An on-chip integrated superlens with electrically controlled zoom

Abstract

The present invention provides an on-chip integrated superlens with electrically controlled zoom, which belongs to the field of optoelectronic devices and integrated technology, and includes a superlens structure based on a slot waveguide array and an electrically controlled heater structure based on a metal resistor; wherein the superlens structure based on the slot waveguide array is used to achieve on-chip beam focusing, and the electrically controlled heater structure based on a metal resistor wire accurately controls the temperature of the waveguide by designing the geometric shape of the resistor wire, thereby achieving the regulation of the local effective refractive index of the waveguide, and finally achieving the forward and backward movement of the focused beam by applying different electric powers to the heater. The present invention only requires two heaters to achieve the zoom function of the on-chip focused beam, significantly reduces the number of electrodes, has a simple electrical control scheme, and is fully compatible with the standard silicon photonic process platform, and is expected to be integrated and applied to beam shaping, on-chip switching networks, and reconfigurable photonic integrated systems.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic devices and integrated technologies, and in particular relates to an on-chip integrated superlens with electrically controlled zoom. Background Art

[0002] The development of optoelectronic devices and on-chip integration technology has greatly promoted their applications in optical communications, signal processing, imaging, and quantum information. Various photonic structures have been shown to interact with and manipulate propagating light beams in planar waveguides. Recently, on-chip superlens structures based on subwavelength slot waveguide arrays have shown great potential in optical computing, imaging processing, and artificial intelligence. The dynamic tuning mechanism, especially the zoom function, is a key step in the application of on-chip superlens systems. The tunable mechanisms of on-chip superlenses that have been reported include electro-optical effect, thermo-optical effect, and phase change materials. However, conventional tunable lenses based on thermo-optical and electro-optical effects require more control electrodes and larger size areas; the manufacturing and control process of phase change materials is complex and difficult to be compatible with complex metal oxide semiconductor (CMOS) processes. Summary of the invention

[0003] In view of the above shortcomings of the prior art, the present invention discloses an on-chip integrated superlens with electrically controlled zoom, which only requires two heater structures to realize the zoom function of the on-chip focused light beam, solving the problems of the existing on-chip integrated superlens zoom scheme and structure having too many control electrodes, large size, and complex preparation and control processes.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] An on-chip integrated superlens with electrically controlled zoom comprises a superlens structure based on a slot waveguide array and an electrically controlled heater structure based on a metal resistor; the on-chip integrated superlens structure with electrically controlled zoom comprises, from top to bottom, an electrode layer, an upper cladding layer, a waveguide layer, a lower cladding layer, and a substrate layer; wherein the superlens structure based on the slot waveguide array is in the waveguide layer.

[0006] A further improvement of the technical solution of the present invention is that the metalens structure based on the slot waveguide array is used to achieve on-chip light beam focusing, and the electrically controlled heater structure based on metal resistors accurately controls the temperature of the waveguide by designing the geometric shape of the resistor wire, thereby achieving the regulation of the local effective refractive index of the waveguide, and finally achieving the forward and backward movement of the focused light beam by applying different electric powers to the heater.

[0007] A further improvement of the technical solution of the present invention is that the electrically controlled heater structure based on metal resistors includes two independently cascaded heater structures, namely heater one and heater two, which are respectively controlled to achieve lengthening and shortening of the focal length, and the functions of the two are superimposed to achieve forward and backward movement of the focused light beam.

[0008] A further improvement of the technical solution of the present invention is that: the heater structure is a rectangular distribution formed by bending and folding the resistance wire, the overall width of the rectangle is determined by the diameter of the superlens based on the slot waveguide array, and the width of the rectangle is greater than or equal to the diameter of the lens; the overall length of the rectangle is determined by the power consumption requirement and the focal length adjustment range requirement, the longer the overall length of the rectangle, the lower the power consumption requirement and the larger the focal length adjustment range.

[0009] A further improvement of the technical solution of the present invention is that the width of the folded resistance line of heater one is defined as w1, w2, ..., wi from the center to the edge, respectively, where i is a positive integer; heater one realizes the function of lengthening the focal length, and after heating the waveguide, heater one acts as a concave lens, and according to the requirement that the required phase formula of the concave lens and the heating phase change formula must be equal, the width distribution of the folded resistance line of heater one is calculated; heater two realizes the function of shortening the focal length, and after heating the waveguide, heater two acts as a convex lens, and according to the requirement that the required phase formula of the convex lens and the heating phase change formula must be equal, the width distribution of the folded resistance line of heater two is calculated.

[0010] A further improvement of the technical solution of the present invention is that the required phase formula of the concave lens is The required phase formula for a convex lens is The heating phase change formula is: Where λ is the operating wavelength of the device, λ = 1.55 μm, n slab,eff is the waveguide effective refractive index of the device, f is the focal length of the lens of the device, y is the length of the device from the center to the edge along the y axis, Δn slab,eff is the change of the waveguide effective refractive index of the device with temperature, L is the length of the heater L=L1=L2=200 μm, α is the normalization coefficient, and w is the width of the folded resistance line of the heater;

[0011] For the zoom function

[0012] The width distribution is solved as

[0013] Zoom function

[0014] The width distribution is solved as

[0015] A further improvement of the technical solution of the present invention is that the resistance line width of heater one gradually decreases from the center to the edge along the y-axis direction, and the resistance line width of heater two gradually increases from the center to the edge along the y-axis direction.

[0016] A further improvement of the technical solution of the present invention is that the resistance value of the resistance line at the position is controlled by adjusting the width of the resistance line at the position, and the waveguide temperature at the position is controlled by applying electric power, thereby realizing the regulation of the local effective refractive index of the waveguide, and finally affecting the wavefront distribution of the focused light beam to realize the change of the focal length.

[0017] A further improvement of the technical solution of the present invention is that the waveguide layer and the base layer are made of silicon, the upper cladding and the lower cladding are made of silicon dioxide, and the material of the electrically controlled heater based on the metal resistance wire is selected from gold, silver, copper, and titanium nitride resistance materials.

[0018] As a further improvement of the present invention, the working band, diameter and focal length parameters of the metalens based on the slot waveguide array can be defined according to design requirements.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present application sets a super lens structure based on a slot waveguide array in the waveguide layer, and the electrically controlled heater structure based on a metal resistor wire is numerically set in the electrode layer. There is an upper cladding layer between the electrode layer and the waveguide layer, which can ensure that the light beam in the waveguide layer and the metal resistor of the electrode layer do not interact with each other, and can ensure that the electric drive of the metal resistor wire in the electrode layer generates heat and transfers it to the waveguide layer, resulting in an increase in the temperature of the waveguide. With this technical solution, when the light beam is focused in the waveguide layer through the super lens structure based on a slot waveguide array, the electrically controlled heater structure based on the metal resistor wire accurately controls the temperature of the waveguide by designing the geometric shape of the resistor wire, thereby realizing the regulation of the local effective refractive index of the waveguide, and finally realizing the forward and backward movement of the focused light beam by applying different electric powers to the heater.

[0021] Compared with the existing technology, the present invention only needs two heaters to realize the zoom function of the on-chip focused beam, significantly reducing the number of electrodes, simplifying the electrical control scheme, and having a large tolerance for device preparation errors and a small device size, and is fully compatible with the standard silicon photonics process platform. This structure provides a new solution for the zoom control of the on-chip superlens structure, and is an important and meaningful work in the development of on-chip integrated optical chip technology.

[0022] The device manufacturing process of the present invention is fully compatible with the standard silicon photonic process platform, has simple preparation and large tolerance for preparation errors, which makes the device easy to integrate and expand, and can be widely used in reconfigurable on-chip photonic integrated systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the three-dimensional structure and a schematic diagram of the yz cross-sectional structure of an on-chip integrated superlens with electrically controlled zoom according to an embodiment of the present invention;

[0024] Figure 2It is a schematic diagram of the planar structure of an on-chip integrated superlens with electrically controlled zoom according to an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the structure and parameters of two heaters according to an embodiment of the present invention;

[0026] Figure 4 The width distribution of the resistance wires from the center to the edge of the two heaters of the embodiment of the present invention;

[0027] Figure 5 This is a simulated temperature distribution diagram of the waveguide layer of an embodiment of the present invention when two heaters apply 100 mW of electric power respectively;

[0028] Figure 6 This is a simulated light field distribution diagram of the waveguide layer of an embodiment of the present invention when two heaters apply 100 mW of electric power respectively;

[0029] Figure 7 The movement of the light intensity of the waveguide layer of the embodiment of the present invention along the x-axis when two heaters apply 0-500 mW electric power respectively;

[0030] Among them, 1. Heater 1, 2. Heater 2, 3. Super lens structure, 4. Axis, 5. Focus, 6. Electrode layer, 7. Upper cladding, 8. Waveguide layer, 9. Lower cladding, 10. Base layer. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described in further detail below.

[0032] like Figure 1 and 2 As shown, this embodiment is an on-chip integrated superlens with electrically controlled zoom. The on-chip integrated superlens device with electrically controlled zoom includes an electrode layer 6, an upper cladding layer 7, a waveguide layer 8, a lower cladding layer 9, and a substrate layer 10 from top to bottom. Specifically, the on-chip integrated superlens with electrically controlled zoom is constructed on a silicon platform SOI on an insulator, the waveguide layer 8 and the substrate layer 10 are made of silicon, and the upper cladding layer 7 and the lower cladding layer 9 are made of silicon dioxide. The entire device can be manufactured by a standard silicon photonic flow process. Among them, the superlens structure based on the slot waveguide array is constructed in the waveguide layer 8 by a periodic slot waveguide array with the same width and gradual length. The lens diameter D of the superlens is set to 150μm, and the focal length f is set to 350μm. The electrically controlled heater structure based on metal resistance wire has an upper cladding layer 7 between the electrode layer 6 and the waveguide layer 8, which can ensure that the light beam in the waveguide layer 8 and the metal resistance of the electrode layer 6 do not interact with each other, and can also ensure that the electric drive of the metal resistance wire of the electrode layer generates heat and transfers it to the waveguide layer 8, resulting in an increase in the temperature of the waveguide.

[0033] like Figure 3 As shown, the electrically controlled heater structure based on the metal resistance wire includes two independently cascaded heater structures, heater one and heater two, which are respectively regulated to achieve the lengthening and shortening of the focal length, and the functions of the two are superimposed to achieve the forward and backward movement of the focused light beam. Each independent heater structure is a rectangular distribution formed by bending and folding the resistance wire. The overall width of the rectangle is determined by the diameter of the super lens based on the slot waveguide array. The width of the rectangle is greater than or equal to the diameter of the lens, such as the specific embodiment W1=W2=D=150μm, and the overall length of the rectangle is determined by the power consumption requirement and the focal length adjustment range requirement. The longer the overall length of the rectangle, the lower the power consumption requirement and the larger the focal length adjustment range. For example, in the specific embodiment, the overall length of the rectangle is L1=L2=200μm.

[0034] The widths of the folded resistance wire of the heater 1 are defined as w1, w2, ..., w from the center to the edge. i (i is a positive integer). In order to achieve the focal length variable function, heater 1 heats the waveguide and acts as a concave lens. According to the requirement that the required phase formula of the concave lens and the heating phase change formula must be equal, the width distribution of the folded resistor line of heater 1 is calculated. The width of the folded resistor line of heater 2 is defined as v1, v2, ..., v from the center to the edge. i (i is a positive integer). In order to achieve the function of shortening the focal length, the second heater heats the waveguide to act as a convex lens. According to the requirement that the required phase formula of the convex lens and the heating phase change formula must be equal, the width distribution of the folded resistance line of the second heater is calculated. The required phase formula of the concave lens is The required phase formula for a convex lens is The heating phase change formula is: Where λ is the operating wavelength of the device (λ = 1.55 μm), n slab,eff is the waveguide effective refractive index of the device, f is the focal length of the lens of the device, y is the length of the device from the center to the edge along the y axis, Δn slab,eff is the change of the waveguide effective refractive index of the device with temperature, L is the length of the heater (L=L1=L2=200μm), α is the normalization coefficient, and w is the width of the folded resistance line of the heater.

[0035] For the zoom function

[0036] The width distribution is solved as

[0037] Zoom function

[0038] The width distribution is solved as

[0039] Figure 4 The width distribution of the resistance lines of the two heaters from the center to the edge calculated for the embodiment of the present invention is that the width of the resistance line of heater one gradually decreases from the center to the edge along the y-axis direction, and the width of the resistance line of heater two gradually increases from the center to the edge along the y-axis direction.

[0040] Figure 5 and Figure 6 The simulated temperature distribution diagram and the simulated light field distribution diagram of the waveguide layer of the embodiment of the present invention are respectively applied with 100mW electric power by two heaters. According to the linear proportional relationship between the waveguide refractive index change and the temperature change, the center temperature of the heater 1 is low under the condition of 100mW electric power, and the edge temperatures on both sides are high, that is, the center refractive index of the waveguide is low, and the emissivity of the edges on both sides is high, which plays the role of a concave lens. At this time, the focal length of the super lens becomes longer; the center temperature of the heater 2 is high under the condition of 100mW electric power, and the edge temperatures on both sides are low, that is, the center refractive index of the waveguide is high, and the emissivity of the edges on both sides is low, which plays the role of a convex lens. At this time, the focal length of the super lens becomes shorter.

[0041] Figure 7 The light intensity of the waveguide layer of the embodiment of the present invention moves along the x-axis when two heaters are respectively applied with 0-500mW electric power. The three-dimensional finite time-domain difference (3D FDTD) method is used to simulate and analyze the device. When the light beam is focused in the waveguide layer through the super lens structure based on the slot waveguide array, the forward and backward movement of the focused light beam is achieved by applying different electric powers (0mW, 100mW, 200mW, 300mW, 400mW, 500mW) to heater one and heater two. It can be seen that the light intensity of the focus 5 moves forward and backward along the axis 4 direction (x-axis). Only two heaters are needed to successfully realize the zoom function of the on-chip focused light beam, significantly reduce the number of electrodes, simplify the electrical control scheme, and the device has a simple preparation process and a large tolerance for preparation errors. It can be widely used in reconfigurable on-chip photonic integrated systems.

[0042] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. An on-chip integrated superlens with electrically controlled zoom, characterized in that: From top to bottom, the invention is divided into an electrode layer (6), an upper cladding layer (7), a waveguide layer (8), a lower cladding layer (9) and a substrate layer (10). The on-chip integrated superlens with electrically controlled zoom comprises a superlens structure based on a slot waveguide array and an electrically controlled heater structure based on a metal resistor. The electrically controlled heater structure based on a metal resistor is vertically arranged on the electrode layer. An upper cladding layer is provided between the electrode layer and the waveguide layer. The superlens structure (3) based on the slot waveguide array is arranged on the waveguide layer (8). The electrically controlled heater structure based on a metal resistor is vertically arranged on the electrode layer (6). The controllable heater structure comprises two independently cascaded heater structures, namely heater one (1) and heater two (2), which are respectively controlled to achieve the lengthening and shortening of the focal length, and the functions of the two are superimposed to achieve the forward and backward movement of the focused light beam; the heater structure is a rectangular distribution formed by bending and folding the resistance wire, the overall width of the rectangle is determined by the diameter of the super lens based on the slot waveguide array, and the width of the rectangle is greater than or equal to the diameter of the super lens; the overall length of the rectangle is determined by the power consumption requirement and the focal length adjustment range requirement, the longer the overall length of the rectangle, the lower the power consumption requirement and the larger the focal length adjustment range.

2. The on-chip integrated superlens with electrically controlled zoom according to claim 1, characterized in that: The on-chip integrated superlens with electrically controlled zoom is constructed on a silicon platform SOI on an insulator. The superlens structure (3) based on a slot waveguide array is used to achieve on-chip light beam focusing. The electrically controlled heater structure based on metal resistors accurately controls the temperature of the waveguide by designing the geometric shape of the resistor wire, thereby achieving the regulation of the local effective refractive index of the waveguide. Finally, the forward and backward movement of the focused light beam is achieved by applying different electric powers to the heater.

3. The on-chip integrated superlens with electrically controlled zoom according to claim 1, characterized in that: The widths of the folded resistor line of heater one (1) are defined as w1, w2, ..., wi from the center to the edge, respectively, where i is a positive integer. Heater one (1) realizes the function of lengthening the focal length. After heating the waveguide, heater one (1) acts as a concave lens. According to the requirement that the required phase formula of the concave lens and the heating phase change formula must be equal, the width distribution of the folded resistor line of heater one (1) is calculated. Heater two (2) realizes the function of shortening the focal length. After heating the waveguide, heater two (2) acts as a convex lens. According to the requirement that the required phase formula of the convex lens and the heating phase change formula must be equal, the width distribution of the folded resistor line of heater two (2) is calculated.

4. The on-chip integrated superlens with electrically controlled zoom according to claim 3, characterized in that: The required phase formula for a concave lens is The required phase formula for a convex lens is The heating phase change formula is: Where λ is the operating wavelength of the on-chip integrated metalens, λ = 1.55 μm, n slab,eff is the effective refractive index of the waveguide of the on-chip integrated metalens, f is the focal length of the on-chip integrated metalens, y is the length of the on-chip integrated metalens from the center to the edge along the y-axis, Δn slab,eff is the variation of the effective refractive index of the waveguide of the on-chip integrated metalens with temperature, L is the length of the heater 1 and the heater 2 and L=200 μm, α is the normalization coefficient, and w is the width of the folded resistance line of the heater 1 and the heater 2; For the zoom function The width distribution is solved as Zoom function The width distribution is solved as 5. The on-chip integrated superlens with electrically controlled zoom according to claim 4, characterized in that: The resistance line width of heater 1 (1) gradually decreases from the center to the edge along the y-axis direction, and the resistance line width of heater 2 (2) gradually increases from the center to the edge along the y-axis direction.

6. The on-chip integrated superlens with electrically controlled zoom according to claim 3, characterized in that: By adjusting the width of the resistance wire at different positions, the resistance value of the resistance wire at that position is controlled, and by applying electric power, the waveguide temperature at that position is controlled, thereby achieving regulation of the local effective refractive index of the waveguide, ultimately affecting the wavefront distribution of the focused light beam and achieving a change in the focal length.

7. The on-chip integrated metalens with electrically controlled zoom according to claim 1, characterized in that: The waveguide layer (8) and the base layer (10) are made of silicon, the upper cladding layer (7) and the lower cladding layer (9) are made of silicon dioxide, and the material of the metal resistor-based electrically controlled heater is selected from one of gold, silver, copper, and titanium nitride resistor materials.

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