Silicon-based Mach-Zehnder modulator and optical chip

Abstract

The invention provides a silicon-based Mach-Zehnder modulator and an optical chip. The silicon-based Mach-Zehnder modulator comprises N traveling wave phase shifters and M radio frequency filters which are alternately arranged and electrically connected in sequence; n is a natural number greater than or equal to 1; when N is equal to 1, M is equal to N; when N is greater than or equal to 2, M is equal to N or N-1; each traveling wave phase shifter acts on a waveguide arm of the Mach-Zehnder interference structure to modulate the phase of an optical signal; and the radio frequency terminal is electrically connected to the output end of the last stage of traveling wave phase shifter. According to the silicon-based Mach-Zehnder modulator and the optical chip, the defect that the bandwidth and the modulation amplitude of a traditional traveling wave Mach-Zehnder modulator are difficult to optimize at the same time is overcome, and the frequency response of the silicon-based Mach-Zehnder modulator is adjusted through the radio frequency filter; and through alternate arrangement of the traveling wave phase shifters and the radio frequency filters and the high-pass filtering characteristic of the radio frequency filters, the bandwidth is improved while the modulation amplitude is increased, and the performance of the Mach-Zehnder modulator is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of optical communication, and in particular to a silicon-based Mach-Zehnder modulator and optical chip. Background Technology

[0002] Silicon photonic transmitter chips based on traveling-wave Mach-Zehnder modulators (TW-MZM) have been widely used in data centers and long-distance communication fields with single-wavelength 100G communication rates due to their advantages of high speed, high integration, and low cost. With the shift of communication rates to single-wavelength 200G and the continuous development of linear-drive pluggable optical modules (LPOs), higher requirements are being placed on the bandwidth performance of silicon TW-MZM.

[0003] In a traveling-wave Mach-Zehnder modulator, the amplitude of optical signal modulation is determined by the phase difference generated by the traveling-wave phase shifters of the two waveguide arms, and this phase difference is proportional to the length of the traveling-wave phase shifters. When radio frequency electromagnetic waves propagate along the traveling-wave electrodes, the propagation loss of high-frequency components is greater than that of low-frequency components. Therefore, the longer the traveling-wave phase shifter, the lower the overall bandwidth of the traveling-wave Mach-Zehnder modulator. Thus, in the design of a traveling-wave Mach-Zehnder modulator, there is a trade-off between modulation amplitude and bandwidth; to increase the bandwidth of a traveling-wave Mach-Zehnder modulator, a certain amount of modulation efficiency is often sacrificed.

[0004] Therefore, how to balance the bandwidth and modulation amplitude of a traveling wave Mach-Zehnder modulator has become one of the problems that urgently needs to be solved by those skilled in the art.

[0005] It should be noted that the above description of the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of the present invention and facilitating understanding by those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because they have been described in the background section of this invention. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a silicon-based Mach-Zehnder modulator and optical chip to solve the problem that the bandwidth and modulation amplitude of the traveling wave Mach-Zehnder modulator in the prior art cannot be simultaneously achieved.

[0007] To achieve the above and other related objectives, the present invention provides a silicon-based Mach-Zehnder modulator, wherein the silicon-based Mach-Zehnder modulator comprises at least:

[0008] The system consists of a Mach-Zehnder interferometer structure, radio frequency terminals, N traveling-wave phase shifters, and M radio frequency filters, where N is a natural number greater than or equal to 1. When N equals 1, M equals N; when N equals 2, M equals N or N-1.

[0009] Each traveling wave phase shifter acts on the waveguide arm of the Mach-Zehnder interference structure to modulate the phase of the optical signal in the Mach-Zehnder interference structure;

[0010] Each traveling wave phase shifter and each radio frequency filter are alternately set and electrically connected in sequence; when M equals N, each traveling wave phase shifter has a corresponding radio frequency filter at its input terminal; when M equals N-1, a radio frequency filter is set between each two adjacent traveling wave phase shifters.

[0011] The radio frequency terminal is electrically connected to the output of the last stage traveling wave phase shifter.

[0012] Optionally, the Mach-Zehnder interferometer structure includes a beam splitter, a beam combiner, a first waveguide arm, and a second waveguide arm; the two waveguide arms are arranged side by side between the beam splitter and the beam combiner.

[0013] Alternatively, each traveling wave phase shifter includes a first traveling wave electrode, a second traveling wave electrode, a first PN junction on the first waveguide arm, and a second PN junction on the second waveguide arm;

[0014] The first traveling wave electrode is electrically connected to the first end of the first PN junction to modulate the optical signal in the first waveguide arm; the second traveling wave electrode is electrically connected to the first end of the second PN junction to modulate the optical signal in the second waveguide arm.

[0015] The second ends of the first PN junction and the second PN junction are connected together and connected to a common potential; and both the first PN junction and the second PN junction are in a reverse bias state.

[0016] Wherein, the first end of the first PN junction and the second PN junction are anodes and the second end are cathodes; or, the first end of the first PN junction and the second PN junction are cathodes and the second end are anodes.

[0017] Alternatively, the first traveling wave electrode and the second traveling wave electrode each receive one electrical signal, and the two electrical signals are differential signals.

[0018] Alternatively, the first traveling wave electrode receives an electrical signal, and the second traveling wave electrode is grounded.

[0019] Optionally, each traveling wave phase shifter includes a first traveling wave electrode, a second traveling wave electrode, and a first PN junction on the first waveguide arm;

[0020] The first traveling-wave electrode is electrically connected to the first end of the first PN junction; the second traveling-wave electrode is electrically connected to the second end of the first PN junction and connected to the corresponding common potential; and the first PN junction is in reverse bias; the first traveling-wave electrode and the second traveling-wave electrode are respectively connected to an electrical signal and a signal ground; the traveling-wave phase shifter modulates the optical signal in the first waveguide arm;

[0021] Wherein, the first end of the first PN junction is the anode and the second end is the cathode; or, the first end of the first PN junction is the cathode and the second end is the anode.

[0022] Alternatively, when N is greater than or equal to 2, the common potential of each traveling wave phase shifter can be connected to the same potential or to different potentials.

[0023] Alternatively, when N is greater than or equal to 2, the design parameters of each traveling wave phase shifter can be set to be consistent or inconsistent.

[0024] Optionally, when the silicon-based Mach-Zehnder modulator is a differential structure, the RF filter includes a first filtering unit and a second filtering unit; the first filtering unit performs high-pass filtering on one of the differential signals, and the second filtering unit performs high-pass filtering on the other of the differential signals; or, the RF filter includes a filtering unit that performs high-pass filtering on the differential signals.

[0025] When the silicon-based Mach-Zehnder modulator is a single-ended structure, the radio frequency filter includes a first filtering unit; the first filtering unit performs high-pass filtering on the electrical signal.

[0026] Optionally, when the silicon-based Mach-Zehnder modulator is a differential structure, the radio frequency terminal includes a first terminating resistor and a second terminating resistor; the first ends of the first terminating resistor and the second terminating resistor are respectively connected to the differential output terminal of the last stage traveling wave phase shifter, and the second ends are connected together;

[0027] When the silicon-based Mach-Zehnder modulator is a single-ended structure, the radio frequency terminal includes a first terminating resistor; the first end of the first terminating resistor is connected to the output of the last stage traveling wave phase shifter, and the second end is connected to the common-mode voltage or ground.

[0028] Alternatively, when the silicon-based Mach-Zehnder modulator is a differential structure, the second terminals of the first terminating resistor and the second terminating resistor are also connected to a common-mode voltage or ground.

[0029] Optionally, at least one RF filter is connected to a common-mode voltage; when at least two RF filters are connected to corresponding common-mode voltages, each common-mode voltage is set to a different value or the same value.

[0030] Optionally, when N is greater than or equal to 2, each RF filter has a different circuit design and / or parameter design.

[0031] To achieve the above and other related objectives, the present invention also provides an optical chip, which includes at least the aforementioned silicon-based Mach-Zehnder modulator.

[0032] As described above, the silicon-based Mach-Zehnder modulator and optical chip of the present invention have the following beneficial effects:

[0033] The silicon-based Mach-Zehnder modulator and optical chip of the present invention overcome the shortcomings of traditional traveling-wave Mach-Zehnder modulators in that it is difficult to optimize the bandwidth and modulation amplitude at the same time. By adjusting the frequency response of the silicon-based Mach-Zehnder modulator through an RF filter, and by alternating the setting of the traveling-wave phase shifter and the RF filter, as well as the high-pass filtering characteristics of the RF filter, the bandwidth is increased while the modulation amplitude is increased, which greatly improves the performance of the Mach-Zehnder modulator. Attached Figure Description

[0034] Figure 1 The diagram shown is a schematic representation of the silicon-based Mach-Zehnder modulator of the present invention.

[0035] Figure 2 The image shown is an example of a silicon-based Mach-Zehnder modulator according to the present invention.

[0036] Figure 3 Displayed as Figure 2 Circuit diagram of a silicon-based Mach-Zehnder modulator.

[0037] Figure 4 This is another example of the silicon-based Mach-Zehnder modulator of the present invention.

[0038] Figure 5 This is yet another example of a silicon-based Mach-Zehnder modulator of the present invention.

[0039] Figure 6 The diagram shows a performance comparison between the silicon-based Mach-Zehnder modulator of the present invention and a conventional structure.

[0040] Component designation explanation

[0041] 1 Silicon-based Mach-Zehnder modulator

[0042] 11 Mach-Zehnder Interference Structure

[0043] 111 beam splitter

[0044] 112a First Waveguide Arm

[0045] 112b second waveguide arm

[0046] 113 Bundle Combiner

[0047] 12-traveling-wave phase shifter

[0048] 12a First Traveling Wave Phase Shifter

[0049] 12b Second Traveling Wave Phase Shifter

[0050] 121a First Traveling Wave Electrode

[0051] 121b Second Traveling Wave Electrode

[0052] 122a First PN Junction

[0053] 122b Second PN Junction

[0054] 13 RF Filters

[0055] 13a First RF Filter

[0056] 13b Second RF Filter

[0057] 14 RF terminals Detailed Implementation

[0058] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0059] Please see Figures 1-6 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0060] For the reasons stated above, the present invention provides a silicon-based Mach-Zehnder modulator 1, such as... Figure 1 As shown, the silicon-based Mach-Zehnder modulator 1 includes: a Mach-Zehnder interferometer (MZI) structure 11, N traveling-wave phase shifters 12, M radio frequency filters 13, and a radio frequency terminal 14; wherein N is a natural number greater than or equal to 1; when N equals 1, M equals N; when N is greater than or equal to 2 (preferred), M equals N or N-1. Through structural optimization, without the need for a trade-off between modulation amplitude and bandwidth, it can simultaneously satisfy large modulation amplitude and high bandwidth, thereby improving the performance of the Mach-Zehnder modulator. The silicon-based Mach-Zehnder modulator of the present invention will be described below.

[0061] Example 1

[0062] like Figure 2 As shown, this embodiment provides a silicon-based Mach-Zehnder modulator 1, wherein N is set to 2, and each traveling wave phase shifter 12 is defined as a first traveling wave phase shifter 12a and a second traveling wave phase shifter 12b based on the transmission order of the input signal; M is set to 2 (i.e., M=N, and each traveling wave phase shifter has a corresponding RF filter at its input terminal), and each RF filter 13 is defined as a first RF filter 13a and a second RF filter 13b based on the transmission order of the input signal. In actual use, the number of traveling wave phase shifters 12 and RF filters 13 can be set according to the specific configuration, and is not limited to this embodiment.

[0063] like Figure 1 and Figure 2 As shown, the Mach-Zehnder interference structure 11 serves as an optical structure, providing a propagation path for optical signals.

[0064] Specifically, in this embodiment, the Mach-Zehnder interference structure 11 includes a beam splitter 111, a first waveguide arm 112a, a second waveguide arm 112b, and a beam combiner 113; the two waveguide arms are arranged side by side between the beam splitter 111 and the beam combiner 113.

[0065] More specifically, as an example, beam splitter 111 is implemented based on a beam-splitting waveguide. The input end of beam splitter 111 is a single waveguide, and the output end is split into two waveguides, thereby achieving the purpose of splitting the input optical signal into two beams. In this embodiment, beam splitter 111 is configured as a 50 / 50 beam-splitting waveguide structure, that is, the two waveguides at the output end each receive 50% of the input optical signal.

[0066] More specifically, the first ends of the first waveguide arm 112a and the second waveguide arm 112b are respectively connected to the two output ends of the beam splitter 111, so that the two beams of light after beam splitting are transmitted and modulated in the corresponding waveguide arms respectively. In this embodiment, the lengths of the two waveguide arms are equal to ensure that the propagation paths of the two beams of light signals after beam splitting are the same. The first waveguide arm 112a and the second waveguide arm 112b are disposed on the substrate, and each waveguide arm includes a P-doped region and an N-doped region to form a PN junction. As an example, the N-doped regions of the first waveguide arm 112a and the second waveguide arm 112b are arranged adjacent to each other, and the P-doped region is disposed on the outside.

[0067] More specifically, as an example, the beam combiner 113 is implemented based on a beam combining waveguide. The input end of the beam combiner 113 consists of two waveguides, and the output end is combined into a single waveguide. The two input ends are respectively connected to the second ends of the first waveguide arm 112a and the second waveguide arm 112b, so that the two beams of light output from the first waveguide arm 112a and the second waveguide arm 112b interfere in the beam combining region, and the interfered light is then output from the output end of the beam combiner 113. In this embodiment, the beam combiner 113 is configured as a 50 / 50 beam combining waveguide structure, that is, the two waveguides at the input end each provide 50% of the optical signal for beam combining.

[0068] like Figure 1 and Figure 2 As shown, each traveling wave phase shifter 12 acts on the waveguide arm of the Mach-Zehnder interference structure 11 to modulate the phase of the optical signal in the Mach-Zehnder interference structure 11.

[0069] Specifically, in this embodiment, each traveling wave phase shifter 12 includes a first traveling wave electrode 121a (TWE), a second traveling wave electrode 121b, a first PN junction 122a on the first waveguide arm 112a, and a second PN junction 122b on the second waveguide arm 112b. The first traveling wave electrode 121a is electrically connected to the anode (or cathode) of the first PN junction 122a, forming a first phase shifter to modulate the optical signal in the first waveguide arm 112a. The second traveling wave electrode 121b is electrically connected to the anode (or cathode) of the second PN junction 122b, forming a second phase shifter to modulate the optical signal in the second waveguide arm 112b. The cathodes (or anodes) of the first PN junction 122a and the second PN junction 122b are connected together and connected to a corresponding common potential; and both the first PN junction 122a and the second PN junction 122b are in a reverse bias state. In this example, each waveguide arm and each traveling wave electrode are arranged in parallel.

[0070] It should be noted that the structures of each traveling wave phase shifter 12 are generally the same, but the design parameters can be set to be the same or different, as long as the purpose of increasing the modulation amplitude and improving the bandwidth is achieved simultaneously. These design parameters include, but are not limited to, the type and structural parameters of the transmission line, the doping position and concentration of the PN junction, its length, and impedance, which will not be elaborated here. At least one of these parameters can be set to be the same, or all parameters can be different, depending on actual needs. For example... Figure 1 and Figure 2 As shown, the common potential of each traveling wave phase shifter 12 can be set to different potentials (Vbias1, Vbias2...Vbiasn) or connected to the same potential (Vbias) as needed.

[0071] More specifically, such as Figure 2As shown, in this embodiment, the silicon-based Mach-Zehnder modulator 1 is configured as a differential structure, and the first traveling wave electrode 121a and the second traveling wave electrode 121b in each traveling wave phase shifter 12 receive one electrical signal (S+ and S-) respectively. The two electrical signals (S+ and S-) are differential signals.

[0072] like Figure 1 and Figure 2 As shown, each RF filter 13 is alternately arranged with each traveling wave phase shifter 12 and electrically connected in sequence to provide additional design freedom for frequency response.

[0073] Specifically, such as Figure 2 As shown, in this embodiment, the first RF filter 13a is disposed before the first traveling-wave phase shifter 12a, and the second RF filter 13b is disposed before the second traveling-wave phase shifter 12b, respectively absorbing the low-frequency electrical signals at the input terminals of the corresponding traveling-wave phase shifters 12a and allowing high-frequency signals to pass through; the electrical signals pass sequentially through the first RF filter 13a, the first traveling-wave phase shifter 12a, the second RF filter 13b, and the second traveling-wave phase shifter 12b. In this embodiment, the silicon-based Mach-Zehnder modulator 1 is a differential structure, and the RF filter 13 includes a first filtering unit and a second filtering unit; the first filtering unit performs high-pass filtering on one path of the differential signal, and the second filtering unit performs high-pass filtering on the other path of the differential signal. As an example, such as Figure 3 As shown, each filter unit in the first RF filter 13a includes a first filter resistor R1 and a filter inductor L1. One end of the inductor L1 serves as the input / output terminal of the corresponding filter unit, and the other end is grounded through the first filter resistor R1. Each filter unit in the second RF filter 13b includes a second filter resistor R2 and a filter capacitor C1. The first end of the filter capacitor C1 serves as the input terminal of the corresponding filter unit, and the second end serves as the output terminal of the corresponding filter unit. One end of the second filter resistor R2 is connected to the common-mode voltage Vcc, and the other end is connected to the first end of the filter capacitor C1.

[0074] It should be noted that any circuit structure capable of high-pass filtering is applicable to this invention, including but not limited to structures composed of one or more passive network components (inductors, capacitors, resistors); the structure of the RF filter may or may not require connection to a common-mode voltage; the RF filter may also employ a single filter structure (i.e., including only one filter unit) to simultaneously filter two differential signals, which will not be elaborated upon here. Furthermore, the structures of the various RF filters may be identical or different, and the parameters of the components in each RF filter are set according to the actual node requirements (as an example, each RF filter has different circuit designs and / or parameter designs). Figure 1 and Figure 2As shown, when the structures of at least two RF filters 13 require connection to common-mode voltage, each common-mode voltage is set to a different value (Vcc1, Vcc2...Vccn) or the same value (Vcc).

[0075] like Figure 1 and Figure 2 As shown, the radio frequency terminal 14 is electrically connected to the output of the last stage traveling wave phase shifter 12.

[0076] Specifically, such as Figure 2 As shown, in this embodiment, the RF terminal 14 includes a first terminating resistor RL1 and a second terminating resistor RL2. The first ends of the first terminating resistor RL1 and the second terminating resistor RL2 are respectively connected to the differential output terminal of the last stage traveling-wave phase shifter 12, and their second ends are connected together (connected to the same potential or floating). As an example, the resistance values ​​of the first terminating resistor RL1 and the second terminating resistor RL2 are the same, denoted as RL. Further, in another example, the second ends of the first terminating resistor RL1 and the second terminating resistor RL2 are also connected to a common-mode voltage or ground. It should be noted that when the RF terminal 14 is connected to a common-mode voltage Vcc, this common-mode voltage can be configured to be the same as or different from the common-mode voltage of each RF filter, depending on actual needs.

[0077] It should be noted that any structure that can serve as a radio frequency terminal to absorb the electrical signal output by the last-stage traveling wave phase shifter 12 is applicable to the present invention, including but not limited to structures composed of one or more passive network elements (inductors, capacitors, resistors); it is not limited to this embodiment.

[0078] During operation, the PN junctions on the two waveguide arms are in a reverse-biased state. The reverse-bias voltage is determined by the potential difference between the common potential (Vbias) and the common-mode voltage (Vcc) of the PN junctions on both arms. After beam splitting, the optical signal enters the two waveguide arms. The differential electrical signal is input through an RF filter (in practical applications, it can also be input through traveling-wave electrodes, depending on the actual structure), propagating along the alternating traveling-wave electrodes and RF filter, and modulating the optical signals propagating in the two waveguide arms. This results in opposite phase differences between the optical signals in the two waveguide arms. Finally, the electrical signal is absorbed by the terminating resistor. When the optical signals propagating in the two waveguide arms are combined, the phase difference is converted into an intensity-modulated optical signal. Figure 3The diagram shows the circuit of the silicon-based Mach-Zehnder modulator 1 with a differential structure in this embodiment. The low-frequency signal in the differential electrical signal Vdiff is absorbed by the first RF filter 13a, and the high-frequency signal is coupled to the first traveling-wave phase shifter 12a. The low-frequency signal after passing through the first traveling-wave phase shifter 12a is absorbed by the filter resistor R2 in the second RF filter 13b, and the high-frequency signal is coupled to the second traveling-wave phase shifter 12b through the filter capacitor C1 in the second RF filter 13b, and finally absorbed by the terminating resistor. This invention, through the segmented setting of the traveling-wave phase shifter and the combined effect of the RF filter, enhances the high-frequency response without increasing the low-frequency response, that is, it achieves bandwidth improvement while maintaining the modulation amplitude.

[0079] Example 2

[0080] like Figure 4 As shown, this embodiment provides a silicon-based Mach-Zehnder modulator 1. The difference from the first embodiment is that the silicon-based Mach-Zehnder modulator 1 is a single-ended structure, and M is set to 1 (i.e., M = N-1, and an RF filter is set between each of the two adjacent traveling wave phase shifters).

[0081] Specifically, such as Figure 4 As shown, the structure of the Mach-Zehnder interference structure 11 is the same as that in Embodiment 1, and will not be described in detail here.

[0082] Specifically, such as Figure 4 As shown, the structure of the traveling wave phase shifter is the same as in Embodiment 1, and will not be described in detail here. The difference is that the first traveling wave electrode 121a receives one electrical signal (S), and the second traveling wave electrode 121b is grounded (G); that is, the first phase shifter is formed only on the first waveguide arm 112a and modulates the optical signal in the first waveguide arm 112a, while the optical signal in the second waveguide arm 112b is not modulated.

[0083] Accordingly, the RF filter 13 includes only a first filtering unit; the first filtering unit filters the electrical signal. Any structure capable of high-pass filtering is applicable to the first filtering unit of this invention, and will not be described in detail here. The RF terminal 14 includes only a first terminating resistor RL1, the first end of which is connected to the output of the last stage traveling wave phase shifter (second traveling wave phase shifter 12b), and the second end is connected to the common-mode voltage or ground.

[0084] During operation, the optical signal is split and enters two waveguide arms. The electrical signal is input through traveling wave electrodes and propagates along the alternately distributed traveling wave electrodes and RF filters, modulating the optical signal propagating in the first waveguide arm. The optical signal propagating in the second waveguide arm is not modulated, resulting in a phase difference between the optical signals in the two waveguide arms. Finally, the electrical signal is absorbed by the terminating resistor. When the optical signals propagating on the two waveguide arms are combined, the phase difference is converted into an intensity-modulated optical signal. Other structures and settings are the same as in Embodiment 1, and will not be described in detail here.

[0085] Example 3

[0086] like Figure 5 As shown, this embodiment provides a silicon-based Mach-Zehnder modulator 1, which differs from Embodiment 2 in that the structure of the traveling wave phase shifter is different.

[0087] Specifically, such as Figure 5 As shown, the traveling-wave phase shifter 12 includes only a first traveling-wave electrode 121a, a second traveling-wave electrode 121b, and a first PN junction 122a. The first traveling-wave electrode 121a is electrically connected to the anode (or cathode) of the first PN junction 122a; the second traveling-wave electrode 121b is electrically connected to the cathode (or anode) of the first PN junction 122a and connected to the corresponding common potential (Vbias); and the first PN junction 122a is in a reverse-biased state; wherein, the first traveling-wave electrode is connected to an electrical signal (S), and the second traveling-wave electrode is connected to signal ground (G). The above structure forms a first phase shifter to modulate the optical signal in the first waveguide arm 112a.

[0088] In this embodiment, a second phase shifter is not formed to modulate the second waveguide arm 112b; thus, a single-ended silicon-based Mach-Zehnder modulator is obtained.

[0089] Other structures, settings, and working principles are the same as in Embodiment 2, and will not be described in detail here.

[0090] like Figure 6 As shown, the performance of the silicon-based Mach-Zehnder modulator of the present invention is compared with that of the traditional silicon-based Mach-Zehnder modulator (the traveling wave phase shifter is not segmented and no radio frequency filter is set). The solid line is the performance curve of the present invention, and the dashed line is the performance curve of the traditional structure. It can be seen that the modulation amplitude of the present invention is larger than that of the traditional structure, and the bandwidth of the present invention is wider than that of the traditional structure. Therefore, the present invention can greatly expand the design space of bandwidth and modulation amplitude of the traveling wave Mach-Zehnder modulator.

[0091] The present invention also provides an optical chip, which includes at least the silicon-based Mach-Zehnder modulator 1 of the present invention. As an example, the optical chip is a silicon photoelectric emitter chip.

[0092] In summary, this invention provides a silicon-based Mach-Zehnder modulator and optical chip, comprising: a Mach-Zehnder interference structure, a radio frequency (RF) terminal, N traveling-wave phase shifters, and M RF filters; wherein N is a natural number greater than or equal to 1; when N equals 1, M equals N; when N equals 2, M equals N or N-1; each traveling-wave phase shifter acts on the waveguide arm of the Mach-Zehnder interference structure to modulate the phase of the optical signal in the Mach-Zehnder interference structure; each traveling-wave phase shifter and each RF filter are alternately arranged and electrically connected in sequence; when M equals N, a corresponding RF filter is provided at the input end of each traveling-wave phase shifter; when M equals N-1, an RF filter is provided between each two adjacent traveling-wave phase shifters; the RF terminal is electrically connected to the output end of the last traveling-wave phase shifter. The silicon-based Mach-Zehnder modulator and optical chip of this invention overcome the limitation of traditional traveling-wave Mach-Zehnder modulators, which struggle to simultaneously optimize bandwidth and modulation amplitude. By adjusting the frequency response of the silicon-based Mach-Zehnder modulator through an RF filter, and further by alternating the use of a traveling-wave phase shifter and an RF filter, along with the high-pass filtering characteristics of the RF filter, the modulation amplitude is increased while the bandwidth is enhanced, significantly improving the performance of the Mach-Zehnder modulator. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and possesses high industrial applicability.

[0093] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A silicon-based Mach-Zehnder modulator, characterized in that, The silicon-based Mach-Zehnder modulator includes at least: The system consists of a Mach-Zehnder interferometer structure, radio frequency terminals, N traveling-wave phase shifters, and M radio frequency filters; where N is a natural number greater than or equal to 1; when N equals 1, M equals N; when N equals 2, M equals N or N-1. Each traveling wave phase shifter acts on the waveguide arm of the Mach-Zehnder interference structure to modulate the phase of the optical signal in the Mach-Zehnder interference structure; Each traveling wave phase shifter and each radio frequency filter are alternately set and electrically connected in sequence; when M equals N, each traveling wave phase shifter has a corresponding radio frequency filter at its input terminal; when M equals N-1, a radio frequency filter is set between each two adjacent traveling wave phase shifters. The radio frequency terminal is electrically connected to the output of the last stage traveling wave phase shifter.

2. The silicon-based Mach-Zehnder modulator according to claim 1, characterized in that: The Mach-Zehnder interferometer structure includes a beam splitter, a beam combiner, a first waveguide arm, and a second waveguide arm; the two waveguide arms are arranged side by side between the beam splitter and the beam combiner.

3. The silicon-based Mach-Zehnder modulator according to claim 2, characterized in that: Each traveling wave phase shifter includes a first traveling wave electrode, a second traveling wave electrode, a first PN junction on the first waveguide arm, and a second PN junction on the second waveguide arm; The first traveling wave electrode is electrically connected to the first end of the first PN junction to modulate the optical signal in the first waveguide arm; the second traveling wave electrode is electrically connected to the first end of the second PN junction to modulate the optical signal in the second waveguide arm. The second ends of the first PN junction and the second PN junction are connected together and connected to a common potential; and both the first PN junction and the second PN junction are in a reverse bias state. Wherein, the first end of the first PN junction and the second PN junction are anodes and the second end are cathodes; or, the first end of the first PN junction and the second PN junction are cathodes and the second end are anodes.

4. The silicon-based Mach-Zehnder modulator according to claim 3, characterized in that: The first traveling wave electrode and the second traveling wave electrode each receive one electrical signal, and the two electrical signals are differential signals.

5. The silicon-based Mach-Zehnder modulator according to claim 3, characterized in that: The first traveling wave electrode receives one electrical signal, and the second traveling wave electrode is grounded.

6. The silicon-based Mach-Zehnder modulator according to claim 1, characterized in that: Each traveling wave phase shifter includes a first traveling wave electrode, a second traveling wave electrode, and a first PN junction on the first waveguide arm; The first traveling-wave electrode is electrically connected to the first end of the first PN junction; the second traveling-wave electrode is electrically connected to the second end of the first PN junction and connected to the corresponding common potential; and the first PN junction is in reverse bias; the first traveling-wave electrode and the second traveling-wave electrode are respectively connected to an electrical signal and a signal ground; the traveling-wave phase shifter modulates the optical signal in the first waveguide arm; Wherein, the first end of the first PN junction is the anode and the second end is the cathode; or, the first end of the first PN junction is the cathode and the second end is the anode.

7. The silicon-based Mach-Zehnder modulator according to any one of claims 1-6, characterized in that: When N is greater than or equal to 2, the common potential of each traveling wave phase shifter is connected to the same potential or to different potentials.

8. The silicon-based Mach-Zehnder modulator according to any one of claims 1-6, characterized in that: When N is greater than or equal to 2, the design parameters of each traveling wave phase shifter can be set to be consistent or inconsistent.

9. The silicon-based Mach-Zehnder modulator according to claim 1, characterized in that: When the silicon-based Mach-Zehnder modulator is a differential structure, the RF filter includes a first filtering unit and a second filtering unit; the first filtering unit performs high-pass filtering on one path of the differential signal, and the second filtering unit performs high-pass filtering on the other path of the differential signal; or, the RF filter includes a single filtering unit that performs high-pass filtering on the differential signal. When the silicon-based Mach-Zehnder modulator is a single-ended structure, the radio frequency filter includes a first filtering unit; The first filtering unit performs high-pass filtering on the electrical signal.

10. The silicon-based Mach-Zehnder modulator according to claim 1, characterized in that: When the silicon-based Mach-Zehnder modulator is a differential structure, the radio frequency terminal includes a first terminating resistor and a second terminating resistor; the first ends of the first terminating resistor and the second terminating resistor are respectively connected to the differential output terminal of the last stage traveling wave phase shifter, and the second ends are connected together; When the silicon-based Mach-Zehnder modulator is a single-ended structure, the radio frequency terminal includes a first terminating resistor; the first end of the first terminating resistor is connected to the output of the last stage traveling wave phase shifter, and the second end is connected to the common-mode voltage or ground.

11. The silicon-based Mach-Zehnder modulator according to claim 10, characterized in that: When the silicon-based Mach-Zehnder modulator is a differential structure, the second terminals of the first terminating resistor and the second terminating resistor are also connected to a common-mode voltage or ground.

12. The silicon-based Mach-Zehnder modulator according to claim 1, characterized in that: At least one RF filter is connected to a common-mode voltage; when at least two RF filters are connected to the corresponding common-mode voltage, each common-mode voltage is set to a different value or the same value.

13. The silicon-based Mach-Zehnder modulator according to claim 1, characterized in that: When N is greater than or equal to 2, each RF filter has a different circuit design and / or parameter design.

14. An optical chip, characterized in that, The optical chip includes at least a silicon-based Mach-Zehnder modulator as described in any one of claims 1-13.

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