0033] like Figure 4 The diagram shows the electric field intensity distribution in the all-optical switch device under the condition that the incident signal light wavelength is 1550 nm and there is no pump light. Since there is no pump light, the refractive index of the third-order nonlinear material GaAs is linear, changing the excitation conditions of the optical Tamm state. This alters the excitation wavelength and consequently changes the position of the Fano resonance peak. At this point, the 1550 nm signal light no longer satisfies the resonance condition, and the all-optical switch changes from an "on" to an "off" state.

[0034] like Figure 5 The figure shows the relationship between the electric field intensity of the signal light pulse and the pump light pulse and time in an embodiment of the present invention. The pump light pulse is a Gaussian pulse with a wavelength of 980 nm and an electric field intensity of 10. 8 V / m, pulse duration 0.2ps, pulse width 2.2361×10 -14 As can be seen from the data, the switch response time is 46fs.

[0035] It is to be understood that the terminology used herein such as first and second, and the like, is only intended to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, in the description of the present application, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are used only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present application. In the drawings of the present application, the filling patterns are only for distinguishing layers, and do not have any other limitations.

[0036] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, alternatives, and variations can be made in the embodiments without departing from the spirit and scope of the present application as defined by the appended claims and their equivalents.

Claims

1. An all-optical switch based on optical Tamm state, comprising a substrate layer (1) and a noble metal film (2) connected with each other, characterized in that, The noble metal film (2) is provided with a main waveguide (31) and a branch waveguide (32), the main waveguide (31) and the branch waveguide (32) are both MDM waveguides, a metal coupling layer (6) is arranged between the main waveguide (31) and the branch waveguide (32), a metal baffle (4) is arranged in the main waveguide (31), the main waveguide (31) and the branch waveguide (32) are connected through the metal baffle (4) and the metal coupling layer (6), a photonic crystal (5) is arranged in the branch waveguide (32), the photonic crystal (5) is composed of a plurality of high refractive index dielectric layers (51) and low refractive index dielectric layers (52) arranged alternately; The main waveguide (31) and the branch waveguide (32) are designed in a non-collinear manner, signal light is input from the main waveguide (31), and pump light is input from the branch waveguide (32), and the two are physically isolated; The signal light of the all-optical switch is transmitted along the main waveguide (31), part of the light is reflected through the metal baffle (4), and the other part of the light is transmitted, and the transmitted light forms a continuous state; when the signal light coupled into the branch waveguide (32) satisfies the wave vector matching condition, the optical Tamm state on the interface of the coupling metal layer (6) and the photonic crystal (5) is excited, and a discrete state is formed; The continuous state and the discrete state are coupled with each other, and an asymmetrically distributed Fano resonance type transmission spectrum is formed; When there is no pump light in the branch waveguide (32), the wavelength of the signal light is located at the minimum value of the transmission spectrum, and at this time, the all-optical switch is "off"; when pump light is injected along the branch waveguide (32), the wavelength of the signal light is located at the maximum value of the transmission spectrum, and at this time, the all-optical switch changes from "off" to "on"; By controlling the presence or absence of pump light, the "on" and "off" state switching of the all-optical switch is realized.

2. The all-optical switch based on optical Tamm state according to claim 1, characterized in that, The material of the low refractive index dielectric layer (52) is aluminum oxide.

3. The all-optical switch based on optical Tamm state according to claim 1, characterized in that, The material of the high refractive index dielectric layer (51) is gallium arsenide which is a third-order nonlinear material.

4. The all-optical switch based on optical Tamm state according to claim 1, characterized in that, The number of the high refractive index dielectric layer (51) and the low refractive index dielectric layer (52) is both 3.

5. The all-optical switch based on optical Tamm state according to claim 1, characterized in that, The thickness of the high refractive index dielectric layer (51) is 130 nm, and the thickness of the low refractive index dielectric layer (52) is 276 nm.

6. The all-optical switch based on optical Tamm state according to claim 1, characterized in that, The material of the metal baffle (4) is silver, the thickness of the metal baffle (4) is 10 nm, the material of the metal coupling layer (6) is silver, and the thickness of the metal coupling layer (6) is 15 nm.

7. The all-optical switch based on optical Tamm state according to claim 1, characterized in that: The product of the amplitude reflection coefficient of the signal light at the metal coupling layer (6) and the amplitude reflection coefficient at the photonic crystal layer (5) is 1, i.e. .

8. The all-optical switch based on optical Tamm state according to claim 1, characterized in that: The refractive index of each high refractive index medium layer (51) in the photonic crystal (5) is: The high refractive index medium layer (51) uses a third-order nonlinear material gallium arsenide, wherein is a linear part of the refractive index of the gallium arsenide material, is a Kerr coefficient, is an electric field intensity; and the refractive index of each low refractive index medium layer (52) in air is 1.

63.

9. The all-optical switch based on optical Tamm state according to claim 8, characterized in that: The thickness of the high refractive index medium layer (51) is λ / 4n1 L The thickness of the low refractive index medium layer (52) is λ / 4n2; wherein λ is the center wavelength of the photonic crystal band gap, and n2 is the refractive index of the low refractive index medium layer (52).

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