Thermo-optic phase shifter, thermo-optic phase shifter network and optoelectronic device

Abstract

The present disclosure relates to a thermo-optical phase shifter, a thermo-optical phase shifter network and an optoelectronic device. A thermo-optical phase shifter is provided, comprising: a plurality of first waveguides, each of which has a first width and extends in a first direction; and a plurality of second waveguides, each of which has a second width different from the first width and extends in the first direction, wherein the plurality of first waveguides and the plurality of second waveguides are alternately arranged in a second direction different from the first direction, wherein at least one of the plurality of first waveguides and the plurality of second waveguides is doped to serve as a heat generating unit of the thermo-optical phase shifter, and wherein undoped waveguides of the plurality of first waveguides and the plurality of second waveguides are optically coupled in series to provide an optical input port and an optical output port of the thermo-optical phase shifter at both ends, respectively.

Description

Technical Field

[0001] The present disclosure relates generally to the field of optoelectronic devices, and more particularly, to thermo-optical phase shifters, thermo-optical phase shifter networks, and optoelectronic devices. Background Art

[0002] In optoelectronic devices and their related applications, various functional devices can usually be realized through various physical effects such as photoelectric effect, electro-optic effect, acousto-optic effect, magneto-optic effect, and thermo-optic effect. Among them, the thermo-optic phase shifter that uses the thermo-optic effect to realize the phase modulation of light is an important functional device among optoelectronic devices. It has the advantages of simple production, high yield, low cost, and easy integration. Existing thermo-optic phase shifters generally set a heater outside the waveguide, so as to modulate the phase of the light propagating in the waveguide by the heat provided by the heater. However, this type of thermo-optic phase shifter is large in size, has high power consumption, slow modulation speed, and low phase shifting efficiency. These problems are more serious when the thermo-optic phase shifter is used as a unit device in a large-scale network structure. Summary of the Invention

[0003] According to a first aspect of the present disclosure, a thermo-optical phase shifter is provided, comprising: a plurality of first waveguides, each of which has a first width and extends along a first direction; and a plurality of second waveguides, each of which has a second width different from the first width and extends along the first direction, wherein the plurality of first waveguides and the plurality of second waveguides are alternately arranged in a second direction different from the first direction, wherein at least one waveguide among the plurality of first waveguides and the plurality of second waveguides is doped to serve as a heat generating unit of the thermo-optical phase shifter, and wherein undoped waveguides among the plurality of first waveguides and the plurality of second waveguides are optically coupled in series to provide an optical input port and an optical output port of the thermo-optical phase shifter at both ends, respectively.

[0004] In some embodiments, the first direction is perpendicular to the second direction.

[0005] In some embodiments, the plurality of first waveguides and the plurality of second waveguides are straight waveguides parallel to each other.

[0006] In some embodiments, the plurality of first waveguides and the plurality of second waveguides are arranged at equal intervals in the second direction.

[0007] In some embodiments, spacing of the plurality of first waveguides and the plurality of second waveguides in the second direction is configured such that a coupling strength between adjacent waveguides is below a predetermined threshold.

[0008] In some embodiments, the first width is smaller than the second width.

[0009] In some embodiments, the at least one waveguide that is doped is a second waveguide.

[0010] In some embodiments, there is at least one undoped waveguide between two adjacent doped waveguides.

[0011] In some embodiments, three undoped waveguides exist between two adjacent doped waveguides.

[0012] In some embodiments, the thermo-optical phase shifter further includes a plurality of third waveguides, each third waveguide having a bent portion, wherein adjacent two undoped waveguides among the plurality of first waveguides and the plurality of second waveguides are optically coupled via corresponding third waveguides among the plurality of third waveguides.

[0013] In some embodiments, a bending radius of the curved portion of each third waveguide is determined based on at least one of the spacing and relative angles between the waveguides coupled to both ends of the third waveguide among the plurality of first waveguides and the plurality of second waveguides, and a relative angle between the first direction and the second direction.

[0014] In some embodiments, a width of each third waveguide is configured to be equal to a minimum width among widths of waveguides coupled to both ends of the third waveguide among the plurality of first waveguides and the plurality of second waveguides.

[0015] In some embodiments, the thermo-optical phase shifter further includes a plurality of fourth waveguides, wherein a third waveguide of the plurality of third waveguides coupled between the first waveguide and the second waveguide is optically coupled to the second waveguide via a corresponding fourth waveguide of the plurality of fourth waveguides, and each fourth waveguide has the first width at an end thereof coupled to the third waveguide and has the second width at an end thereof coupled to the second waveguide.

[0016] In some embodiments, each doped waveguide includes at least one first doped region and at least one second doped region, and the at least one first doped region and the at least one second doped region are alternately arranged in the doped waveguide along the first direction.

[0017] In some embodiments, the first doped region is a P-type doped region, and the second doped region is an N-type doped region.

[0018] In some embodiments, adjacent doped regions in each doped waveguide contact each other to form at least one PN junction.

[0019] In some embodiments, the thermo-optical phase shifter further includes a first electrical port and a second electrical port different from the first electrical port, wherein the thermo-optical phase shifter is configured such that the PN junction in each doped waveguide is turned on when a voltage at the first electrical port is higher than a voltage at the second electrical port.

[0020] In some embodiments, each first doped region of each doped waveguide is electrically coupled to the first electrical port, and each second doped region of each doped waveguide is electrically coupled to the second electrical port.

[0021] In some embodiments, a first doped region of each doped waveguide closest to the first end of the doped waveguide is electrically coupled to the first electrical port, and a second doped region of each doped waveguide closest to the second end of the doped waveguide is electrically coupled to the second electrical port, the second end being opposite to the first end.

[0022] In some embodiments, the thermo-optic phase shifter further includes at least one metal strip disposed over at least one waveguide of the plurality of first waveguides and the plurality of second waveguides, each metal strip of the at least one metal strip being configured to be electrically coupled to a corresponding PN junction in the doped waveguide.

[0023] In some embodiments, the thermo-optical phase shifter further includes at least one additional resistor electrically coupled in series with a corresponding one of the at least one doped waveguide, the at least one additional resistor being configured to have a temperature coefficient of resistance that matches a temperature coefficient of resistance of the doped waveguide.

[0024] In some embodiments, the additional resistor has a positive temperature coefficient of resistance.

[0025] In some embodiments, the additional resistor is a metal resistor.

[0026] In some embodiments, the additional resistor is implemented as a metal film disposed over the doped waveguide electrically coupled in series with the additional resistor.

[0027] According to a second aspect of the present disclosure, a thermo-optical phase shifter network is provided, comprising: a plurality of first electrical network ports; a plurality of second electrical network ports different from the plurality of first electrical network ports; and a plurality of thermo-optical phase shifting units arranged in an array, each thermo-optical phase shifting unit comprising at least one thermo-optical phase shifter according to any embodiment of the first aspect of the present disclosure, wherein each thermo-optical phase shifting unit is electrically coupled between a corresponding first electrical network port among the plurality of first electrical network ports and a corresponding second electrical network port among the plurality of second electrical network ports, wherein each thermo-optical phase shifting unit is configured to change the phase of light passing through the thermo-optical phase shifting unit when a voltage at a first electrical network port corresponding to the thermo-optical phase shifting unit is higher than a voltage at a second electrical network port corresponding to the thermo-optical phase shifting unit.

[0028] In some embodiments, the thermo-optical phase shift units located in the same row among the multiple thermo-optical phase shift units are all electrically coupled to the same first electrical network port among the multiple first electrical network ports, and the thermo-optical phase shift units located in the same column among the multiple thermo-optical phase shift units are all electrically coupled to the same second electrical network port among the multiple second electrical network ports.

[0029] In some embodiments, the thermo-optical phase shifters in each thermo-optical phase shift unit are electrically coupled to each other in parallel or in series.

[0030] In some embodiments, the thermo-optical phase shifters in each thermo-optical phase shift unit are optically coupled to each other in parallel or in series.

[0031] According to a third aspect of the present disclosure, an optoelectronic device is provided, which is one of an optical switching device, an optical modulation device, an optical field programmable gate array network, a phased array radar and a photonic artificial intelligence chip, and the optoelectronic device includes the thermo-optical phase shifter described in any embodiment of the first aspect of the present disclosure.

[0032] According to a fourth aspect of the present disclosure, an optoelectronic device is provided, which is one of an optical switching device, an optical modulation device, an optical field programmable gate array network, a phased array radar and a photonic artificial intelligence chip, and the optoelectronic device includes the thermo-optical phase shifter network described in any embodiment of the second aspect of the present disclosure.

[0033] Other features and advantages of the present disclosure will become more apparent from the following detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The foregoing and other features and advantages of the present disclosure will become apparent from the following description of the embodiments of the present disclosure taken in conjunction with the accompanying drawings, which are incorporated herein and form a part of the specification and serve to further explain the principles of the present disclosure and enable those skilled in the art to make and use the present disclosure.

[0035] Figure 1 is a schematic plan view of a thermo-optical phase shifter according to some embodiments of the present disclosure;

[0036] Figure 2 is a schematic plan view of a thermo-optical phase shifter according to some embodiments of the present disclosure;

[0037] Figures 3A to 3C is a schematic partial plan view of a thermo-optical phase shifter according to some embodiments of the present disclosure;

[0038] Figure 4 is a schematic plan view of a thermo-optical phase shifter according to some embodiments of the present disclosure;

[0039] Figure 5 is a schematic plan view of a thermo-optical phase shifter according to some embodiments of the present disclosure;

[0040] Figure 6A yes Figure 5 A schematic plan view of a thermo-optical phase shifter is shown, wherein an exemplary metal wiring structure of the thermo-optical phase shifter is shown;

[0041] Figure 6B It is along Figure 6A The line II-II' in Figure 6A A schematic cross-sectional view of a thermo-optical phase shifter;

[0042] Figure 6C It is along Figure 6A The line III-III' in Figure 6A A schematic cross-sectional view of a thermo-optical phase shifter;

[0043] Figure 7A is a schematic plan view of a thermo-optical phase shifter according to some embodiments of the present disclosure, showing an exemplary metal wiring structure of the thermo-optical phase shifter;

[0044] Figure 7B It is along Figure 7A The line IV-IV' in Figure 7A A schematic cross-sectional view of a thermo-optical phase shifter;

[0045] Figure 7C yes Figure 7B A schematic cross-sectional view of an example of a thermo-optical phase shifter;

[0046] Figure 8is a schematic diagram of an N×M thermo-optical phase shifter network according to some embodiments of the present disclosure;

[0047] Figure 9 is a schematic diagram of a 2×2 thermo-optical phase shifter network according to some embodiments of the present disclosure; and

[0048] Figures 10A to 10C Is used for operation Figure 9 An exemplary timing diagram of a 2×2 thermo-optical phase shifter network.

[0049] Note that in the embodiments described below, the same reference numerals are sometimes used in common across different drawings to denote the same parts or parts having the same functions, and their repeated descriptions are omitted. In some cases, similar reference numerals and letters are used to denote similar items, so once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0050] For ease of understanding, the positions, sizes, and ranges of various structures shown in the drawings and the like may not represent actual positions, sizes, and ranges, etc. Therefore, the present disclosure is not limited to the positions, sizes, and ranges disclosed in the drawings and the like. DETAILED DESCRIPTION

[0051] Various exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0052] The following description of at least one exemplary embodiment is merely illustrative and is not intended to limit the present disclosure, its application, or use. In other words, the structures and methods herein are presented in an exemplary manner to illustrate various embodiments of the structures and methods of the present disclosure. However, those skilled in the art will appreciate that these are merely exemplary of the disclosure that may be implemented, and are not exhaustive. Furthermore, the drawings are not necessarily drawn to scale, and some features may be exaggerated to illustrate details of specific components.

[0053] In addition, technologies, methods and devices known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods and devices should be considered part of the authorization specification.

[0054] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0055] A thermo-optic phase shifter is a device that uses the thermo-optic effect to modulate the phase of light. Typically, a thermo-optic phase shifter is fabricated by first forming a waveguide on a substrate, then forming a heater near the waveguide to provide heat to the waveguide. The heater is typically a resistive type and can be, for example, formed as a metal strip located above or on either side of the waveguide. The metal strip can be configured as an elongated structure extending along the waveguide. When power is applied externally to the resistive heater, it generates heat due to the Joule effect. This heat diffuses and is partially transferred to the waveguide, causing the temperature of at least some portion of the waveguide to rise. As a result, the refractive index of the heated portion of the waveguide changes, causing the effective waveguide length to change, resulting in a phase shift in the light exiting the waveguide relative to its entry. However, such thermo-optic phase shifters are large, consume high power, have slow modulation speeds, and exhibit low phase shifting efficiency. These issues are particularly severe when thermo-optic phase shifters are used as unit devices in large-scale network structures. For example, when multiple thermo-optical phase shifters are provided in a photonic circuit having multiple channels for performing optical phase modulation in each channel, if each thermo-optical phase shifter has high power consumption and a large size, the total power consumption and overall size of the entire photonic circuit will be very high, which is undesirable.

[0056] To reduce power consumption, some thermo-optical phase shifters incorporate thermal insulation grooves on both sides of the waveguide or remove portions of the substrate beneath the waveguide, creating a bridge-like structure on the substrate. This structure leverages the relatively low thermal conductivity of air to minimize heat loss. However, while this structure reduces power consumption, it significantly slows the modulation speed, increases manufacturing complexity, and increases the overall size of the device.

[0057] Therefore, there is a need for a thermo-optical phase shifter with an improved structure.

[0058] A first aspect of the present disclosure provides a thermo-optical phase shifter. The thermo-optical phase shifter includes a plurality of first waveguides and a plurality of second waveguides. Each first waveguide has a first width and extends along a first direction, and each second waveguide has a second width different from the first width and extends along the first direction. The first waveguides and the second waveguides are alternately arranged in a second direction different from the first direction. At least one waveguide among the plurality of first waveguides and the plurality of second waveguides is doped to serve as a heat generating unit of the thermo-optical phase shifter. The undoped waveguides among the plurality of first waveguides and the plurality of second waveguides are optically coupled in series to provide an optical input port and an optical output port of the thermo-optical phase shifter at both ends, respectively.

[0059] The thermo-optical phase shifter according to the first aspect of the present disclosure effectively reduces coupling between adjacent waveguides and improves optical crosstalk by alternately arranging waveguides of different widths so that adjacent waveguides have different widths. This allows the waveguides to be arranged compactly with a smaller spacing, thereby reducing the overall size of the device. Furthermore, the thermo-optical phase shifter according to the present disclosure uses doped waveguides as heat-generating units. These doped waveguides are closely adjacent to the waveguides used to transmit light and can be configured to have appropriate conductivity so that when energized, they generate heat due to the Joule effect, inducing a thermo-optical effect in the nearby waveguides used to transmit light. This causes light input from the optical input port of the thermo-optical phase shifter to undergo a phase change when it is emitted from the optical output port of the thermo-optical phase shifter after passing through the heated waveguides. By using doped waveguides as heat-generating units and arranging them compactly with the waveguides used to transmit light, the thermo-optical phase shifter according to the present disclosure can achieve low power consumption while maintaining a high modulation speed and significantly improved phase shifting efficiency.

[0060] Refer to the following Figure 1 The thermo-optical phase shifter 100 according to some embodiments of the present disclosure is described in detail. It should be noted that an actual thermo-optical phase shifter may have other components, which are not shown in the drawings and will not be discussed herein to avoid obscuring the main points of the present disclosure.

[0061] like Figure 1 As shown, the thermo-optical phase shifter includes a plurality of first waveguides 101-1, 101-2, 101-3, 101-4, 101-5, 101-6, and 101-7 (hereinafter, collectively referred to as first waveguides 101) and a plurality of second waveguides 102-1, 102-2, 102-3, 102-4, 102-5, 102-6, and 102-7 (hereinafter, collectively referred to as second waveguides 102). Each of the first waveguides 101 has a first width w1 and extends along a first direction D1, and each of the second waveguides has a second width w2 different from the first width w1 and extends along the first direction D1.

[0062] In some embodiments, the first width w1 can be smaller than the second width w2. In some examples, the first width w1 can be in the range of 400 nm to 500 nm, or in the range of 425 nm to 475 nm, or can be, for example, 450 nm. In some examples, the second width w2 can be in the range of 450 nm to 550 nm, or in the range of 475 nm to 525 nm, or can be, for example, 500 nm. It will be understood that the first widths of the first waveguides 101 can be the same or different from each other, and the second widths of the second waveguides 102 can be the same or different from each other, as long as the widths of adjacent waveguides in the thermo-optical phase shifter are different. In addition, the lengths of the first waveguides 101 and the second waveguides 102 are not particularly limited herein; one or more of them can be the same or different, which can be specifically set according to actual needs.

[0063] Although Figure 1 The thermo-optical phase shifter 100 is depicted as having seven first waveguides and seven second waveguides, but this is merely exemplary and non-limiting. It will be appreciated that the number of first waveguides and second waveguides included in the thermo-optical phase shifter can be specifically set according to actual needs, and the number of first waveguides and second waveguides does not need to be the same.

[0064] The shapes of the first and second waveguides are not particularly limited, but may adopt any suitable shapes. As non-limiting examples, the first and second waveguides may be straight waveguides, curved waveguides, etc. As used herein, "the waveguide extends along a first direction" may mean that the angle between the tangent direction at each point on the centerline of the waveguide and the first direction does not exceed 15°, or does not exceed 10°, or does not exceed 5°, or does not exceed 1°.

[0065] For example, reference Figures 3A to 3C , the dotted line indicates the center line of the waveguide, and the dashed line indicates a direction parallel to the first direction D1. Figure 3A In the embodiment, the first waveguide (e.g., 101-1') is a straight waveguide, the angle between its centerline and the first direction is θ1, and the second waveguide (e.g., 102-1') is a straight waveguide, the angle between its centerline and the first direction is θ2, wherein θ1 and θ2 do not exceed 15°, or do not exceed 10°, or do not exceed 5°, or do not exceed 1°. θ1 and θ2 may have the same value or different values. In some embodiments, the plurality of first waveguides and the plurality of second waveguides may be straight waveguides parallel to each other. For example, as Figure 3CAs shown, the first waveguide and the second waveguide are straight waveguides parallel to each other and extending parallel to the first direction D1, that is, θ1 and θ2 are equal to 0°. In other examples, the first waveguide and the second waveguide may also be straight waveguides parallel to each other and extending at the same angle to the first direction D1. Figure 3B In the embodiment, the first waveguide (e.g., 101-1") is a curved waveguide, and the angle between the tangent direction at each point on the centerline and the first direction is θ1. The second waveguide (e.g., 102-1") is a curved waveguide, and the angle between the tangent direction at each point on the centerline and the first direction is θ2. For the first and second waveguides as curved waveguides, the angles θ1 and θ2 between the tangent direction at each point on their centerlines and the first direction are not necessarily constant, but always satisfy the aforementioned range, so that the first waveguide and the second waveguide extend along the first direction D1.

[0066] The first waveguide 101 and the second waveguide 102 are alternately arranged in a second direction D2 different from the first direction D1. The angle between the first direction D1 and the second direction D2 can be expressed as α. In some embodiments, the first direction D1 can be perpendicular to the second direction D2, that is, α is equal to 90°, for example, Figure 1 In some other embodiments, the first direction D1 may not be perpendicular to the second direction D2, for example, Figure 3C The angle α between the first direction D1 and the second direction D2 can be set according to specific circumstances.

[0067] Herein, the interval d between adjacent first waveguides 101 and second waveguides 102 is defined as the minimum distance between the center line of the first waveguide 101 and the center line of the second waveguide 102 in the second direction D2, for example, Figure 1 and Figures 3A to 3CAs shown. In some embodiments, a plurality of first waveguides 101 and a plurality of second waveguides 102 are arranged at equal intervals d in the second direction D2. However, it should be understood that the intervals between all adjacent waveguides do not need to be the same, but can be specifically set according to actual needs. In some embodiments, the intervals between the plurality of first waveguides 101 and the plurality of second waveguides 102 in the second direction D2 are configured so that the coupling strength between adjacent waveguides is lower than a predetermined threshold. The predetermined threshold can be set according to the specific performance requirements of the thermo-optical phase shifter. Generally, the lower the coupling strength between adjacent waveguides, the less optical crosstalk therebetween. In this embodiment, since the first waveguides 101 and the second waveguides 102 have different widths and are arranged alternately in the second direction, the widths of adjacent waveguides are different from each other. Since waveguides of different widths have different equivalent propagation constants, the coupling between two adjacent waveguides of different widths is significantly weakened compared to two adjacent waveguides of the same width, thereby achieving a smaller spacing d for adjacent waveguides of different widths. Thus, in the present disclosure, the plurality of first waveguides 101 and the plurality of second waveguides 102 can be arranged more compactly, significantly reducing the overall size of the thermo-optical phase shifter 100. For example, when the first width w1 of the first waveguide 101 is 450 nm and the second width w2 of the second waveguide 102 is 500 nm, the plurality of first waveguides 101 and the plurality of second waveguides 102 can be closely alternately arranged at intervals of 1.0 μm without significant crosstalk, thereby significantly reducing the device size.

[0068] At least one of the plurality of first waveguides 101 and the plurality of second waveguides 102 may be doped to serve as a heat generating unit of the thermo-optical phase shifter. One or more of the plurality of first waveguides 101 and the plurality of second waveguides 102 may be doped according to specific circumstances so as to have a desired resistance for heat generation. In some embodiments, at least one undoped waveguide may exist between two adjacent doped waveguides. Preferably, one or more of the waveguides having a larger width may be doped. For example, in Figure 1In the illustrated thermo-optical phase shifter 100, the second width w2 of the second waveguide 102 is greater than the first width w1 of the first waveguide 101. Among the multiple second waveguides 102, second waveguides 102-2, 102-4, and 102-6 are doped to serve as heat generating units in the thermo-optical phase shifter 100. Three undoped waveguides exist between any two adjacent second waveguides 102-2, 102-4, and 102-6. The undoped waveguides on either side of each doped waveguide share the heat generated by the doped waveguide. The specific location and number of doped waveguides in the thermo-optical phase shifter 100 can be determined based on factors such as the size of the thermo-optical phase shifter 100 and the phase shifting efficiency. The doped region in the doped waveguide can occupy part or all of the waveguide's volume. The waveguides can be doped using at least one of P-type and N-type doping. The doping of the waveguides serving as heat generating units will be described in detail later.

[0069] The undoped waveguides among the plurality of first waveguides 101 and the plurality of second waveguides 102 are optically coupled in series to provide an optical input port and an optical output port of the thermo-optical phase shifter at both ends. Figure 1 As shown, the undoped first waveguide 101-1, the second waveguide 102-1, the first waveguide 101-2, the first waveguide 101-3, the second waveguide 102-3, the first waveguide 101-4, the first waveguide 101-5, the second waveguide 102-5, the first waveguide 101-6, the first waveguide 101-7, and the second waveguide 102-7 are optically coupled in series (as shown by Figure 1), so as to provide an optical input port 110 and an optical output port 120 of the thermo-optical phase shifter 100 at the first end of the first waveguide 101-1 and the second end of the second waveguide 102-7, respectively. Thus, after light enters the thermo-optical phase shifter 100 at the optical input port 110, it passes through the first waveguide 101-1, the second waveguide 102-1, the first waveguide 101-2, the first waveguide 101-3, the second waveguide 102-3, the first waveguide 101-4, the first waveguide 101-5, the second waveguide 102-5, the first waveguide 101-6, the first waveguide 101-7, and the second waveguide 102-7 in sequence, and finally exits from the optical output port 120. When the doped second waveguides 102-2, 102-4, and 102-6 are energized, they generate heat and induce thermo-optic effects in nearby waveguides, causing changes in the refractive index of these waveguides. This causes the phase of light emitted from the optical output port 120 after passing through the heated first waveguide 101-1, second waveguide 102-1, first waveguide 101-2, first waveguide 101-3, second waveguide 102-3, first waveguide 101-4, first waveguide 101-5, second waveguide 102-5, first waveguide 101-6, first waveguide 101-7, and second waveguide 102-7 to change compared to the phase of light entering the optical input port 110. For example, assuming that the length of the waveguide through which light passes in the thermo-optical phase shifter 100 is L and the temperature change of the waveguide is ΔT, the phase change of the light is can be expressed as

[0070]

[0071] where λ represents the wavelength of light, and It represents the thermo-optic coefficient of the waveguide material. For example, for silicon material, the thermo-optic coefficient is generally 1.86×10 -4 / K.

[0072] Optical coupling between adjacent undoped waveguides can be achieved using any suitable method. For example, after light exits the previous undoped waveguide (e.g., first waveguide 101-1), its propagation direction can be changed by any suitable optical element (such as a mirror, lens, etc.) or a combination thereof that can change the direction of the optical path. The light then re-enters the next undoped waveguide (e.g., second waveguide 102-1) through any suitable coupling device (such as a grating, prism, etc.) that can couple light into a waveguide. Furthermore, optical coupling between adjacent undoped waveguides can also be achieved using additional waveguides.

[0073] In some embodiments, the thermo-optical phase shifter may further include a plurality of third waveguides, each of which may have a bent portion, wherein adjacent two undoped waveguides in the plurality of first waveguides and the plurality of second waveguides are optically coupled via corresponding third waveguides in the plurality of third waveguides.

[0074] Figure 2 A thermo-optical phase shifter 100A according to some embodiments of the present disclosure is shown. The thermo-optical phase shifter 100A differs from the thermo-optical phase shifter 100 in that the thermo-optical phase shifter 100A further includes a plurality of third waveguides 103-1, 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-8, 103-9, and 103-10 (hereinafter collectively referred to as third waveguides 103). The third waveguide 103-1 optically couples the first waveguide 101-1 with the second waveguide 102-1, and similarly, the third waveguides 103-2, 103-3, 103-4, 103-5, 103-6, 103-7, 103-8, 103-9, 103-10 optically couple the second waveguide 102-1 with the first waveguide 101-2, the first waveguide 101-2 with the first waveguide 101-3, and the third waveguides 103-10 respectively. A waveguide 101-3 is optically coupled to a second waveguide 102-3, a second waveguide 102-3 to a first waveguide 101-4, a first waveguide 101-4 to a first waveguide 101-5, a first waveguide 101-5 to a second waveguide 102-5, a second waveguide 102-5 to a first waveguide 101-6, a first waveguide 101-6 to a first waveguide 101-7, and a first waveguide 101-7 to a second waveguide 102-7. A third waveguide can be used to change the propagation direction of light and couple light from a waveguide coupled to one end of the third waveguide to a waveguide coupled to the other end of the third waveguide. Using a third waveguide to achieve optical coupling between undoped waveguides not only simplifies the layout of the thermo-optical phase shifter, reduces device size, but also maintains low optical loss.

[0075] The third waveguide 103 may have a curved portion. In some embodiments, the bending radius of the curved portion of each third waveguide 103 is determined based on at least one of the intervals and relative angles between waveguides coupled to both ends of the third waveguide 103 among the plurality of first waveguides 101 and the plurality of second waveguides 102, and the relative angle between the first direction and the second direction.

[0076] For example, in Figure 2In the example shown, the waveguides at both ends of each third waveguide 103 are parallel to each other (i.e., the relative angle is 0°), and the first direction is perpendicular to the second direction (α is 90°). In this case, the bending radius of the curved portion of the third waveguide 103 can be determined based on the spacing between the waveguides at both ends of the third waveguide 103. If the centerline of the third waveguide is aligned with the centerline of the waveguide to which it is coupled at the waveguide coupling point, the bending radius of the curved portion of the third waveguide 103 can be half the spacing between the waveguides coupled to both ends of the third waveguide 103. For example, if a plurality of first waveguides 101 and a plurality of second waveguides 102 are closely alternated at intervals of 1.0 μm, the bending radius of the curved portion of the third waveguide 103 can be 0.5 μm.

[0077] For example, in Figure 3C In the example shown, the waveguides at both ends of each third waveguide 103 are parallel to each other (i.e., the relative angle is 0°) and the first direction is not perpendicular to the second direction. In this case, the bending radius of the curved portion of the third waveguide 103-1" can be determined based on the interval d between the first waveguide 101-1 and the second waveguide 102-1 and the relative angle α between the first direction and the second direction. In some examples, the bending radius of the curved portion of the third waveguide 103 can be dsinα / 2.

[0078] In addition, when the waveguides at both ends of the third waveguide 103 are not parallel to each other, for example, Figure 3A As shown, the third waveguide 103-1' optically couples the first waveguide 101-1' and the second waveguide 102-1', wherein the relative angle between the first waveguide 101-1' and the second waveguide 102-1' is (θ1+θ2). In this case, the bending radius of the curved portion of the third waveguide 103-1' can be determined based on the interval d between the first waveguide 101-1' and the second waveguide 102-1' and the relative angle (θ1+θ2). In some examples, the bending radius of the curved portion of the third waveguide 103-1' can be equal to d / (cosθ1+cosθ2).

[0079] It should be understood that although the curved portion of the third waveguide 103 is depicted as circular in the drawings, it is understood that the curved portion of the third waveguide 103 may also be a non-circular curved portion. In addition, in some embodiments, the third waveguide 103 may have a straight portion in addition to the curved portion, and the straight portion may be regarded as an extension of the waveguide coupled to the third waveguide 103, so as to arrange the curved portion of the third waveguide 103. For example, Figure 3C As shown, Figure 2 Compared to the thermo-optical phase shifter 100A shown, Figure 3CThe first waveguide and the second waveguide are alternately arranged at intervals in a second direction D2 that is not perpendicular to the first direction D1 (101-1, 102-1, 101-2, 102-2, 101-3, ……). In Figure 3C , the lengths of the first waveguide and the second waveguide are the same, but since the first direction D1 and the second direction D2 are not perpendicular, when viewed from an angle perpendicular to the first direction D1, the first waveguide and the second waveguide are offset relative to each other. In this case, the third waveguides 103-1”, 103-2”, 103-3”, …… include straight portions in addition to the bent portions to compensate for the relative offset between the waveguides coupled to both ends thereof.

[0080] In some embodiments, the width of each third waveguide is configured to be equal to the minimum width among the widths of the waveguides coupled to both ends of the third waveguide among the plurality of first waveguides and the plurality of second waveguides.

[0081] Specifically, for example, referring to Figure 2 , the third waveguide 103-1 is coupled between the first waveguide 101-1 having a first width w1 and the second waveguide 102-1 having a second width w2 (w1 < w2), and the width of the third waveguide 103-1 may be equal to the first width w1 of the first waveguide 101-1. The third waveguide 103-3 is coupled between the first waveguides 101-2 and 101-3, and the width of the third waveguide 103-3 may be equal to the smaller value of the widths of the first waveguides 101-2 and 101-3 (for the case where the first width w1 of each first waveguide 101 is the same, the width of the third waveguide 103-3 may be equal to the first width w1). Additionally, if the third waveguide is coupled between two second waveguides, the width of the third waveguide may be equal to the smaller value of the widths of the two second waveguides (for the case where the second width w2 of each second waveguide 102 is the same, the width of the third waveguide may be equal to the second width w2). By making the width of the third waveguide equal to the minimum width among the widths of the waveguides coupled to both ends of the third waveguide, the optical loss of the device can be further reduced.

[0082] In some embodiments, the thermo-optic phase shifter may further include a plurality of fourth waveguides, wherein the third waveguides among the plurality of third waveguides that are coupled between the first waveguide and the second waveguide are optically coupled to the second waveguide via corresponding fourth waveguides among the plurality of fourth waveguides, and each fourth waveguide has a first width at the end where the fourth waveguide is coupled to the third waveguide and a second width at the end where the fourth waveguide is coupled to the second waveguide.

[0083] Figure 4Thermo-optic phase shifter 100A according to some embodiments of the present disclosure is shown. Thermo-optic phase shifter 100B differs from the thermo-optic phase shifter 100A in that the thermo-optic phase shifter 100B further includes a plurality of fourth waveguides 104-1, 104-2, 104-3, 104-4, 104-5, 104-6, and 104-7 (hereinafter collectively referred to as fourth waveguides 104). The fourth waveguides 104-1, 104-2, 104-3, 104-4, 104-5, 104-6, and 104-7 optically couple the third waveguide 103-1 to the second waveguide 102-1, the second waveguide 102-1 to the third waveguide 103-2, the third waveguide 103-4 to the second waveguide 102-3, the second waveguide 102-3 to the third waveguide 103-5, the third waveguide 103-7 to the second waveguide 102-5, the second waveguide 102-5 to the third waveguide 103-8, and the third waveguide 103-10 to the second waveguide 102-7, respectively. Each of the fourth waveguides 104 has the same width as the third waveguide 103 at one end coupled to the third waveguide 103 and the same width as the second waveguide 102 at one end coupled to the second waveguide 102. A fourth waveguide is used to provide a connection between waveguides of different widths, thereby further reducing the optical loss of the device.

[0084] In some embodiments, the width of the third waveguide may be different from the width of each of the waveguides coupled to both ends of the third waveguide. In such an embodiment, the third waveguide may include a fourth waveguide at each end thereof and be optically coupled to each of the waveguides coupled to both ends of the third waveguide via the corresponding fourth waveguide.

[0085] In some embodiments, as described later Figure 5 As shown, the undoped waveguides in the plurality of first waveguides and the plurality of second waveguides are coupled together through the plurality of third waveguides and the plurality of fourth waveguides to form a continuous serpentine waveguide. In some embodiments, the serpentine waveguide can be formed integrally.

[0086] The specific configuration of the doped waveguides in the thermo-optical phase shifter according to the present disclosure is described in detail below. In some embodiments, each doped waveguide may include one or more doped regions having the same doping type. In some embodiments, each doped waveguide may include multiple doped regions having different doping types. The "doping type" described herein includes P-type doping and N-type doping.

[0087] In some embodiments, each doped waveguide may include at least one first doped region and at least one second doped region, wherein the at least one first doped region and the at least one second doped region are alternately arranged along a first direction in the doped waveguide. In some embodiments, the first doped region is a P-type doped region, and the second doped region is an N-type doped region. In other embodiments, the first doped region is an N-type doped region, and the second doped region is a P-type doped region. In some embodiments, adjacent doped regions in each doped waveguide contact each other to form at least one PN junction.

[0088] For example, Figure 5 As shown, the thermo-optical phase shifter 200 includes a serpentine waveguide 210 and a light input port 211 and a light output port 212 located at both ends of the serpentine waveguide 210. Compared with the thermo-optical phase shifter 100B, the serpentine waveguide 210 of the thermo-optical phase shifter 200 can be, for example, Figure 4 The plurality of first waveguides 101, the plurality of second waveguides 102, the plurality of third waveguides 103, and the plurality of fourth waveguides 104 are shown as being combined or alternatively integrally formed. The thermo-optical phase shifter 200 differs from the thermo-optical phase shifter 100B in that the three doped second waveguides 221, 222, and 223 of the thermo-optical phase shifter 200 each include five doped regions. Specifically, the second waveguide 221 includes, in sequence, a first doped region 221a, a second doped region 221b, a first doped region 221c, a second doped region 221d, and a first doped region 221e; the second waveguide 222 includes, in sequence, a first doped region 222a, a second doped region 222b, a first doped region 222c, a second doped region 222d, and a first doped region 222e; and the second waveguide 223 includes, in sequence, a first doped region 223a, a second doped region 223b, a first doped region 223c, a second doped region 223d, and a first doped region 223e. In each of the doped second waveguides 221, 222, and 223, the first doped regions and the second doped regions are alternately arranged and contact each other to form a plurality of PN junctions.

[0089] Although Figure 5 In the embodiment of the present invention, the doped waveguide is described as including three first doped regions and two second doped regions. However, it is understood that the doped waveguide can be configured to include any suitable number of first doped regions and second doped regions, and the number of first doped regions and second doped regions can also be the same. The number of PN junctions can be adjusted by adjusting the number of first doped regions and second doped regions in the doped waveguide.

[0090] The advantage of forming a PN junction may be that, compared with a waveguide that does not include a PN junction (for example, a waveguide that only includes a P-type doped region or only includes an N-type doped region), the waveguide that includes a PN junction has a smaller resistance, so that a thermo-optical phase shifter that includes such a doped waveguide as a heat-generating unit has a smaller driving voltage.

[0091] For the sake of convenience, the following text will use the example of the first doping region being a P-type doping region and the second doping region being an N-type doping region for explanation, but those skilled in the art will understand that the various embodiments described below are also applicable to the case where the first doping region is an N-type doping region and the second doping region is a P-type doping region.

[0092] Parameters such as the doping concentration, width, and length of each doped region can be specifically set according to actual needs. In some embodiments, both the P-type doped region and the N-type doped region are heavily doped. In some embodiments, the width of the doped region can be in the range of 200 nm to 400 nm, or in the range of 250 nm to 350 nm, for example, 300 nm. In some embodiments, the length of the doped region can be in the range of 30 μm to 70 μm, or in the range of 40 μm to 60 μm, for example, 50 μm.

[0093] In some embodiments, the thermo-optical phase shifter 200 may further include a first electrical port and a second electrical port different from the first electrical port. The thermo-optical phase shifter 200 may be configured such that when the voltage at the first electrical port is higher than the voltage at the second electrical port, the PN junction in each doped waveguide is turned on. Due to the unidirectional current conduction of the PN junction, when a forward bias is applied, the PN junction in the doped waveguide is turned on and generates heat, while when a reverse bias is applied, the PN junction in the doped waveguide is turned off and does not generate heat. Thus, although a single thermo-optical phase shifter 200 requires two electrical ports to control operation, like the conventional thermo-optical phase shifter with a resistive heater (bidirectional conduction) described previously, when applied to a large-scale network structure, the number of electrical ports required for a network structure including the thermo-optical phase shifter 200 as a unit device is significantly reduced compared to the number of electrical ports required for a network structure including conventional thermo-optical phase shifters as unit devices, as will be described in further detail below.

[0094] The electrical coupling between the PN junctions in each doped waveguide 221, 222, and 223 can be configured according to specific needs. For example, in some embodiments, multiple PN junctions in the same doped waveguide can be connected in parallel to increase the thermal output at a given voltage. In other embodiments, multiple PN junctions in the same doped waveguide can be connected in series to adjust the drive voltage of the thermo-optical phase shifter. In other embodiments, multiple PN junctions in the same doped waveguide can be mixed in series to achieve the desired drive voltage and thermal output. The electrical coupling between the PN junctions of different doped waveguides can also be configured according to specific needs. For example, in some embodiments, multiple PN junctions in the same doped waveguide can be connected in series, while the PN junctions of different doped waveguides are connected in parallel. The above description is merely illustrative and is not intended to limit the present disclosure. In practice, the equivalent resistance of the doped waveguide can be appropriately adjusted by adjusting the doping concentration, number, and electrical coupling of the PN junctions in the doped waveguide to achieve the desired drive voltage and thermal output.

[0095] The following combination Figures 6A to 6C An exemplary metal wiring structure of the thermo-optical phase shifter 200 is described as follows. Figure 6A As shown, the thermo-optical phase shifter 200 includes a first electrical port 230 and a second electrical port 240. Each first doped region of each doped waveguide 221, 222, 223 of the thermo-optical phase shifter 200 is electrically coupled to the first electrical port 230, and each second doped region of each doped waveguide is electrically coupled to the second electrical port 240. Specifically, the first doped regions 221a, 222a, 223a are electrically coupled to the first electrical port 230 via a metal line 231, the first doped regions 221c, 222c, 223c are electrically coupled to the first electrical port 230 via a metal line 232, and the first doped regions 221e, 222e, 223e are electrically coupled to the first electrical port 230 via a metal line 233. In addition, the second doped regions 221b, 222b, and 223b are electrically coupled to the second electrical port 240 via a metal line 241, and the second doped regions 221d, 222d, and 223d are electrically coupled to the second electrical port 240 via a metal line 242. In this configuration, the multiple PN junctions in each of the doped waveguides 221, 222, and 223 are connected in parallel. For example, the material of the metal line can include, but is not limited to, a metal with good conductivity, such as copper, aluminum, or a combination thereof.

[0096] refer to Figure 6B and Figure 6CThe various waveguides included in the thermo-optical phase shifter 200 can be formed on a substrate 261. The substrate 261 can be any substrate suitable for forming a waveguide thereon, such as a silicon substrate, a germanium substrate, a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GOI) substrate, a silicon-germanium-on-insulator (SGOI) substrate, a silicon-germanium-on-Si substrate, a germanium-on-SOI (Ge-on-SOI) substrate, or a silicon-germanium-on-SOI (SiGe-on-SOI) substrate. Accordingly, the material of the various waveguides included in the thermo-optical phase shifter 200 can include, but is not limited to, silicon, germanium, silicon nitride, silicon oxide, silicon oxynitride, and the like. For example, taking the substrate 261 as an SOI substrate, the waveguide structure of the thermo-optical phase shifter 200 can be formed in a top silicon layer on a buried oxide layer of the substrate 261. Each waveguide can have, for example, a ridge structure or other suitable structures. The waveguides 210, 221, 222, and 223 of the thermo-optical phase shifter 200 (or the first to fourth waveguides of the aforementioned thermo-optical phase shifter) can be formed through a single etching process using the same mask, or can be formed through multiple etching processes using multiple masks. Some of the waveguides (e.g., waveguides 221, 222, and 223) are then doped to form multiple first doped regions and multiple second doped regions. A dielectric layer 262 covers the waveguides. When the waveguides included in the thermo-optical phase shifter 200 are silicon waveguides, the dielectric layer 262 can be made of, for example, silicon oxide. The dielectric layer 262 not only serves as a cladding for the waveguides but also serves to isolate the waveguides from subsequently deposited metal wiring. It will be appreciated that the dielectric layer 262 can be made of other suitable materials based on the waveguide material, as long as its refractive index matches that of the waveguide material and is able to isolate the waveguides from the metal wiring structure.

[0097] Each doped region of each doped waveguide is connected to the metal line through a through hole. Figure 6BAs shown, doped regions 222a, 222b, 222c, 222d, 222e are connected to metal lines 231, 241, 232, 242, 233 via through holes 282a, 282b, 282c, 282d, 282e, respectively, wherein the through holes are filled with metal material. Typically, the metal material filled in the through holes is the same as the metal line. In some embodiments, an insulating layer, a diffusion barrier layer, and / or a seed layer may be included between the sidewalls of the through holes and the filler metal. In some embodiments, the metal material in the through holes may directly contact the doped regions. Preferably, in some embodiments, the metal material in the through holes may indirectly contact the doped regions via a contact layer provided on the doped regions. For example, the doped regions 222a, 222b, 222c, 222d, and 222e are in contact with the through holes 282a, 282b, 282c, 282d, and 282e via contact layers 272a, 272b, 272c, 272d, and 272e, respectively. The contact layers 272a, 272b, 272c, 272d, and 272e may include, for example, metal silicide or a combination of tungsten and metal silicide. Figure 6C As shown, the doped regions 221e, 222e, and 223e are electrically coupled to the same metal line 233 via the contact layer 271e and the via 281e, the contact layer 272e and the via 282e, and the contact layer 273e and the via 283e, respectively.

[0098] In some embodiments, the first doped region of each doped waveguide closest to the first end of the doped waveguide can be electrically coupled to the first electrical port, and the second doped region of each doped waveguide closest to the second end of the doped waveguide can be electrically coupled to the second electrical port, where the second end is opposite the first end. In such a configuration, multiple PN junctions in the same doped waveguide can be connected in series, while different doped waveguides can be connected in parallel.

[0099] For example, reference Figure 7A The difference between the thermo-optical phase shifter 300 and the thermo-optical phase shifter 200 is that the doped waveguides 221, 222, and 223 further include second doped regions 221f, 222f, and 223f, respectively. The first doped regions 221a, 222a, and 223a are electrically coupled to the first electrical port 250a through the metal line 251, and the second doped regions 221f, 222f, and 223f are electrically coupled to the first electrical port 250b through the metal line 252. Figure 7BTaking the doped waveguide 222 as an example, the first doped region 222a is connected to the metal line 251 via a contact layer 272a and a via 282a, while the second doped region 222f is connected to the metal line 252 via a contact layer 272f and a via 282f. Furthermore, gate dielectric layers 2532a and 2542a and gates 2532b and 2542b may be formed on the first doped regions 222c and 222e, respectively. Gates 2532b and 2542b are connected to the electrical port 250c via metal lines 253 and 254, respectively, to receive a gate control voltage. Thus, when the voltage at the first electrical port 250a is higher than the voltage at the second electrical port 250b and the gate control voltage at the electrical port 250c is at a high level, the multiple PN junctions in the doped waveguide 222 are connected in series. Gates 2532b and 2542b may be made of the same material as the metal line, or may be made of other suitable gate materials. The material of the gate dielectric layers 2532b and 2542b can include one or more of the following: silicon oxide, silicon nitride, silicon oxynitride, etc. In some examples, the gates 2532b and 2542b can be connected to different electrical ports via metal lines 253 and 254, respectively, to receive gate control voltages. In some examples, the gate structure including the gate dielectric layer and the gate can also be formed on the second doped regions 222b and 222d. That is, the gate structure can be formed on a first doped region of the plurality of first doped regions that is not connected to the first electrical port, or alternatively, on a second doped region of the plurality of second doped regions that is not connected to the second electrical port. In some examples, the gate dielectric layers 2532a and 2542a can also be omitted, and instead the portion of the dielectric layer 262 between the bottom of the gates 2532b and 2542b and the top of the corresponding first doped regions 222c and 222e below can be used as the corresponding gate dielectric layer.

[0100] In some embodiments, the thermo-optical phase shifter may further include at least one additional resistor electrically coupled in series with a corresponding one of the doped waveguides, the at least one additional resistor being configured to have a temperature coefficient of resistance matching that of the doped waveguide.

[0101] Taking the thermo-optical phase shifter 300 as an example, for a doped waveguide including a PN junction, since the resistance temperature coefficient of the PN junction is negative (i.e., the resistance of the PN junction decreases as the temperature increases), in some embodiments, the additional resistor can be configured to have a positive resistance temperature coefficient (the resistance increases as the temperature increases). For example, such an additional resistor may include, but is not limited to, a metal resistor. By providing an additional resistor with a resistance temperature coefficient that matches the resistance temperature coefficient of the doped waveguide, the equivalent resistance of the thermo-optical phase shifter can be easily adjusted and the equivalent resistance of the thermo-optical phase shifter does not change significantly with temperature changes, thereby improving the control accuracy of the thermo-optical phase shifter.

[0102] In some embodiments, such an additional resistor can be implemented as a metal film disposed above the doped waveguide electrically coupled in series with the additional resistor. The metal film can be configured to have an elongated structure extending along the waveguide. The material of the metal film can include, but is not limited to, tungsten, titanium nitride, or other suitable metals. For example, Figure 7C As shown, the thermo-optical phase shifter 300' is different from the thermo-optical phase shifter 300 in that it further includes a metal film (eg, metal film 292) disposed above the doped waveguide (eg, waveguide 222). Figure 7C As shown, the metal film 292 is formed in the additional dielectric layer 263 above the dielectric layer 262, and is connected to the second doped region 222f through the through hole 282f and the contact layer 272f, and then connected to the metal line 252' at the other end via the through hole 2921 set in the additional dielectric layer 263, thereby connecting to the second electrical port 250b. The additional dielectric layer 263 can be made of the same material as the dielectric layer 262, or any other suitable dielectric material, as long as isolation between the metal structures can be achieved. Thus, the multiple PN junctions included in the doped waveguide 222 and the metal film 292 are coupled in series between the first electrical port 250a and the second electrical port 250b. Note that although Figure 7C Not shown Figure 7B , but it is understood that the thermo-optical phase shifter 300' may include Figure 7B The gate structures depicted in the figure are shown, and those skilled in the art will appreciate that these gate structures and the metal films serving as additional resistors and other metal wiring structures can be appropriately arranged and reasonably disposed in one or more dielectric layers without conflicting with each other.

[0103] The thickness, width, length, and material of the metal film 292 can be specifically set according to the desired equivalent resistance. It is understood that each doped waveguide can be correspondingly provided with one or more additional resistors, and the electrical coupling between these additional resistors and the doped waveguide or the PN junction included therein is not limited to a pure series connection, but can achieve a variety of electrical coupling modes through appropriate metal wiring structures.

[0104] Furthermore, such additional resistors do not necessarily need to be located above their corresponding doped waveguides. Instead, they can be located at any suitable location within the additional dielectric layer 263, as long as they can be electrically coupled to the corresponding doped waveguides via appropriate metal wiring structures. For example, they can also be located above undoped waveguides. Furthermore, these additional resistors can be distributed across different additional dielectric layers.

[0105] The doped waveguide serving as a heating element can also be electrically coupled to other conventional heating elements (e.g., a tungsten heater, a titanium nitride heater, or other metal strips) via appropriate metal wiring structures, thereby providing greater freedom in resistance adjustment and structural design of the thermo-optical phase shifter. In some embodiments, the thermo-optical phase shifter can include at least one metal strip disposed above at least one of the plurality of first waveguides and the plurality of second waveguides, each metal strip being configured to electrically couple to a corresponding PN junction in the doped waveguide.

[0106] The thermo-optical phase shifter according to the present disclosure can obtain an area less than 0.006 m 2 A phase shifter with a power of less than 2.0mW that achieves π phase shifting. Compared to existing thermo-optical phase shifters that do not use the thermal isolation groove process, this power is reduced by more than 10 times. Compared to existing thermo-optical phase shifters that use the thermal isolation groove process, the modulation speed is significantly improved.

[0107] A second aspect of the present disclosure provides a thermo-optical phase shifter network, which may include a plurality of first electrical network ports, a plurality of second electrical network ports different from the plurality of first electrical network ports, and a plurality of thermo-optical phase shifting units arranged in an array. Each thermo-optical phase shifting unit may include at least one thermo-optical phase shifter as described in any of the above embodiments. Each thermo-optical phase shifting unit may be electrically coupled between a corresponding first electrical network port among the plurality of first electrical network ports and a corresponding second electrical network port among the plurality of second electrical network ports. Each thermo-optical phase shifting unit may be configured to change the phase of light passing through the thermo-optical phase shifting unit when the voltage at the first electrical network port corresponding to the thermo-optical phase shifting unit is higher than the voltage at the second electrical network port corresponding to the thermo-optical phase shifting unit.

[0108] Reference below Figure 8The N×M thermo-optical phase shifter network 400 according to the present disclosure is described in detail: The thermo-optical phase shifter network 400 includes a plurality of first electrical network ports P1, P2, P3, ..., PN and a plurality of second electrical network ports Q1, Q2, ..., QM. Figure 8 The dotted box in the figure indicates a thermo-optical phase shifter unit. Thus, the thermo-optical phase shifter network 400 may include N×M thermo-optical phase shifters, each electrically coupled between a corresponding first electrical network port and a corresponding second electrical network port. Note that the resistor and diode hybrid circuit in the dashed box merely schematically represents the equivalent circuit of the thermo-optical phase shifter unit and does not represent the actual equivalent circuit of the thermo-optical phase shifter unit.

[0109] Each thermo-optical phase shift unit may include at least one thermo-optical phase shifter as described in any of the above embodiments. In some embodiments, the thermo-optical phase shifters in each thermo-optical phase shift unit may be optically coupled in parallel or in series with each other. In some embodiments, the thermo-optical phase shifters in each thermo-optical phase shift unit may be electrically coupled in parallel or in series with each other, thereby adjusting the overall driving voltage of each thermo-optical phase shift unit and the thermal power that can be generated at the same voltage. Each thermo-optical phase shift unit may be configured to change the phase of light passing through the thermo-optical phase shift unit when the voltage at the first electrical network port Pi (i=1,2,…,N) corresponding to the thermo-optical phase shift unit is higher than the voltage at the second electrical network port Qj (j=1,2,…,M) corresponding to the thermo-optical phase shift unit.

[0110] In some embodiments, the thermo-optical phase shifters in the same row of the plurality of thermo-optical phase shifters are all electrically coupled to the same first electrical network port among the plurality of first electrical network ports, and the thermo-optical phase shifters in the same column of the plurality of thermo-optical phase shifters are all electrically coupled to the same second electrical network port among the plurality of second electrical network ports. For example, in the thermo-optical phase shifter network 400, the thermo-optical phase shifters in the i-th row (i=1, 2, ..., N) are all electrically coupled to the first electrical network port Pi (i=1, 2, ..., N), and the thermo-optical phase shifters in the j-th column (j=1, 2, ..., M) are all electrically coupled to the second electrical network port Qj (j=1, 2, ..., M).

[0111] In particular, as previously discussed, for thermo-optical phase shifters whose doped waveguides include PN junctions, the unidirectional current conductivity of the PN junctions can be utilized to address the thermo-optical phase shifting elements in the thermo-optical phase shifter network 400. The switching state of the thermo-optical phase shifter element (i, j) can be controlled by applying forward and reverse bias voltages to the thermo-optical phase shifter element (i, j) via the first electrical network port Pi and the second electrical network port Qj. Consequently, only (N+M) ports are required to independently control the switching state of each thermo-optical phase shifter element in the thermo-optical phase shifter network 400. In contrast, for a network comprising N×M conventional thermo-optical phase shifters that do not include PN junctions, at least (N×M+1) ports are required to independently control the switching state of each thermo-optical phase shifter element. Therefore, the number of ports required for the thermo-optical phase shifter network formed using the thermo-optical phase shifters according to the embodiments of the present disclosure is greatly reduced, thereby greatly reducing the difficulty and cost of device electrical packaging. These effects are more significant when the scale of the thermo-optical phase shifter network is larger.

[0112] The following combination Figure 9 as well as Figures 10A to 10C The addressing operation of the thermo-optical phase shifter network according to the present disclosure is described by taking a 2×2 thermo-optical phase shifter network as an example. In the 2×2 thermo-optical phase shifter network, each thermo-optical phase shift unit includes a thermo-optical phase shifter. The 2×2 thermo-optical phase shifter network includes four thermo-optical phase shifters PS11, PS12, PS21, and PS22, wherein the thermo-optical phase shifter PS11 is electrically coupled between the first electrical network port V1 and the second electrical network port VV1, the thermo-optical phase shifter PS12 is electrically coupled between the first electrical network port V1 and the second electrical network port VV2, the thermo-optical phase shifter PS21 is electrically coupled between the first electrical network port V2 and the second electrical network port VV1, and the thermo-optical phase shifter PS22 is electrically coupled between the first electrical network port V2 and the second electrical network port VV2. Each thermo-optical phase shifter PS11, PS12, PS21, and PS22 can be a thermo-optical phase shifter as described in any of the embodiments discussed above regarding the doped waveguide including a PN junction. Utilizing the unidirectional conductivity of the PN junction in the thermo-optical phase shifter, according to the voltage conditions of the thermo-optical phase shifter being on (the PN junction included in the thermo-optical phase shifter is conductive) and off (the PN junction included in the thermo-optical phase shifter is cut off) as indicated in Table 1 below, different voltages can be set at V1, V2, VV1, and VV2, respectively, thereby selectively allowing a certain thermo-optical phase shifter in the network to operate while the other thermo-optical phase shifters do not operate; or allowing a certain row (column) of thermo-optical phase shifters in the network to operate while the other rows (columns) of thermo-optical phase shifters do not operate. In other words, addressing (point addressing, row addressing, and column addressing) of the thermo-optical phase shifter network can be achieved, such as Figures 10A to 10CBased on this feature, by controlling the timing of the voltage, specifically, by controlling the voltage of each electrical network port and its change over time, the heating power and heating time of each thermo-optical phase shifter can be controlled, thereby achieving the desired phase change. Figures 10A to 10C This timing control method will be described in more detail.

[0113] Table 1

[0114] Thermo-optical phase shifter Open closure PS11 VV1<V1 VV1≥V1 PS12 VV2<V1 VV2≥V1 PS21 VV1<V2 VV1≥V2 PS22 VV2<V2 VV2≥V2

[0115] exist Figure 10A The timing control shown can achieve point addressing of a 2×2 thermo-optical phase shifter network. Here, the time intervals between t0, t1, t2, t3, and t4 are all T, where T represents the time required for each thermo-optical phase shifter to achieve a phase change of 2π. Specifically, during the time period t0 to t1, V1 and VV2 are always at a high level, while V2 and VV1 are always at a low level. Therefore, during this time period, only thermo-optical phase shifter PS11 operates, while the other thermo-optical phase shifters do not operate, and thermo-optical phase shifter PS11 achieves a phase change of 2π. During the time period t1 to t2, V1 is high for the first T / 2 period and low for the last T / 2 period. VV1 is always high, while V2 and VV2 are always low. Therefore, during this time period, only thermo-optical phase shifter PS12 operates, while the other thermo-optical phase shifters do not operate, and thermo-optical phase shifter PS12 achieves a phase change of π. During the time period from t2 to t3, V2 is high for the first T / 4 and low for the next 3T / 4. VV2 remains high, while V1 and VV1 remain low. Therefore, during this time period, only thermo-optical phase shifter PS21 operates, while the other thermo-optical phase shifters do not. Thermo-optical phase shifter PS21 achieves a phase change of π / 2. During the time period from t3 to t4, V2 is high for the first T / 6 and low for the next 5T / 6. VV1 remains high, while V1 and VV2 remain low. Therefore, during this time period, only thermo-optical phase shifter PS22 operates, while the other thermo-optical phase shifters do not operate. Thermo-optical phase shifter PS22 achieves a phase change of π / 3.

[0116] exist Figure 10BThe timing control shown in the figure can achieve row addressing of a 2×2 thermo-optical phase shifter network. Here, the time intervals between t0, t1, t2, t3, and t4 are all T, where T represents the time required for each thermo-optical phase shifter to achieve a phase change of 2π. Specifically, during the time period from t0 to t1, V1 is always high and V2 is always low. VV1 is low for the first T / 2 period and high for the next T / 2 period. VV2 is low for the first 2T / 3 periods and high for the next T / 3 period. Therefore, during this period, only the thermo-optical phase shifters PS11 and PS12 in the first row operate, while the other thermo-optical phase shifters do not. Furthermore, the thermo-optical phase shifter PS11 achieves a phase change of π, while the thermo-optical phase shifter PS12 achieves a phase change of 4π / 3. In the time period from t1 to t2, V2 is always at a high level and V1 is always at a low level. VV1 is at a low level in the first T / 2 time period and at a high level in the second T / 2 time period. VV2 is at a low level in the first 2T / 3 time period and at a high level in the second T / 3 time period. Therefore, in this time period, only the thermo-optical phase shifters PS21 and PS22 located in the second row work while the other thermo-optical phase shifters do not work, and the thermo-optical phase shifter PS21 realizes a phase change of π, and the thermo-optical phase shifter PS22 realizes a phase change of 4π / 3. During the time period from t2 to t3, V1 is always at a high level and V2 is always at a low level. VV1 is at a low level in the first T / 3 time period and at a high level in the next 2T / 3 time period. VV2 is at a low level in the first T / 4 time period and at a high level in the next 3T / 4 time period. Therefore, during this time period, only the thermo-optical phase shifters PS11 and PS12 located in the first row work while the other thermo-optical phase shifters do not work. The thermo-optical phase shifter PS11 achieves a phase change of 2π / 3, and the thermo-optical phase shifter PS12 achieves a phase change of π / 2. During the time period from t3 to t4, V2 is always at a high level while V1 and VV2 are always at a low level. VV1 is at a low level in the first T / 2 time period and at a high level in the second T / 2 time period. Therefore, during this time period, only the thermo-optical phase shifters PS21 and PS22 located in the second row work while the other thermo-optical phase shifters do not work. The thermo-optical phase shifter PS21 achieves a phase change of π, and the thermo-optical phase shifter PS22 achieves a phase change of 2π.

[0117] exist Figure 10CThe timing control shown in the figure can achieve column addressing of a 2×2 thermo-optical phase shifter network. Here, the time intervals between t0, t1, t2, t3, and t4 are all T, where T represents the time required for each thermo-optical phase shifter to achieve a phase change of 2π. Specifically, during the time period from t0 to t1, V1 and V2 are at a high level during the first T / 2 period and at a low level during the second T / 2 period. VV1 is always at a low level, while VV2 is always at a high level. Therefore, during this time period, only the thermo-optical phase shifters PS11 and PS21 in the first column operate, while the other thermo-optical phase shifters do not operate. The thermo-optical phase shifter PS11 achieves a phase change of π, and the thermo-optical phase shifter PS21 achieves a phase change of π. In the time period from t1 to t2, V1 is at a high level in the first T / 4 time period and at a low level in the next 3T / 4 time period, VV2 is always at a low level, while VV1 and V2 are always at a high level. Therefore, in this time period, only the thermo-optical phase shifters PS12 and PS22 located in the second column work while the other thermo-optical phase shifters do not work, and the thermo-optical phase shifter PS12 achieves a phase change of π / 2, and the thermo-optical phase shifter PS22 achieves a phase change of 2π. In the time period from t2 to t3, V1 is at a high level in the first T / 4 time period and at a low level in the last 3T / 4 time period. V2 is at a high level in the first T / 6 time period and at a low level in the last 5T / 6 time period. VV1 is always at a low level and VV2 is always at a high level. Therefore, in this time period, only the thermo-optical phase shifters PS11 and PS21 located in the first column work while the other thermo-optical phase shifters do not work. The thermo-optical phase shifter PS11 achieves a phase change of π / 2, and the thermo-optical phase shifter PS21 achieves a phase change of π / 3. In the time period from t3 to t4, V1 is at a high level in the first T / 2 time period and at a low level in the second T / 2 time period, V2 is at a high level in the first T / 4 time period and at a low level in the second 3T / 4 time period, VV2 is always at a low level and VV1 is always at a high level. Therefore, in this time period, only the thermo-optical phase shifters PS12 and PS22 located in the second column work while the other thermo-optical phase shifters do not work, and the thermo-optical phase shifter PS12 realizes a phase change of π, and the thermo-optical phase shifter PS22 realizes a phase change of π / 2.

[0118] The thermo-optical phase shifter and thermo-optical phase shifter network according to the present disclosure can be applied to a variety of optoelectronic devices. For example, for an optical switching device, the input waveguide is divided into two branch waveguides at the input port, at least one of the two branch waveguides can be connected to the thermo-optical phase shifter according to the present disclosure or the thermo-optical phase shifter network or its thermo-optical phase shift unit according to the present disclosure, and the two branch waveguides are recombined into an output waveguide at the output port, thereby realizing an optical switching device. Specifically, if the phases of the light components propagating in the two branch waveguides are offset by π from each other, the output at the output port is zero. If no phase shift occurs, the light is output as it was when it was input. In this way, the on / off control of the optical switching device can be realized. In addition, the thermo-optical phase shifter according to the present disclosure or the thermo-optical phase shifter network according to the present disclosure can also be combined as an optical phase modulation element in an optical modulation device, an optical field programmable gate array network, a phased array radar, and a photonic artificial intelligence chip. The above applications are merely exemplary and not restrictive. The thermo-optical phase shifter and thermo-optical phase shifter network according to the present disclosure can be used to perform phase modulation of light in any suitable application scenario.

[0119] The words "left," "right," "front," "back," "top," "bottom," "up," "down," "high," "low," and the like, if any, in the specification and claims, are used for descriptive purposes and are not necessarily intended to describe invariant relative positions. It should be understood that the words so used are interchangeable under appropriate circumstances so that the embodiments of the present disclosure described herein, for example, can operate in other orientations than those shown or otherwise described herein. For example, when the device in the figures is turned over, features previously described as "above" other features could now be described as "below" the other features. The device can also be otherwise oriented (rotated 90 degrees or in other orientations) and relative spatial relationships will be interpreted accordingly.

[0120] In the specification and claims, when an element is referred to as being "on," "attached" to, "connected" to, "coupled" to, "coupled to," or "in contact with," the element may be directly on, directly attached to, directly connected to, directly coupled to, directly coupled to, or directly in contact with, another element, or one or more intervening elements may be present. In contrast, when an element is referred to as being "directly" "on," "directly attached" to, "directly connected" to, "directly coupled" to, "directly coupled to," or "in direct contact with," another element, there may be no intervening elements. In the specification and claims, when a feature is arranged "adjacent" to another feature, it may mean that the feature has a portion that overlaps with the adjacent feature or a portion that is located above or below the adjacent feature.

[0121] As used herein, the word "exemplary" means "serving as an example, instance, or illustration," rather than as a "model" to be precisely copied. Any implementation described as exemplary is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, this disclosure is not to be bound by any expressed or implied theory presented in the technical field, background, summary, or detailed description.

[0122] As used herein, the term "substantially" is intended to encompass any minor variations due to design or manufacturing imperfections, device or component tolerances, environmental influences, and / or other factors. The term "substantially" also allows for deviations from a perfect or ideal condition due to parasitic effects, noise, and other practical considerations that may be present in actual implementations.

[0123] Additionally, terms such as "first," "second," and the like may also be used herein for reference purposes only and are not intended to be limiting. For example, the terms "first," "second," and other numerical terms referring to structures or elements do not imply a sequence or order unless the context clearly indicates otherwise.

[0124] It should also be understood that when the term “include / comprises” is used in this document, it indicates the presence of the specified features, integers, steps, operations, units and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, units and / or components and / or their combinations.

[0125] In this disclosure, the term "provide" is used in a broad sense to cover all ways of obtaining an object, and thus "providing an object" includes but is not limited to "purchasing", "preparing / manufacturing", "arranging / setting up", "installing / assembling", and / or "ordering" an object, etc.

[0126] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0127] Those skilled in the art will appreciate that the boundaries between the above-mentioned operations are merely illustrative. Multiple operations can be combined into a single operation, a single operation can be distributed among additional operations, and operations can be performed at least partially overlapping in time. Moreover, alternative embodiments can include multiple instances of a particular operation, and the order of operations can be changed in various other embodiments. However, other modifications, variations, and replacements are also possible. Aspects and elements of all embodiments disclosed above can be combined in any manner and / or in combination with aspects or elements of other embodiments to provide multiple additional embodiments. Therefore, this specification and the accompanying drawings should be considered illustrative, not restrictive.

[0128] This disclosure may also include the following examples:

[0129] 1. A thermo-optical phase shifter, comprising:

[0130] a plurality of first waveguides, each first waveguide having a first width and extending in a first direction; and

[0131] a plurality of second waveguides, each second waveguide having a second width different from the first width and extending along the first direction,

[0132] wherein the plurality of first waveguides and the plurality of second waveguides are alternately arranged in a second direction different from the first direction.

[0133] wherein at least one of the plurality of first waveguides and the plurality of second waveguides is doped to serve as a heat generating unit of the thermo-optical phase shifter,

[0134] And wherein the undoped waveguides among the plurality of first waveguides and the plurality of second waveguides are optically coupled in series to provide an optical input port and an optical output port of the thermo-optical phase shifter at both ends, respectively.

[0135] 2. The thermo-optical phase shifter according to Example 1, wherein the first direction is perpendicular to the second direction.

[0136] 3. The thermo-optical phase shifter according to Example 1, wherein the plurality of first waveguides and the plurality of second waveguides are straight waveguides parallel to each other.

[0137] 4. The thermo-optical phase shifter according to Example 1, wherein the plurality of first waveguides and the plurality of second waveguides are arranged at equal intervals in the second direction.

[0138] 5. The thermo-optic phase shifter according to Example 1, wherein the spacing between the plurality of first waveguides and the plurality of second waveguides in the second direction is configured such that a coupling strength between adjacent waveguides is lower than a predetermined threshold.

[0139] 6. The thermo-optic phase shifter of Example 1, wherein the first width is smaller than the second width.

[0140] 7. The thermo-optic phase shifter of example 6, wherein the at least one waveguide that is doped is a second waveguide.

[0141] 8. The thermo-optical phase shifter according to Example 1, wherein there is at least one undoped waveguide between two adjacent doped waveguides.

[0142] 9. The thermo-optical phase shifter according to Example 8, wherein three undoped waveguides exist between two adjacent doped waveguides.

[0143] 10. The thermo-optical phase shifter according to Example 6 further includes a plurality of third waveguides, each third waveguide having a curved portion, wherein two adjacent undoped waveguides among the plurality of first waveguides and the plurality of second waveguides are optically coupled via corresponding third waveguides among the plurality of third waveguides.

[0144] 11. A thermo-optical phase shifter according to Example 10, wherein the bending radius of the curved portion of each third waveguide is determined based on the spacing and relative angles between the waveguides coupled to both ends of the third waveguide among the plurality of first waveguides and the plurality of second waveguides, and at least one of the relative angles between the first direction and the second direction.

[0145] 12. The thermo-optical phase shifter according to Example 10, wherein the width of each third waveguide is configured to be equal to the minimum width among the widths of the waveguides coupled to both ends of the third waveguide among the plurality of first waveguides and the plurality of second waveguides.

[0146] 13. The thermo-optical phase shifter according to Example 12 further includes a plurality of fourth waveguides, wherein a third waveguide of the plurality of third waveguides coupled between the first waveguide and the second waveguide is optically coupled to the second waveguide via a corresponding fourth waveguide of the plurality of fourth waveguides, and each fourth waveguide has the first width at an end where the fourth waveguide is coupled to the third waveguide and has the second width at an end where the fourth waveguide is coupled to the second waveguide.

[0147] 14. A thermo-optical phase shifter according to any one of Examples 1 to 13, wherein each doped waveguide includes at least one first doping region and at least one second doping region, and the at least one first doping region and the at least one second doping region are alternately arranged in the doped waveguide along the first direction.

[0148] 15. The thermo-optical phase shifter according to Example 14, wherein the first doped region is a P-type doped region, and the second doped region is an N-type doped region.

[0149] 16. The thermo-optic phase shifter of example 15, wherein adjacent doped regions in each doped waveguide contact each other to form at least one PN junction.

[0150] 17. The thermo-optical phase shifter according to Example 16 further includes a first electrical port and a second electrical port different from the first electrical port, wherein the thermo-optical phase shifter is configured so that the PN junction in each doped waveguide is turned on when the voltage at the first electrical port is higher than the voltage at the second electrical port.

[0151] 18. The thermo-optical phase shifter of Example 17, wherein each first doped region of each doped waveguide is electrically coupled to the first electrical port, and each second doped region of each doped waveguide is electrically coupled to the second electrical port.

[0152] 19. A thermo-optical phase shifter according to Example 17, wherein a first doped region of each doped waveguide closest to the first end of the doped waveguide is electrically coupled to the first electrical port, and a second doped region of each doped waveguide closest to the second end of the doped waveguide is electrically coupled to the second electrical port, the second end being opposite to the first end.

[0153] 20. The thermo-optical phase shifter according to Example 16 further includes at least one metal strip disposed above at least one waveguide among the plurality of first waveguides and the plurality of second waveguides, each of the at least one metal strip being configured to be electrically coupled to a corresponding PN junction in the doped waveguide.

[0154] 21. The thermo-optical phase shifter according to Example 1 further includes at least one additional resistor electrically coupled in series with a corresponding doped waveguide in the at least one doped waveguide, wherein the at least one additional resistor is configured to have a resistance temperature coefficient that matches the resistance temperature coefficient of the doped waveguide.

[0155] 22. The thermo-optic phase shifter of example 21, wherein the temperature coefficient of resistance of the additional resistor is positive.

[0156] 23. The thermo-optical phase shifter of Example 22, wherein the additional resistor is a metal resistor.

[0157] 24. The thermo-optical phase shifter according to example 23, wherein the additional resistor is implemented as a metal film disposed above the doped waveguide electrically coupled in series with the additional resistor.

[0158] 25. A thermo-optical phase shifter network comprising:

[0159] a plurality of first electrical network ports;

[0160] a plurality of second electrical network ports different from the plurality of first electrical network ports; and

[0161] a plurality of thermo-optical phase shifting units arranged in an array, each thermo-optical phase shifting unit comprising at least one thermo-optical phase shifter according to any one of Examples 1 to 24, wherein each thermo-optical phase shifting unit is electrically coupled between a corresponding first electrical network port among the plurality of first electrical network ports and a corresponding second electrical network port among the plurality of second electrical network ports,

[0162] Each thermo-optical phase shift unit is configured to change the phase of light passing through the thermo-optical phase shift unit when the voltage at the first electrical network port corresponding to the thermo-optical phase shift unit is higher than the voltage at the second electrical network port corresponding to the thermo-optical phase shift unit.

[0163] 26. A thermo-optical phase shifter network according to Example 25, wherein the thermo-optical phase shifters located in the same row among the multiple thermo-optical phase shifters are all electrically coupled to the same first electrical network port among the multiple first electrical network ports, and the thermo-optical phase shifters located in the same column among the multiple thermo-optical phase shifters are all electrically coupled to the same second electrical network port among the multiple second electrical network ports.

[0164] 27. The thermo-optical phase shifter network of example 25, wherein the thermo-optical phase shifters in each thermo-optical phase shift unit are electrically coupled to each other in parallel or in series.

[0165] 28. The thermo-optical phase shifter network of example 25, wherein the thermo-optical phase shifters in each thermo-optical phase shift unit are optically coupled to each other in parallel or in series.

[0166] 29. An optoelectronic device, which is one of an optical switching device, an optical modulation device, an optical field programmable gate array network, a phased array radar, and a photonic artificial intelligence chip, and includes a thermo-optical phase shifter according to any one of Examples 1 to 24.

[0167] 30. An optoelectronic device, wherein the optoelectronic device is one of an optical switching device, an optical modulation device, an optical field programmable gate array network, a phased array radar, and a photonic artificial intelligence chip, and the optoelectronic device includes a thermo-optical phase shifter network according to any one of Examples 25 to 28.

[0168] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. The various embodiments disclosed herein may be combined in any manner without departing from the spirit and scope of the present disclosure. It should also be understood by those skilled in the art that various modifications may be made to the embodiments without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A thermo-optical phase shifter, comprising: a plurality of first waveguides, each first waveguide having a first width and extending in a first direction; as well as a plurality of second waveguides, each second waveguide having a second width different from the first width and extending along the first direction, wherein the plurality of first waveguides and the plurality of second waveguides are alternately arranged in a second direction different from the first direction. wherein at least one of the plurality of first waveguides and the plurality of second waveguides is doped to serve as a heat generating unit of the thermo-optical phase shifter, And wherein the undoped waveguides among the plurality of first waveguides and the plurality of second waveguides are optically coupled in series to provide a light input port and a light output port of the thermo-optical phase shifter at both ends, respectively.

2. The thermo-optical phase shifter according to claim 1, wherein: The first direction is perpendicular to the second direction.

3. The thermo-optical phase shifter according to claim 1, wherein: The plurality of first waveguides and the plurality of second waveguides are straight waveguides parallel to each other.

4. The thermo-optical phase shifter according to claim 1, wherein: The plurality of first waveguides and the plurality of second waveguides are arranged at equal intervals in the second direction.

5. The thermo-optical phase shifter according to claim 1, wherein: The intervals between the plurality of first waveguides and the plurality of second waveguides in the second direction are configured such that a coupling strength between adjacent waveguides is below a predetermined threshold.

6. The thermo-optical phase shifter according to claim 1, wherein: The first width is smaller than the second width.

7. The thermo-optical phase shifter according to claim 6, wherein: The at least one waveguide that is doped is a second waveguide.

8. The thermo-optical phase shifter according to claim 1, wherein: There is at least one undoped waveguide between two adjacent doped waveguides.

9. The thermo-optical phase shifter according to claim 8, wherein: There are three undoped waveguides between two adjacent doped waveguides.

10. The thermo-optical phase shifter according to claim 6, further comprising a plurality of third waveguides, each of the third waveguides having a bent portion, wherein adjacent two undoped waveguides among the plurality of first waveguides and the plurality of second waveguides are optically coupled via corresponding third waveguides among the plurality of third waveguides.

11. The thermo-optical phase shifter according to claim 10, wherein: A bending radius of the curved portion of each third waveguide is determined based on at least one of an interval and a relative angle between waveguides coupled to both ends of the third waveguide among the plurality of first waveguides and the plurality of second waveguides and a relative angle between the first direction and the second direction.

12. The thermo-optical phase shifter according to claim 10, wherein: The width of each third waveguide is configured to be equal to a minimum width among widths of waveguides coupled to both ends of the third waveguide among the plurality of first waveguides and the plurality of second waveguides.

13. The thermo-optical phase shifter according to claim 12, further comprising a plurality of fourth waveguides, wherein a third waveguide coupled between the first waveguide and the second waveguide among the plurality of third waveguides is optically coupled to the second waveguide via a corresponding fourth waveguide among the plurality of fourth waveguides, and each fourth waveguide has the first width at an end thereof coupled to the third waveguide and has the second width at an end thereof coupled to the second waveguide.

14. The thermo-optical phase shifter according to any one of claims 1 to 13, wherein: Each doped waveguide includes at least one first doped region and at least one second doped region, and the at least one first doped region and the at least one second doped region are alternately arranged in the doped waveguide along the first direction.

15. The thermo-optical phase shifter according to claim 14, wherein: The first doped region is a P-type doped region, and the second doped region is an N-type doped region.

16. The thermo-optical phase shifter according to claim 15, wherein: Adjacent doped regions in each doped waveguide contact each other to form at least one PN junction.

17. The thermo-optic phase shifter according to claim 16, further comprising a first electrical port and a second electrical port different from the first electrical port, wherein the thermo-optic phase shifter is configured such that when a voltage at the first electrical port is higher than a voltage at the second electrical port, the PN junction in each doped waveguide is turned on.

18. The thermo-optical phase shifter according to claim 17, wherein: Each first doped region of each doped waveguide is electrically coupled to the first electrical port, and each second doped region of each doped waveguide is electrically coupled to the second electrical port.

19. The thermo-optical phase shifter according to claim 17, wherein: A first doped region of each doped waveguide closest to the first end of the doped waveguide is electrically coupled to the first electrical port, and a second doped region of each doped waveguide closest to the second end of the doped waveguide is electrically coupled to the second electrical port, the second end being opposite to the first end.

20. The thermo-optic phase shifter of claim 16, further comprising at least one metal strip disposed over at least one of the plurality of first waveguides and the plurality of second waveguides, each of the at least one metal strip being configured to be electrically coupled to a corresponding PN junction in the doped waveguide.

21. The thermo-optical phase shifter of claim 1, further comprising at least one additional resistor electrically coupled in series with a corresponding doped waveguide of the at least one doped waveguide, the at least one additional resistor being configured to have a temperature coefficient of resistance that matches a temperature coefficient of resistance of the doped waveguide.

22. The thermo-optical phase shifter according to claim 21, wherein: The resistance temperature coefficient of the additional resistor is positive.

23. The thermo-optical phase shifter according to claim 22, wherein: The additional resistor is a metal resistor.

24. The thermo-optical phase shifter according to claim 23, wherein: The additional resistor is implemented as a metal film disposed above the doped waveguide electrically coupled in series with the additional resistor.

25. A thermo-optical phase shifter network, comprising: a plurality of first electrical network ports; a plurality of second electrical network ports different from the plurality of first electrical network ports; as well as a plurality of thermo-optical phase shifting units arranged in an array, each thermo-optical phase shifting unit comprising at least one thermo-optical phase shifter according to any one of claims 1 to 24, wherein each thermo-optical phase shifting unit is electrically coupled between a corresponding first electrical network port among the plurality of first electrical network ports and a corresponding second electrical network port among the plurality of second electrical network ports, Each thermo-optical phase shift unit is configured to change the phase of light passing through the thermo-optical phase shift unit when the voltage at the first electrical network port corresponding to the thermo-optical phase shift unit is higher than the voltage at the second electrical network port corresponding to the thermo-optical phase shift unit.

26. The thermo-optical phase shifter network of claim 25, wherein: The thermo-optical phase shift units located in the same row among the multiple thermo-optical phase shift units are all electrically coupled to the same first electrical network port among the multiple first electrical network ports, and the thermo-optical phase shift units located in the same column among the multiple thermo-optical phase shift units are all electrically coupled to the same second electrical network port among the multiple second electrical network ports.

27. The thermo-optical phase shifter network of claim 25, wherein: The thermo-optical phase shifters in each thermo-optical phase shift unit are electrically coupled to each other in parallel or in series.

28. The thermo-optical phase shifter network of claim 25, wherein: The thermo-optical phase shifters in each thermo-optical phase shift unit are optically coupled to each other in parallel or in series.

29. An optoelectronic device, wherein the optoelectronic device is one of an optical switching device, an optical modulation device, an optical field programmable gate array network, a phased array radar, and a photonic artificial intelligence chip, and the optoelectronic device comprises a thermo-optical phase shifter according to any one of claims 1 to 24.

30. An optoelectronic device, which is one of an optical switching device, an optical modulation device, an optical field programmable gate array network, a phased array radar and a photonic artificial intelligence chip, and the optoelectronic device comprises a thermo-optical phase shifter network according to any one of claims 25 to 28.

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