CN115774345A - Electro-optic modulator - Google Patents
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Abstract
An embodiment of the present disclosure discloses an electro-optical modulator, including: electrodes including at least linear first and second electrodes; the first electrode and the second electrode both extend in a first direction; an optical waveguide including a first optical waveguide and a second optical waveguide which are bent; the first optical waveguide and the second optical waveguide are both positioned between the first electrode and the second electrode; the orthographic projection of a point on a line segment where the first optical waveguide is located on a straight line where the first electrode is located corresponds to the point of the straight line where the first electrode is located one by one; the orthographic projection of a point on the line segment where the second optical waveguide is located on the straight line where the second electrode is located corresponds to the point of the straight line where the second electrode is located one by one.
Description
Technical Field
The embodiment of the disclosure relates to the technical field of optical communication, in particular to an electro-optical modulator.
Background
With the rapid development of the communication industry, both the communication of data among massive users and the calculation and transmission of a large amount of data generated thereby inevitably require an electro-optical modulator for modulation, and also impose higher speed requirements on the electro-optical modulator.
However, in the process of modulating light, there are problems of low modulation bandwidth and low modulation efficiency.
Disclosure of Invention
In view of this, the present disclosure provides an electro-optical modulator.
An electro-optic modulator according to the present disclosure includes:
electrodes including at least a first electrode and a second electrode in a linear shape; the first electrode and the second electrode both extend in a first direction;
an optical waveguide including a first optical waveguide and a second optical waveguide which are bent; the first optical waveguide and the second optical waveguide are both positioned between the first electrode and the second electrode;
the orthographic projection of a point on a line segment where the first optical waveguide is located on a straight line where the first electrode is located corresponds to the point of the straight line where the first electrode is located one by one; and the orthographic projection of a point on the line segment of the second optical waveguide on the straight line of the second electrode corresponds to the point of the straight line of the second electrode one by one.
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.
In the above scheme, the optical waveguide includes a waved structure; the wavy structure is periodically reciprocated and extends along the first direction. The undulating structure comprises arcuate portions and/or linear portions.
In the above scheme, a first included angle is formed between the linear part of the wavy structure and the first direction, and the first included angle is related to the ratio of the group refractive index of the optical waveguide to the group refractive index of the electrode.
In the above scheme, the first optical waveguide and the second optical waveguide are symmetrical with respect to a central axis, and the central axis is parallel to the first direction and is equal to a distance between the first electrode and the second electrode.
In the above scheme, the electro-optical modulator further includes:
an active region 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 positioned between the first electrode and the first optical waveguide;
the second doped region is positioned between the first optical waveguide and the second optical waveguide;
the third doped region is positioned between the second optical waveguide and the second electrode;
the second doped region has a doping type different from the doping types of the first doped region and the third doped region.
In the above-mentioned scheme, the first step of the method,
the doping types of the first doping area and the third doping area are P type and the doping type of the second doping area is N type; or,
the doping type of the first doping area and the doping type of the third doping area are N type, and the doping type of the second doping area is P type.
In the above scheme, the electrodes include the first electrode and the second electrode; the first electrode and the second electrode both act on the optical waveguide;
or,
the electrode includes: the first electrode, the 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.
In the above aspect, the optical waveguide includes a ridge optical waveguide.
In the above scheme, the electro-optical modulator further includes:
the beam splitter is respectively connected with the input end of the first optical waveguide and the input end of the second optical waveguide;
and the beam combiner is respectively connected with the output end of the first optical waveguide and the output end of the second optical waveguide.
In embodiments of the present disclosure, an electro-optic modulator is provided, comprising: electrodes including at least a first electrode and a second electrode in a linear shape; the first electrode and the second electrode both extend in a first direction; an optical waveguide including a first optical waveguide and a second optical waveguide which are bent; the first optical waveguide and the second optical waveguide are both positioned between the first electrode and the second electrode; the orthographic projection of a point on a line segment where the first optical waveguide is located on a straight line where the first electrode is located corresponds to the point of the straight line where the first electrode is located one by one; the orthographic projection of a point on the line segment where the second optical waveguide is located on the straight line where the second electrode is located corresponds to the point of the straight line where the second electrode is located one by one. The electro-optical modulator provided by the embodiment of the disclosure uses the first curved optical waveguide and the second curved optical waveguide as the phase modulation region structure of the modulator, firstly, the length of the electrodes matched with the first curved optical waveguide is effectively shortened, the loss of electric signals can be reduced due to the shorter length of the electrodes, secondly, the capacitance of the optical waveguide between the electrodes is increased due to the curved optical waveguide, so that the characteristic impedance of the modulation region of the electro-optical modulator is influenced to meet the impedance matching with an external system, thirdly, the reduced length of the electrodes is beneficial to reducing the overall size of the device, the cost of a single device is reduced, and the structure is compatible with the existing process manufacturing flow and is easy to manufacture in batches.
Drawings
Fig. 1 is a schematic structural diagram of an electro-optic modulator according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of an optical waveguide according to an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of another electro-optic modulator provided by an embodiment of the present disclosure;
FIG. 4 is a cross-sectional view of an electro-optic modulator provided by an embodiment of the present disclosure.
Detailed Description
In order to make the technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the present disclosure will be further elaborated with reference to the drawings and the embodiments. While exemplary implementations of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The present disclosure is more particularly described in the following paragraphs with reference to the accompanying drawings by way of example. Advantages and features of the present disclosure will become apparent from the following description and claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present disclosure.
It is understood that the meaning of "on 8230; \8230on," \8230, above "\8230; \8230, above" and "on 8230, above \8230shouldbe read in the broadest manner in this disclosure, such that" on 8230 "; above 8230not only means that it is" on something "with no intervening features or layers therebetween (i.e., directly on something), but also includes the meaning of" on "something with intervening features or layers therebetween.
Moreover, spatially relative terms such as "on 8230; \8230; above", "on 8230; above", "on", "upper", etc., may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
In the embodiments of the present disclosure, the terms "first", "second", and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present disclosure, "a plurality" means two or more and, unless specifically limited otherwise.
In the embodiments of the present disclosure, unless otherwise explicitly stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present disclosure can be understood as a specific case by a person of ordinary skill in the art.
The technical means described in the embodiments of the present disclosure may be arbitrarily combined without conflict.
With the rapid development of the communication industry, both the communication of data among massive users and the calculation and transmission of massive data generated thereby inevitably require an electro-optical modulator for modulation, which puts higher requirements on the electro-optical modulator.
The silicon-based electro-optical modulator relies on the process technology accumulation of low-cost silicon materials and silicon-based microelectronic chips, has mature production flow and complete industrial chain, is the current mainstream commercial modulator scheme, and is widely applied to long-distance and ultra-high-speed data communication and ultra-large-capacity data centers.
At present, a high-speed silicon-based electro-optical modulator usually adopts a Mach-Zehnder interferometer matched with a traveling wave electrode.
The Mach-Zehnder interferometer is adopted, an input optical signal is divided into two beams of a first optical signal and a second optical signal through a beam splitter, the two beams of the first optical signal and the second optical signal are subjected to phase modulation through a first optical waveguide and a second optical waveguide respectively, and the two modulated optical signals are combined through a beam combiner finally. According to the principle of optical interference, the power of the output optical signal is determined by the magnitude of the phase difference between the first optical signal and the second optical signal.
The method comprises the following steps of utilizing the property that a traveling wave electrode is described by adopting a transmission line model, and transmitting an electric signal on the electrode at a certain speed v, wherein the electric signal can be a radio frequency signal or an electric microwave signal; the optical signal modulated at the same time is likewise at a constant group velocity v in the optical waveguide g The phase change of the optical signal is continuously modulated and accumulated during the transmission along the optical waveguide. In the process, modulation phase changes are accumulated, and high-frequency attenuation of radio-frequency signals on the traveling wave electrode is small, so that the electro-optical modulator with the traveling wave electrode matched with the Mach-Zehnder interferometer has the performance advantages of high modulation efficiency, high electro-optical modulation bandwidth and the like.
However, for the silicon-based electro-optical modulator with the traveling wave electrode structure, the characteristic impedance of the electro-optical modulator, the matching degree of the speed of the optical signal and the electrical signal, and the length of the modulation region determine the high-frequency characteristics of the electro-optical modulator, and the characteristic impedance of the electro-optical modulator, the matching degree of the speed of the optical signal and the electrical signal, and the length of the modulation region are determined by the material characteristics and the optical waveguide structure, the electro-optical modulator generally has the problems that the characteristic impedance is lower than that of a driving system, and the refractive index of an optical waveguide group is lower than that of an electrode group, which also results in that the bandwidth of the electro-optical modulator is lower.
Further, the modulation efficiency of the electro-optical modulator is related to the modulation length of the modulator, and a longer phase modulation region can achieve higher modulation efficiency, which is also a commonly used method for reducing modulation voltage in the silicon-based electro-optical modulator design, but due to the skin effect of the radio-frequency signal in the traveling wave electrode, the longer phase modulation region means a longer traveling wave electrode, so that a larger attenuation of the radio-frequency signal is caused, and meanwhile, the bandwidth attenuation caused by the mismatch of the speed of the electrical signal and the speed of the optical signal is increased, and the modulation bandwidth is reduced. Thus, the bandwidth and modulation efficiency of the silicon-based electro-optic modulator are further limited.
Based on this, the present disclosure provides an electro-optical modulator comprising:
electrodes including at least a first electrode and a second electrode in a linear shape; the first electrode and the second electrode extend along a first direction;
an optical waveguide including a first optical waveguide and a second optical waveguide in a curved shape; the first optical waveguide and the second optical waveguide are both positioned between the first electrode and the second electrode;
the orthographic projection of a point on a line segment where the first optical waveguide is located on a straight line where the first electrode is located corresponds to the point of the straight line where the first electrode is located one by one; the orthographic projection of the point on the line segment where the second optical waveguide is located on the straight line where the second electrode is located corresponds to the point on the straight line where the second electrode is located one by one.
Here, the electro-optic modulator includes, but is not limited to, a silicon-based electro-optic modulator.
Here, the optical waveguide is a medium in which a light signal is guided to travel, and the light signal is transmitted while being confined in the optical waveguide and a limited region around the optical waveguide by a total reflection phenomenon.
Here, the electrode is used to modulate an optical signal in the optical waveguide.
In some embodiments, the electro-optic modulator further comprises an active region between the first electrode and the second electrode.
In some embodiments, the electro-optic modulator further comprises:
the beam splitter is respectively connected with the input end of the first optical waveguide and the input end of the second optical waveguide;
and the beam combiner is respectively connected with the output end of the first optical waveguide and the output end of the second optical waveguide.
As shown in fig. 1, fig. 1 is a schematic structural diagram of an electro-optical modulator according to an embodiment of the present disclosure. The electro-optical 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, where 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 each extend in a first direction, where the first direction is parallel to the surface of the substrate. Illustratively, the first direction here is the X-axis direction shown in fig. 1.
In some embodiments, the substrate may comprise an elemental semiconductor material substrate (e.g., a Silicon (Si) substrate), a Silicon On Insulator (SOI) substrate, or the like. In some embodiments, the substrate is a silicon-on-insulator.
The electro-optical modulator further comprises a beam splitter 201 and a beam combiner 202, wherein 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; and a beam combiner 202 connected to the output end of the first optical waveguide 103 and the output end of the second optical waveguide 104, respectively.
It can be understood that the work flow of the electro-optical modulator is as follows: the input optical signal is divided into two beams by the beam splitter 201, the two beams of optical signals respectively enter the electric modulator through the first optical waveguide 103 and the second optical waveguide 104 for phase modulation, and the phase modulation process is performed under the action of the electric signal loaded on the electrode. Optical signals are transmitted in the optical waveguide, electric signals are transmitted on the electrodes, phase change accumulation is continuously carried out in the modulation process, and two modulated optical signals are finally output through the beam combiner 202.
In order to realize the high characteristic impedance design of the electro-optical modulation region and meet the requirement that the impedance is matched with the impedance of a driving circuit or an external system, the size and the structure of the traveling wave electrode are often required to be adjusted, at this time, the transmission speed of an electrical signal in the electrode is seriously mismatched with the transmission speed of an optical signal in the optical waveguide, and the transmission speed of the electrical signal in the electrode is generally slower than that of the optical signal in the optical waveguide.
The refractive index of the group of electrodes in the traveling wave electrode electro-optical modulator is generally larger, and the refractive index of the group of electrodes can be the refractive index of the microwave group of electrodes, for example, the refractive index of the microwave group of electrodes in the silicon-based electro-optical modulator is generally about 5; the group refractive index of the optical waveguide is generally relatively small, and the group refractive index of the optical waveguide here may be a mode group refractive index of the optical waveguide, for example, the mode group refractive index of a conventional silicon optical waveguide is generally about 4. This results in a mismatch between the transmission speed of the electrical signal at the electrode and the transmission speed of the optical signal in the optical waveguide, where the transmission speeds of the electrical and optical signals are equal to the speed of light divided by the group index of refraction. Therefore, the electro-optic modulator needs to be specially designed to match the transmission speed of the electrical signal on the electrodes to that of the optical signal in the optical waveguide, which would otherwise cause a rapid attenuation of the electro-optic response bandwidth.
The optical waveguide is designed to be curvilinear, so that the physical length of the optical waveguide is greater than that of the electrode, that is, the distance traveled by the optical signal in the optical waveguide is greater than that traveled by the electrical signal in the electrode, in other words, in the same time, the equivalent distance traveled by the optical signal in the direction of the electrode, that is, in the first direction is equal to the distance traveled by the electrical signal in the first direction, and therefore the transmission speed of the electrical signal on the electrode is matched with the transmission speed of the optical signal in the optical waveguide.
Enabling orthographic projections of points on the line segment of the first optical waveguide on the straight line of the first electrode to correspond to the points of the straight line of the first electrode one by one; the orthographic projection of a point on a line segment where the second optical waveguide is located on a straight line where the second electrode is located corresponds to a point on a straight line where the second electrode is located one by one, and the orthographic projection can be understood that an electric signal is transmitted on an electrode plate, the electrode plate extends along a first direction, and the electric signal is transmitted along the first direction; meanwhile, the optical signal is transmitted along the curve in which the optical waveguide is located, because the orthographic projection of the point on the line segment in which the optical waveguide is located on the straight line in which the electrode is located corresponds to the point on the straight line in which the electrode is located one by one, in other words, the optical waveguide extends towards the first direction, and the situation of folding back does not occur, the component direction of the speed of the optical signal transmitted in the optical waveguide in the first direction is always the same as the direction of the electric signal in the electrode.
The design can make the transmission speed of the electric signal on the electrode match with the transmission speed of the optical signal in the optical waveguide in real time in the whole electro-optical modulation region.
And the optical waveguide is folded back, that is, the orthographic projection of two or more points on the line segment of the optical waveguide on the straight line of the electrode corresponds to the points on the straight line of the electrode, that is, the optical signal in the optical waveguide is folded back in the transmission process, that is, the direction of the component of the speed of the optical signal transmitted in the optical waveguide in the first direction is opposite to the direction of the electrical signal in the electrode. When the direction of the component of the speed of the optical signal transmitted in the optical waveguide in the first direction is opposite to the direction of the electrical signal in the electrode, at this time, the transmission speed of the electrical signal on the electrode does not match the transmission speed of the optical signal in the optical waveguide, that is, the transmission speed of the electrical signal on the electrode does not match the transmission speed of the optical signal in the optical waveguide in real time throughout the modulation region of the electro-optical modulator.
In some embodiments, the optical waveguide comprises a waved structure; the wavy structure is periodically reciprocated and extends along the first direction; the undulating structure comprises arcuate portions and/or linear portions.
Here, the first direction is parallel to the surface of the aforementioned substrate, and the second direction is perpendicular to the first direction and parallel to the surface of the substrate. For example, the first direction may be an X-axis direction, and the second direction may be a Y-axis direction.
It can be understood that, by the wave-shaped structure periodically reciprocating and extending along the first direction, the distance projected by the optical waveguide along the second direction can be reduced as much as possible on the basis of increasing the physical length of the optical waveguide, so as to reduce the projected length of the optical waveguide on the Y axis, and reducing the projected length of the optical waveguide on the Y axis can effectively reduce the distance between the first electrode 101 and the second electrode 102, which is beneficial to reducing the volume of the electro-optical modulator.
In some embodiments, the undulating structure may include arcuate portions 1032 and linear portions 1031, and the undulating structure shown in fig. 2 includes arcuate portions 1032 and linear portions 1031. In other embodiments, the undulating configuration may include arcuate portions 1032 in which case the shape of the optical waveguide resembles an arc of a circle or a sine wave or euler curve.
In other embodiments, the undulating structure may include a straight portion 1031, in which case the optical waveguide is shaped like a sawtooth.
It will be appreciated that the optical waveguide is arranged in a wavelike configuration; when the wave-shaped structure is periodically reciprocated and extends along the first direction, the effective speed rate of the optical signal transmission in the first direction is v eff At the effective velocity v eff Equal to the velocity of the electrical signal in the first direction, the effective velocity v eff Can be understood as v g The component velocity in the first direction, which has the following relationship:
v eff ＝k×v g (k<1)
here, k is a constant less than 1, the magnitude of which is determined by the design of the curved waveguide.
It will be appreciated that the speed of transmission of the optical signal in said optical waveguide in said first direction is the same as the speed of transmission of the electrical signal in said electrode, and that the speed of transmission of the electrical signal on the electrode is matched in real time to the speed of transmission of the optical signal in the optical waveguide at any time throughout the modulation region.
In some embodiments, the straight portions of the waved structure form a first angle with the first direction, the first angle being related to a ratio of a group refractive index of the optical waveguide to a group refractive index of the electrode.
Here, the straight line part of the waved structure forms a first included angle θ with the first direction, and in some specific examples, the equivalent length of the optical waveguide can be increased by changing θ, so that the value of the constant k is controlled to be 0.8. In this case, the mode group refractive index of the optical waveguide is about 4, the equivalent refractive index of the optical waveguide obtained from k is 4/0.8=5, and the microwave group refractive index of the electrode is about 5, matching the group refractive index of the electrode.
When the optical waveguide is curved, the physical length of the electrode corresponding to the optical waveguide along the first direction is L 1 The physical length of the electrodes corresponding to the linear optical waveguides with the same length along the first direction is L 2 At this time L 1 ＝k×L 2 In other words, the curved optical waveguide arrangement effectively reduces the physical length of the electrode, reduces the device volume, reduces the loss of the electrical signal on the electrode, and improves the modulation efficiency and the modulation bandwidth of the electro-optical modulator.
In some embodiments, the first optical waveguide and the second optical waveguide are symmetric about a central axis parallel to the first direction and equidistant between the first electrode and the second electrode.
It can be understood that such a symmetrical design is advantageous to control the phase difference between the optical signals on the first optical waveguide and the second optical waveguide, and the phase information is converted into intensity information according to the principle of cancellation and constructive interference in light, so as to easily implement the modulation of the output optical signal.
In practical applications, the impedance of the external system to be matched is a fixed resistance, such as 100 Ω. Besides increasing the characteristic impedance of the modulation region through the curved optical waveguide design, the characteristic impedance of the modulation region can also be increased through the electrodes, so that the 100 omega impedance matching requirement of an external system is met.
The characteristic impedance of the electro-optical modulator in the related art is usually about 70 Ω, and if the electro-optical modulator in the prior art is matched with the impedance of 100 Ω of the external system, some other performance indexes, such as half-wave voltage, modulation width, modulation efficiency, etc., will be greatly sacrificed.
In some embodiments, the optical waveguide comprises a ridge waveguide.
It is understood that different types of optical waveguides, such as a strip waveguide structure, a ridge waveguide structure, and a slab waveguide structure, may be selected according to different application scenarios and different optical waveguide structures of the electro-optic modulator in practical applications.
In some specific embodiments, the electrode is a traveling wave electrode.
Illustratively, as shown in fig. 1, the electrode includes: the light guide plate comprises a first electrode 101 and a second electrode 102, wherein the first electrode 101 and the second electrode 102 are both directly connected with an active area, and a voltage or a circuit is applied to the light guide through the active area.
In some embodiments, the electrode comprises: the first electrode, the 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.
Illustratively, as shown in fig. 3, the electrode includes: the light guide plate comprises a first electrode 101, a second electrode 102, a plurality of first connecting structures 1011 connected with the first electrode 101 and a plurality of second connecting structures 1021 connected with the second electrode 102, wherein the connecting structures 1011 and 1021 are connected with an active area, and the electrodes act on the active area through the connecting structures so as to act on the light guide.
In some embodiments, the active region comprises:
an active region between the first electrode and the second electrode; the active region includes: the first doping area, the second doping area and the third doping area; wherein,
the first doped region is positioned between the first electrode and the first optical waveguide;
the second doped region is positioned between the first optical waveguide and the second optical waveguide;
the third doped region is positioned between the second optical waveguide and the second electrode;
the second doped region has a doping type different from the doping types of the first doped region and the third doped region.
In some embodiments, the doping type of the first and third doping regions is P-type and the doping type of the second doping region is N-type; or,
the doping type of the first doping area and the doping type of the third doping area are N type, and the doping type of the second doping area is P type.
Illustratively, the first doped region 105 and the third doped region 106 are doped P-type, and the second doped region 107 is doped N-type; alternatively, the first doped region 105 and the third doped region 106 are doped N-type, and the second doped region 107 is doped P-type. For example, the P-type doping may use boron as an impurity, and the N-type doping may use phosphorus as an impurity.
Here, the optical waveguide may also be a semiconductor with different doping types, where the PN boundary line is located at a middle line of the optical waveguide, as shown in fig. 2, fig. 2 is a schematic structural diagram of an optical waveguide provided in the embodiment of the present disclosure, where when the optical waveguide is a straight line, the middle line is a straight line AA'; when the optical waveguide is of a curved type, the central line is a curve AA' in the figure.
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.
During the operation of the electro-optic modulator, a dc bias is applied to the second doped region 107, and according to the properties of the PN junction, a depletion region is formed in the optical waveguide, and the concentration distribution of carriers changes with the voltage of the first doped region and the third doped region.
The electric signal acts on the central area of the optical waveguide, namely the area near the central line of the optical waveguide through the first doping area, the second doping area and the third doping area, so that the concentration distribution of carriers is changed, and the refractive index distribution of the optical waveguide is changed through the carrier dispersion effect or the electro-optical effect, so that the phase modulation of the optical signal is realized.
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 points from the first doped region to the second doped region;
the doping concentration of the second doping region is increased along the second direction and then decreased;
the doping concentration of the third doped region increases along the second direction.
The concentration variation of the doped region is stepwise, that is, the doping concentration in a certain interval is constant, and the doping concentration in the adjacent interval varies.
Fig. 4 is a cross-sectional view of an electro-optic modulator provided by an embodiment of the present disclosure, as shown in fig. 4. The cross section is parallel to a third direction perpendicular to both the first direction and the second direction, and perpendicular to the surface of the substrate. For example, the third direction may be a Z-axis direction. The active region comprises 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, and the doping concentration of the first doped region 105 is reduced along a second direction; the second direction is perpendicular to the first direction and is directed from the first doped region to the second doped region.
Here the first direction is perpendicular to the direction of the paper and the second direction is perpendicular to the first direction and directed from the first doped region to the second doped region, which is exemplarily a positive Y-axis direction. The doping concentration of the first doping region decreases in the second direction, which can be understood as that the first doping region 105 includes a region 1 and a region 2, and the doping concentration of the region 1 is higher than that of the region 2. Similarly, the first optical waveguide 103 includes region 3 and region 4, the second doped region 107 includes region 5, region 6 and region 7, the second optical waveguide 104 includes region 8 and region 9, and the third doped region includes region 10 and region 11, where the doping concentration of region 5 is lower than the doping concentration of region 6, the doping concentration of region 6 is higher than the doping concentration of region 7, and the doping concentration of region 10 is lower than the doping concentration of region 11.
Illustratively, the doping type of the first doping region is P-type, and the doping types and doping concentrations of the regions 1 to 11 are: ultra-high concentration P-type doping, medium 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 P-type doping, medium concentration P-type doping, ultra-high concentration P-type dopingAnd (4) mixing. Wherein the ultrahigh concentration is 1 × 10 20 cm -3 Medium concentration of 5X 10 18 cm -3 Low concentration of 2X 10 17 cm -3 。
It can be understood that the first doped region, the second doped region and the third doped region are more beneficial to controlling the distribution of the carrier concentration in the optical waveguide through different doping concentrations in the regions.
An embodiment of the present disclosure provides an electro-optical modulator, including: electrodes including at least linear first and second electrodes; the first electrode and the second electrode both extend in a first direction; an optical waveguide including a first optical waveguide and a second optical waveguide in a curved shape; the first optical waveguide and the second optical waveguide are both positioned between the first electrode and the second electrode; the orthographic projection of a point on a line segment where the first optical waveguide is located on a straight line where the first electrode is located corresponds to the point of the straight line where the first electrode is located one by one; the orthographic projection of a point on the line segment where the second optical waveguide is located on the straight line where the second electrode is located corresponds to the point of the straight line where the second electrode is located one by one. The electro-optical modulator provided by the embodiment of the disclosure uses the first curved optical waveguide and the second curved optical waveguide as the phase modulation region structure of the modulator, firstly, the length of the electrodes matched with the first curved optical waveguide is effectively shortened, the loss of electric signals can be reduced due to the shorter length of the electrodes, secondly, the capacitance of the optical waveguide between the electrodes is increased due to the curved optical waveguide, so that the characteristic impedance of the modulation region of the electro-optical modulator is influenced to meet the impedance matching with an external system, thirdly, the reduced length of the electrodes is beneficial to reducing the overall size of the device, the cost of a single device is reduced, and the structure is compatible with the existing process manufacturing flow and is easy to manufacture in batches.
The features disclosed in the several method or apparatus embodiments provided in this disclosure may be combined in any combination to arrive at a new method or apparatus embodiment without conflict.
The scope of the present disclosure is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.
Claims (10)
1. An electro-optic modulator, comprising:
electrodes including at least a first electrode and a second electrode in a linear shape; the first electrode and the second electrode both extend in a first direction;
an optical waveguide including a first optical waveguide and a second optical waveguide which are bent; the first optical waveguide and the second optical waveguide are both positioned between the first electrode and the second electrode;
the orthographic projection of a point on a line segment where the first optical waveguide is located on a straight line where the first electrode is located corresponds to the point of the straight line where the first electrode is located one by one; the orthographic projection of a point on the line segment where the second optical waveguide is located on the straight line where the second electrode is located corresponds to the point of the straight line where the second electrode is located one by one.
2. The electro-optic modulator of claim 1, wherein the optical signal travels in the optical waveguide in the first direction at the same speed as the electrical signal travels in the electrodes.
3. The electro-optic modulator of claim 2,
the optical waveguide comprises a wave-shaped structure; the wavy structure is periodically reciprocated and extends along the first direction; the wavy structure comprises an arc-shaped part and/or a linear part.
4. The electro-optic modulator of claim 3, wherein the linear portions of the undulating structure form a first angle with the first direction, the first angle being related to a ratio of a group index of refraction of the optical waveguides to a group index of refraction of the electrodes.
5. The electro-optic modulator of claim 3,
the first optical waveguide and the second optical waveguide are symmetrical about a central axis, and the central axis is parallel to the first direction and is equal to the distance between the first electrode and the second electrode.
6. The electro-optic modulator of claim 1, further comprising:
an active region 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 positioned between the first electrode and the first optical waveguide;
the second doped region is positioned between the first optical waveguide and the second optical waveguide;
the third doped region is positioned between the second optical waveguide and the second electrode;
the second doped region has a doping type different from the doping types of the first doped region and the third doped region.
7. The electro-optic modulator of claim 6,
the doping types of the first doping area and the third doping area are P type and the doping type of the second doping area is N type; or,
the doping type of the first doping area and the doping type of the third doping area are N type, and the doping type of the second doping area is P type.
8. The electro-optic modulator of claim 6,
the electrodes include the first electrode and the second electrode; the first electrode and the second electrode both act on the optical waveguide;
or,
the electrode includes: the first electrode, the 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.
9. The electro-optic modulator of claim 1, wherein the optical waveguide comprises a ridge optical waveguide.
10. The electro-optic modulator of claim 1, further comprising:
the beam splitter is respectively connected with the input end of the first optical waveguide and the input end of the second optical waveguide;
and the beam combiner is respectively connected with the output end of the first optical waveguide and the output end of the second optical waveguide.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116760477A (en) * | 2023-08-22 | 2023-09-15 | 腾讯科技（深圳）有限公司 | Signal modulation method, chip, system, device and storage medium |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116760477A (en) * | 2023-08-22 | 2023-09-15 | 腾讯科技（深圳）有限公司 | Signal modulation method, chip, system, device and storage medium |
| CN116760477B (en) * | 2023-08-22 | 2023-11-21 | 腾讯科技（深圳）有限公司 | Signal modulation method, chip, system, device and storage medium |
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