Electro-optic modulator

Abstract

The embodiment of the present disclosure discloses an electro-optical modulator, comprising: electrodes, at least comprising a first electrode and a second electrode in a straight line; the first electrode and the second electrode both extend along a first direction; an optical waveguide, comprising a first optical waveguide and a second optical waveguide in a curved line; the first optical waveguide and the second optical waveguide are both located between the first electrode and the second electrode; the point on the line segment of the first optical waveguide corresponds to the point on the straight line of the first electrode in one-to-one correspondence; the point on the line segment of the second optical waveguide corresponds to the point on the straight line of the second electrode in one-to-one correspondence.

Description

Technical Field

[0001] This disclosure relates to the field of optical communication technology, and more particularly to an electro-optic modulator. Background Technology

[0002] With the rapid development of the communications industry, both the communication of data between massive numbers of users and the calculation and transmission of the resulting large amounts of data inevitably require electro-optic modulators for modulation, which also puts forward higher speed requirements for electro-optic modulators.

[0003] However, in the process of optical modulation, there are problems such as low modulation bandwidth and low modulation efficiency. Summary of the Invention

[0004] In view of this, embodiments of the present disclosure provide an electro-optic modulator.

[0005] An electro-optic modulator according to this disclosure includes:

[0006] The electrode includes at least a linear first electrode and a second electrode; both the first electrode and the second electrode extend along a first direction.

[0007] An optical waveguide includes a curved first optical waveguide and a second optical waveguide; both the first optical waveguide and the second optical waveguide are located between the first electrode and the second electrode.

[0008] The orthographic projection of a point on the line segment of the first optical waveguide onto the straight line of the first electrode corresponds one-to-one with the point on the straight line of the first electrode; the orthographic projection of a point on the line segment of the second optical waveguide onto the straight line of the second electrode corresponds one-to-one with the point on the straight line of the second electrode.

[0009] In the above scheme, the transmission speed of the optical signal in the optical waveguide along the first direction is the same as the transmission speed of the electrical signal in the electrode.

[0010] In the above scheme, the optical waveguide includes a wave-shaped structure; the wave-shaped structure reciprocates periodically and extends along the first direction. The wave-shaped structure includes arc-shaped portions and / or straight portions.

[0011] In the above scheme, the straight portion of the wave-shaped structure forms a first angle with the first direction, and the first angle is related to the ratio of the group refractive index of the optical waveguide to the group refractive index of the electrode.

[0012] In the above scheme, the first optical waveguide and the second optical waveguide are symmetrical about the central axis, and the central axis is parallel to the first direction and is equidistant from the first electrode and the second electrode.

[0013] In the above scheme, the electro-optic modulator further includes:

[0014] An active region is located between the first electrode and the second electrode; the active region includes: a first doped region, a second doped region, and a third doped region; wherein,

[0015] The first doped region is located between the first electrode and the first optical waveguide;

[0016] The second doped region is located between the first optical waveguide and the second optical waveguide;

[0017] The third doped region is located between the second optical waveguide and the second electrode;

[0018] The doping type of the second doped region is different from that of the first doped region and the third doped region.

[0019] In the above scheme,

[0020] The first doped region and the third doped region are P-type doped, and the second doped region is N-type doped; or...

[0021] The first doped region and the third doped region are of N-type doping, and the second doped region is of P-type doping.

[0022] In the above scheme, the electrode includes a first electrode and a second electrode; both the first electrode and the second electrode act on the optical waveguide;

[0023] or,

[0024] The electrode includes: a first electrode, a second electrode, a plurality of first connection structures connected to the first electrode, and a plurality of second connection structures connected to the second electrode; the first electrode acts on the optical waveguide through the plurality of first connection structures, and the second electrode acts on the optical waveguide through the plurality of second connection structures.

[0025] In the above scheme, the optical waveguide includes a ridge waveguide.

[0026] In the above scheme, the electro-optic modulator further includes:

[0027] The beam splitter is connected to the input end of the first optical waveguide and the input end of the second optical waveguide, respectively.

[0028] The beam combiner is connected to the output terminals of the first optical waveguide and the second optical waveguide, respectively.

[0029] This disclosure provides an electro-optic modulator in various embodiments, the electro-optic modulator comprising: electrodes, including at least a linear first electrode and a second electrode; both the first electrode and the second electrode extending along a first direction; and an optical waveguide, including a curved first optical waveguide and a second optical waveguide; both the first optical waveguide and the second optical waveguide being located between the first electrode and the second electrode; the orthographic projection of a point on the line segment of the first optical waveguide onto the line where the first electrode is located corresponds one-to-one with the point on the line where the first electrode is located; and the orthographic projection of a point on the line segment of the second optical waveguide onto the line where the second electrode is located corresponds one-to-one with the point on the line where the second electrode is located. The electro-optic modulator provided in this embodiment uses a curved first optical waveguide and a curved second optical waveguide as the phase modulation region structure of the modulator. First, it effectively shortens the length of the corresponding electrode, and the shorter electrode length can reduce the loss of electrical signal. Second, the curved optical waveguide increases the capacitance between the optical waveguide and the electrode, thereby affecting the characteristic impedance of the modulation region of the electro-optic modulator to meet the impedance matching with the external system. Third, the reduced electrode length helps to reduce the overall size of the device and reduce the cost of a single device. Furthermore, this structure is compatible with existing manufacturing processes and is easy to mass-produce. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of an electro-optic modulator provided in an embodiment of the present disclosure;

[0031] Figure 2 This is a schematic diagram of an optical waveguide structure provided in an embodiment of the present disclosure;

[0032] Figure 3 This is a schematic diagram of another electro-optic modulator provided in an embodiment of the present disclosure;

[0033] Figure 4 This is a cross-sectional view of an electro-optic modulator provided in an embodiment of this disclosure. Detailed Implementation

[0034] To make the technical solutions and advantages of the embodiments of this disclosure clearer, the technical solutions of this disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. Although exemplary implementation methods of this disclosure are shown in the accompanying drawings, it should be understood that this disclosure can be implemented in various forms and should not be limited to the implementation methods set forth herein. Rather, these implementation methods are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0035] The present disclosure is described in more detail below by way of example with reference to the accompanying drawings. The advantages and features of the present disclosure will become clearer from the following description and claims. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present disclosure.

[0036] It is understood that the meanings of “on”, “above” and “above” in this disclosure should be interpreted in the broadest sense, such that “on” means not only that it is “on” something without any intervening feature or layer (i.e., directly on something), but also that it is “on” something with an intervening feature or layer.

[0037] Furthermore, for ease of description, spatial relative terms such as “on,” “above,” “above,” “upper,” “above,” “upper,” etc., may be used herein to describe the relationship between one element or feature and another element or feature as shown in the figures. In addition to the orientations depicted in the figures, the spatial relative terms are intended to cover different orientations of the device in use or operation. The device may be oriented in other ways (rotated 90 degrees or in other orientations) and the spatial relative descriptive terms used herein may be interpreted accordingly.

[0038] In embodiments of this disclosure, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0039] In the embodiments of this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0040] It should be noted that the technical solutions described in the embodiments of this disclosure can be combined arbitrarily without conflict.

[0041] With the rapid development of the communications industry, whether it is the communication of data between massive numbers of users or the calculation and transmission of the resulting large amounts of data, electro-optic modulators are inevitably needed for modulation, which places higher demands on electro-optic modulators.

[0042] Silicon-based electro-optic modulators rely on the accumulation of low-cost silicon materials and silicon-based microelectronic chip technology, have mature production processes and a complete industrial chain, and are currently the mainstream commercial modulator solution, widely used in long-distance, ultra-high-speed data communication and ultra-large capacity data centers.

[0043] Currently, high-speed silicon-based electro-optic modulators typically employ a Mach-Zehnder interferometer in conjunction with a traveling wave electrode.

[0044] A Mach-Zehnder interferometer is used. The input optical signal is split into two beams, a first optical signal and a second optical signal, by a beam splitter. The two beams are then phase-modulated by a first optical waveguide and a second optical waveguide, respectively. Finally, the two modulated beams are combined by a beam combiner. According to the principle of light interference, the power of the output optical signal is determined by the phase difference between the first and second optical signals.

[0045] Utilizing the property that traveling wave electrodes are described using a transmission line model, an electrical signal propagates along the electrode at a certain velocity v. This electrical signal can be a radio frequency signal or a microwave signal. Simultaneously, the modulated optical signal also propagates in the optical waveguide at a certain group velocity v. g As the optical signal propagates along the optical waveguide, the phase change of the optical signal is continuously modulated and accumulated during transmission. During this process, the high-frequency attenuation of the radio frequency signal on the traveling wave electrode is relatively small. Therefore, the electro-optic modulator using the traveling wave electrode in conjunction with a Mach-Zehnder interferometer has advantages such as high modulation efficiency and high electro-optic modulation bandwidth.

[0046] However, for silicon-based electro-optic modulators with traveling-wave electrode structures, the high-frequency characteristics of the electro-optic modulator are determined by the characteristic impedance of the electro-optic modulator, the matching degree between the optical signal and the electrical signal speed, and the length of the modulation region. The characteristic impedance of the electro-optic modulator, the matching degree between the optical signal and the electrical signal speed, and the length of the modulation region are determined by the material properties and the optical waveguide structure. These types of electro-optic modulators generally have the problem that the characteristic impedance is lower than that of the driving system and the refractive index of the optical waveguide group is lower than that of the electrode group, which also leads to the low bandwidth of the electro-optic modulator.

[0047] Furthermore, the modulation efficiency of an electro-optic modulator is related to its modulation length. A longer phase modulation region can achieve higher modulation efficiency, which is a common method used in silicon-based electro-optic modulator design to reduce modulation voltage. However, due to the skin effect of the radio frequency signal in the traveling wave electrode, a longer phase modulation region means a longer traveling wave electrode, resulting in greater radio frequency signal attenuation. Simultaneously, it exacerbates the bandwidth attenuation caused by the speed mismatch between the electrical and optical signals, leading to a reduction in modulation bandwidth. This further restricts the bandwidth and modulation efficiency of silicon-based electro-optic modulators.

[0048] Based on this, the present disclosure provides an electro-optic modulator, which includes:

[0049] The electrode includes at least a linear first electrode and a second electrode; both the first electrode and the second electrode extend along a first direction.

[0050] An optical waveguide includes a curved first optical waveguide and a second optical waveguide; both the first optical waveguide and the second optical waveguide are located between a first electrode and a second electrode.

[0051] Points on the line segment of the first optical waveguide have a one-to-one orthogonal projection onto the straight line of the first electrode, and points on the straight line of the first electrode have a one-to-one orthogonal projection onto the straight line of the second optical waveguide, and points on the line segment of the second optical waveguide have a one-to-one orthogonal projection onto the straight line of the second electrode, and points on the straight line of the second electrode.

[0052] Here, the electro-optic modulator includes, but is not limited to, silicon-based electro-optic modulators.

[0053] Here, the optical waveguide is the medium that guides the transmission of optical signals. Through total internal reflection, the optical signals are confined to the optical waveguide and a limited area around it for transmission.

[0054] Here, the electrode is used to modulate the optical signal in the optical waveguide.

[0055] In some embodiments, the electro-optic modulator further includes an active region located between the first electrode and the second electrode.

[0056] In some embodiments, the electro-optic modulator further includes:

[0057] The beam splitter is connected to the input end of the first optical waveguide and the input end of the second optical waveguide, respectively.

[0058] The beam combiner is connected to the output terminals of the first optical waveguide and the second optical waveguide, respectively.

[0059] like Figure 1 As shown, Figure 1 This is a schematic diagram of an electro-optic modulator provided in an embodiment of the present disclosure. The electro-optic modulator includes an active region 100, a linear first electrode 101, a linear second electrode 102, a curved first optical waveguide 103, and a curved second optical waveguide 104. The active region 100, the first electrode 101, the second electrode 102, the first optical waveguide 103, and the second optical waveguide 104 are all located on a substrate. The first electrode 101 and the second electrode 102 both extend along a first direction, which is parallel to the surface of the substrate. For example, the first direction is... Figure 1 The X-axis direction is shown.

[0060] In some specific embodiments, the substrate may include a single-element semiconductor material substrate (e.g., a silicon (Si) substrate), a silicon-on-insulator (SOI) substrate, etc. In some specific embodiments, the substrate is silicon-on-insulator.

[0061] The electro-optic modulator also includes a beam splitter 201 and a beam combiner 202. The beam splitter 201 is connected to the input end of the first optical waveguide 103 and the input end of the second optical waveguide 104, respectively. The beam combiner 202 is connected to the output end of the first optical waveguide 103 and the output end of the second optical waveguide 104, respectively.

[0062] Understandably, the electro-optic modulator operates as follows: the input optical signal is split into two beams by beam splitter 201, and the two beams enter the electro-modulator for phase modulation via first optical waveguide 103 and second optical waveguide 104, respectively. Phase modulation occurs while an electrical signal is applied to the electrodes. The optical signal propagates in the optical waveguides, and the electrical signal propagates on the electrodes. During modulation, phase changes accumulate continuously, and the two modulated beams are finally output via combiner 202.

[0063] To achieve a high characteristic impedance design for the electro-optic modulation region and ensure that the impedance matches the impedance of the driving circuit or external system, it is often necessary to adjust the size and structure of the traveling wave electrode. In this case, the transmission speed of the electrical signal in the electrode and the transmission speed of the optical signal in the optical waveguide will be severely mismatched. Generally, the transmission speed of the electrical signal in the electrode will be slower than the transmission speed of the optical signal in the optical waveguide.

[0064] In electro-optic modulators with traveling-wave electrodes, the group refractive index of the electrodes is generally quite high. This group refractive index can be the microwave group refractive index; for example, the microwave group refractive index of the electrodes in silicon-based electro-optic modulators is typically around 5. Conversely, the group refractive index of optical waveguides is generally quite low; this group refractive index can be the mode group refractive index; for example, the mode group refractive index of a conventional silicon optical waveguide is typically around 4. This mismatch between the propagation speed of the electrical signal on the electrodes and the propagation speed of the optical signal in the optical waveguide (where the propagation speeds of the electrical and optical signals are equal to the speed of light divided by the group refractive index) necessitates a special design for the electro-optic modulator to match the propagation speed of the electrical signal on the electrodes with that of the optical signal in the optical waveguide; otherwise, a rapid attenuation of the electro-optic response bandwidth will occur.

[0065] The optical waveguide is designed to be curved, so that the physical length of the optical waveguide is greater than the physical length of the electrode. In other words, the distance that the optical signal travels in the optical waveguide is greater than the distance that the electrical signal travels in the electrode. In other words, in the same amount of time, the equivalent distance that the optical signal travels in the direction where the electrode is located, that is, the first direction, is equal to the distance that the electrical signal travels in the first direction. This achieves the matching of the transmission speed of the electrical signal on the electrode with the transmission speed of the optical signal in the optical waveguide.

[0066] The points on the line segment of the first optical waveguide are projected onto the straight line containing the first electrode in a one-to-one correspondence with the points on the straight line containing the first electrode; similarly, the points on the line segment of the second optical waveguide are projected onto the straight line containing the second electrode in a one-to-one correspondence. This can be understood as the electrical signal being transmitted along the electrode plate, which extends along the first direction. Simultaneously, the optical signal is transmitted along the curve containing the optical waveguide. Because the projections of the points on the line segment of the optical waveguide onto the straight line containing the electrode in a one-to-one correspondence, in other words, the optical waveguide extends in the first direction without any backsliding. Therefore, the component of the speed of the optical signal transmitted in the optical waveguide in the first direction is always in the same direction as the electrical signal in the electrode.

[0067] This design allows the transmission speed of the electrical signal on the electrode to match the transmission speed of the optical signal in the optical waveguide in real time throughout the entire electro-optic modulation region.

[0068] However, the optical waveguide exhibits a "backward" behavior. This means that two or more points on the line segment of the optical waveguide correspond to the orthogonal projections of points on the line segment of the electrode. In other words, the optical signal in the optical waveguide experiences a "backward" phenomenon during transmission. Specifically, the velocity component of the optical signal propagating in the optical waveguide in the first direction may be opposite to the direction of the electrical signal in the electrode. When the velocity component of the optical signal propagating in the optical waveguide is opposite to the direction of the electrical signal in the electrode, at that moment, the transmission speed of the electrical signal on the electrode and the transmission speed of the optical signal in the optical waveguide are mismatched. In other words, throughout the entire modulation region of the electro-optic modulator, the transmission speed of the electrical signal on the electrode and the transmission speed of the optical signal in the optical waveguide are not matched in real time.

[0069] In some embodiments, the optical waveguide includes a wave-shaped structure; the wave-shaped structure is periodically reciprocating and extends along the first direction; the wave-shaped structure includes arcuate portions and / or straight portions.

[0070] Here, the first direction is parallel to the aforementioned substrate surface, and the second direction is perpendicular to the first direction and parallel to the substrate surface. For example, the first direction can be the X-axis direction, and the second direction can be the Y-axis direction.

[0071] It is understandable that by using a wave-shaped structure to periodically repeat and extend along the first direction, the distance of the optical waveguide projected along the second direction can be minimized while increasing the physical length of the optical waveguide. This reduces the projected length of the optical waveguide on the Y-axis, which can effectively reduce the distance between the first electrode 101 and the second electrode 102, thus facilitating the reduction of the electro-optic modulator's volume.

[0072] In some specific embodiments, the wavy structure may include an arc-shaped portion 1032 and a straight portion 1031, such as... Figure 2 The wave-shaped structure shown includes an arc-shaped portion 1032 and a straight portion 1031. In some other embodiments, the wave-shaped structure may include the arc-shaped portion 1032, in which case the shape of the optical waveguide is similar to a circular arc, a sine wave, or an Euler bend.

[0073] In some other embodiments, the wave-shaped structure may include a straight section 1031, in which case the shape of the optical waveguide is similar to a sawtooth wave.

[0074] It is understandable that when the optical waveguide is configured as a wave-shaped structure, and the wave-shaped structure reciprocates periodically and extends along the first direction, the effective transmission rate of the optical signal in the first direction is v. eff The effective rate v at this time eff The effective rate v is equal to the velocity of the electrical signal in the first direction. eff It can be understood as v g The velocity component in the first direction has the following relationship:

[0075] v eff =k×v g (k<1)

[0076] Here, k is a constant less than 1, the magnitude of which is determined by the design of the curved waveguide.

[0077] It is understandable that when the transmission speed of the optical signal in the optical waveguide along the first direction is the same as the transmission speed of the electrical signal in the electrode, the transmission speed of the electrical signal on the electrode and the transmission speed of the optical signal in the optical waveguide are matched in real time at any moment throughout the entire modulation region.

[0078] In some embodiments, the straight portion of the wavy structure forms a first angle with the first direction, and the first angle is related to the ratio of the group refractive index of the optical waveguide to the group refractive index of the electrode.

[0079] Here, the straight portion of the wavy structure forms a first angle θ with the first direction. In some specific examples, the equivalent length of the optical waveguide can be increased by changing θ, thereby controlling the value of the constant k to be around 0.8. At this time, the mode group refractive index of the optical waveguide is around 4, and according to k, the equivalent refractive index of the optical waveguide is 4 / 0.8 = 5, while the microwave group refractive index of the electrode is around 5, which matches the group refractive index of the electrode.

[0080] When the optical waveguide is curved, the physical length of the electrode corresponding to the optical waveguide along the first direction is L1, and the physical length of the electrode corresponding to the straight optical waveguide of the same length along the first direction is L2. At this time, L1 = k × L2. In other words, the curved optical waveguide effectively reduces the physical length of the electrode, reduces the device size, reduces the loss of electrical signals on the electrode, and improves the modulation efficiency and modulation bandwidth of the electro-optic modulator.

[0081] In some embodiments, the first optical waveguide and the second optical waveguide are symmetrical about a central axis, which is parallel to the first direction and is equidistant from the first electrode and the second electrode.

[0082] Understandably, this symmetrical design is advantageous for controlling the phase difference between the optical signals on the first and second optical waveguides. Based on the principles of destructive and constructive interference in light, the phase information is converted into intensity information, thereby easily achieving modulation of the output optical signal.

[0083] In practical applications, the impedance of the external system to be matched is a fixed value, such as 100Ω. In addition to increasing the characteristic impedance of the modulation region through a curved optical waveguide design, the characteristic impedance of the modulation region can also be increased through electrodes to meet the 100Ω impedance matching requirement of the external system.

[0084] The characteristic impedance of electro-optic modulators in related technologies is usually around 70Ω. If the electro-optic modulator in the prior art is matched with the 100Ω impedance of the external system, some other performance indicators, such as half-wave voltage, modulation width, and modulation efficiency, will be greatly sacrificed. In this embodiment, by using the curved design of the optical waveguide and the matching electrodes, the characteristic impedance of the electro-optic modulator can reach 90Ω without sacrificing other performance indicators, so as to match the 100Ω impedance of the external system.

[0085] In some embodiments, the optical waveguide includes a ridge waveguide.

[0086] Understandably, in practical applications, different types of optical waveguides, such as strip waveguides, ridge waveguides, and planar waveguides, can be selected depending on the application scenario of the electro-optic modulator and the structure of the optical waveguide.

[0087] In some specific embodiments, the electrode is a traveling wave electrode.

[0088] For example, such as Figure 1 As shown, the electrode includes a first electrode 101 and a second electrode 102. The first electrode 101 and the second electrode 102 are directly connected to the active region and act on the optical waveguide by applying voltage or circuit through the active region.

[0089] In some embodiments, the electrode includes: a first electrode, a second electrode, a plurality of first connection structures connected to the first electrode, and a plurality of second connection structures connected to the second electrode; the first electrode acts on the optical waveguide through the plurality of first connection structures, and the second electrode acts on the optical waveguide through the plurality of second connection structures.

[0090] For example, such as Figure 3 As shown, the electrode includes: a first electrode 101, a second electrode 102, a plurality of first connection structures 1011 connected to the first electrode 101, and a plurality of second connection structures 1021 connected to the second electrode 102. The connection structures 1011 and 1021 are connected to the active region, and the electrode acts on the active region through the connection structures, thereby acting on the optical waveguide.

[0091] In some embodiments, the active region includes:

[0092] An active region is located between the first electrode and the second electrode; the active region includes: a first doped region, a second doped region, and a third doped region; wherein,

[0093] The first doped region is located between the first electrode and the first optical waveguide;

[0094] The second doped region is located between the first optical waveguide and the second optical waveguide;

[0095] The third doped region is located between the second optical waveguide and the second electrode;

[0096] The doping type of the second doped region is different from that of the first doped region and the third doped region.

[0097] In some embodiments, the first doped region and the third doped region are P-type doped, and the second doped region is N-type doped; or...

[0098] The first doped region and the third doped region are of N-type doping, and the second doped region is of P-type doping.

[0099] For example, the first doped region 105 and the third doped region 106 are P-type doped, and the second doped region 107 is N-type doped; or, the first doped region 105 and the third doped region 106 are N-type doped, and the second doped region 107 is P-type doped. For example, boron can be used as an impurity for P-type doping, and phosphorus can be used as an impurity for N-type doping.

[0100] Here, the optical waveguide can also be a semiconductor with different doping types, where the PN junction is located at the centerline of the optical waveguide, such as... Figure 2 As shown, Figure 2 This is a schematic diagram of an optical waveguide provided in an embodiment of the present disclosure. When the optical waveguide is straight, the center line is the straight line AA' in the figure; when the optical waveguide is curved, the center line is the curve AA' in the figure.

[0101] Here, the portion of the optical waveguide near the first doped region has the same doping type as the first doped region, the portion near the second doped region has the same doping type as the second doped region, and the portion near the third doped region has the same doping type as the third doped region.

[0102] During the operation of the electro-optic modulator, a DC bias voltage is applied to the second doped region 107. According to the properties of the PN junction, a depletion region will be formed in the optical waveguide at this time, and the concentration distribution of charge carriers will change with the voltage magnitude of the first and third doped regions.

[0103] The electrical signal acts on the central region of the optical waveguide, that is, the region near the centerline of the optical waveguide, through the first doped region, the second doped region, and the third doped region, changing the concentration distribution of charge carriers. Through the carrier dispersion effect or the electro-optic effect, the refractive index distribution of the optical waveguide is changed, thereby realizing the phase modulation of the optical signal.

[0104] In some embodiments, the doping concentration of the first doped region decreases along a second direction; the second direction is perpendicular to the first direction and extends from the first doped region to the second doped region.

[0105] The doping concentration in the second doped region first increases and then decreases along the second direction;

[0106] The doping concentration of the third doped region increases along the second direction.

[0107] The concentration variation in the doped region here is stepwise, meaning that the doping concentration is constant within a certain range, but varies with the doping concentration in adjacent ranges.

[0108] like Figure 4 As shown, Figure 4 This is a cross-sectional view of an electro-optic modulator provided in an embodiment of this disclosure. The cross-section is parallel to a third direction, which is perpendicular to both the first and second directions, and is perpendicular to the surface of the substrate. For example, the third direction can be the Z-axis direction. The active region includes a first doped region 105, a first optical waveguide 103, a second doped region 107, a second optical waveguide 104, and a third doped region 106. The doping concentration of the first doped region 105 decreases along a second direction; the second direction is perpendicular to the first direction and extends from the first doped region to the second doped region.

[0109] Here, the first direction is perpendicular to the plane of the paper, and the second direction is perpendicular to the first direction and points from the first doped region to the second doped region. For example, the second direction is the positive Y-axis direction. The decrease in doping concentration along the second direction in the first doped region can be understood as the first doped region 105 including regions 1 and 2, with the doping concentration of region 1 being higher than that of region 2. Similarly, the first optical waveguide 103 includes regions 3 and 4, the second doped region 107 includes regions 5, 6, and 7, the second optical waveguide 104 includes regions 8 and 9, and the third doped region includes regions 10 and 11. In this case, the doping concentration of region 5 is lower than that of region 6, the doping concentration of region 6 is higher than that of region 7, and the doping concentration of region 10 is lower than that of region 11.

[0110] For example, the first doped region is P-type. In this case, the doping types and concentrations of regions 1-11 are as follows: ultra-high concentration P-type doping, medium concentration P-type doping, low concentration P-type doping, low concentration N-type doping, medium concentration N-type doping, ultra-high concentration N-type doping, medium concentration N-type doping, low concentration N-type doping, low concentration P-type doping, medium concentration P-type doping, and ultra-high concentration P-type doping. The ultra-high concentration is 1 × 10⁻⁶. 20 cm -3 The medium concentration is 5×10 18 cm -3 The low concentration is 2×10 17 cm -3 .

[0111] It is understandable that the different doping concentrations in the first, second, and third doping regions are more conducive to controlling the distribution of carrier concentration in the optical waveguide.

[0112] This disclosure provides an electro-optic modulator, comprising: electrodes, including at least a linear first electrode and a second electrode; both the first electrode and the second electrode extend along a first direction; and an optical waveguide, including a curved first optical waveguide and a curved second optical waveguide; both the first optical waveguide and the second optical waveguide are located between the first electrode and the second electrode; the orthographic projection of a point on the line segment of the first optical waveguide onto the line where the first electrode is located corresponds one-to-one with the point on the line where the first electrode is located; the orthographic projection of a point on the line segment of the second optical waveguide onto the line where the second electrode is located corresponds one-to-one with the point on the line where the second electrode is located. The electro-optic modulator provided in this disclosure, by setting the curved first optical waveguide and the second optical waveguide as the phase modulation region structure of the modulator, firstly, effectively shortens the length of the corresponding electrodes, resulting in less signal loss; secondly, the curved optical waveguide increases the capacitance between the optical waveguide and the electrode, thereby affecting the characteristic impedance of the modulation region of the electro-optic modulator to meet impedance matching with the external system; thirdly, the reduced electrode length helps to reduce the overall device size and lower the cost of a single device; and the structure is compatible with existing manufacturing processes and is easy to mass-produce.

[0113] The features disclosed in the several method or device embodiments provided in this disclosure can be arbitrarily combined without conflict to obtain new method or device embodiments.

[0114] This disclosure provides specific embodiments, but its scope of protection is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed herein should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. An electro-optic modulator, characterized by Comprising: electrodes, at least including a first electrode and a second electrode; the first electrode and the second electrode both extend along a first direction; optical waveguides, including a first optical waveguide and a second optical waveguide; the first optical waveguide and the second optical waveguide are both located between the first electrode and the second electrode; a point on a line segment of the first optical waveguide corresponds to a point on a straight line of the first electrode in a one-to-one manner; a point on a line segment of the second optical waveguide corresponds to a point on a straight line of the second electrode in a one-to-one manner; the optical waveguides include a wave structure; the wave structure extends along the first direction in a periodic manner; the wave structure includes a straight line portion or the wave structure includes an arc portion and a straight line portion; a straight line portion of the wave structure forms a first included angle with the first direction; the first included angle is related to a ratio of a group refractive index of the optical waveguides to a group refractive index of the electrodes.

2. The electro-optic modulator of claim 1, wherein, A transmission speed of an optical signal in the optical waveguides along the first direction is the same as a transmission speed of an electrical signal in the electrodes.

3. The electro-optical modulator according to claim 2, wherein: the first optical waveguide and the second optical waveguide are symmetrical about a central axis; the central axis is parallel to the first direction and equal to a distance between the first electrode and the second electrode.

4. The electro-optic modulator of claim 1, wherein, The electro-optical modulator further comprises: an active region located between the first electrode and the second electrode; the active region includes a first doped region, a second doped region and a third doped region; wherein: the first doped region is located between the first electrode and the first optical waveguide; the second doped region is located between the first optical waveguide and the second optical waveguide; the third doped region is located between the second optical waveguide and the second electrode; a doping type of the second doped region is different from doping types of the first doped region and the third doped region.

5. The electro-optical modulator according to claim 4, wherein: the doping types of the first doped region and the third doped region are P type and the doping type of the second doped region is N type; or the doping types of the first doped region and the third doped region are N type and the doping type of the second doped region is P type.

6. The electro-optical modulator according to claim 4, wherein: the electrodes include the first electrode and the second electrode; the first electrode and the second electrode both act on the optical waveguides; or the electrodes include the first electrode, the second electrode, a plurality of first connecting structures connected to the first electrode and a plurality of second connecting structures connected to the second electrode; the first electrode acts on the optical waveguides through the plurality of first connecting structures and the second electrode acts on the optical waveguides through the plurality of second connecting structures. The optical waveguides include ridge optical waveguides.

7. The electro-optic modulator of claim 1, wherein, The electro-optical modulator further comprises:

8. The electro-optic modulator of claim 1, wherein, a beam splitter connected to an input end of the first optical waveguide and an input end of the second optical waveguide respectively; ​ A combiner is connected to the output end of the first optical waveguide and the output end of the second optical waveguide, respectively.

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