Driving method and driving circuit of carrier modulator and carrier modulator

Abstract

The invention provides a driving method and a driving circuit of a carrier modulator and the carrier modulator, and relates to the technical field of integrated photonics, and the driving method comprises the steps: applying a direct current bias voltage in the same direction as a PN junction to the carrier modulator, enabling carriers of a P-doped region and an N-doped region to be injected into a waveguide region, and enabling the carriers of the P-doped region and the N-doped region to be injected into the waveguide region; the carrier concentration of the waveguide region is increased; wherein the direct-current bias voltage is smaller than a built-in electric field of the PN junction; applying a radio frequency signal opposite to the PN junction to the carrier modulator, so that the PN junction is in a reverse bias state; and coupling and outputting the direct current bias voltage and the radio frequency signal to a carrier modulator to ensure that the direct current bias voltage and the radio frequency signal are superposed. Wherein the carrier modulator comprises a silicon-based ridge waveguide, the silicon-based ridge waveguide comprises a P doped region, an N doped region and a waveguide region, and the waveguide region comprises a PN junction.

Description

Technical Field

[0001] At least one embodiment of the present disclosure relates to the technical field of integrated photonics, and in particular to a driving method, a driving circuit, and a carrier modulator of a carrier modulator. Background Art

[0002] Phase modulators based on the electro-optic effect change the refractive index of crystal materials (such as lithium niobate) under the action of an external electric field. By changing the electric field intensity, the propagation phase of light in the crystal material can be changed, thereby achieving phase modulation. Phase modulators based on the principle of carrier dispersion use changes in carrier concentration in semiconductor materials (such as silicon) to affect the propagation characteristics of light. When carriers are injected or extracted, the refractive index of the semiconductor material changes, thereby changing the phase of the light. Phase modulators based on the principle of carrier dispersion have a higher degree of integration and are compatible with CMOS processes. They have more advantages in large-scale integration and cost control, and have been widely used in the field of optical communications.

[0003] The quantum key distribution system is based on the quantum non-cloning and uncertainty principles, and can provide high-level information security protection to resist high-computing power cracking. The quantum state modulation of the quantum key distribution system requires the use of a high-speed phase modulator, and multiple quantum states need to be randomly modulated, and the phase shift often needs to reach 1.5π. In related technologies, a phase modulator based on the carrier dispersion principle (or "carrier modulator") can be used to achieve the above phase modulation. However, since multiple random-level high-swing RF drive circuits are required, the driving circuit of the phase modulator used in the quantum key distribution system has technical problems such as complexity, difficulty, and high cost.

[0004] Therefore, there is an urgent need for a phase modulator based on the carrier dispersion principle with high modulation efficiency to meet the needs of the quantum key distribution system and benefit the development of quantum key distribution technology. Summary of the invention

[0005] In view of this, the present disclosure provides a driving method, a driving circuit and a carrier modulator of a carrier modulator, which can improve the performance of a phase modulator based on the carrier dispersion principle.

[0006] One aspect of the present disclosure provides a method for driving a carrier modulator, wherein the carrier modulator comprises a silicon-based ridge waveguide, the silicon-based ridge waveguide comprises a P-doped region, an N-doped region and a waveguide region, and the waveguide region comprises a PN junction; the driving method comprises: applying a DC bias in the same direction as the PN junction to the carrier modulator, so that carriers in the P-doped region and the N-doped region are injected into the waveguide region to increase the carrier concentration in the waveguide region; wherein the DC bias is less than the built-in electric field of the PN junction; applying a radio frequency signal in the opposite direction to the PN junction to the carrier modulator, so that the PN junction is in a reverse bias state; and coupling the DC bias and the radio frequency signal to output to the carrier modulator to ensure that the DC bias and the radio frequency signal are superimposed.

[0007] According to an embodiment of the present disclosure, the method further includes: controlling the amplitude of the RF signal to change the phase shift and modulation depth of the carrier modulator, wherein the greater the amplitude of the RF signal, the greater the phase shift and modulation depth of the carrier modulator.

[0008] Another aspect of the present disclosure provides a driving circuit for a carrier modulator, which is applicable to the above-mentioned driving method, and the above-mentioned driving circuit includes: a DC driver, configured to apply a DC bias in the same direction as the PN junction to the carrier modulator, so that carriers in the P-doped area and the N-doped area are injected into the waveguide area to increase the carrier concentration in the above-mentioned waveguide area; wherein the above-mentioned DC bias is smaller than the built-in electric field of the above-mentioned PN junction; an RF driver, configured to apply an RF signal in the opposite direction to the above-mentioned PN junction to the above-mentioned carrier modulator, so that the above-mentioned PN junction is in a reverse biased state; and a biaser, configured to couple the above-mentioned DC bias and the above-mentioned RF signal to the above-mentioned carrier modulator to ensure that the above-mentioned DC bias and the above-mentioned RF signal are superimposed.

[0009] According to an embodiment of the present disclosure, the bias device includes a DC terminal, a RF terminal and a common terminal; the DC terminal is used to transmit the DC bias voltage to the common terminal and prevent the RF signal from being transmitted to the DC driver; the RF terminal is used to transmit the RF signal to the common terminal and prevent the DC bias voltage from being transmitted to the RF driver; the common terminal is used to output the DC bias voltage and the RF signal to the carrier modulator.

[0010] Another aspect of the present disclosure provides a carrier modulator, which includes: a silicon-based ridge waveguide, including a P-doped region, an N-doped region and a waveguide region, and the waveguide region includes a PN junction; the carrier modulator is configured to change the refractive index of the waveguide region based on the change of the carrier concentration of the waveguide region, so as to achieve modulation of the optical signal by changing the phase or intensity of the input optical signal.

[0011] According to an embodiment of the present disclosure, the electrode of the carrier modulator is configured as a copper metal material or a tungsten metal material, and is connected to the P-doped region and the N-doped region through an ohmic contact.

[0012] According to an embodiment of the present disclosure, the above-mentioned P-doped region is obtained by doping in a single-stage manner with the same concentration.

[0013] According to an embodiment of the present disclosure, the P-doped region is obtained by doping in a multi-level manner with different concentrations.

[0014] According to an embodiment of the present disclosure, the N-doped region is obtained by doping in a single-stage manner with the same concentration.

[0015] According to an embodiment of the present disclosure, the N-doped region is obtained by doping in a multi-level manner with different concentrations.

[0016] According to the embodiments of the present disclosure, unlike the conventional method of loading a DC bias in the opposite direction of the PN junction and a radio frequency drive signal in the opposite direction of the PN junction to a carrier depletion modulator (high bandwidth, low modulation efficiency), and also unlike the conventional method of loading a DC bias in the same direction as the PN junction and a radio frequency drive signal in the same direction as the PN junction to a carrier injection modulator (low bandwidth, high modulation efficiency), by applying a forward DC bias less than the built-in electric field of the PN junction to the carrier modulator based on the PN junction, and applying a radio frequency voltage in the opposite direction of the PN junction, the modulation efficiency of the carrier modulation is effectively improved. A carrier modulator with large bandwidth and high modulation efficiency is formed, which is applied to the quantum key distribution system and can effectively reduce the swing requirements of the radio frequency drive circuit. At the same time, the carrier modulator based on the PN junction structure based on this scheme applies a forward DC bias less than the built-in electric field of the PN junction, which can also adjust the carrier concentration of the modulator and improve the process error tolerance during carrier doping. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings.

[0018] Figure 1 The operation flow chart of the driving method of the carrier modulator according to the embodiment of the present disclosure is schematically shown;

[0019] Figure 2 A schematic diagram schematically shows a driving circuit of a carrier modulator according to an embodiment of the present disclosure;

[0020] Figure 3 The schematic diagram shows the structure of a carrier modulator according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0022] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0023] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0024] When using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc. When using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, or C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.

[0025] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure.

[0026] Phase modulators based on the principle of carrier dispersion are mainly silicon-based carrier modulators, which mainly include carrier injection modulators and carrier depletion modulators. The performance parameters of carrier modulators mainly include modulation efficiency and bandwidth. Modulation efficiency refers to the amount of optical phase change that can be caused by the carrier modulator under the action of unit voltage, and bandwidth refers to the highest frequency range in which the carrier modulator can effectively modulate the signal.

[0027] The carrier injection modulator can be based on a forward biased PIN structure, that is, the waveguide body of the modulator is an intrinsic semiconductor or only background-doped silicon. The forward biased PIN structure includes: P region, high-concentration P-type doped silicon; N region, high-concentration N-type doped silicon; I region, an intrinsic semiconductor region or lightly doped, with a doping concentration much lower than that of the P region and the N region, and free carriers can be ignored. The two sides of the waveguide body I region are the P region and the N region respectively, and the direction of the bias voltage is consistent with the hole diffusion direction, that is, the diode conduction direction. Generally, a forward bias voltage is applied to the carrier injection modulator. Under the action of the forward bias voltage, the holes in the P region and the electrons in the N region are injected into the I region and recombine in the I region, making the carrier concentration in the I region higher than its intrinsic level. The injected carriers diffuse and recombine in the I region, significantly changing the effective refractive index of the waveguide body. Therefore, the modulation efficiency of the carrier injection modulator is relatively high. High modulation efficiency means that the modulator can achieve a large light intensity change under a small driving voltage. Usually, the driving voltage of the carrier injection modulator is less than 1V. However, due to the limitation of carrier lifetime, the bandwidth of carrier injection modulators is generally not high.

[0028] The carrier depletion type modulator can be based on the reverse biased PN junction structure, that is, the two sides of the modulator's waveguide are P-type doped silicon and N-type doped silicon, respectively, and the two doped regions are in direct contact, so a carrier depletion region is formed in the reverse biased PN junction region. Generally, a reverse bias voltage is applied to the carrier depletion type modulator, and a reverse bias voltage is loaded in the reverse biased PN junction region. The built-in electric field of the reverse biased PN junction is enhanced, causing the depletion region to become wider. The carriers in the depletion region are repelled by the built-in electric field, which reduces the carrier concentration. The carrier concentration is regulated by changing the width of the depletion region to achieve the effect of modulating the phase. The bandwidth of the carrier depletion type modulator is relatively high, but because the width of the depletion region varies in a small range, the modulation efficiency of the carrier depletion type modulator is relatively low, and the modulation efficiency is usually 1 to 2 orders of magnitude lower than that of the carrier injection type modulator.

[0029] In the quantum key distribution system, the modulation efficiency and bandwidth of the phase modulator directly affect the performance of the system. The modulation efficiency of the carrier injection modulator is high, but the bandwidth is low, and it cannot respond quickly to high-frequency signals. The bandwidth of the carrier depletion modulator is high, but the modulation efficiency is low. In order to achieve the required modulation depth, a larger RF drive circuit swing is required, which not only increases the complexity of the circuit, but may also lead to higher power consumption and higher costs.

[0030] In the related art, the performance of the phase modulator is improved by optimizing the doping area, doping concentration, cascading multiple PN junctions, increasing the DC bias voltage, etc. However, these methods have certain limitations, resulting in limited improvement effects. In addition, process adjustments are also involved. In the manufacturing process of the phase modulator, deviations in lithography and doping concentration are inevitable. These deviations will cause differences in the performance of phase modulators between different wafers and different chips. For example, the actual doping concentration and doping area may not match the design values, resulting in problems such as reduced modulation efficiency and reduced bandwidth.

[0031] The present disclosure provides a driving method, a driving circuit and a carrier modulator of a carrier modulator, in order to solve at least one of the above technical problems.

[0032] Figure 1 The operation flow chart of the driving method of the carrier modulator according to the embodiment of the present disclosure is schematically shown.

[0033] like Figure 1 As shown, the driving method of the carrier modulator includes operations S110 to S130.

[0034] According to an embodiment of the present disclosure, a carrier modulator includes a silicon-based ridge waveguide, the silicon-based ridge waveguide includes a P-doped region, an N-doped region and a waveguide region, and the waveguide region includes a PN junction.

[0035] According to an embodiment of the present disclosure, a silicon-based ridge waveguide is an optical waveguide realized by a specific structural design on a silicon-based platform. The silicon-based ridge waveguide may include a top silicon layer, a buried oxide layer, and a substrate, and a ridge structure is formed by partially or completely etching the top silicon layer. The ridge waveguide has a high light field confinement capability and can effectively enhance the interaction between light and the waveguide material.

[0036] According to an embodiment of the present disclosure, a PN junction is a region formed by contact between a P-type semiconductor and an N-type semiconductor. The silicon-based ridge waveguide forms a P-doped region and an N-doped region by performing P-doping and N-doping on both sides of the waveguide region, and forms a PN junction in the waveguide region.

[0037] In operation S110 , a DC bias in the same direction as the PN junction is applied to the carrier modulator, so that carriers in the P-doped region and the N-doped region are injected into the waveguide region to increase the carrier concentration in the waveguide region.

[0038] According to the embodiments of the present disclosure, the DC bias direction is the conduction direction of the PN junction in the waveguide region, and the DC bias is configured to be smaller than the built-in electric field of the PN junction, so that the PN junction is in a non-conducting state to ensure that the carrier modulator maintains the function of a carrier depletion type modulator. If an excessively high DC voltage is applied, the PN junction will break down, causing the bandwidth performance of the carrier modulator to deteriorate. By adjusting the DC bias, the number and distribution of carrier injection can be controlled, thereby improving the modulation efficiency.

[0039] In operation S120, a radio frequency signal in a direction opposite to the PN junction is applied to the carrier modulator, so that the PN junction is in a reverse bias state.

[0040] According to an embodiment of the present disclosure, an RF signal in the opposite direction to the PN junction is loaded at the RF input port of the carrier modulator. The RF signal puts the PN junction in the waveguide region in a reverse bias state. The reverse bias state reduces the junction capacitance of the PN junction, thereby improving the bandwidth characteristics of the carrier modulator.

[0041] In operation S130 , the DC bias voltage and the radio frequency signal are coupled and output to the carrier modulator to ensure that the DC bias voltage and the radio frequency signal are superimposed.

[0042] According to the embodiments of the present disclosure, unlike the conventional method of loading a DC bias in the opposite direction of the PN junction and a radio frequency drive signal in the opposite direction of the PN junction to a carrier depletion modulator (high bandwidth, low modulation efficiency), and also unlike the conventional method of loading a DC bias in the same direction as the PN junction and a radio frequency drive signal in the same direction as the PN junction to a carrier injection modulator (low bandwidth, high modulation efficiency), by applying a forward DC bias less than the built-in electric field of the PN junction to the carrier modulator based on the PN junction, and applying a radio frequency voltage in the opposite direction of the PN junction, the modulation efficiency of the carrier modulation is effectively improved. A carrier modulator with large bandwidth and high modulation efficiency is formed, which is applied to the quantum key distribution system and can effectively reduce the swing requirements of the radio frequency drive circuit. At the same time, the carrier modulator based on the PN junction structure based on this scheme applies a forward DC bias less than the built-in electric field of the PN junction, which can also adjust the carrier concentration of the modulator and improve the process error tolerance during carrier doping.

[0043] According to an embodiment of the present disclosure, the driving method of the carrier modulator also includes: controlling the amplitude of the radio frequency signal to change the phase shift and modulation depth of the carrier modulator, wherein the larger the amplitude of the radio frequency signal, the larger the phase shift and modulation depth of the carrier modulator.

[0044] According to the embodiments of the present disclosure, the performance of the carrier modulator can be dynamically controlled by adjusting the amplitude of the RF signal. The larger the amplitude of the RF signal, the stronger the reverse bias electric field applied to the PN junction, which leads to a greater change in the carrier concentration in the waveguide region. Since the change in carrier concentration causes a change in refraction through the plasma dispersion effect, it will cause the phase shift and modulation depth of the carrier modulator to increase.

[0045] Based on this, the embodiments of the present disclosure can achieve precise adjustment of the phase shift and modulation depth of the modulator by controlling the amplitude of the RF signal, thereby providing flexibility and controllability for performance optimization of the modulator.

[0046] Figure 2 The figure schematically shows a driving circuit of a carrier modulator according to an embodiment of the present disclosure.

[0047] like Figure 2 As shown, the driving circuit 210 of the carrier modulator 220 includes a DC driver 211, a RF driver 212 and a bias device 213. The carrier modulator 220 may be an on-chip modulator to be suitable for an integrated photonic chip.

[0048] According to an embodiment of the present disclosure, the DC driver 211 is configured to apply a DC bias in the same direction as the PN junction to the carrier modulator 220, so that the carriers in the P-doped region and the N-doped region are injected into the waveguide region to increase the carrier concentration in the waveguide region. The DC driver 211 can be an analog DC driver or a digital DC driver, such as a DAC, for providing a stable and accurate DC voltage. The DC driver 211 can provide a stable DC voltage to a circuit or other device through a power module, which can ensure the accuracy of the DC voltage.

[0049] According to an embodiment of the present disclosure, the bias magnitude of the DC bias is configured to be smaller than the built-in electric field of the PN junction to prevent excessive bias from causing PN junction breakdown or bandwidth performance degradation.

[0050] According to an embodiment of the present disclosure, the RF driver 212 is configured to apply a RF signal in the opposite direction of the PN junction to the carrier modulator 220, so that the PN junction is in a reverse bias state, the depletion region is expanded, and the free carrier concentration in the waveguide region is reduced, thereby improving the bandwidth performance of the modulator. The RF driver 212 can output a fixed RF signal with high stability and high accuracy, and can provide customized RF signals according to different application scenarios.

[0051] According to an embodiment of the present disclosure, the bias device 213 is configured to couple the DC bias and the RF signal to the carrier modulator 220 to ensure that the DC bias and the RF signal are effectively superimposed. The bias device 213 may be a Bias Tee (bias T-type device), an adjustable bias device (Adjustable Bias), an integrated bias device (Integrated Bias), etc.

[0052] According to an embodiment of the present disclosure, the bias device 213 includes a DC terminal, a RF terminal and a common terminal.

[0053] According to an embodiment of the present disclosure, the DC terminal is used to transmit a DC bias voltage from a DC power source to a common terminal, and to prevent a radio frequency signal from being transmitted to a DC driver 211, so as to avoid interference to the DC driver. The radio frequency terminal is used to transmit a radio frequency signal from a radio frequency source to a common terminal, and to prevent a DC bias voltage from being transmitted to a radio frequency driver 212. The common terminal is used to output a DC bias voltage and a radio frequency signal to a carrier modulator 220.

[0054] According to an embodiment of the present disclosure, when a DC bias is applied to the bias breaker through the DC terminal, it is transmitted to the common terminal and applied to the carrier modulator through the common terminal. At the same time, the RF signal is transmitted to the common terminal through the RF terminal and applied to the modulator together with the DC signal. Due to the design of the bias breaker, the DC bias and the RF signal can be effectively superimposed and coupled into the carrier modulator, and the DC signal and the RF signal remain isolated during the transmission process and do not interfere with each other, so as to ensure the driving function of the driving circuit.

[0055] Figure 3 The schematic diagram shows the structure of a carrier modulator according to an embodiment of the present disclosure.

[0056] like Figure 3 As shown, the carrier modulator includes a silicon-based ridge waveguide, which includes a P-doped region, an N-doped region and a waveguide region, and the waveguide region includes a PN junction.

[0057] According to an embodiment of the present disclosure, the carrier modulator is configured to change the refractive index of the waveguide region based on the change of the carrier concentration of the waveguide region, so as to modulate the optical signal by changing the phase or intensity of the input optical signal.

[0058] like Figure 3 As shown, the carrier modulator further includes an electrode, which can be configured as a copper or tungsten metal material and connected to the P-doped region and the N-doped region through an ohmic contact.

[0059] like Figure 3As shown, in one example, the electrode includes a metal electrode 1 and a metal electrode 2, the metal electrode 1 is in ohmic contact with the P-doped region, and the metal electrode 2 is in ohmic contact with the N-doped region.

[0060] According to an embodiment of the present disclosure, the metal electrode 2 is connected to the common end of the bias device, and the metal electrode 1 is grounded.

[0061] The carrier modulator of the disclosed embodiment is based on a PN junction structure. By applying a forward DC bias voltage less than the built-in electric field, the carriers in the doped regions on both sides can be injected into the waveguide region, thereby changing the carrier concentration in the waveguide region. By applying a reverse RF signal, the width of the reverse bias structure of the PN junction can be enlarged, thereby increasing the bandwidth of the waveguide region.

[0062] According to an embodiment of the present disclosure, the P-doped region may be obtained by doping in a single-stage manner with the same concentration.

[0063] According to an embodiment of the present disclosure, the P-doped region may be obtained by doping in a multi-level manner with different concentrations.

[0064] According to an embodiment of the present disclosure, the N-doped region may be obtained by doping in a single-stage manner with the same concentration.

[0065] According to an embodiment of the present disclosure, the N-doped region may be obtained by doping in a multi-level manner with different concentrations.

[0066] According to the embodiments of the present disclosure, a single-stage doping method with the same concentration means that the concentration of the dopant remains the same during the entire doping process, and only one doping step is performed. The process of the single-stage doping method with the same concentration is relatively simple. A multi-stage doping method with different concentrations means that different doping concentrations are achieved in different regions through multiple doping steps. A multi-stage doping method with different concentrations can achieve a more complex doping concentration distribution, thereby optimizing the performance of the carrier modulator.

[0067] The carrier modulator and its driving circuit of the disclosed embodiment improve the modulation efficiency of the phase modulator based on the carrier dispersion principle, and can also adjust the bandwidth, increase the phase shift and modulation depth of the phase modulator based on the carrier dispersion principle, and meet the requirements of quantum state modulation of the quantum key distribution system. Higher modulation efficiency does not require a higher driving voltage, reduces the swing requirements of the RF driving circuit, and reduces the technical complexity and cost of the driving circuit. In addition, the carrier concentration is adjusted by the driving circuit, which improves the processing error tolerance of the carrier modulator.

[0068] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A method for driving a carrier modulator, wherein the carrier modulator comprises a silicon-based ridge waveguide, wherein the silicon-based ridge waveguide comprises a P-doped region, an N-doped region and a waveguide region, wherein the waveguide region comprises a PN junction; characterized in that: The driving method comprises: Applying a DC bias in the same direction as the PN junction to the carrier modulator so that the carriers in the P-doped region and the N-doped region are injected into the waveguide region to increase the carrier concentration in the waveguide region; wherein the DC bias is less than the built-in electric field of the PN junction; Applying a radio frequency signal in the opposite direction to the PN junction to the carrier modulator, so that the PN junction is in a reverse bias state; and The DC bias voltage and the radio frequency signal are coupled and output to the carrier modulator to ensure that the DC bias voltage and the radio frequency signal are superimposed.

2. The driving method according to claim 1, characterized in that: The method further comprises: The amplitude of the radio frequency signal is controlled to change the phase shift and modulation depth of the carrier modulator, wherein the larger the amplitude of the radio frequency signal is, the larger the phase shift and modulation depth of the carrier modulator is.

3. A driving circuit of a carrier modulator, suitable for the driving method according to any one of claims 1 to 2, characterized in that: The driving circuit comprises: A DC driver is configured to apply a DC bias voltage in the same direction as the PN junction to the carrier modulator, so that the carriers in the P-doped region and the N-doped region are injected into the waveguide region to increase the carrier concentration in the waveguide region; wherein the DC bias voltage is less than the built-in electric field of the PN junction; A radio frequency driver configured to apply a radio frequency signal in the opposite direction of the PN junction to the carrier modulator, so that the PN junction is in a reverse bias state; and A bias device is configured to couple the DC bias voltage and the radio frequency signal to the carrier modulator to ensure that the DC bias voltage and the radio frequency signal are superimposed.

4. The driving circuit according to claim 3, characterized in that: The bias device includes a DC terminal, a radio frequency terminal and a common terminal; The DC terminal is used to transmit the DC bias voltage to the common terminal and prevent the RF signal from being transmitted to the DC driver; The RF terminal is used to transmit the RF signal to the common terminal and prevent the DC bias voltage from being transmitted to the RF driver; The common end is used to output the DC bias voltage and the radio frequency signal to the carrier modulator.

5. A carrier modulator, characterized in that: The carrier modulator comprises: A silicon-based ridge waveguide, comprising a P-doped region, an N-doped region and a waveguide region, wherein the waveguide region comprises a PN junction; The carrier modulator is configured to change the refractive index of the waveguide region based on the change of the carrier concentration of the waveguide region, so as to modulate the optical signal by changing the phase or intensity of the input optical signal.

6. The carrier modulator according to claim 5, characterized in that: The electrode of the carrier modulator is configured as a copper metal material or a tungsten metal material, and is connected to the P-doped region and the N-doped region through an ohmic contact.

7. The carrier modulator according to claim 5 or 6, characterized in that: The P-doped region is obtained by doping in a single-stage manner with the same concentration.

8. The carrier modulator according to claim 5 or 6, characterized in that: The P-doped region is obtained by doping in a multi-level manner with different concentrations.

9. The carrier modulator according to claim 5 or 6, characterized in that: The N-doped region is obtained by doping in a single-stage manner with the same concentration.

10. The carrier modulator according to claim 5 or 6, characterized in that: The N-doped region is obtained by doping in a multi-level manner with different concentrations.

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