A 1×2 thermo-optical switch based on silica / polymer hybrid waveguide and its preparation method

Abstract

A 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide and its manufacturing method, belonging to the technical field of silica / polymer hybrid waveguide optical integrated chips. It is composed of an Si substrate, an SiO2 lower cladding, a polymer core layer, a polymer upper cladding, and electrodes; the polymer core layer is coated within the polymer upper cladding, and the polymer core layer consists of an input waveguide, a 1×2 3dB multimode interferometer, a first input S-bending waveguide, a second input S-bending waveguide, a first modulation arm waveguide, a second modulation arm waveguide, a first output S-bending waveguide, a second output S-bending waveguide, a 2×2 3dB multimode interferometer, a first output waveguide, and a second output waveguide; the first modulation arm waveguide and the second modulation arm waveguide are parallel to each other. When a modulation voltage is applied to the electrodes on the first modulation arm waveguide or the second modulation arm waveguide, the signal light is output from the first output waveguide or the second output waveguide, thereby realizing the optical switch function.

Description

Technical Field

[0001] The invention belongs to the technical field of silica / polymer hybrid waveguide optical integrated chips, and in particular relates to a 1×2 thermo-optical switch based on a silica / polymer hybrid waveguide and a preparation method thereof. Background Art

[0002] Optical switches are important components of optical switching networks. With the rapid growth of information demand in the information society, the number of interactive ports used for optical switching has increased rapidly, which has greatly increased the number of switches in optical crossovers. The cooling system currently used in optical networks has its limits. In order to increase the scale of optical crossovers, optical switches with lower power consumption are needed. The commercially available silica planar lightwave circuit (PLC) devices on the market have the advantages of low loss, good stability, and high coupling efficiency. However, the thermo-optical coefficient of silica material is only 1.19×10 -5 K -1 , when preparing active devices, high power consumption is often required, often tens to hundreds of milliwatts. At the same time, since the silicon dioxide planar optical waveguide adopts the form of doping to prepare the core layer, the refractive index difference between the core and the cladding is small, Δn = 0.75%, resulting in a large size of the prepared device, making it difficult to achieve large-scale integration. Polymer materials have a thermo-optical coefficient that is one order of magnitude higher than that of silicon dioxide (-1.86×10 -4 K -1 ), suitable for making active photonic chips such as thermo-optic switches and tunable filters. At the same time, polymer core layers often have a higher refractive index. With silica as the lower cladding, the refractive index difference can reach Δn = 2.5% to 10%, making the device size and bending radius much smaller than silica-based planar optical waveguide devices, making it easy to realize the preparation of large-scale photonic integrated devices. Summary of the invention

[0003] In order to solve the above problems existing in the prior art, the present invention proposes a 1×2 thermo-optical switch based on a silica / polymer hybrid waveguide and a preparation method thereof.

[0004] like Figure 1 and Figure 4 As shown, the 1×2 thermo-optic switch based on silicon dioxide / polymer hybrid waveguide of the present invention is composed of Si substrate (1), SiO 2 The polymer core layer (3) and the polymer upper cladding layer (4) are located on the SiO 2The polymer core layer (3) is coated on the lower cladding layer (2), and the polymer core layer (3) is coated in the polymer upper cladding layer (4), the polymer core layer (3) is composed of an input waveguide (101), a 1×2 3dB multimode interferometer (300), a first input S-bend waveguide (102), a second input S-bend waveguide (102'), a first modulation arm waveguide (103), a second modulation arm waveguide (104), a first output S-bend waveguide (105), a second output S-bend waveguide (105'), a 2×2 3dB multimode interferometer (4 00), a first output waveguide (106) and a second output waveguide (107); wherein the first modulation arm waveguide (103) and the second modulation arm waveguide (104) are parallel to each other, and a first metal electrode (201) and a second metal electrode (202) are arranged parallel to each other on the polymer upper cladding (4) at the positions where the first modulation arm waveguide (103) and the second modulation arm waveguide (104) are located, and the first metal electrode (201) and the second metal electrode (202) together constitute an Al electrode (5).

[0005] Depending on whether the interference is general, we can divide the self-imaging laws of multimode interferometers into two categories: general interference and restricted interference. General interference means that all modes in the multimode waveguide are excited, that is, there is no restriction on the excited modes; restricted interference means that some modes in the multimode waveguide are not excited, thus obtaining other self-imaging laws. In this sense, restricted interference is just a special type of general interference. Depending on the different restricted excitation modes, restricted interference can also be divided into two categories, namely: paired interference and symmetrical interference. Symmetrical interference excites odd-order modes, while paired interference excites even-order modes. Multimode interferometers with symmetrical interference can only be input at input positions located on the symmetry axis parallel to the long side of the multimode interferometer, and it will be Generate the first N ghost image points, where n eff is the effective refractive index of the waveguide, W MMI is the effective width of the multimode interferometer, and λ is the wavelength of the signal light; the paired interference multimode interferometer has two symmetrical input positions about the symmetry axis parallel to the long side of the multimode interferometer, located on the left and right sides of the symmetry axis respectively. , which will be The first time, N ghost image points are generated; except for the above three positions, input at any other position can produce a multi-mode interferometer with general interference, which will be N ghost image points are generated for the first time. In the 1×2 thermo-optic switch based on silica / polymer hybrid waveguide described in the present invention, the 1×2 multimode interferometer (300) adopts the interference type of symmetric interference, and the 2×2 multimode interferometer (400) adopts the interference type of paired interference.

[0006] like Figure 2As shown, a 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide according to the present invention, wherein the 1×2 3dB multimode interferometer (300) is composed of an input Taper waveguide (301), a first multimode interference region (302) and two output Taper waveguides (303, 303'), the input Taper waveguide (301) and the output Taper waveguide (303, 303') having the same structure, being symmetrically arranged at the input end and the output end of the first multimode interference region (320) and having a sinusoidal shape; the signal light transmitted in the optical fiber is coupled into the input waveguide (101) ( Figure 2 The input channel a in the multimode interference region is the input waveguide (101), and then transmitted to the first multimode interference region (302) through the input Taper waveguide (301) to generate a self-image effect. When the transmission length of the signal light in the multimode interference region is When the double image is generated for the first time, n eff is the effective refractive index of the waveguide, W MMI is the effective width of the multimode interferometer, and λ is the wavelength of the signal light. The signal light is divided into two beams of light with the same light intensity and the same phase from the position where the double image is first generated, and is output to two output Taper waveguides (303, 303') respectively, and then passes through the first input S-bend waveguide (102) and the second input S-bend waveguide (102') ( Figure 2 The output channel a and the output channel b in the multimode interference region are the first input S-bend waveguide (102) and the second input S-bend waveguide (102') respectively input into the first modulation arm waveguide (103) and the second modulation arm waveguide (104). The present invention can make the mode output from the image point of the multimode interference region more matched with the mode in the Taper waveguide by designing the sinusoidal input Taper waveguide (301) and the output Taper waveguide (303, 303'), thereby reducing the insertion loss introduced by the multimode interferometer.

[0007] like Figure 5As shown, a 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide according to the present invention, wherein the 2×2 3dB multimode interferometer (400) is composed of two input Taper waveguides (401, 401'), a second multimode interference region (402) and two output Taper waveguides (403, 403'), the input Taper waveguides (401, 401') and the output Taper waveguides (403, 403') have the same structure, are symmetrically arranged at the input end and the output end of the second multimode interference region (420) and have a sinusoidal shape; the signal light outputted through the first modulation arm waveguide (103) and the second modulation arm waveguide (104) is respectively inputted into the two input Taper waveguides (401, 401') of the 2×2 3dB multimode interferometer (400) through the first output S-bend waveguide (105) and the second output S-bend waveguide (105') ( Figure 5 The input channel A and the input channel B in the multimode interference region are the first output S-bend waveguide (105) and the second output S-bend waveguide (105'), and then input into the second multimode interference region (402) to generate self-image effects. When the transmission length of the signal light in the multimode interference region is When , a double image will be generated for the first time (for each beam of light, when it passes through the input Taper waveguide and enters the multimode interference region, the self-image effect will occur independently of each other, and the two beams of light will have the same light intensity and a phase difference of 2 double images of eff is the effective refractive index of the waveguide, W MMI is the effective width of the multimode interferometer, and λ is the wavelength of the signal light. Each beam of light is output from the position where the double image is first generated to the output Taper waveguide (403, 403'), and then output from the first output waveguide (106) and the second output waveguide (107) respectively ( Figure 5 The output channel A and the output channel B in the multimode interference region are the first output waveguide (106) and the second output waveguide (107); by designing the sinusoidal input Taper waveguide (401, 401') and the output Taper waveguide (403, 403'), the mode output from the image point in the multimode interference region can be more matched with the mode in the Taper waveguide, thereby reducing the insertion loss introduced by the multimode interferometer.

[0008] When no voltage is applied to the modulation arm, the input signal light is split into two beams of light with exactly the same power and phase through a 1×2 beam splitter:

[0009]

[0010] where ω 0 represents the angular frequency, represents ψ 0 The wave function of the input signal light, ζ jRepresents the phase delay of the input signal light after passing through the beam splitter. When the two light signals pass through the two modulated waveguides, the wave function is:

[0011]

[0012]

[0013] in, They respectively represent the phase delay of the two signal lights after passing through the first modulation arm (103) and the second modulation arm (104).

[0014] The wave function of the signal light of the first modulation arm after passing through the 2×2 3dB multimode interferometer is:

[0015]

[0016]

[0017] Among them, σ 1 It is the fixed phase difference generated after the first modulation arm is input to the 2×2 3dB multimode interferometer.

[0018] The wave function of the signal light of the second modulation arm after passing through the 2×2 3dB multimode interferometer is:

[0019]

[0020]

[0021] Among them, σ 2 It is the fixed phase difference generated after the first modulation arm is input to the 2×2 3dB multimode interferometer.

[0022] At this time, the wave function of the output light of output channel ① is:

[0023]

[0024] The output light intensity is:

[0025]

[0026] At this time, the wave function of the output light of output channel ② is:

[0027]

[0028] The output light intensity is:

[0029]

[0030] Since in the system, the 1×2 3dB multimode interferometer (300) and the 2×2 3dB multimode interferometer (400) are symmetrical about the central axis of the device, let ζ 1 =ζ 2 , σ 1 =σ 2 , we can get the following formula:

[0031]

[0032]

[0033] When no voltage is applied to the two modulation arms, At this time, the output light intensity of output channel ① and output channel ② is equal, both are half of the maximum light intensity (the upper and lower modulation arms have exactly the same structure, and when no voltage is applied, the phases of the upper and lower modulation arms are the same). When voltage is applied to the metal electrode, the electric power loaded on the metal electrode is changed, thereby heating the polymer modulation arm waveguide. Due to the thermo-optical effect, the refractive index of the polymer modulation arm changes with the increase in temperature, thereby causing the phase of the signal light in the polymer modulation arm waveguide to change when it reaches the 2×2 3dB multimode interferometer (400). We record the phase difference of the signal light before and after the voltage is applied as Where n represents the nth modulation arm (n=1 or 2). When a voltage is applied only to the first heating electrode (201), the phase difference between the signal light in the first modulation arm waveguide (103) and the signal light in the second modulation arm waveguide (104) is When the voltage is applied to the second metal electrode (202), the phase difference between the signal light in the second modulation arm waveguide (104) and the signal light in the first modulation arm waveguide (103) is When , light will be output from output channel ①, thus realizing the function of two channel switches. When voltage is applied to the first heating electrode (201) and the second metal electrode (202) so that the phase difference is other cases, signal light will be output from output channel ① and output channel ②, but the light intensity of each channel is different, and theoretically any proportion of splitting ratio can be realized.

[0034] The polymer upper cladding material is one of polymethyl methacrylate (PMMA), polyethylene (PE), polyester (PET), polystyrene (PS), and EpoClad. In the present invention, PMMA is used, and its refractive index is 1.47606 at a wavelength of 1550 nm.

[0035] The polymer core layer material is one of the polymer materials SU-8 2002, SU-82005 and EpoCore having a negative thermo-optic coefficient. In the present invention, SU-8 2002 is used, and its refractive index is 1.5802 at a wavelength of 1550 nm.

[0036] The metal electrode material may be an alloy material composed of one or more materials selected from the group consisting of gold, silver, copper and aluminum. In this patent, aluminum is used.

[0037] The method for preparing a 1×2 multimode interferometer cascade thermo-optic switch based on a silica / polymer hybrid waveguide according to the present invention comprises the following steps:

[0038] 1) On the silicon wafer substrate, a layer of densely structured silicon dioxide with a thickness of 10 to 20 μm is grown by thermal oxidation as the lower cladding layer;

[0039] 2) Spin-coat the polymer core material on the silicon dioxide lower cladding and pre-bake it to remove the polymer

[0040] The excess solvent in the core layer material is then cooled naturally to obtain a polymer core layer film;

[0041] 3) by ultraviolet lithography, development and post-baking, the pattern on the mask I which is the same as the polymer core layer structure to be prepared (the polymer core layer material is positive photoresist) or complementary (the polymer core layer material is negative photoresist) is transferred to the polymer core layer film to obtain a polymer core layer structure, wherein the input waveguide (101), the first input S-bend waveguide (102), the second input S-bend waveguide (102'), the first modulation arm waveguide (103), the second modulation arm waveguide (104), the first output S-bend waveguide (105), the second output S-bend waveguide (105'), the first output waveguide (106) and the second output waveguide (107) in the polymer core layer have a thickness of 2 to 5 μm and a width of 2 to 5 μm;

[0042] 4) using a vacuum coating machine to spin-coat a polymer upper cladding material on the silica lower cladding and the polymer core layer, wherein the thickness of the polymer upper cladding above the polymer core layer is 2 to 7 μm, and then naturally cooling and curing after baking;

[0043] 5) Vapor depositing a metal film with a thickness of 50 to 400 nm on the polymer upper cladding layer;

[0044] 6) Spin-coat a layer of photoresist on the metal surface using a vacuum coating machine, pre-bake to remove the photoresist solvent, and then cool and solidify naturally;

[0045] 7) Obtaining a photoresist pattern identical to the metal electrode structure to be prepared on the metal film through ultraviolet exposure, development, and post-baking;

[0046] 8) using a metal etching solution corresponding to the metal to corrode the metal without the photoresist pattern to obtain a metal electrode, and then removing the photoresist layer covering the metal electrode; the metal electrode is located on the polymer upper cladding directly above the first modulation arm waveguide and the second modulation arm waveguide, the symmetry center of the metal electrode along the width and length directions is aligned with the symmetry center of the modulation arm waveguide along the width and length directions, the length of the metal electrode is equal to the length of the modulation arm waveguide, and the width of the metal electrode is greater than the width of the modulation arm waveguide, thereby preparing a 1×2 multimode interferometer cascade thermo-optical switch based on a silica / polymer hybrid waveguide.

[0047] Compared with the prior art, the invention is innovative in that:

[0048] 1. The thermo-optic switch is an organic-inorganic hybrid integrated composite waveguide structure, using silicon dioxide as the lower cladding layer to reduce device loss.

[0049] 2. The thermo-optic switch adopts an organic-inorganic hybrid integrated composite waveguide structure, with a polymer as the core layer and a core-clad refractive index difference of Δn=2.5% to 10%, which can achieve a more compact end face size and bending radius, and prepare a large-scale, low-power, and fast planar optical waveguide integrated circuit;

[0050] 3. The thermo-optic switch is an organic-inorganic composite waveguide structure. The device can be prepared by simple contact exposure, and the processing cost is extremely low;

[0051] 4. The thermo-optic switch uses polymer material as the modulation arm waveguide, and the power consumption required to realize the switching function is relatively small.

[0052] 5. The thermo-optic switch uses a sinusoidal Taper waveguide structure on the MMI to reduce the loss of the device; it uses a paired interference 2×2 MMI structure, which is smaller in size than the general interference 2×2 MMI. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 : Schematic diagram of the 1×2 thermo-optical switch structure of the present invention;

[0055] Figure 2 : A schematic structural diagram of a 1×2 3dB multimode interferometer (300) according to the present invention;

[0056] Figure 3 : Transmission spectrum diagram of the 1×2 3dB multimode interferometer (300) of the present invention;

[0057] Figure 4 : A schematic cross-sectional view of the 1×2 thermo-optical switch of the present invention;

[0058] Figure 5 : A schematic diagram of the structure of a 2×2 3dB multimode interferometer (400) according to the present invention;

[0059] Figure 6 : Transmission spectrum diagram of output channel A and output channel B when input channel A is input into the 2×2 3dB multimode interferometer (400) of the present invention;

[0060] Figure 7 : A flow chart of the preparation process of the 1×2 thermo-optic switch of the present invention;

[0061] Figure 8 : A light field simulation diagram (a) of the 1×2 thermo-optic switch of the present invention when no voltage is applied to any heating electrode; a light field simulation diagram (b) when a voltage is applied only to the first modulation arm (103) so that the modulation arm produces a 1.1K temperature change; a light field simulation diagram (c) when a voltage is applied only to the second modulation arm (104) so ​​that the modulation arm produces a 1.1K temperature change;

[0062] Fig. 9 : The transmission spectrum diagram of output channel ① and output channel ② when the 1×2 thermo-optic switch of the present invention applies a voltage to the first modulation arm (103) so that the modulation arm produces a temperature change of 1.1K;

[0063] Fig.10 : The transmission spectrum diagram of output channel ① and output channel ② when the 1×2 thermo-optic switch of the present invention applies a voltage to the second modulation arm (104) so ​​that the modulation arm produces a temperature change of 1.1K; DETAILED DESCRIPTION

[0064] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] Embodiment 1:

[0066] As attached Figure 1As shown, it is a schematic diagram of the structure of a 1×2 thermo-optic switch. It consists of an input waveguide (101), a 1×2 3dB multimode interferometer (300), a first input S-bend waveguide (102), a second input S-bend waveguide (102'), a first modulation arm (103) and a second modulation arm (104) parallel to each other, a first output S-bend waveguide (105), a second output S-bend waveguide (105'), a 2×2 multimode interferometer (400), a first output waveguide (106), and a second output waveguide (107). Considering the relationship between modulation efficiency and size, the length of the first modulation arm (103) and the second modulation arm (104) is set to 2000 μm.

[0067] The signal light output by the light source is coupled into an input straight waveguide (101), and is split into two beams of light with the same power through a 1×2 3dB multimode interferometer (300), a first input S-bend waveguide (102) and a second input S-bend waveguide (102'). The two beams of light enter a first modulation arm (103) and a second modulation arm (104) respectively, and are then input into a 2×2 multimode interferometer (400) through a first output S-bend waveguide (105) and a second output S-bend waveguide (105'), and are finally output from a first output waveguide (106) and a second output waveguide (107). When we apply a voltage to the first metal electrode (201) on the first modulation arm waveguide (103) and change the electric power loaded on the first metal electrode (201) to heat the first modulation arm waveguide (103), due to the thermo-optical effect, the refractive index of the polymer modulation arm changes with the increase of temperature, thereby causing the phase difference of light after passing through the modulation arm to change. The phase difference before and after modulation is recorded as , where n represents the nth modulation arm, when we apply a voltage such that When , light will be output from output port ②; voltage is applied to the second metal electrode (202) on the second modulation arm waveguide (104) to change the power loaded on the second metal electrode (202) to heat the second modulation arm waveguide (104). When we apply voltage to make When , light will be output from output port ①, thus realizing the switching function of two channels.

[0068] As attached Figure 2As shown, the schematic diagram of the structure of the 1×2 3dB multimode interferometer (300) of the present invention. From left to right, there are 1 input sinusoidal Taper waveguide (301), 1 first multimode interference zone (302) and 2 output sinusoidal Taper waveguides (303, 303'). In this example, considering the device size and the actual preparation difficulty, the length of the sinusoidal Taper waveguides (301 and 303) is selected to be 132.2μm, the narrow side width is 3μm, and the wide side width is 7μm (the side is a sinusoidal structure). The width of the first multimode interference zone (302) is 20μm, the length is 221μm, and the center distance between the two output sinusoidal Taper waveguides (303, 303') is 10.16μm. The sinusoidal Taper waveguide uses the difference between half the width of the wide side and half the width of the narrow side (i.e. 7 / 2-3 / 2=2μm) as the amplitude of the sine. After the first 1 / 4 sine cycle, the width of the Taper waveguide changes from 3μm in the narrow side to 7μm in the wide side.

[0069] As attached Figure 3 As shown, the transmission spectrum diagram of the 1×2 3dB multimode interference zone (300) of the present invention. It can be found that at a wavelength of 1500nm to 1630nm, the light splitting of the upper and lower channels is uniform, and the loss of each channel is less than 3.2dB.

[0070] As attached Figure 4 The figure shows a cross-sectional view of an inorganic / polymer organic material hybrid waveguide. From bottom to top, there are a silicon substrate (1), a silicon dioxide lower cladding (2), a polymer core layer (3), a polymer upper cladding (4), and a metal electrode (5). In this example, a dense silicon dioxide layer is grown by thermal oxidation, and its refractive index is 1.4448. The polymer core layer material (3) used is SU-8 2002 negative photoresist, and its refractive index at a wavelength of 1550nm is 1.5802. The polymer upper cladding material used is polymethyl methacrylate (PMMA), and its refractive index at a wavelength of 1550nm is 1.47606. In this example, in order to reduce the crosstalk between modes and to reduce the difficulty of process manufacturing, we design the width and thickness dimensions of the input waveguide (101), the first input S-bend waveguide (102), the second input S-bend waveguide (102'), the first modulation arm waveguide (103), the second modulation arm waveguide (104), the first output S-bend waveguide (105), the second output S-bend waveguide (105'), the first output waveguide (106) and the second output waveguide (107) to be 3μm×3μm.

[0071] As attached Figure 5As shown, the schematic diagram of the structure of the 2×2 3dB multimode interferometer (400) of the present invention. From left to right, there are two input sinusoidal Taper waveguides (401, 401'), one second multimode interference zone (402), and two output sinusoidal Taper waveguides (403, 403'). In this example, considering the device size and the actual preparation difficulty, the length of the input / output sinusoidal Taper waveguides (401, 401' and 403, 403') is selected to be 132.2μm, the narrow side width is 3μm, and the wide side width is 7μm. The width of the multimode interference zone is 30μm, the length is 642.6μm, and the center spacing of the input / output sinusoidal Taper waveguides is 10.16μm. The sinusoidal Taper waveguide uses the difference between half the width of the wide side and half the width of the narrow side as the amplitude of the sine. After the first 1 / 4 sine cycle, the width of the Taper waveguide changes from 3μm in the narrow side to 7μm in the wide side.

[0072] As attached Figure 6 As shown, the transmission spectrum diagram of the 2×2 3dB multimode interferometer (400) of the present invention when inputting signal light into channel A. At a wavelength of 1500nm to 1630nm, the loss of each channel is less than 4dB.

[0073] As attached Figure 7 As shown, the preparation method of the 1×2 thermo-optic switch based on the silica / polymer hybrid waveguide of the present invention comprises the following steps:

[0074] 1) growing a dense 15 μm thick silicon dioxide lower cladding layer (2) on a silicon wafer substrate (1) by thermal oxidation;

[0075] 2) using a vacuum coating machine to spin-coat SU-8 2002 photoresist on the surface of the lower silica cladding layer, first pre-baking at 60° C. for 10 minutes and at 90° C. for 20 minutes and naturally cooling and curing, and then controlling the speed to 600 rpm and the spin coating time to 20 seconds to form a 3 μm thick SU-8 photoresist layer (3);

[0076] 3) Place the device in step 2) under a 365nm UV lithography machine with an optical power of 23mW / cm 2, the structure and shape of the mask plate I used are complementary to the structure and shape of the SU-8 core waveguide to be prepared, the exposure time is 3.5s, and then post-baking is performed at 65°C for 10 minutes and 95°C for 20 minutes, cooled to room temperature, developed in PGMEA (Propyleneglygol-monomethylether-acetate) developer, and then rinsed in isopropanol to remove the residual glue, and the reaction solution is washed with deionized water; then hardened at 120°C for 30 minutes to form a SU-8 2002 core layer. In order to be polarization-insensitive, the width and height of the strip-shaped SU-8 core layer (3) are the same, both 3μm;

[0077] 4) using a vacuum coating machine to spin-coat a PMMA polymer upper cladding layer (4) with a thickness of 7 μm on the chip, wherein the PMMA polymer upper cladding layer (4) on the SU-8 core waveguide has a thickness of 4 μm, and then curing at 120° C. for 30 minutes, and cooling to room temperature;

[0078] 5) evaporating a metal Al film (51) with a thickness of 100 nm on the PMMA polymer upper cladding layer (4);

[0079] 6) using a spin coating process, spin coating a positive photoresist BP212 (61) with a thickness of 1.5 μm on the metal Al film (51), and baking at a temperature of 87° C. for 20 minutes;

[0080] 7) placing the sample under an ultraviolet lithography machine, bringing it into close contact with the mask plate II for plate alignment photolithography, wherein the structure and shape of the mask plate II used are the same as the structure and shape of the metal electrode to be prepared, and the structure of the mask plate II is larger than the SU-8 core waveguide, exposing for 2 seconds, removing the mask plate II, developing with a NaOH solution with a mass concentration of 5wt‰, and baking at 90°C for 20 minutes, transferring the pattern on the mask plate II with the same structure as the metal electrode to be prepared to the BP212 photoresist layer (62);

[0081] 8) Using a NaOH solution with a mass concentration of 5 wt‰ to remove the metal Al film not masked by the photoresist, exposing again for 10 seconds, and using an ethanol solution to remove the remaining BP212 to expose the Al metal electrode (51), thereby preparing a 1×2 thermo-optical switch based on a polymer / silicon dioxide hybrid waveguide; the width of the first metal modulation electrode (201) and the second metal modulation electrode (202) are both 21 μm, and the spacing between the two metal modulation electrodes is 49 μm.

[0082] As attached Figure 8 (a) shows the optical field diagram of the 1×2 thermo-optic switch based on silica / polymer hybrid waveguide according to the present invention when no voltage is applied. When no voltage is applied, output channel ① and output channel ② are approximately equal in power output.

[0083] As attached Figure 8 (b) shows the light field diagram of the 1×2 thermo-optic switch based on silica / polymer hybrid waveguide of the present invention when a voltage is applied to the first modulation arm (103) to produce a temperature change of 1.1K. From this figure, we can find that when a voltage is applied to the first modulation arm waveguide (103) to produce a temperature change of 1.1K, light will only be output from the output channel ②. At this time, the simulated loss at a wavelength of 1550nm is -0.05769dB, and the extinction ratio is greater than 40dB.

[0084] As attached Figure 8 (c) shows the light field diagram of the 1×2 thermo-optic switch based on silica / polymer hybrid waveguide of the present invention when a voltage is applied to the second modulation arm (104) to produce a temperature change of 1.1K. From this figure, we can find that when a voltage is applied to the second modulation arm waveguide (104) to produce a temperature change of 1.1K, light will only be output from the output channel ①. At this time, the simulated loss at a wavelength of 1550nm is -0.05769dB, and the extinction ratio is greater than 40dB.

[0085] As attached Fig. 9 As shown, the transmission spectrum diagram of the 1×2 thermo-optic switch of the present invention when a voltage is applied to the first modulation arm waveguide (103) to produce a temperature change of 1.1K. We can find that at a wavelength of 1500nm to 1630nm, the loss of the output channel ② is less than 1dB and the crosstalk is less than -27dB.

[0086] As attached Fig.10 As shown, the transmission spectrum diagram of the 1×2 thermo-optic switch of the present invention when a voltage is applied to the second modulation arm waveguide (104) to produce a temperature change of 1.1K. It can be found that at a wavelength of 1500nm to 1630nm, the loss of the output channel ① is less than 1dB and the crosstalk is less than -27dB.

Claims

1. A 1×2 thermo-optical switch based on silica / polymer hybrid waveguide, Features: From bottom to top, Si substrate (1), SiO 2 The polymer core layer (3) and the polymer upper cladding layer (4) are located on the SiO 2 The polymer core layer (3) is coated on the lower cladding layer (2), and the polymer core layer (3) is coated in the polymer upper cladding layer (4), the polymer core layer (3) is composed of an input waveguide (101), a 1×2 3dB multimode interferometer (300), a first input S-bend waveguide (102), a second input S-bend waveguide (102'), a first modulation arm waveguide (103), a second modulation arm waveguide (104), a first output S-bend waveguide (105), a second output S-bend waveguide (105'), a 2×2 3dB multimode interferometer ( 400), a first output waveguide (106) and a second output waveguide (107); wherein the first modulation arm waveguide (103) and the second modulation arm waveguide (104) are parallel to each other, and a first metal electrode (201) and a second metal electrode (202) are arranged on the polymer upper cladding (4) at the positions where the first modulation arm waveguide (103) and the second modulation arm waveguide (104) are located, and the first metal electrode (201) and the second metal electrode (202) together constitute an electrode (5); The 1×2 3dB multimode interferometer (300) is composed of an input Taper waveguide (301), a multimode interference region (302) and two output Taper waveguides (303, 303'), wherein the input Taper waveguide (301) and the output Taper waveguides (303, 303') have the same structure and a sinusoidal shape; the signal light transmitted in the optical fiber is coupled into the input waveguide (101), and then transmitted to the multimode interference region (302) via the input Taper waveguide (301) to generate a self-image effect; the signal light is divided into two beams of light with the same light intensity and the same phase from the position where the double image is first generated, and are respectively output to the two output Taper waveguides (303, 303'), and then respectively input to the first modulation arm waveguide (103) and the second modulation arm waveguide (104) via the first input S-bend waveguide (102) and the second input S-bend waveguide (102'); The 2×2 3dB multimode interferometer (400) is composed of two input Taper waveguides (401, 401'), one multimode interference region (402) and two output Taper waveguides (403, 403'). The input Taper waveguides (401, 401') and the output Taper waveguides (403, 403') have the same structure and have a sinusoidal shape. The signal light outputted through the first modulation arm waveguide (103) and the second modulation arm waveguide (104) is respectively transmitted through the first output The S-bend waveguide (105) and the second output S-bend waveguide (105') are input into two input Taper waveguides (401, 401') of a 2×2 3dB multimode interferometer (400), and then input into a multimode interference region (402) to generate self-image effects, and two beams of signals are respectively output from the positions where the double image is generated for the first time to output Taper waveguides (403, 403'), and then respectively output from the first output waveguide (106) and the second output waveguide (107); When a voltage is applied only to the first heating electrode (201), the phase difference between the signal light in the first modulation arm waveguide (103) and the signal light in the second modulation arm waveguide (104) is When the voltage is applied to the second metal electrode (202), the phase difference between the signal light in the second modulation arm waveguide (104) and the signal light in the first modulation arm waveguide (103) is When , light is output from output channel ①, thus realizing the function of two channel switches.

2. A 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide as claimed in claim 1, Features: The polymer upper cladding material is one of polymethyl methacrylate, polyethylene, polyester, polystyrene, and EpoClad.

3. A 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide as claimed in claim 1, Features: The polymer core layer material is one of SU-8 2002, SU-8 2005, and EpoCore.

4. A 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide as claimed in claim 1, Features: The electrode material is an alloy consisting of one or more materials selected from the group consisting of gold, silver, copper and aluminum.

5. A 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide as claimed in claim 1, Features: The thickness of the silicon dioxide lower cladding is 10 to 20 μm; the thickness of the input waveguide (101), the first input S-bend waveguide (102), the second input S-bend waveguide (102'), the first modulation arm waveguide (103), the second modulation arm waveguide (104), the first output S-bend waveguide (105), the second output S-bend waveguide (105'), the first output waveguide (106) and the second output waveguide (107) are the same, which is 2 to 5 μm, and the width is the same, which is 2 to 5 μm; the thickness of the polymer upper cladding is 2 to 7 μm, and the thickness of the electrode is 50 to 400 nm.

6. A 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide as claimed in claim 5, Features: The thickness of the silicon dioxide lower cladding is 15 μm, the length of the first modulation arm (103) and the second modulation arm (104) is set to 2000 μm, the thickness of the input waveguide (101), the first input S-bend waveguide (102), the second input S-bend waveguide (102'), the first modulation arm waveguide (103), the second modulation arm waveguide (104), the first output S-bend waveguide (105), the second output S-bend waveguide (105'), the first output waveguide (106) and the second output waveguide (107) are 3 μm and 3 μm in width; the thickness of the polymer upper cladding is 4 μm, and the thickness of the electrode is 100 nm.

7. A 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide as claimed in claim 6, Features: The length of the sinusoidal input Taper waveguide (301) and output Taper waveguide (303, 303') is 132.2 μm, the narrow side width is 3 μm, and the wide side width is 7 μm. The side sinusoidal structure uses the difference between half the wide side width and half the narrow side width as the sine amplitude, and changes from the narrow side width to the wide side width after the first 1 / 4 sinusoidal cycle. The width of the multimode interference zone (302) is 20 μm and the length is 221 μm. The center distance between the two output sinusoidal Taper waveguides (303, 303') is 10.16 μm.

8. A 1×2 thermo-optic switch based on a silica / polymer hybrid waveguide as claimed in claim 6, Features: The length of the sinusoidal input Taper waveguide (401, 401') and the output Taper waveguide (403, 403') is 132.2 μm, the narrow side width is 3 μm, and the wide side width is 7 μm. The side sinusoidal structure uses the difference between half the wide side width and half the narrow side width as the sine amplitude, and changes from the narrow side width to the wide side width after the first 1 / 4 sinusoidal cycle. The width of the multimode interference zone (402) is 30 μm and the length is 642.6 μm. The center distance between the two input Taper waveguides (401, 401') and the two output Taper waveguides (403, 403') is 10.16 μm.

9. A method for preparing a 1×2 thermo-optical switch based on a silica / polymer hybrid waveguide, the steps of which are as follows: 1) On a silicon wafer substrate, a layer of densely structured silicon dioxide with a thickness of 10 to 20 μm is grown by thermal oxidation as a lower cladding layer; 2) spin coating a polymer core layer material on the silicon dioxide lower cladding layer, pre-baking the material to remove excess solvent in the polymer core layer material, and then naturally cooling the material to obtain a polymer core layer film; 3) by ultraviolet lithography, development and post-baking, the pattern on the mask I which is identical or complementary to the polymer core layer structure to be prepared is transferred to the polymer core layer film to obtain the polymer core layer structure, wherein the input waveguide (101), the first input S-bend waveguide (102), the second input S-bend waveguide (102'), the first modulation arm waveguide (103), the second modulation arm waveguide (104), the first output S-bend waveguide (105), the second output S-bend waveguide (105'), the first output waveguide (106) and the second output waveguide (107) in the polymer core layer have a thickness of 2 to 5 μm and a width of 2 to 5 μm; 4) using a vacuum coating machine to spin-coat a polymer upper cladding material on the silica lower cladding and the polymer core layer, wherein the thickness of the polymer upper cladding above the polymer core layer is 2 to 7 μm, and then naturally cooling and curing after baking; 5) Vapor depositing a metal film with a thickness of 50 to 400 nm on the polymer upper cladding layer; 6) Spin-coat a layer of photoresist on the metal surface using a vacuum coating machine, pre-bake to remove the photoresist solvent, and then cool and solidify naturally; 7) Obtaining a photoresist pattern identical to the metal electrode structure to be prepared on the metal film through ultraviolet exposure, development, and post-baking; 8) using a metal etching solution corresponding to the metal to corrode the metal not covered by the photoresist pattern to obtain a metal electrode, and then removing the photoresist layer covering the metal electrode; the metal electrode is located on the polymer upper cladding directly above the first modulation arm waveguide and the second modulation arm waveguide, the symmetry center of the metal electrode along the width and length directions is aligned with the symmetry center of the modulation arm waveguide along the width and length directions, the length of the metal electrode is equal to the length of the modulation arm waveguide, and the width of the metal electrode is greater than the width of the modulation arm waveguide, thereby preparing a 1×2 multimode interferometer cascade thermo-optical switch based on a silica / polymer hybrid waveguide.

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