Optical switch and silicon photonic chip

Abstract

The application provides a kind of optical switch and silicon optical chip, optical switch includes first waveguide and second waveguide, first waveguide is arranged with second waveguide in parallel;Second waveguide includes main body and first gap arranged in main body;First waveguide is composed of first material, main body is composed of the first material, first gap is filled with second material;Thermal-optical coefficient of first material is greater than thermal-optical coefficient of second material;Along the direction of light propagation, optical switch is sequentially provided with input port area, input coupling area, non-coupling phase modulation area, output coupling area and output port area, input port area, input coupling area, non-coupling phase modulation area, output coupling area and output port area are all arranged on first waveguide and second waveguide;The width of first waveguide in non-coupling phase modulation area is 450 nanometers, and the width of second waveguide in non-coupling phase modulation area is 600 nanometers.The application realizes optical switch while reducing cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical communication, and in particular to an optical switch and a silicon optical chip. BACKGROUND

[0002] In the field of modern photonic integration technology, active selection and power distribution of optical signal paths are the basis for building complex optical systems. Currently, the industry generally uses a Mach-Zehnder interferometer (MZI) based thermal light modulator to complete the above functions. The working principle of this technology is as follows: after splitting the input optical signal, the two independent waveguide arms are introduced, and by heating one or more waveguide arms, a man-made temperature difference is formed, and then a phase difference is generated between the two optical signals; when the two optical signals recombine at the output end, based on the interference effect caused by the phase difference, optical path switching and power distribution are realized.

[0003] However, this technical solution has a defect. In order to avoid heat conduction from one waveguide arm to another waveguide arm when heating one waveguide arm, a sufficient physical distance between the two waveguide arms is required, or a special isolation structure is prepared through a complex deep etching process. This rigid requirement for spatial isolation significantly increases the footprint of a single MZI thermal light modulator functional unit, resulting in an overall area enlargement of the chip.

[0004] The existing optical switch includes an optical input port arranged on one side, an optical beam splitter with a first optical output port and a second optical output port arranged on the other side; an optical beam combiner with a first optical input port and a second optical input port arranged on one side and an optical output port arranged on the other side; a negative thermal coefficient material optical waveguide connected between the first optical output port and the first optical input port, a silicon optical waveguide connected between the second optical output port and the second optical input port, and a hot electrode arranged between the negative thermal coefficient material optical waveguide and the silicon optical waveguide. However, the optical switch uses a material with a negative thermal coefficient, such as titanium oxide, which is expensive and increases the cost of manufacturing the chip. SUMMARY

[0005] The first object of the present application is to provide an optical switch using two positive thermal coefficient materials to achieve the effect of an optical switch.

[0006] The second object of the present application is to provide a silicon optical chip using the above-mentioned optical switch.

[0007] To achieve the first object of the present application, the optical switch provided by the present application comprises a first waveguide and a second waveguide, the first waveguide and the second waveguide are arranged side by side; the second waveguide comprises a main body and a first gap arranged in the main body; the first waveguide is composed of a first material, the main body is composed of the first material, and the first gap is filled with a second material; the thermo-optic coefficient of the first material is greater than the thermo-optic coefficient of the second material, and the first material and the second material are both positive thermo-optic coefficient materials; along the propagation direction of the input light, the optical switch is sequentially provided with an input port area, an input coupling area, a non-coupling phase modulation area, an output coupling area and an output port area, and the input port area, the input coupling area, the non-coupling phase modulation area, the output coupling area and the output port area are all arranged on the first waveguide and the second waveguide; the width of the first waveguide in the non-coupling phase modulation area is 450 nanometers, and the width of the second waveguide in the non-coupling phase modulation area is 600 nanometers.

[0008] As can be seen from the above scheme, the first waveguide only uses the first material, and the second waveguide is filled with the second material with a lower thermo-optic coefficient than the first material. When the optical switch is uniformly heated, the effective refractive indices of the two waveguides are different due to the different thermo-optic coefficients, resulting in phase errors. By setting the width of the first waveguide in the non-coupling phase modulation area to 450 nanometers and the width of the second waveguide in the non-coupling phase modulation area to 600 nanometers, it can be seen through simulation that the difference between the effective refractive index of the first waveguide and the equivalent thermo-optic coefficient of the second waveguide can be maximized at this time, thereby destroying the conditions for energy exchange between the two waveguides. When the light propagates in the non-coupling phase modulation area, the respective light propagates in the respective waveguide without interference. Since the effective refractive indices in the non-coupling phase modulation area are different, the accumulated phase differences of the light propagating in the first waveguide and the second waveguide are inconsistent. Therefore, when the light reinterferes in the output coupling area, the accumulated phase difference causes the output ports to be inconsistent, thereby realizing the function of the optical switch. Moreover, the first material of the present application is a positive thermo-optic coefficient material, and the second material is also a positive thermo-optic coefficient material, so the material cost is relatively low.

[0009] In a further scheme, in the input coupling area, the effective refractive index of the first waveguide is the same as the effective refractive index of the second waveguide.

[0010] As can be seen from the above scheme, by adjusting the width of the first waveguide in the input coupling area and the width of the second waveguide in the input coupling area, the effective refractive indices of the two waveguides are the same, so when the light is input from the input port area, energy is coupled and exchanged between the first waveguide and the second waveguide. The effective refractive index of the first waveguide is the same as the effective refractive index of the second waveguide, so as to produce effective coupling exchange.

[0011] In a further scheme, the first gap traverses the input coupling area, the non-coupling phase modulation area and the output coupling area.

[0012] Therefore, the first gap traverses the input coupling region, the non-coupling phase modulation region and the output coupling region, so that the second waveguide does not need to transition when coupling to the non-coupling region.

[0013] In a further aspect, a first taper region is further arranged between the input coupling region and the non-coupling phase modulation region, and the first waveguide of the first taper region is a linear taper structure.

[0014] Therefore, the width of the first waveguide in the input coupling region is a first width, the width of the first waveguide in the non-coupling phase modulation region is a second width, the first width and the second width are different, and a linear taper structure is needed for transition, so that the energy of light is not lost and mode conversion does not occur.

[0015] In a further aspect, a second taper region is arranged between the output coupling region and the non-coupling phase modulation region, and the second waveguide of the second taper region is a linear taper structure.

[0016] Therefore, the width of the first waveguide in the non-coupling phase modulation region is a second width, the width of the first waveguide in the output coupling region is a third width, the third width and the second width are different, and a linear taper structure is needed for transition, so that the energy of light is not lost and mode conversion does not occur.

[0017] In a further aspect, a thermo-optic phase shifter is arranged above the first waveguide and the second waveguide.

[0018] Therefore, the thermo-optic phase shifter can heat the first waveguide and the second waveguide, so that light in the first waveguide and the second waveguide undergoes different phase accumulation.

[0019] In a further aspect, in the input port region, the first waveguide is provided with a first input port, and the second waveguide is provided with a second input port.

[0020] In a further aspect, in the output port region, the first waveguide is provided with a first output port, and the second waveguide is provided with a second output port.

[0021] Therefore, each waveguide is provided with an input and output port.

[0022] In a further aspect, a first width is arranged between the first waveguide and the second waveguide.

[0023] Therefore, the first width is relatively small, and the first waveguide and the second waveguide are very close and do not interfere with each other in the non-coupling phase modulation region.

[0024] In order to achieve the second purpose, the silicon optical chip provided by the application is characterized in that the optical switch is applied. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1is a structural schematic diagram of an optical switch embodiment of the present application.

[0026] Figure 2 is a first simulation diagram of an optical switch embodiment of the present application.

[0027] Figure 3 is a second simulation diagram of an optical switch embodiment of the present application.

[0028] Figure 4 is a simulation diagram of a first waveguide design width of an optical switch embodiment of the present application.

[0029] The present application is further described below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0030] The optical switch provided by the present application uses only a first material for a first waveguide, fills a second waveguide with a second material having a lower thermo-optic coefficient than the first material, and designs the widths of the first waveguide and the second waveguide, so that the first waveguide can be coupled in an input coupling region, and different phase accumulations are achieved without interference in a non-coupling phase modulation region, thereby being output at different output ports, so as to achieve the function of an optical switch.

[0031] Optical switch embodiment:

[0032] The optical switch of the present application includes a first waveguide 1 and a second waveguide 2, which are arranged side by side. The optical switch divides the first waveguide 1 and the second waveguide 2 into seven regions, wherein, along the light propagation direction, the optical switch is sequentially provided with an input port region 11, an input coupling region 12, a first gradual change region 13, a non-coupling phase modulation region 14, a second gradual change region 15, an output coupling region 16, and an output port region 17. The input port region 11, the input coupling region 12, the first gradual change region 13, the non-coupling phase modulation region 14, the second gradual change region 15, the output coupling region 16, and the output port region 17 are sequentially arranged on the first waveguide 1 and the second waveguide 2 along the light propagation direction, and the input port region 11, the input coupling region 12, the first gradual change region 13, the non-coupling phase modulation region 14, the second gradual change region 15, the output coupling region 16, and the output port region 17 all cover the first waveguide 1 and the second waveguide 2.

[0033] In the input port region 11, the first waveguide 1 is provided with a first input port I1, and the second waveguide is provided with a second input port I2. In the output port region 17, the first waveguide is provided with a first output port O1, and the second waveguide is provided with a second output port O2.

[0034] The first waveguide 1 is composed of a first material, which can be silicon.

[0035] The second waveguide 2 comprises a main body 21 composed of a first material, i.e. silicon, and a first slit 22 arranged in the main body, the first slit 22 being filled with a second material, i.e. silicon dioxide. The thermo-optic coefficient of the first material is greater than that of the second material, the thermo-optic coefficient of silicon being , and the thermo-optic coefficient of silicon dioxide being . The thermo-optic coefficient of silicon dioxide is much lower than that of silicon. The thermo-optic coefficient is an inherent property of the material itself, describing the rate of change of the refractive index of the material with temperature.

[0036] The first slit 22 traverses the input coupling region 12, the uncoupled phase modulation region 14 and the output coupling region 16.

[0037] The first waveguide of the first taper region 13 arranged between the input coupling region 12 and the uncoupled phase modulation region 14 is a linear taper structure. The width of the first waveguide 1 at the input coupling region 12 is a second width w 1a , the width of the first waveguide 1 at the uncoupled phase modulation region 14 is a third width w 1b , the second width w 1a and the third width w 1b are different, and a linear taper structure is needed to make the transition so that the energy of the light is not lost and mode conversion does not occur.

[0038] The second waveguide of the second taper region 15 arranged between the uncoupled phase modulation region 14 and the output coupling region 16 is a linear taper structure. The width of the first waveguide 1 at the uncoupled phase modulation region 14 is a third width w 1b , the width of the first waveguide 1 at the output coupling region 16 is a fourth width, and the fourth width and the third width w 1b are different, and a linear taper structure is needed to make the transition so that the energy of the light is not lost and mode conversion does not occur. The fourth width is consistent with the second width.

[0039] A first width w gap is arranged between the first waveguide 1 and the second waveguide 2. The first width can be 350 nanometers, i.e. the first width of the first waveguide 1 and the second waveguide can be very narrow. Even though the first width between the first waveguide 1 and the second waveguide 2 is very narrow, the first waveguide 1 and the second waveguide 2 do not interfere with each other in the uncoupled phase modulation region 14. Compared with a traditional Mach-Zehnder interferometer, the total width of the optical switch of the embodiment is 1.4 microns, which is relatively narrow.

[0040] A thermo-optic phase shifter 18 is arranged above the first waveguide 1 and the second waveguide 2. The thermo-optic phase shifter 18 can uniformly heat the first waveguide 1 and the second waveguide 2.

[0041] In the input coupling region 12, the effective refractive index of the first waveguide 1 is the same as that of the second waveguide. This is achieved by modulating the second width w of the first waveguide 1 in the input coupling region 12. 1a The width w2 of the first waveguide 1 and the second waveguide 2 in the input coupling region 12 is such that their effective refractive indices are the same. Therefore, when light enters from the input port region 11, energy is coupled and exchanged between the first waveguide 1 and the second waveguide 2 in the input coupling region 12. Effective coupling exchange can only occur when the effective refractive indices of the first waveguide and the second waveguide are the same. By modulating the lengths of the first waveguide 1 and the second waveguide 2 within the input port region 11, the input light energy is distributed in a specific proportion between the two waveguides. For example, with energy distributed in a specific proportion between the two waveguides, the function of the input coupling region is equivalent to the first beam splitter of a Mach-Zehnder interferometer.

[0042] See Figure 4 In this context, curve "neff-strip" represents the effective refractive index change of the first waveguide, and curve "neff-slot" represents the effective refractive index change of the second waveguide. Curve "TO-strip" represents the change in the equivalent thermo-optical coefficient of the first waveguide with width, and curve "TO-slot" represents the change in the equivalent thermo-optical coefficient of the second waveguide with width. The second width w of the first waveguide 1 in the input coupling region 12 is selected as... 1a The width of the first waveguide is 303 nm, and the width w2 of the second waveguide 2 in the input coupling region 12 is 600 nm, at which point the refractive indices of both are the same. The equivalent thermo-optic coefficient is a derived property of the optical waveguide structure, representing the rate of change of the effective refractive index of the waveguide with temperature.

[0043] The width of the first waveguide in the uncoupled phase modulation region 14 is 450 nm. See [link / reference] Figure 4 As can be seen from the experiment, when w 1b =450 nm, while the width w2 of the second waveguide 2 in the input coupling region 12 is 600 nm, at this time the first equivalent thermo-optic coefficient of the first waveguide ( ) and the second equivalent thermo-optic coefficient of the second waveguide ( When the difference between the two waveguides reaches a large value, the difference between the effective refractive index of the first waveguide and the effective refractive index of the second waveguide can reach its maximum, which destroys the condition for light to exchange energy between the two waveguides. When light propagates in the uncoupled phase modulation region, each light propagates in its own waveguide and does not interfere with each other.

[0044] The input light can enter from the first input port I1 or the second input port I2, and then be coupled in the input coupling region 12. The energy of the input light is exchanged between the two waveguides. Then, the input light passes through the first taper region 13 and reaches the uncoupling phase modulation region 14 in the first waveguide and the second waveguide. Due to the change in the width of the first waveguide, the effective refractive index of the first waveguide 1 is greatly different from the effective refractive index of the second waveguide 2 in the uncoupling phase modulation region 14, which destroys the condition for the energy exchange between the two waveguides, and the light is locked in the respective waveguide and does not interfere with each other. Referring to Figure 2 and Figure 3 The energy of the first waveguide 1 is concentrated in the first waveguide 1, and the energy of the second waveguide 2 is concentrated in the first gap 22 of the second waveguide 2.

[0045] Due to the difference between the first effective thermo-optic coefficient ( ) of the first waveguide and the second effective thermo-optic coefficient ( ) of the second waveguide reaching a maximum value, at this time, according to the phase modulation formula: where ΔΦ is the total phase shift, ΔT is the temperature difference, and L is the length of the first waveguide or the second waveguide of the uncoupling phase modulation region 14. When the thermo-optic phase shifter 18 uniformly heats the first waveguide 1 and the second waveguide 2, the input light of the first waveguide 1 and the input light of the second waveguide 2 do not have the same total phase shift, and when the light is recoupled in the output coupling region 16, the input light with different total phase shifts is output from different output ports, thereby realizing optical path switching.

[0046] The first material of the present application is a positive thermo-optic coefficient material, and the second material is also a positive thermo-optic coefficient material, which has low material cost and reduces the cost of chip manufacturing.

[0047] The optical switch of the embodiment is used in the manufacture of optoelectronic devices, such as the manufacture of silicon optical chips.

[0048] Silicon optical chip embodiment:

[0049] The silicon optical chip of the embodiment applies the optical switch of the above embodiment.

[0050] The above is only the preferred embodiment of the present application, but the design concept of the present application is not limited thereto. More other equivalent embodiments can be included without departing from the concept of the present application, and various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present application.

Claims

1. An optical switch, comprising a first waveguide and a second waveguide, wherein the first waveguide and the second waveguide are arranged side by side; Its features are: The second waveguide includes a body and a first slit disposed in the body; The first waveguide is composed of a first material, the main body is composed of the first material, and the first gap is filled with a second material; The thermo-optic coefficient of the first material is greater than that of the second material, and both the first material and the second material are materials with positive thermo-optic coefficients. Along the propagation direction of the input light, the optical switch is sequentially provided with an input port area, an input coupling area, an uncoupled phase modulation area, an output coupling area, and an output port area. The input port area, the input coupling area, the uncoupled phase modulation area, the output coupling area, and the output port area are all disposed on the first waveguide and the second waveguide. The width of the first waveguide in the uncoupled phase modulation region is 450 nanometers, and the width of the second waveguide in the uncoupled phase modulation region is 600 nanometers. In the input coupling region, the effective refractive index of the first waveguide is the same as that of the second waveguide.

2. The optical switch according to claim 1, characterized in that: The first gap traverses the input coupling region, the uncoupled phase modulation region, and the output coupling region.

3. The optical switch according to claim 2, characterized in that: A first gradient region is also provided between the input coupling region and the uncoupled phase modulation region, and the first waveguide of the first gradient region is a linear tapered structure.

4. The optical switch according to claim 3, characterized in that: A second gradient region is provided between the output coupling region and the uncoupled phase modulation region, and the second waveguide of the second gradient region is a linear tapered structure.

5. The optical switch according to claims 1 to 1, characterized in that: A thermo-optical phase shifter is disposed above the first waveguide and the second waveguide.

6. The optical switch according to claims 1 to 1, characterized in that: In the input port area, the first waveguide is provided with a first input port, and the second waveguide is provided with a second input port.

7. The optical switch according to claims 1 to 1, characterized in that: In the output port area, the first waveguide is provided with a first output port, and the second waveguide is provided with a second output port.

8. The optical switch according to claims 1 to 1, characterized in that: A first width is provided between the first waveguide and the second waveguide.

9. A silicon photonics chip, characterized in that, The optical switch according to any one of claims 1 to 8 is applied.

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