Multimode independent tuning 2*2MZI interferometer based on electro-optical effect

Abstract

The invention discloses a 2 * 2 MZI (Mach Zehnder Interferometer) based on electro-optical effect multimode independent tuning. Comprising two 3dB couplers, an input waveguide, an output waveguide and two phase shift interference arms, the two ends of one side of one 3dB coupler are connected with the input waveguide, the two ends of the other side of one 3dB coupler are connected with one ends of the two phase shift interference arms through multi-mode bent waveguides, and the two ends of the two phase shift interference arms are connected with the two ends of one side of the other 3dB coupler. Two ends of the other side of the other 3dB coupler are connected with an output waveguide; the phase shift interference arm comprises a plurality of tapered waveguides and a plurality of phase shift waveguides which are sequentially and alternately connected. According to the 2 * 2MZI interferometer based on electro-optical effect multimode independent tuning, the different phase shift waveguides with different electro-optical modulation efficiencies for multimode are adopted, multimode phase shift is introduced, loss is reduced by introducing the gradual change waveguides between the phase shift waveguides, the 2 * 2MZI interferometer based on electro-optical effect multimode independent tuning is achieved, and the 2 * 2MZI interferometer based on electro-optical effect multimode independent tuning has the advantages of being independent and adjustable in mode, excellent in performance, low in loss, extensible and the like.

Description

Technical Field

[0001] The present invention belongs to the field of integrated optoelectronic devices, and in particular relates to a 2×2 MZI interferometer based on electro-optical effect multi-mode independent tuning. Background Art

[0002] With the rapid development of the information age, the demand for internet services has increased dramatically, placing higher demands on the construction of large-capacity data communication centers. Optical interconnection has gradually become the main technical means to replace electrical interconnection, and optical switching has gradually replaced traditional electrical switching. Compared with electrical switching, optical switching has significant advantages such as low crosstalk, low latency, and large capacity, which can well meet the needs of next-generation data centers for efficient interconnection technology. In this context, silicon-based photonics technology has become an ideal process platform for achieving large-scale photonic integration due to its compatibility with complementary metal oxide semiconductor (CMOS) process production lines, as well as its low cost and high integration density.

[0003] Optical switches, core components in optical switching networks, come in a wide variety of types. Based on the physical effects they utilize, they can be categorized as thermo-optical, electro-optical, magneto-optical, and acousto-optic. Among them, the 2×2 electro-optical switch based on the Mach-Zehnder Interferometer (MZI) is particularly typical.

[0004] With society's growing demand for information, optical communication networks urgently need to expand their capacity to meet this demand. However, traditional MZI interferometers can only support transmission in one mode. Therefore, existing technologies lack an MZI interferometer that can independently tune multiple modes.

[0005] Among them, how to flexibly and efficiently perform dynamic routing and mode tuning of multimode optical signals has become a core issue and a technical problem that needs to be solved in order to achieve efficient operation of multimode communication systems using existing technologies. Summary of the Invention

[0006] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide a 2×2MZI interferometer based on electro-optical effect multi-mode independent tuning, which meets the application requirements of low loss, low power consumption, high integration, easy expansion and easy control.

[0007] The technical solution adopted in the present invention is:

[0008] The present invention includes two 3dB couplers, an input waveguide, an output waveguide, and two phase-shifting interference arms, wherein the two ends of one side of one 3dB coupler are respectively connected to one input waveguide of each, and the two ends of the other side are connected to one end of a phase-shifting interference arm of each via a multimode curved waveguide. The two ends of the two phase-shifting interference arms are respectively connected to the two ends of one side of another 3dB coupler, and the two ends of the other side of the other 3dB coupler are respectively connected to one output waveguide of each. The phase-shifting interference arm is mainly composed of a plurality of gradient waveguides and a plurality of phase-shifting waveguides alternately connected end to end, and the connecting waveguides at both ends of the phase-shifting interference arm can be set as gradient waveguides. The phase-shifting waveguide adopts phase control based on the electro-optical effect.

[0009] The innovation of the present invention is to set up phase-shifting interferometer arms with different electro-optical modulation efficiencies for different modes for multi-mode switching. The phase-shifting interferometer arms are used to independently transmit multiple modes, control the phase changes of different modes in the structure, and achieve the optical switching effect / advantage of multiple modes being independently tunable.

[0010] The phase-shift interference arm is composed of at least three gradient waveguides and two phase-shift waveguides which are alternately connected end to end, and every two adjacent gradient waveguides are connected via a phase-shift waveguide.

[0011] The multimode curved waveguide is a multimode curved structure with a gradually changing width. The width of the multimode curved waveguide at the end connected to the 3dB coupler is the same as the width of the waveguide at the output end of the 3dB coupler. The width of the multimode curved waveguide at the end connected to the phase-shifting interference arm is the same as the width of the gradually changing waveguide at the output end of the phase-shifting interference arm.

[0012] The phase-shifting interferometer arm is composed of three gradient waveguides and two phase-shifting waveguides connected end to end in sequence, and each two adjacent gradient waveguides are connected by a phase-shifting waveguide. Specifically, the phase-shifting interferometer arm includes a mode 1 front gradient waveguide, a mode 1 phase-shifting waveguide, a mode 2 front gradient waveguide, a mode 2 phase-shifting waveguide, a mode 3 front gradient waveguide, a mode 3 phase-shifting waveguide, and a rear gradient waveguide, which are arranged in sequence along the light propagation direction.

[0013] Mode 1 phase-shift waveguide, mode 2 phase-shift waveguide, and mode 3 phase-shift waveguide are used for phase shift modulation of optical signals of different wavelengths. Mode 1 front-end gradient waveguide, mode 2 front-end gradient waveguide, mode 3 front-end gradient waveguide, and rear-end gradient waveguide are used to ensure that each mode is transmitted between different phase-shift waveguides with reduced loss and crosstalk, that is, low-loss and low-crosstalk transmission.

[0014] The mode 1 phase-shift waveguide modulations of the two phase-shift interferometer arms are different / opposite, the mode 2 phase-shift waveguide modulations of the two phase-shift interferometer arms are different / opposite, and the mode 3 phase-shift waveguide modulations of the two phase-shift interferometer arms are different / opposite.

[0015] The phase-shift waveguide is a slot-waveguide type multimode optical waveguide;

[0016] The gradient waveguide is a connecting optical waveguide of a linear gradient structure, a nonlinear gradient structure, a tapered structure, an on-chip super lens structure, a reverse design structure, etc.

[0017] The phase-shift waveguide adjusts the phase of the optical signal passing through it by 0 or π, adopts any waveguide structure that supports transmission in multiple modes that need to be regulated and has different regulation efficiencies for various modes, and adopts phase regulation based on the electro-optical effect.

[0018] The multimode curved waveguide adopts but is not limited to an S-shaped multimode curved structure based on a circular arc, an Euler curve, or a Bezier curve.

[0019] Preferably, all the gradient waveguides in the phase-shifting interference arm are superlens waveguides, and all the phase-shifting waveguides are strip waveguides. In this case, the phase-shifting interference arm is more conducive to phase-shift modulation of optical signals in two modes.

[0020] Preferably, the phase-shifting interference arm is mainly composed of the first gradient waveguide of the super lens waveguide, the first phase-shifting waveguide of the single-slot waveguide, the second gradient waveguide of the tapered waveguide, the second phase-shifting waveguide of the double-slot waveguide, the third gradient waveguide of the tapered waveguide, the third phase-shifting waveguide of the triple-slot waveguide, and the fourth / last gradient waveguide of the super lens waveguide, connected in sequence along the direction of light propagation. At this time, the phase-shifting interference arm is more conducive to phase-shift modulation of three modes of optical signals.

[0021] The principles of the present invention are as follows:

[0022] Taking the three-mode electro-optic modulation scheme as an example, the multi-terminal phase-shift waveguides are connected in series, and the refractive index change of the electro-optic material in the phase-shift waveguide is Among them, Δn represents the change in the refractive index of the electro-optic material in the phase change material, ΔE represents the change in the electric field intensity, n represents the refractive index of the electro-optic material, and r represents the electro-optic coefficient of the electro-optic material. The refractive index of the electro-optic material after electro-optic modulation is n+Δn, and the equivalent refractive index n of each mode after electrical modulation is obtained by MODE simulation. eff , so the electric regulation efficiency of each mode is obtained Assume that each phase-shift waveguide has a characteristic matrix η 21 is the electro-optical modulation efficiency of the second phase-shift waveguide for mode 1, L1, L2, and L3 represent the lengths of the three phase-shift waveguides. The electric field strength of each waveguide segment is The final phase changes of the three modes are They represent the total phase shift of the three mode lights after passing through the three phase shift waveguides. The equations are obtained exist In the case of variables, to make the equation solvable, |A|≠0, and further, to make |η|≠0, That is, the three-segment phase-shift waveguide is linearly independent of the vectors of the electro-optical modulation efficiency of the three modes, η 21 is the electro-optical modulation efficiency of the second phase-shift waveguide for mode 1. Thus, independent tunability of the three modes can be achieved.

[0023] From the above, it can be seen that, in particular, when the electro-optical modulation efficiency of the first phase-shifted waveguide for the first mode is greater than that of the other two modes, the electro-optical modulation efficiency of the second phase-shifted waveguide for the second mode is greater than that of the other two modes, and the electro-optical modulation efficiency of the third phase-shifted waveguide for the third mode is greater than that of the other two modes, it must be satisfied that the vectors composed of the electro-optical modulation efficiencies of the three phase-shifted waveguides for the three modes are linearly independent, and independent tunability of the three modes can be achieved.

[0024] The beneficial effects of the present invention are:

[0025] The present invention solves the problem that an optical switch can only tune a single mode or a fundamental mode, and enables multiple modes to be tuned independently in the optical switch, which has important application scenarios in the field of optical communications.

[0026] In the scheme of the present invention, multiple modes have very low inter-modal crosstalk after passing through the gradient waveguide and phase-shift waveguide. By introducing phase-shift waveguides with different adjustment efficiencies for different modes and utilizing principles such as the electro-optic effect for phase adjustment, different modes can be tuned separately. At the same time, through the special design of the gradient waveguide, multiple modes can be transmitted from one phase-shift waveguide to the next phase-shift waveguide with low crosstalk and low loss.

[0027] The present invention can be manufactured using a standard planar integrated optical waveguide process, which features simplicity, low cost, low loss, high extinction ratio, easy scalability, and controllability. It is compatible with CMOS technology and has the potential for large-scale production, paving the way for on-chip multimode optical communications. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the structure of the 2×2 MZI interferometer based on electro-optical effect multi-mode independent tuning proposed in the present invention (taking three modes as an example);

[0029] Figure 2 This is a schematic diagram of the 3dB coupler structure proposed by the present invention, wherein Figure 3 (a) is a multimode coupler, Figure 3 (b) is a directional coupler, Figure 3 (c) is a ring coupler, Figure 3 (d) is an adiabatic coupler;

[0030] Figure 3is a schematic diagram of the multimode curved waveguide structure proposed by the present invention, wherein Figure 3 (a) is a curved waveguide based on circular arc, Figure 3 (b) is a curved waveguide based on Euler curve, Figure 3 (c) a curved waveguide based on Bezier curve;

[0031] Figure 4 is a schematic diagram of the gradient waveguide structure proposed by the present invention, wherein Figure 4 (a) is a linear gradient waveguide, Figure 4 (b) is a nonlinear graded waveguide, Figure 4 (c) is the superlens waveguide, Figure 4 (d) is a tapered waveguide, Figure 4 (e) is the topology optimized waveguide, Figure 4 (f) is a pixelated waveguide;

[0032] Figure 5 is a schematic diagram of the phase-shift waveguide structure proposed in the present invention, wherein Figure 5 (a) is a single-slot phase-shift waveguide, Figure 5 (b) is a double-slot phase-shift waveguide, 5(c) is a triple-slot phase-shift waveguide;

[0033] Figure 6 1 is a diagram showing simulation results of the electro-optical modulation efficiency of the multi-mode phase-shift waveguide in transmitting different modes according to Example 1;

[0034] In the figure: 1a is the first input waveguide, 1b is the second input waveguide, 2 is the first 3dB coupler, 3a is the first front multimode curved waveguide, 3b is the second front multimode curved waveguide,

[0035] 4a is a first mode-front end gradient waveguide, 4b is a second mode-front end gradient waveguide, 5a is a first mode-phase shift waveguide, 5b is a second mode-phase shift waveguide;

[0036] 6a is the first mode two front end gradient waveguide, 6b is the second mode two front end gradient waveguide, 7a is the first mode two phase shift waveguide, 7b is the second mode two phase shift waveguide;

[0037] 8a is the first mode three-front end gradient waveguide, 8b is the second mode three-front end gradient waveguide, 9a is the first mode three-phase shift waveguide, 9b is the second mode three-phase shift waveguide;

[0038] 10a is the first rear end gradient waveguide, 10b is the second rear end gradient waveguide;

[0039] 11a is a first rear multimode curved waveguide, 11b is a second rear multimode curved waveguide, 12 is a second 3dB coupler, 13a is a first output waveguide, and 13b is a second output waveguide. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and examples.

[0041] like Figure 1 As shown, the interferometer includes two 3dB couplers, an input waveguide, an output waveguide, and two phase-shifting interference arms, wherein the two ends of one side of one 3dB coupler are respectively connected to one input waveguide of each, and the two ends of the other side are connected to one end of each phase-shifting interference arm via a multimode curved waveguide, the two ends of the two phase-shifting interference arms are respectively connected to the two ends of one side of another 3dB coupler, and the two ends of the other side of the other 3dB coupler are respectively connected to one output waveguide of each; the phase-shifting interference arm is mainly composed of a plurality of gradient waveguides and a plurality of electro-optically controlled phase-shifting waveguides alternately connected end to end, and the waveguides at both ends of the phase-shifting interference arm are both configured as gradient waveguides.

[0042] The phase-shifting interference arm is composed of at least three gradient waveguides and two phase-shifting waveguides which are alternately connected end to end, and every two adjacent gradient waveguides are connected via a phase-shifting waveguide.

[0043] A phase-shifting unit is formed by a front-end gradient waveguide and a phase-shifting waveguide arranged sequentially along the light propagation direction. A rear-end gradient waveguide is then provided at the end of each phase-shifting unit. The front-end gradient waveguides 4a, 4b, 6a, 6b, 8a, 8b and the phase-shifting waveguides 5a, 5b, 7a, 7b, 9a, 9b can be extended to the Nth mode N, i.e., having N phase-shifting units.

[0044] The phase-shifting interferometer arm is composed of three gradient waveguides and two phase-shifting waveguides connected end to end in alternating order. Every two adjacent gradient waveguides are connected by a phase-shifting waveguide. Specifically, the phase-shifting interferometer arm includes a mode 1 front gradient waveguide, a mode 1 phase-shifting waveguide, a mode 2 front gradient waveguide, a mode 2 phase-shifting waveguide, a mode 3 front gradient waveguide, a mode 3 phase-shifting waveguide, and a rear gradient waveguide, which are arranged in sequence along the light propagation direction.

[0045] Mode 1 phase-shift waveguide, mode 2 phase-shift waveguide, and mode 3 phase-shift waveguide are used for phase shift modulation of optical signals of different wavelengths to form different modes. Mode 1 front-end gradient waveguide, mode 2 front-end gradient waveguide, mode 3 front-end gradient waveguide, and rear-end gradient waveguide are used to ensure that each mode is transmitted with low loss and low crosstalk between different phase-shift waveguides.

[0046] More specifically, the mode-one phase-shift waveguides of the two phase-shifting interferometer arms have different / opposite modulations, i.e., if the mode-one phase-shift waveguide of one phase-shifting interferometer arm performs a phase-shift adjustment of 0 on the passing optical signal, the mode-one phase-shift waveguide of the other phase-shifting interferometer arm performs a phase-shift adjustment of π on the passing optical signal. The mode-two phase-shift waveguides of the two phase-shifting interferometer arms have different / opposite modulations, i.e., if the mode-two phase-shift waveguide of one phase-shifting interferometer arm performs a phase-shift adjustment of 0 on the passing optical signal, the mode-two phase-shift waveguide of the other phase-shifting interferometer arm performs a phase-shift adjustment of π on the passing optical signal. The mode-three phase-shift waveguides of the two phase-shifting interferometer arms have different / opposite modulations, i.e., if the mode-three phase-shift waveguide of one phase-shifting interferometer arm performs a phase-shift adjustment of 0 on the passing optical signal, the mode-three phase-shift waveguide of the other phase-shifting interferometer arm performs a phase-shift adjustment of π on the passing optical signal.

[0047] The end of the 3dB coupler and the end of the phase-shifting interference arm are connected by a multimode curved waveguide. The multimode curved waveguide is a multimode curved structure with a gradually changing width. The width of the multimode curved waveguide at the end connected to the 3dB coupler 2, 11 is the same as the width of the waveguide at the output end of the 3dB coupler 2, 11. The width of the multimode curved waveguide at the end connected to the phase-shifting interference arm is the same as the width of the gradually changing waveguide at the output end of the phase-shifting interference arm.

[0048] A 3dB coupler is a coupler with a splitting ratio of 50:50. Figure 2 As shown, the 3dB couplers 2 and 12 are, but not limited to, multimode couplers, directional couplers and ring couplers.

[0049] like Figure 5 As shown, phase-shift waveguides 5a, 5b, 7a, 7b, 9a, and 9b are slot-type multimode optical waveguides, with the slots filled with electro-optic polymer. Phase-shift waveguides 5a, 5b, 7a, 7b, 9a, and 9b adjust the phase of the optical signal passing through them by 0 or π. They employ any waveguide structure that supports transmission in multiple modes and has varying adjustment efficiencies for each mode, using phase control based on the electro-optic effect.

[0050] like Figure 4 As shown, the gradient waveguides of the front-end gradient waveguides 4a, 4b, 6a, 6b, 8a, 8b and the rear-end gradient waveguides 10a, 10b are connecting optical waveguides of linear gradient structure, nonlinear gradient structure, tapered structure, on-chip super lens structure, inverse design structure, etc.

[0051] like Figure 3 As shown, the multimode curved waveguides of the first front multimode curved waveguide 3a, the second front multimode curved waveguide 3b, the first rear multimode curved waveguide 11a and the second rear multimode curved waveguide 11b adopt but are not limited to S-shaped multimode curved structures based on circular arcs, Euler curves and Bezier curves.

[0052] In a specific implementation, each phase-shift waveguide is provided with a corresponding control electrode, and the control electrode is placed on the side or above the MZI interferometer waveguide.

[0053] In specific implementation, Figure 1 As shown, taking tuning of three modes as an example, the device includes a first input waveguide 1a, a second input waveguide 1b, a first 3dB coupler 2, a first front multimode curved waveguide 3a, a second front multimode curved waveguide 3b, a first mode 1 front end tapered waveguide 4a, a second mode 1 front end tapered waveguide 4b, a first mode 1 phase-shifted waveguide 5a, a second mode 1 phase-shifted waveguide 5b, a first mode 2 front end tapered waveguide 6a, a second mode 2 front end tapered waveguide 6b, a first mode 2 phase-shifted waveguide 7a, a second mode 2 phase-shifted waveguide 7b, a first mode 3 front end tapered waveguide 8a, a second mode 3 front end tapered waveguide 8b, a first mode 3 phase-shifted waveguide 9a, a second mode 3 phase-shifted waveguide 9b, a first rear end tapered waveguide 10a, a second rear end tapered waveguide 10b, a first rear multimode curved waveguide 11a, a second rear multimode curved waveguide 11b, a second 3dB coupler 12, a first output waveguide 13a, and a second output waveguide 13b.

[0054] The first input waveguide 1a and the second input waveguide 1b are connected to the two input ends of the first 3dB coupler 2 respectively, and the two output ends of the first 3dB coupler 2 are connected to one end of the first front multimode curved waveguide 3a and the second front multimode curved waveguide 3b respectively; the other end of the first front multimode curved waveguide 3a is connected to one end of the first mode one phase-shift waveguide 5a via the first mode one front end gradient waveguide 4a; the other end of the first mode one phase-shift waveguide 5a is connected to one end of the first mode two phase-shift waveguide 7a via the first mode two front end gradient waveguide 6a; the other end of the first mode two phase-shift waveguide 7a is connected to one end of the first mode three phase-shift waveguide 9a via the first mode three front end gradient waveguide 8a; The other end of the one-mode three-phase-shift waveguide 9a is connected to one end of the first rear multimode curved waveguide 11a via the first rear-end gradient waveguide 10a; the other end of the second front multimode curved waveguide 3b is connected to one end of the second mode one phase-shift waveguide 5b via the second mode one front-end gradient waveguide 4b; the other end of the second mode one phase-shift waveguide 5b is connected to one end of the second mode two phase-shift waveguide 7b via the second mode two front-end gradient waveguide 6b; the other end of the second mode two phase-shift waveguide 7b is connected to one end of the second mode three front-end gradient waveguide 8b and the second mode three phase-shift waveguide 9b; the other end of the second mode three phase-shift waveguide 9b is connected to one end of the second rear multimode curved waveguide 11b via the second rear-end gradient waveguide 10b.

[0055] The other ends of the first rear multimode bend waveguide 11a and the second rear multimode bend waveguide 11b are connected to two input ends of the second 3dB coupler 12, and the two output ends of the second 3dB coupler 12 are connected to the first output waveguide 13a and the second output waveguide 13b respectively.

[0056] The first front multimode curved waveguide 3a, the second front multimode curved waveguide 3b, the first rear multimode curved waveguide 11a, and the second rear multimode curved waveguide 11b are all multimode curved structures with gradually varying widths. The width of the multimode curved waveguide at the end close to the 3dB couplers 2 and 11 is the same as the width of the waveguide at the output end of the 3dB couplers 2 and 11.

[0057] The first group of interference arms is mainly composed of the first front curved gradient waveguide 3a, the first mode one front end gradient waveguide 4a, the first mode one phase-shift waveguide 5a, the first mode two front end gradient waveguide 6a, the first mode two phase-shift waveguide 7a, the first mode three front end gradient waveguide 8a, the first mode three phase-shift waveguide 9a, the first rear end gradient waveguide 10a, and the first rear curved gradient waveguide 11a. The second group of interference arms is mainly composed of the first front curved gradient waveguide 3b, the first mode one front end gradient waveguide 4b, the first mode one phase-shift waveguide 5b, the first mode two front end gradient waveguide 6b, the first mode two phase-shift waveguide 7b, the first mode three front end gradient waveguide 8b, the first mode three phase-shift waveguide 9b, the first rear end gradient waveguide 10b, and the first rear curved gradient waveguide 11b.

[0058] Specifically, in the preferred embodiment of the above scheme, all gradient waveguides in the phase-shifting interference arm adopt superlens waveguides, and all phase-shifting waveguides adopt strip waveguides. At this time, the phase-shifting interference arm is more conducive to phase-shift modulation of optical signals of two modes, and the transmission loss of each modulation mode in different phase-shifting waveguides is lower, the design is simpler, and the performance parameters are improved.

[0059] Specifically, in an embodiment, the phase-shifting interference arm of the above scheme is mainly composed of the first gradient waveguide of the tapered waveguide, the first phase-shifting waveguide of the single-slot waveguide, the second gradient waveguide of the tapered waveguide, the second phase-shifting waveguide of the double-slot waveguide, the third gradient waveguide of the tapered waveguide, the third phase-shifting waveguide of the triple-slot waveguide, and the fourth / last gradient waveguide of the superlens waveguide, which are connected in sequence along the direction of light propagation. At this time, the phase-shifting interference arm is more conducive to phase-shift modulation of three modes of optical signals, and the modulation performance parameters are improved.

[0060] The present invention operates as follows: utilizing the electro-optic effect, the phase difference between the phase-shift waveguides of each mode in the two interferometer arms can be controlled. When the phase difference between the two phase-shift waveguides is 0, i.e., when the mode is in the "off" state of the 2×2 optical switch, the mode light entering from the first input waveguide 1a is output from the second output waveguide 13b, and the mode light entering from the second input waveguide 1b is output from the first output waveguide 13a. When the phase difference between the two phase-shift waveguides is π, i.e., when the mode is in the "on" state of the 2×2 optical switch, the mode light entering from the first input waveguide 1a is output from the first output waveguide 13a, and the mode light entering from the second input waveguide 1b is output from the second output waveguide 13b, thereby realizing the function of the 2×2 optical switch.

[0061] like Figure 2 As shown, the first 3dB coupler 2 and the second 3dB coupler 12 both have the performance of large bandwidth, low loss, etc., and can adopt a multimode coupler (such as Figure 2 (a)), directional coupler (as shown in Figure 2 (b)), a ring coupler (as shown Figure 2 (c)).

[0062] like Figure 3 As shown, the multi-mode curved waveguide structure proposed by the present invention adopts a waveguide structure based on an arc to reduce waveguide bending loss and support multi-mode transmission.

[0063] like Figure 4 As shown, the gradient waveguide can be a linear gradient waveguide (such as Figure 4 (a)), nonlinear gradient waveguide (as shown in Figure 4 (b)), waveguide based on on-chip superlens (as shown in Figure 4 (c)), tapered waveguide (as shown in Figure 4 (d)), topology optimized waveguide (as shown in Figure 4 (e)) or pixelated waveguides (as shown Figure 4 (f)), where the waveguide based on the on-chip superlens contains a positive lens 1 and a negative lens 2.

[0064] like Figure 5 As shown, the phase-shift waveguide for regulating each mode can be a slot waveguide, with the slot filled with electro-optic polymer. Phase-shift waveguides include but are not limited to the types mentioned above.

[0065] Specific examples are given below.

[0066] Example 1:

[0067] This example uses a silicon nanowire optical waveguide based on silicon-on-insulator (SOI) material: the core layer is silicon with a thickness of 220nm; the upper and lower cladding layers are both made of silicon dioxide, with the lower cladding being 2μm thick and the upper cladding being 1.2μm thick. The electro-optic polymer material has a refractive index of 1.6 and an electro-optic coefficient of 100pm / V. Utilizing the electro-optic effect, the control electrode is located directly above the waveguide. Using TE0, TE1, and TE2 modes as an example, the light source is 1550nm.

[0068] For Figure 2 The 3dB coupler shown uses a multimode coupler, and its relevant parameters are: the length and width of the middle rectangle are 106.5um and 5.5um respectively, the width of the connecting waveguides on both sides is 2.41um, and the spacing is 0.678um.

[0069] For Figure 3The multimode curved waveguide shown uses an S-shaped arc waveguide with a uniform width, a width of 1000 nm, and a center radius of 15 μm.

[0070] For Figure 4 and Figure 5 The front-end gradient waveguide and phase shift waveguide shown in the figure, TE0 phase shift waveguide adopts single slot waveguide (such as Figure 5 a), the width of the waveguides on both sides is 0.7um, and the groove width is 0.15um; the TE1 phase-shift waveguide adopts a double-slot waveguide (such as Figure 5 b), the widths of the waveguides on both sides are 0.3um and 0.4um from top to bottom, and the groove widths are both 0.15um; the TE2 phase-shift waveguide uses a three-groove waveguide (such as Figure 5 c), the width of the waveguides on both sides is 0.3um, and the width of the groove is 0.15um. The TE0 front-end gradient waveguide can be connected to the front-end multimode bend using a strip waveguide with a width of 1um; the TE1 front-end gradient waveguide can be connected to the front-end multimode bend using a tapered waveguide (such as Figure 4 a) Connected to TE0 phase-shift waveguide; TE2 front-end gradient waveguide can use a tapered waveguide (such as Figure 4 a) Connected to TE1 phase shift waveguide. The back-end gradient waveguide can be a tapered waveguide (such as Figure 4 a) Connected to the second multimode bend.

[0071] like Figure 6 As shown, the vectors composed of the electro-optical modulation efficiencies of different modes in each phase-shifted waveguide are linearly independent, i.e. And |η|≠0. Therefore, there must be a solution to achieve an optical switch that can tune each mode independently.

[0072] From this implementation, it can be seen that the present invention introduces multimode phase shift by adopting different phase-shift waveguides with different electro-optical modulation efficiencies for multimodes, and reduces the loss by introducing a gradient waveguide between the phase-shift waveguides, thereby ultimately realizing a 2×2 MZI interferometer with independent multimode tuning based on electro-optical modulation, which has the advantages of mode-independent adjustability, superior performance, low loss, and scalability.

[0073] The above embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A 2×2 MZI interferometer with independent multi-mode tuning based on electro-optic effect, characterized by: The invention comprises two 3dB couplers, an input waveguide, an output waveguide and two phase-shifting interference arms, wherein the two ends of one side of one 3dB coupler are respectively connected to one input waveguide of the respective one, and the two ends of the other side are connected to one end of the respective phase-shifting interference arm via a multimode curved waveguide. The two ends of the two phase-shifting interference arms are respectively connected to the two ends of one side of another 3dB coupler, and the two ends of the other side of the other 3dB coupler are respectively connected to one output waveguide of the respective one. The phase-shifting interference arms are mainly composed of multiple gradient waveguides and multiple phase-shifting waveguides connected alternately in sequence. There are two electrodes on both sides of the phase-shifting waveguide to form a potential difference. The phase-shifting waveguide adopts phase control based on the electro-optical effect.

2. The 2×2 MZI interferometer with independent multi-mode tuning based on electro-optic effect according to claim 1, characterized in that: The phase-shifting interference arm is composed of at least three gradient waveguides and two phase-shifting waveguides connected alternately in sequence, and every two adjacent gradient waveguides are connected by a phase-shifting waveguide.

3. The 2×2 MZI interferometer based on electro-optic effect multi-mode independent tuning according to claim 1, characterized in that: The multimode curved waveguide is a multimode curved structure. The width of the multimode curved waveguide at one end connected to the 3dB coupler (2, 11) is the same as the width of the waveguide at the output end of the 3dB coupler (2, 11). The width of the multimode curved waveguide at one end connected to the phase-shift interference arm is the same as the width of the gradient waveguide at the output end of the phase-shift interference arm.

4. The 2×2 MZI interferometer with independent multi-mode tuning based on electro-optic effect according to claim 2, characterized in that: The phase-shifting interferometer arm is composed of three gradient waveguides and two phase-shifting waveguides connected alternately in sequence, and each two adjacent gradient waveguides are connected by a phase-shifting waveguide, specifically including a mode 1 front gradient waveguide, a mode 1 phase-shifting waveguide, a mode 2 front gradient waveguide, a mode 2 phase-shifting waveguide, a mode 3 front gradient waveguide, a mode 3 phase-shifting waveguide, and a rear gradient waveguide arranged in sequence along the light propagation direction; Mode 1 phase-shift waveguide, mode 2 phase-shift waveguide and mode 3 phase-shift waveguide are used for phase shift modulation of optical signals of different wavelengths. Mode 1 front-end gradient waveguide, mode 2 front-end gradient waveguide, mode 3 front-end gradient waveguide and back-end gradient waveguide are used to ensure that each mode is transmitted between different phase-shift waveguides with reduced loss and crosstalk.

5. The 2×2 MZI interferometer with independent multi-mode tuning based on electro-optic effect according to claim 3, characterized in that: The mode 1 phase-shift waveguide modulations of the two phase-shift interferometer arms are different / opposite, the mode 2 phase-shift waveguide modulations of the two phase-shift interferometer arms are different / opposite, and the mode 3 phase-shift waveguide modulations of the two phase-shift interferometer arms are different / opposite.

6. A 2×2 MZI interferometer with independent multi-mode tuning based on electro-optic effect according to any one of claims 1 to 5, characterized in that: The phase-shift waveguides (5a, 5b, 7a, 7b, 9a, 9b) are groove-type waveguides, and the grooves are filled with electro-optic polymers; the gradient waveguides are connecting optical waveguides with linear gradient structures, nonlinear gradient structures, conical structures, super lens structures, reverse design structures, etc.

7. A 2×2 MZI interferometer with independent multi-mode tuning based on electro-optic effect according to any one of claims 1 to 5, characterized in that: The phase-shift waveguides (5a, 5b, 7a, 7b, 9a, 9b) adjust the phase of the optical signal passing therethrough by 0 or π, and adopt any waveguide structure that supports transmission in multiple modes that need to be regulated and has different regulation efficiencies for each mode.

8. A 2×2 MZI interferometer with independent multi-mode tuning based on electro-optic effect according to any one of claims 1 to 5, characterized in that: The multimode curved waveguide adopts but is not limited to an S-shaped multimode curved structure based on a circular arc, an Euler curve, or a Bezier curve.

9. The 2×2 MZI interferometer with independent multi-mode tuning based on electro-optic effect according to claim 3, characterized in that: All the gradient waveguides in the phase-shift interference arm adopt superlens waveguides, and all the phase-shift waveguides adopt strip waveguides.

10. The 2×2 MZI interferometer based on electro-optic effect multi-mode independent tuning according to claim 3, characterized in that: The phase-shifting interferometer arm is mainly composed of the first gradient waveguide of the superlens waveguide, the first phase-shifting waveguide of the strip waveguide, the second gradient waveguide of the tapered waveguide, the second phase-shifting waveguide of the double-slot waveguide, the third gradient waveguide of the tapered waveguide, the third phase-shifting waveguide of the strip waveguide, and the last gradient waveguide of the superlens waveguide, which are connected in sequence along the direction of light propagation.

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