A broadband differential drive electro-optic modulator chip

Abstract

The present application discloses a broadband differential drive electro-optic modulator chip, which relates to the field of optical communication technology. The disclosed broadband differential drive electro-optic modulator chip includes: an electrode structure, an upper arm waveguide, a lower arm waveguide, and an electro-optic frequency domain equalizer; a differential electric field formed by multiple differential signals exists in the electrode structure; the upper arm waveguide and the lower arm waveguide are respectively in differential electric fields with opposite directions; in the electro-optic frequency domain equalizer, the directions of the differential electric fields in which the upper arm waveguide and the lower arm waveguide are located are reversed. The present application adopts multiple differential signals to form a differential electric field in a broadband differential drive electro-optic modulator chip, and sets the upper arm waveguide and the lower arm waveguide in the differential electric field, thereby realizing the modulation of the differential signal into the optical signal, which can effectively avoid the modulation process from being affected by the external electric field, improve the anti-interference ability of the device, and thus improve the transmission performance of the optical communication system.

Description

Technical Field

[0001] The present application relates to the field of optical communication technology, and in particular to a broadband differential drive electro-optic modulator chip. Background Art

[0002] The electro-optic modulator is responsible for modulating electrical signals onto optical signals and is a core component of optical communication systems. The electro-optic bandwidth of the electro-optic modulator reflects the ability of loading electrical signals onto optical signals.

[0003] At present, in order to improve the electro-optic bandwidth of the electro-optic modulator, the existing technology uses a Mach-Zehnder electro-optic modulator, in which an electro-optic frequency domain equalizer is designed in which the waveguide is reversely transformed relative to the electrode. The electro-optic frequency domain equalizer compensates for the decrease in electro-optic bandwidth in the high frequency band caused by the increase in microwave transmission loss in the high frequency band, thereby achieving an increase in electro-optic bandwidth.

[0004] However, the above-mentioned Mach-Zehnder electro-optic modulator adopts a single-ended push-pull structure and uses only one electrical signal, namely a single-ended signal for modulation. In an optical communication system, it is easily affected by an external electric field, which reduces the transmission performance. Summary of the invention

[0005] The main purpose of the present application is to provide a broadband differential drive electro-optical modulator chip, which aims to solve the technical problem that the existing technology uses single-ended signals for modulation and is easily affected by external electric fields in optical communication systems, resulting in reduced transmission performance.

[0006] To achieve the above object, the present application provides a broadband differential drive electro-optic modulator chip, the broadband differential drive electro-optic modulator chip comprising: an electrode structure, an upper arm waveguide, a lower arm waveguide and an electro-optic frequency domain equalizer;

[0007] A differential electric field formed by multiple differential signals exists in the electrode structure;

[0008] The upper arm waveguide and the lower arm waveguide are respectively in differential electric fields in opposite directions;

[0009] In the electro-optical frequency domain equalizer, directions of differential electric fields in which the upper arm waveguide and the lower arm waveguide are located are reversed.

[0010] In one embodiment, the broadband differential drive electro-optic modulator chip further includes: a basic modulation area;

[0011] The basic modulation area is a modulation area without the electro-optical frequency domain equalizer;

[0012] The electrode structure comprises: an upper arm traveling wave electrode structure and a lower arm traveling wave electrode structure;

[0013] The upper arm traveling wave electrode structure forms an upper arm basic differential electric field in the basic modulation area;

[0014] The lower arm traveling wave electrode structure forms a lower arm basic differential electric field in the basic modulation area;

[0015] Wherein, the direction of the upper arm basic differential electric field is opposite to the direction of the lower arm basic differential electric field;

[0016] In the basic modulation region, the upper arm waveguide is in the upper arm basic differential electric field, and the lower arm waveguide is in the lower arm basic differential electric field;

[0017] In the electro-optical frequency domain equalizer, the upper arm waveguide is in a first differential electric field, and the direction of the first differential electric field is opposite to the direction of the upper arm basic differential electric field;

[0018] In the electro-optical frequency domain equalizer, the lower arm waveguide is in a second differential electric field, and the direction of the second differential electric field is opposite to the direction of the lower arm basic differential electric field.

[0019] In one embodiment, the broadband differential drive electro-optic modulator chip further comprises: a plurality of micro-electrode structures provided with electrode pairs;

[0020] Each of the micro-electrode structures is respectively arranged in the upper arm traveling wave electrode structure and the lower arm traveling wave electrode structure;

[0021] The direction of the electric field formed by the electrode pairs of each microelectrode structure is parallel to the direction of the upper arm basic differential electric field and / or the lower arm basic differential electric field;

[0022] The upper arm waveguide is arranged in the electrode pair of the micro-electrode structure in the upper arm traveling wave electrode structure;

[0023] The lower arm waveguide is arranged in the electrode pair of the micro-electrode structure in the lower arm traveling wave electrode structure.

[0024] In one embodiment, the upper arm traveling wave electrode structure includes: an upper arm positive signal electrode and an upper arm negative signal electrode;

[0025] The lower arm traveling wave electrode structure comprises: a lower arm positive signal electrode and a lower arm negative signal electrode;

[0026] The microelectrode structure comprises: an upper arm microelectrode structure and a lower arm microelectrode structure;

[0027] Each of the upper arm microelectrode structures is disposed between the upper arm positive signal electrode and the upper arm negative signal electrode, and each of the lower arm microelectrode structures is disposed between the lower arm positive signal electrode and the lower arm negative signal electrode;

[0028] In the basic modulation area, the upper arm positive signal electrode and the upper arm negative signal electrode form the upper arm basic differential electric field based on the upper arm differential signal, and the lower arm positive signal electrode and the lower arm negative signal electrode form the lower arm basic differential electric field based on the lower arm differential signal;

[0029] In the basic modulation region, the upper arm waveguide is disposed in an electrode pair of each upper arm microelectrode structure, and the lower arm waveguide is disposed in an electrode pair of each lower arm microelectrode structure.

[0030] In one embodiment, the electro-optical frequency domain equalizer includes: a same polarity modulation region, a transition region, and a reverse polarity modulation region;

[0031] In the same polarity modulation area, the upper arm waveguide is in the upper arm basic differential electric field, and the lower arm waveguide is in the lower arm basic differential electric field;

[0032] In the transition region, the upper arm waveguide is bent and enters between the lower arm positive signal electrode and the lower arm negative signal electrode in the reverse polarity modulation region, and the lower arm waveguide is bent and enters between the upper arm positive signal electrode and the upper arm negative signal electrode in the reverse polarity modulation region;

[0033] In the reverse polarity modulation area, the upper arm waveguide is located in the lower arm basic differential electric field formed by the lower arm positive signal electrode and the lower arm negative signal electrode after bending, and the lower arm waveguide is located in the upper arm basic differential electric field formed by the upper arm positive signal electrode and the upper arm negative signal electrode after bending;

[0034] Among them, in the reverse polarity modulation area, the first differential electric field is the lower arm basic differential electric field, and the second differential electric field is the upper arm basic differential electric field.

[0035] In one embodiment, the electro-optical frequency domain equalizer includes: a same polarity modulation region and an opposite polarity modulation region;

[0036] The electrode pair of the upper arm microelectrode structure includes: a first upper arm microelectrode and a second upper arm microelectrode;

[0037] The electrode pair of the lower arm microelectrode structure includes: a first lower arm microelectrode and a second lower arm microelectrode;

[0038] In the basic modulation area and the same polarity modulation area, each of the first upper arm microelectrodes is connected to the upper arm positive signal electrode, each of the second upper arm microelectrodes is connected to the upper arm negative signal electrode, each of the first lower arm microelectrodes is connected to the lower arm positive signal electrode, and each of the second lower arm microelectrodes is connected to the lower arm negative signal electrode;

[0039] In the reverse polarity modulation area, each of the first upper arm microelectrodes is connected to the upper arm negative signal electrode, each of the second upper arm microelectrodes is connected to the upper arm positive signal electrode, each of the first lower arm microelectrodes is connected to the lower arm negative signal electrode, and each of the second lower arm microelectrodes is connected to the upper arm positive signal electrode;

[0040] In the reverse polarity modulation area, the upper arm basic differential electric field passes through the first upper arm microelectrode and the second upper arm microelectrode to form the first differential electric field in the opposite direction;

[0041] In the reverse polarity modulation region, the lower arm basic differential electric field forms the second differential electric field with the opposite direction after passing through the first lower arm microelectrode and the second lower arm microelectrode.

[0042] In one embodiment, the electrode structure further comprises: a common ground electrode;

[0043] The upper arm traveling wave electrode structure includes: a positive signal electrode and an upper arm ground electrode

[0044] The lower arm traveling wave electrode structure comprises: a negative signal electrode and a lower arm ground electrode;

[0045] The microelectrode structure comprises: an upper arm microelectrode structure and a lower arm microelectrode structure;

[0046] Each of the upper arm microelectrode structures is respectively arranged between the positive signal electrode and the upper arm ground electrode and between the positive signal electrode and the common ground electrode, and each of the lower arm microelectrode structures is respectively arranged between the negative signal electrode and the lower arm ground electrode and between the negative signal electrode and the common ground electrode;

[0047] In the basic modulation area, the positive signal electrode and the upper arm ground electrode form the upper arm basic differential electric field based on the upper arm differential signal, and the negative signal electrode and the common ground electrode form the lower arm basic differential electric field based on the lower arm differential signal;

[0048] In the basic modulation region, the upper arm waveguide is in the upper arm basic differential electric field, and the lower arm waveguide is in the lower arm basic differential electric field.

[0049] In one embodiment, the electro-optical frequency domain equalizer includes: a same polarity modulation region, a transition region, and a reverse polarity modulation region;

[0050] In the same polarity modulation area, the upper arm waveguide is in the upper arm basic differential electric field, and the lower arm waveguide is in the lower arm basic differential electric field;

[0051] In the transition region, the upper arm waveguide is bent and enters between the positive signal electrode and the common ground electrode in the reverse polarity modulation region, and the lower arm waveguide is bent and enters between the negative signal electrode and the lower arm ground electrode in the reverse polarity modulation region;

[0052] In the reverse polarity modulation region, the upper arm waveguide is in the first differential electric field formed by the positive signal electrode and the common ground electrode, and the lower arm waveguide is in the second differential electric field formed by the negative signal electrode and the lower arm ground electrode.

[0053] In one embodiment, the electro-optical frequency domain equalizer includes: a same polarity modulation region and an opposite polarity modulation region;

[0054] The electrode pair of the upper arm microelectrode structure includes: a first upper arm microelectrode and a second upper arm microelectrode;

[0055] The electrode pair of the lower arm microelectrode structure includes: a first lower arm microelectrode and a second lower arm microelectrode;

[0056] In the basic modulation area and the same polarity modulation area, each of the first upper arm microelectrodes is connected to the positive signal electrode, each of the second upper arm microelectrodes is connected to the upper arm ground electrode, each of the first lower arm microelectrodes is connected to the common ground electrode, and each of the second lower arm microelectrodes is connected to the negative signal electrode;

[0057] In the reverse polarity modulation area, each of the first upper arm microelectrodes is connected to the upper arm ground electrode, each of the second upper arm microelectrodes is connected to the positive signal electrode, each of the first lower arm microelectrodes is connected to the negative signal electrode, and each of the second lower arm microelectrodes is connected to the common ground electrode;

[0058] In the reverse polarity modulation area, the upper arm basic differential electric field passes through the first upper arm microelectrode and the second upper arm microelectrode to form the first differential electric field in the opposite direction;

[0059] In the reverse polarity modulation region, the lower arm basic differential electric field forms the second differential electric field with the opposite direction after passing through the first lower arm microelectrode and the second lower arm microelectrode.

[0060] In addition, to achieve the above objectives, the present application also provides an optical communication system, which includes the broadband differential drive electro-optic modulator chip as described above.

[0061] One or more technical solutions proposed in this application have at least the following technical effects:

[0062] The broadband differential drive electro-optic modulator chip of the present application includes: an electrode structure, an upper arm waveguide, a lower arm waveguide and an electro-optic frequency domain equalizer; there is a differential electric field formed by multiple differential signals in the electrode structure; the upper arm waveguide and the lower arm waveguide are respectively in differential electric fields with opposite directions; in the electro-optic frequency domain equalizer, the directions of the differential electric fields in which the upper arm waveguide and the lower arm waveguide are located are reversed. Since the present application uses multiple differential signals to form a differential electric field in the broadband differential drive electro-optic modulator chip, and sets the upper arm waveguide and the lower arm waveguide in the differential electric field, the differential signal is modulated into the optical signal. Therefore, compared with the prior art using a single-ended signal driving method, the differential electric field formed by the differential signal of the present application can effectively avoid the modulation process from being affected by the external electric field, improve the anti-interference ability of the device, and thus improve the transmission performance of the optical communication system. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0064] Figure 1 This is a schematic structural diagram of the first embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0065] Figure 2 This is a schematic diagram of the optical structure of the first embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0066] Figure 3 This is a schematic diagram of the microelectrode structure in the first embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0067] Figure 4 This is a first structural schematic diagram of the second embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0068] Figure 5 This is a cross-sectional schematic diagram of the first structure in the second embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0069] Figure 6 This is a second structural schematic diagram of the second embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0070] Figure 7 This is a first structural schematic diagram of the third embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0071] Figure 8 This is a cross-sectional schematic diagram of the first structure in the third embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0072] Fig. 9This is a second structural schematic diagram of the third embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0073] Fig.10 This is a third structural schematic diagram of the third embodiment of the broadband differential drive electro-optic modulator chip of the present application;

[0074] Fig.11 This is a fourth structural diagram of the third embodiment of the broadband differential drive electro-optic modulator chip of the present application.

[0075] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0076] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0077] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0078] The main solution of the embodiment of the present application is: the broadband differentially driven electro-optical modulator chip includes an electrode structure, an upper arm waveguide, a lower arm waveguide and an electro-optical frequency domain equalizer; there is a differential electric field formed by multiple differential signals in the electrode structure; the upper arm waveguide and the lower arm waveguide are respectively in differential electric fields with opposite directions; in the electro-optical frequency domain equalizer, the directions of the differential electric fields in which the upper arm waveguide and the lower arm waveguide are located are reversed.

[0079] With the widespread popularity of technologies such as 5G networks, data centers, cloud computing, and the Internet of Things, the amount of data in the entire communication system has exploded. In order to meet the needs of high-speed, large-capacity, and low-latency data transmission, various emerging optical communication technologies have flourished, among which photonic integration technology, as an innovative solution, has shown great potential. By integrating optical components and circuits onto a single chip, photonic integration technology can significantly improve communication speed and efficiency, and reduce energy consumption and costs. At present, many photonic integration platform materials have emerged, such as silicon, silicon nitride, lithium niobate, indium phosphide, etc. Among them, thin-film lithium niobate materials have excellent nonlinear optical properties and excellent electro-optical effects, which can achieve high-speed and low-power optical signal modulation, show good optical transparency in a wide wavelength range, low waveguide transmission loss, good temperature stability, and can be combined with other optical materials. Thin-film lithium niobate wafers already have mature large-scale manufacturing and processing technology, making them an ideal choice for photonic integration platforms.

[0080] The electro-optic modulator is responsible for modulating electrical signals onto optical signals and is the core component of optical communication systems. With the development of optical communication technology, thin-film lithium niobate photonic integrated electro-optic modulators have been widely studied. In order to increase the capacity of optical communication systems, it is particularly important to increase the electro-optic bandwidth of electro-optic modulators. In the Mach-Zehnder electro-optic modulator, by adopting the electrode structure of the traveling wave electrode, the electro-optic bandwidth of the modulator can break the RC constant limitation of the lumped electrode and achieve broadband modulation.

[0081] The electro-optic bandwidth of the modulator reflects the ability of electrical signals to be loaded onto optical signals. In the electro-optic modulator of thin-film lithium niobate traveling wave electrode, the three factors that affect the electro-optic bandwidth are: the microwave transmission loss of the electrode, whether the optical group velocity and microwave velocity match, and the microwave electrode impedance matching. When the microwave transmission loss is 0, the optical group velocity and microwave velocity are equal, and the electrode impedance is matched, the electro-optic bandwidth of the Mach-Zehnder electro-optic modulator tends to infinity. However, in actual equipment, microwave transmission loss cannot be ignored, and the bandwidth is always limited to a limited frequency. The transmission loss of the microwave electrode includes conductive loss and dielectric loss. The conductive loss plays a dominant role at low frequencies, and the dielectric loss plays a dominant role at high frequencies. In the high frequency band, the transmission loss of the microwave electrode will increase, and then the sensitivity of the traveling wave electrode will decrease, causing the electro-optic bandwidth of the modulator to be in a state of continuous decrease in the frequency domain with the increase of frequency, so the electro-optic bandwidth of the modulator is limited at a decrease of 3dB. Based on this, whether reducing the conductive loss or reducing the dielectric loss, the overall transmission loss of the microwave electrode can be reduced, and the modulator will also produce a larger electro-optical bandwidth. At present, by changing the material of the metal electrode and replacing the gold electrode with a copper electrode, the conductive loss of the microwave can be effectively reduced. The dielectric loss can be affected by changing the substrate material or the cladding material.

[0082] The transmission loss of microwave electrodes cannot be avoided, which will inevitably cause the electro-optic bandwidth of the modulator to decrease. To solve this problem, the prior art proposes a Mach-Zehnder electro-optic modulator with an electro-optic frequency domain equalizer, which mainly utilizes the increase in microwave transmission loss in the high-frequency band and the reduction in the phase effect on the light in the thin-film lithium niobate waveguide, and then designs an electro-optic frequency domain equalizer with a waveguide reverse transformation relative to the electrode. Through this electro-optic frequency domain equalizer, when the microwave electrode is loaded with a low-frequency microwave signal, the phase of the optical signal does not change when passing through the electro-optic frequency domain equalizer, because the transmission loss of low-frequency microwaves is very small, and the front and rear parts of the electro-optic frequency domain equalizer (same polarity modulation area, opposite polarity modulation area) have the same effect on the phase of the optical signal. However, when the microwave electrode is loaded with a high-frequency microwave signal, due to the increase in microwave transmission loss, the intensity of the microwave signal continues to decrease as the transmission distance in the microstrip line increases, resulting in different effects on the optical signal in the front and rear areas of the electro-optical frequency domain equalizer, which do not cancel each other out, that is, the effect of the reverse polarity modulation area on the optical signal phase is much smaller than that of the same polarity modulation area on the optical signal phase. As a result, in the high frequency band, the electro-optical frequency domain equalizer will have an effect on the optical signal phase. The magnitude of this effect is the effect of the same polarity modulation area on the optical signal phase minus the effect of the reverse polarity modulation area on the optical signal phase. The effect of the phase change is ultimately reflected in the change in the intensity of the electro-optic modulator, that is, the intensity change in the high frequency band will be higher than that in the low frequency band. Therefore, through the electro-optical frequency domain equalizer structure, the phenomenon of the electro-optical bandwidth being reduced in the high frequency band due to the increase in microwave transmission loss in the high frequency band is compensated, and finally the electro-optical bandwidth of the electro-optical modulator is improved, thereby widening the electro-optical bandwidth, so that the electro-optical modulator can perform broadband modulation.

[0083] The above-mentioned Mach-Zehnder electro-optic modulator with electro-optical frequency domain equalizer adopts a single-ended push-pull structure, which has the advantage of simple structure. However, it only uses one electrical signal, that is, a single-ended signal for modulation, and is easily affected by external electric fields in optical communication systems, resulting in reduced transmission performance.

[0084] In a solution provided by the present application, a multi-path differential signal is used to form a differential electric field in a broadband differential drive electro-optic modulator chip, and the upper arm waveguide and the lower arm waveguide are arranged in the differential electric field, thereby realizing the modulation of the differential signal into an optical signal. Therefore, compared with the prior art using a single-ended signal driving method, the differential electric field formed by the differential signal in the present application has a strong anti-interference ability, can effectively suppress electric field interference, so as to avoid the modulation process being affected by the external electric field, thereby improving the anti-interference ability of the device, and thus improving the transmission performance of the optical communication system.

[0085] Based on this, the embodiment of the present application provides a broadband differential drive electro-optic modulator chip, referring to Figure 1 , Figure 1This is a schematic structural diagram of the first embodiment of the broadband differential drive electro-optic modulator chip of the present application.

[0086] In this embodiment, the broadband differential drive electro-optic modulator chip includes: an electrode structure, an upper arm waveguide 201, a lower arm waveguide 202, and an electro-optical frequency domain equalizer.

[0087] A differential electric field formed by multiple differential signals exists in the electrode structure.

[0088] It should be noted that the above electrode structure can be composed of multiple electrodes, including but not limited to Figure 1 1 , 2, 3, and 4. The electrodes may include a signal electrode that receives a signal and a ground electrode that is grounded.

[0089] It should be noted that the arbitrary waveform generator is connected to multiple drivers, and the waveform generator can output multiple strictly differential microwave signals (i.e., differential signals) to the drivers. Each driver corresponds to a signal electrode in the electrode structure. The driver is connected to the probe corresponding to the electrode through a high-frequency transmission line, and the probe loads the differential signal onto the signal electrode of the electrode structure. When the signal electrode is a positive signal electrode, the loaded differential signal can be a positive signal, and when the signal electrode is a negative signal electrode, the loaded differential signal can be a negative signal. The above differential electric field can be formed by the positive signal electrode and the negative signal electrode in the electrode structure, or by the positive signal electrode or the negative signal electrode and the ground electrode. Through multiple driving schemes, the application range of the modulator can be further broadened.

[0090] In addition, before loading the differential signal on the electrode, the DC bias voltage needs to be loaded onto the driver first to realize the bias of the working state of the electro-optic modulator; or by heating the adjustment resistor in the optical waveguide attachment, the bias of the modulator working state, that is, the 3dB working point, can be realized through thermal regulation; or in chip design, a special DC bias working point is designed to exert influence, and the electro-optical or thermo-optical effect of the lithium niobate crystal is used to ensure that the chip is at a better working point.

[0091] The upper arm waveguide 201 and the lower arm waveguide 202 are respectively in differential electric fields in opposite directions.

[0092] It should be noted that both the upper arm waveguide 201 and the lower arm waveguide 202 can be thin-film lithium niobate ridge waveguides.

[0093] In a specific implementation, a differential electric field with opposite directions may be formed between the electrodes in the above electrode structure. Figure 1An electric field a1 and an electric field a2 in opposite directions can be formed, the upper arm waveguide 201 is in the electric field a1, and the lower arm waveguide 202 is in the electric field a2. In addition, between the first electrode 1 and the second electrode 2, an electric field directed from the first electrode 1 to the second electrode 2 and an electric field directed from the second electrode 2 to the first electrode 1 can be formed simultaneously; between the third electrode 3 and the fourth electrode 4, an electric field directed from the third electrode 3 to the fourth electrode 4 and an electric field directed from the fourth electrode 4 to the third electrode 3 can be formed simultaneously, and this embodiment does not limit this.

[0094] In the electro-optical frequency domain equalizer, the directions of the differential electric fields of the upper arm waveguide 201 and the lower arm waveguide 202 are reversed.

[0095] In a specific implementation, a corresponding structure may be provided in the above-mentioned electro-optical frequency domain equalizer to reverse the direction of the differential electric field in which the upper arm waveguide 201 and the lower arm waveguide 202 are located. For example, if the upper arm waveguide 201 is in electric field a1 before entering the electro-optical frequency domain equalizer, when entering the electro-optical frequency domain equalizer, the upper arm waveguide 201 is in electric field b1 after inversion, and the directions of the electric field a1 and the electric field b1 are opposite; if the lower arm waveguide 202 is in electric field a2 before entering the electro-optical frequency domain equalizer, when entering the electro-optical frequency domain equalizer, the lower arm waveguide 202 is in electric field b2 after inversion, and the directions of the electric field b1 and the electric field b1 are opposite.

[0096] Furthermore, in this embodiment, the broadband differential drive electro-optic modulator chip further includes: a basic modulation area;

[0097] The basic modulation area is a modulation area in which the electro-optical frequency domain equalizer is not provided.

[0098] The electrode structure includes: an upper arm traveling wave electrode structure and a lower arm traveling wave electrode structure.

[0099] It should be noted that the upper arm traveling wave electrode structure may be an electrode structure for modulating the upper arm waveguide 201, including but not limited to Figure 1 The first electrode 1 and the second electrode 2 in the lower arm traveling wave electrode structure may be an electrode structure for modulating the lower arm waveguide 202, including but not limited to Figure 1 The third electrode 3 and the fourth electrode 4 in.

[0100] The upper arm traveling wave electrode structure forms an upper arm basic differential electric field in the basic modulation area.

[0101] The lower arm traveling wave electrode structure forms a lower arm basic differential electric field in the basic modulation area.

[0102] The direction of the upper arm basic differential electric field is opposite to the direction of the lower arm basic differential electric field.

[0103] In the basic modulation region, the upper arm waveguide 201 is in the upper arm basic differential electric field, and the lower arm waveguide 202 is in the lower arm basic differential electric field.

[0104] In the electro-optical frequency domain equalizer, the upper arm waveguide 201 is in a first differential electric field, and the direction of the first differential electric field is opposite to the direction of the upper arm basic differential electric field.

[0105] In the electro-optical frequency domain equalizer, the lower arm waveguide 202 is in a second differential electric field, and the direction of the second differential electric field is opposite to the direction of the lower arm basic differential electric field.

[0106] It should be noted that, in the basic modulator, an upper arm basic differential electric field can be formed between the first electrode 1 and the second electrode 2 of the upper arm traveling wave electrode structure, and a lower arm basic differential electric field can be formed between the third electrode 3 and the fourth electrode 4 of the lower arm traveling wave electrode structure. The directions of the upper arm basic differential electric field and the lower arm basic differential electric field are opposite, such as Figure 1 The electric field a1 and the electric field a2 are opposite in direction 4, the upper arm waveguide 201 is in the upper arm differential electric field, and the lower arm waveguide 202 is in the lower arm differential electric field. The upper arm basic differential electric field and the lower arm basic differential electric field in opposite directions can make the electro-optic modulator work in push-pull mode.

[0107] It is understandable that in the electro-optical frequency domain equalizer, the differential electric field in the upper arm traveling wave electrode structure can be reversed to obtain a first differential electric field in the opposite direction to the upper arm basic differential electric field, such as Figure 1 The electric field b1 in the lower arm traveling wave electrode structure is opposite to the electric field a1. The differential electric field in the lower arm traveling wave electrode structure can be reversed to obtain a second differential electric field in the opposite direction to the lower arm basic differential electric field, such as Figure 1 The electric field b2 in the direction opposite to the electric field a2 is formed, so that the upper arm waveguide 201 enters the reverse first differential electric field from the upper arm basic differential electric field, and the lower arm waveguide 202 enters the reverse second differential electric field from the lower arm basic differential electric field. The directions of the first differential electric field and the second electric field are opposite, so as to ensure that the electro-optic modulator still works in the push-pull mode in the electro-optical frequency domain equalizer.

[0108] Further, refer to Figure 2 , Figure 2 This is a schematic diagram of the optical structure of the first embodiment of the broadband differential drive electro-optic modulator chip of the present application. Figure 2 , the optical structure of the broadband differentially driven electro-optic modulator chip includes an input waveguide 301, a beam splitter 302, a first curved waveguide 3031, a second curved waveguide 3032, an upper arm waveguide 201, a lower arm waveguide 202, a third curved waveguide 3041, a fourth curved waveguide 3042, a combiner 305 and an output waveguide 306.

[0109] Figure 2 The structure of the basic modulator and electro-optical frequency domain equalizer can be referred to Figure 1 Or described above, no further details will be given here.

[0110] like Figure 2 As shown, the optical signal from the light source enters the input waveguide 301 through the on-chip optical coupling structure, and the optical signal in the input waveguide 301 is divided into two equal light paths by the beam splitter 302, and enters the first curved waveguide 3031 and the second curved waveguide 3032 respectively. The optical signal in the first curved waveguide 3031 enters the upper arm waveguide 201 and enters the upper arm modulation area in the basic modulation area (the upper arm modulation area is composed of the upper arm traveling wave electrode structure and the upper arm waveguide 201), and the light in the second curved waveguide 3032 enters the lower arm waveguide 202 and enters the lower arm modulation area (the lower arm modulation area is composed of the lower arm traveling wave electrode structure and the lower arm waveguide 202). During the transmission of the optical signal in the upper arm waveguide 201 and the lower arm waveguide 202 of the basic modulation region and the electro-optical frequency domain equalizer, the optical signal is affected by the differential electric field in opposite directions, the refractive index of the lithium niobate crystal in the upper arm waveguide 201 and the lower arm waveguide 202 changes, and the optical signals in the upper arm waveguide 201 and the lower arm waveguide 202 are affected by the phase. The affected optical signal in the upper arm waveguide 201 enters the beam combiner 305 through the third curved waveguide 3041, and the affected optical signal in the lower arm waveguide 202 enters the beam combiner 305 through the fourth curved waveguide 3042. The beam combiner 305 combines the two received optical signals to complete destructive and constructive interference, and then transmits them out through the output waveguide 306. The whole process can complete the electro-optical modulation, that is, the electrical signal is loaded into the optical signal.

[0111] In one possible implementation, reference Figure 3 , Figure 3 This is a schematic diagram of the microelectrode structure in the first embodiment of the broadband differential drive electro-optic modulator chip of the present application.

[0112] Figure 3 In the broadband differential drive electro-optic modulator chip, the chip further includes: a plurality of micro-electrode structures provided with electrode pairs.

[0113] Each of the micro-electrode structures is respectively arranged in the upper arm traveling-wave electrode structure and the lower arm traveling-wave electrode structure.

[0114] The direction of the electric field formed by the electrode pairs of each of the micro-electrode structures is parallel to the direction of the upper arm basic differential electric field and / or the lower arm basic differential electric field.

[0115] The upper arm waveguide 201 is disposed in the electrode pair of the micro-electrode structure in the upper arm traveling wave electrode structure.

[0116] The lower arm waveguide 202 is disposed in the electrode pair of the micro-electrode structure in the lower arm traveling wave electrode structure.

[0117] In a specific implementation, each of the above-mentioned microelectrode structures is connected to the corresponding electrodes in the electrode structure. For example, the first electrode 1 and the second electrode 2 in the structure of the upper arm traveling wave electrode are connected to the microelectrode structure, and the third electrode 3 and the fourth electrode 4 in the structure of the lower arm traveling wave electrode are connected to the microelectrode structure, so that the direction of the electric field formed by the electrode pairs in the microelectrode structure is parallel to the direction of the differential electric field.

[0118] Exemplarily, in the basic modulation area, if the upper arm basic differential electric field of the upper arm traveling wave electrode structure is electric field a1, the electrode pair of the microelectrode structure can also form an electric field in the same direction as the electric field a1; if the lower arm basic differential electric field of the lower arm traveling wave electrode structure is electric field a2, the electrode pair of the microelectrode structure can also form an electric field in the same direction as the electric field a2, that is, the direction of the electric field formed by the electrode pair of the microelectrode structure is consistent with the direction of the differential electric field of the electrode structure in the same modulation area, so as to enhance the electro-optical effect and improve the modulation efficiency.

[0119] A broadband differential drive electro-optic modulator chip of the present embodiment includes: an electrode structure, an upper arm waveguide, a lower arm waveguide, and an electro-optic frequency domain equalizer; a differential electric field formed by multiple differential signals exists in the electrode structure; the upper arm waveguide and the lower arm waveguide are respectively in differential electric fields of opposite directions; in the electro-optic frequency domain equalizer, the directions of the differential electric fields in which the upper arm waveguide and the lower arm waveguide are located are reversed. Since the present embodiment uses multiple differential signals to form a differential electric field in the broadband differential drive electro-optic modulator chip, and sets the upper arm waveguide and the lower arm waveguide in the differential electric field, the differential signal is modulated into the optical signal. Therefore, compared with the prior art using a single-ended signal driving method, the differential electric field formed by the differential signal in the present embodiment can effectively avoid the modulation process from being affected by the external electric field, improve the anti-interference ability of the device, and thus improve the transmission performance of the optical communication system.

[0120] Based on the first embodiment of the present application, the second embodiment of the present application is proposed. In the second embodiment of the present application, the same or similar contents as those of the first embodiment can be referred to the above introduction, and will not be repeated later. Figure 4 , Figure 4 This is a first structural schematic diagram of the second embodiment of the broadband differential drive electro-optic modulator chip of the present application.

[0121] In this embodiment, the upper arm traveling wave electrode structure includes: an upper arm positive signal electrode 11 - 1 and an upper arm negative signal electrode 11 - 2 .

[0122] The lower arm traveling wave electrode structure includes: a lower arm positive signal electrode 12 - 1 and a lower arm negative signal electrode 12 - 2 .

[0123] It should be noted that the upper arm traveling wave electrode structure also includes an upper arm ground electrode 11-3, and the lower arm traveling wave electrode structure also includes a lower arm ground electrode 12-3. In this embodiment, a common ground electrode 10 is further provided between the upper arm positive signal electrode 11-1 and the lower arm positive signal electrode 12-1. Among them, the upper arm ground electrode 11-3, the lower arm ground electrode 12-3 and the common ground electrode 10 are all grounded, which can improve the anti-interference ability of the differential electric field in the electrode structure.

[0124] Understandably, Figure 4 In the subsequent figures, the upper arm positive signal electrode 11-1 and the lower arm positive signal electrode 12-1 correspond to electrode S+, the upper arm negative signal electrode 11-2 and the lower arm negative signal electrode 12-2 correspond to electrode S-, and the upper arm ground electrode 11-3, the lower arm ground electrode 12-3 and the common ground electrode 10 correspond to electrode G.

[0125] Among them, the microwave signals of the upper arm traveling wave electrode structure and the lower arm traveling wave electrode structure must be strictly differentiated, and all conditions must be completely consistent. They are loaded on the electrodes at the same time to form a push-pull structure in the upper arm traveling wave electrode structure and the lower arm traveling wave electrode structure.

[0126] The microelectrode structure includes an upper arm microelectrode structure 11 - 4 and a lower arm microelectrode structure 12 - 4 .

[0127] Each of the upper arm microelectrode structures 11 - 4 is disposed between the upper arm positive signal electrode 11 - 1 and the upper arm negative signal electrode 11 - 2, and each of the lower arm microelectrode structures 12 - 4 is disposed between the lower arm positive signal electrode 12 - 1 and the lower arm negative signal electrode 12 - 2.

[0128] For ease of understanding, refer to Figure 5 To explain, Figure 5 This is a cross-sectional schematic diagram of the first structure in the second embodiment of the broadband differential drive electro-optic modulator chip of the present application. Figure 5In the embodiment, the broadband differential drive electro-optic modulator chip adopts an x-cut thin film lithium niobate wafer. The low refractive index buried layer 204 is arranged between the substrate layer 203 and the thin film lithium niobate ridge waveguide structure 205. The thin film lithium niobate ridge waveguide structure 205 is a structure having a ridge waveguide, and the ridge waveguide is formed by optical structure etching using an x-cut lithium niobate wafer. The ridge waveguide includes an upper arm waveguide 201 and a lower arm waveguide 202, and the polarization direction shown can be the polarization direction of the ferroelectric domain of the lithium niobate crystal. The low refractive index upper cladding layer 206 is laid on the thin film lithium niobate ridge waveguide structure 205. The upper arm negative signal electrode 11-2 is arranged between the upper arm ground electrode 11-3 and the microelectrode structure A, the upper arm waveguide 201 is between the microelectrode structure A and the microelectrode structure B, the upper arm positive signal electrode 11-1 is arranged between the microelectrode structure B and the common ground electrode 10, the lower arm positive signal electrode 12-1 is arranged between the common ground electrode 10 and the microelectrode structure C, the lower arm waveguide 202 is arranged between the microelectrode structure C and the microelectrode structure D, the lower arm negative signal electrode 12-2 is arranged between the microelectrode structure D and the lower arm ground electrode 12-3, and each electrode structure adopts a coplanar waveguide structure. The microelectrode structure A and the microelectrode structure B are both upper arm microelectrode structures 11-4; the microelectrode structure C and the microelectrode structure D are both lower arm microelectrode structures 12-4.

[0129] In the basic modulation area, the upper arm positive signal electrode 11-1 and the upper arm negative signal electrode 11-2 form the upper arm basic differential electric field based on the upper arm differential signal, and the lower arm positive signal electrode 12-1 and the lower arm negative signal electrode 12-2 form the lower arm basic differential electric field based on the lower arm differential signal.

[0130] It should be noted that for the upper arm traveling wave electrode structure. The two upper arm differential electrical signals are loaded onto the upper arm positive signal electrode 11-1 and the upper arm negative signal electrode 11-2 through the GSSG probe, generating an upper arm basic differential electric field from the upper arm positive signal electrode 11-1 to the upper arm negative signal electrode 11-2 (i.e., S+ to S-), and the optical signal in the upper arm waveguide 201 is affected by the upper arm differential electric field. For the lower arm traveling wave electrode structure. The two lower arm differential electrical signals are loaded onto the lower arm positive signal electrode 12-1 and the lower arm negative signal electrode 12-2 through the GSSG probe, generating a lower arm basic differential electric field from the lower arm positive signal electrode 12-1 to the lower arm negative signal electrode 12-2 (i.e., S+ to S-), and the optical signal in the lower arm waveguide 202 is affected by the lower arm differential electric field.

[0131] In the basic modulation region, the upper arm waveguide 201 is provided in the electrode pair of each upper arm micro-electrode structure 11 - 4 , and the lower arm waveguide 202 is provided in the electrode pair of each lower arm micro-electrode structure 12 - 4 .

[0132] It should be noted that, in the basic modulation area, the direction of the electric field formed by the electrode pairs of each upper arm microelectrode structure 11-4 disposed between the upper arm positive signal electrode 11-1 and the upper arm negative signal electrode 11-2 is the same as the direction of the upper arm basic differential electric field. When the upper arm waveguide 201 is disposed in the electrode pairs of each upper arm microelectrode structure 11-4, it can be simultaneously in the upper arm basic differential electric field and the electric field formed by the electrode pairs of each upper arm microelectrode structure 11-4. The direction of the electric field formed by the electrode pairs of each lower arm microelectrode structure 12-4 disposed between the lower arm positive signal electrode 12-1 and the lower arm negative signal electrode 12-2 is the same as the direction of the lower arm basic differential electric field. When the lower arm waveguide 202 is disposed in the electrode pairs of each lower arm microelectrode structure 12-4, it can be simultaneously in the lower arm basic differential electric field and the electric field formed by the electrode pairs of each lower arm microelectrode structure 12-4, so as to enhance the electro-optical effect in the basic modulation area. Based on this, the electro-optical effect of the upper arm waveguide 201 and the lower arm waveguide 202 in the basic modulation region can be enhanced, thereby improving the modulation efficiency.

[0133] It is understandable that in the basic modulation region, the upper arm basic differential electric field where the upper arm waveguide 201 is located and the lower arm basic differential electric field where the lower arm waveguide 202 is located are in opposite directions, so that the electro-optic modulator works in the push-pull mode in the basic modulation region.

[0134] In a feasible implementation manner, the electro-optical frequency domain equalizer includes: a same polarity modulation region, a transition region, and a reverse polarity modulation region.

[0135] In the same polarity modulation region, the upper arm waveguide 201 is in the upper arm basic differential electric field, and the lower arm waveguide 202 is in the lower arm basic differential electric field.

[0136] It should be noted that in the same polarity modulation region, the directions of the upper arm basic differential electric field where the upper arm waveguide 201 is located and the lower arm basic differential electric field where the lower arm waveguide 202 is located are opposite, so that the electro-optic modulator operates in push-pull mode in the same polarity modulation region.

[0137] In the transition zone, the upper arm waveguide 201 is bent and enters between the lower arm positive signal electrode 12-1 and the lower arm negative signal electrode 12-2 in the reverse polarity modulation zone, and the lower arm waveguide 202 is bent and enters between the upper arm positive signal electrode 11-1 and the upper arm negative signal electrode 11-2 in the reverse polarity modulation zone.

[0138] In the reverse polarity modulation zone, the upper arm waveguide 201 is located in the lower arm basic differential electric field formed by the lower arm positive signal electrode 12-1 and the lower arm negative signal electrode 12-2 after being bent, and the lower arm waveguide 202 is located in the upper arm basic differential electric field formed by the upper arm positive signal electrode 11-1 and the upper arm negative signal electrode 11-2 after being bent.

[0139] Among them, in the reverse polarity modulation area, the first differential electric field is the lower arm basic differential electric field, and the second differential electric field is the upper arm basic differential electric field.

[0140] It should be noted that the upper arm waveguide 201 and the lower arm waveguide 202 are bent in the transition zone to form an optical cross waveguide structure. Through the optical cross waveguide structure, after the upper arm waveguide 201 is bent between the lower arm positive signal electrode 12-1 and the lower arm negative signal electrode 12-2, it is in the lower arm basic differential electric field formed by the lower arm positive signal electrode 12-1 and the lower arm negative signal electrode 12-2 in the reverse modulation zone. After the lower arm waveguide 202 is bent between the upper arm positive signal electrode 11-1 and the upper arm negative signal electrode 11-2, it is in the upper arm basic differential electric field formed by the upper arm positive signal electrode 11-1 and the upper arm negative signal electrode 11-2 in the reverse modulation zone. Based on this, the electro-optical modulator can operate in the push-pull mode in the reverse polarity modulation zone.

[0141] It should be understood that in this embodiment, the upper arm basic differential electric field of the upper arm waveguide 201 is converted into the lower arm basic differential electric field, and the lower arm basic differential electric field of the lower arm waveguide 202 is converted into the upper arm basic differential electric field through the above-mentioned optical cross-waveguide structure. Therefore, in the reverse polarity modulation area, the first differential electric field can be the lower arm basic differential electric field, and the second differential electric field can be the upper arm basic differential electric field.

[0142] It should be noted that when a high-frequency microwave signal (i.e., a differential signal) is loaded, since the differential electric field of the upper arm waveguide 201 is switched from the upper arm basic differential electric field to the lower arm basic differential electric field in the opposite direction, and the differential electric field of the lower arm waveguide 202 is switched from the lower arm basic differential electric field to the upper arm basic differential electric field in the opposite direction, the influence of the electro-optical frequency domain equalizer on the phase of the optical signal in the upper arm waveguide 201 and the lower arm waveguide 202 is the influence of the same polarity modulation area on the phase of the optical signal, minus the influence of the opposite polarity modulation area on the phase of the optical signal, so that the intensity change in the high frequency band is higher than that in the low frequency band, thereby compensating for the phenomenon that the electro-optical bandwidth decreases in the high frequency band due to the increase in microwave transmission loss in the high frequency band through the electro-optical frequency domain equalizer, thereby achieving an increase in the electro-optical bandwidth, broadening the electro-optical bandwidth, and enabling the electro-optical modulator to perform broadband modulation.

[0143] In addition, if Figure 4As shown, the broadband differential drive electro-optic modulator chip of this embodiment is further provided with a first upper arm on-chip resistor 11-51, a second upper arm on-chip resistor 11-52, a first lower arm on-chip resistor 12-51 and a second lower arm on-chip resistor 12-52. The first upper arm on-chip resistor 11-51 is connected to the upper arm negative signal electrode 11-2, the second upper arm on-chip resistor 11-52 is connected to the upper arm positive signal electrode 11-1, the first lower arm on-chip resistor 12-51 is connected to the lower arm positive signal electrode 12-1, and the second lower arm on-chip resistor 12-52 is connected to the lower arm negative signal electrode 12-2 to achieve impedance matching, so as to improve signal transmission efficiency.

[0144] In another possible implementation, reference Figure 6 , Figure 6 This is a second structural schematic diagram of the second embodiment of the broadband differential drive electro-optic modulator chip of the present application.

[0145] In this implementation, the electro-optical frequency domain equalizer includes: a same polarity modulation area and an opposite polarity modulation area.

[0146] The electrode pair of the upper arm microelectrode structure 11 - 4 includes: a first upper arm microelectrode 11 - 41 and a second upper arm microelectrode 11 - 42.

[0147] The electrode pair of the lower arm microelectrode structure 12 - 4 includes: a first lower arm microelectrode 12 - 41 and a second lower arm microelectrode 12 - 42 .

[0148] In the basic modulation area and the same polarity modulation area, each of the first upper arm microelectrodes 11-41 is connected to the upper arm positive signal electrode 11-1, each of the second upper arm microelectrodes 11-42 is connected to the upper arm negative signal electrode 11-2, each of the first lower arm microelectrodes 12-41 is connected to the lower arm positive signal electrode 12-1, and each of the second lower arm microelectrodes 12-42 is connected to the lower arm negative signal electrode 12-2.

[0149] In the reverse polarity modulation zone, each of the first upper arm microelectrodes 11-41 is connected to the upper arm negative signal electrode 11-2, each of the second upper arm microelectrodes 11-42 is connected to the upper arm positive signal electrode 11-1, each of the first lower arm microelectrodes 12-41 is connected to the lower arm negative signal electrode 12-2, and each of the second lower arm microelectrodes 12-42 is connected to the upper arm positive signal electrode 11-1.

[0150] In the reverse polarity modulation area, the upper arm basic differential electric field forms the first differential electric field in the opposite direction after passing through the first upper arm microelectrode 11 - 41 and the second upper arm microelectrode 11 - 42 .

[0151] It should be noted that, in the reverse polarity modulation area, each first upper arm microelectrode 11-41 is connected to the upper arm negative signal electrode 11-2, and each second upper arm microelectrode 11-42 is connected to the upper arm positive signal electrode 11-1. When the upper arm negative signal electrode 11-2 receives a negative signal, the first upper arm microelectrode 11-41 may also receive a negative signal, and when the upper arm positive signal electrode 11-1 receives a positive signal, the second upper arm microelectrode 11-42 may also receive a positive signal. Based on this, a first differential electric field pointing from the second upper arm microelectrode 11-42 to the first upper arm microelectrode 11-41 may be formed in the reverse polarity modulation area, which is opposite to the direction of the upper arm basic differential electric field pointing from the upper arm positive signal electrode 11-1 to the upper arm negative signal electrode 11-2, thereby switching the differential electric field where the upper arm waveguide 201 is located from the upper arm basic differential electric field to the first differential electric field with the opposite direction.

[0152] In the reverse polarity modulation area, the lower arm basic differential electric field forms the second differential electric field with the opposite direction after passing through the first lower arm microelectrode 12 - 41 and the second lower arm microelectrode 12 - 42 .

[0153] It should be noted that, in the reverse polarity modulation area, each first lower arm microelectrode 12-41 is connected to the lower arm negative signal electrode 12-2, and each second lower arm microelectrode 12-42 is connected to the upper arm positive signal electrode 11-1. When the lower arm negative signal electrode 12-2 receives a negative signal, the first lower arm microelectrode 12-41 can also receive a negative signal, and when the lower arm positive signal electrode 12-1 receives a positive signal, the second lower arm microelectrode 12-42 can also receive a positive signal. Based on this, a second sub-electric field can be formed in the reverse polarity modulation area from the second lower arm microelectrode 12-42 to the first lower arm microelectrode 12-41, which is opposite to the direction of the lower arm basic differential electric field from the lower arm positive signal electrode 12-1 to the lower arm negative signal electrode 12-2, so that the differential electric field where the lower arm waveguide 202 is located is switched from the lower arm basic differential electric field to the second differential electric field with the opposite direction.

[0154] It is understandable that when a high-frequency microwave signal (i.e., a differential signal) is loaded, since the differential electric field in the upper arm waveguide 201 is switched from the upper arm basic differential electric field to the first differential electric field in the opposite direction, and the differential electric field in the lower arm waveguide 202 is switched from the lower arm basic differential electric field to the second differential electric field in the opposite direction, the effect of the electro-optical frequency domain equalizer on the phase of the optical signal in the upper arm waveguide 201 and the lower arm waveguide 202 is the effect of the same polarity modulation area on the phase of the optical signal minus the effect of the opposite polarity modulation area on the phase of the optical signal, so that the intensity change in the high frequency band is higher than that in the low frequency band, thereby compensating for the phenomenon that the electro-optical bandwidth decreases in the high frequency band due to the increase in microwave transmission loss in the high frequency band through the electro-optical frequency domain equalizer, thereby achieving an increase in the electro-optical bandwidth, broadening the electro-optical bandwidth, and enabling the electro-optical modulator to perform broadband modulation.

[0155] In addition, if Figure 6 As shown, in this embodiment, a first upper arm on-chip resistor 11-51, a second upper arm on-chip resistor 11-52, a first lower arm on-chip resistor 12-51 and a second lower arm on-chip resistor 12-52 are also provided. The first upper arm on-chip resistor 11-51 is connected to the upper arm negative signal electrode 11-2, the second upper arm on-chip resistor 11-52 is connected to the upper arm positive signal electrode 11-1, the first lower arm on-chip resistor 12-51 is connected to the lower arm positive signal electrode 12-1, and the second lower arm on-chip resistor 12-52 is connected to the lower arm negative signal electrode 12-2, so as to achieve impedance matching and improve signal transmission efficiency.

[0156] Based on the first embodiment of the present application, the third embodiment of the present application is proposed. In the third embodiment of the present application, the same or similar contents as those of the first and second embodiments can be referred to the above introduction, and will not be repeated in the following. Figure 7 , Figure 7 This is a first structural schematic diagram of the third embodiment of the broadband differential drive electro-optic modulator chip of the present application.

[0157] In this embodiment, the electrode structure further includes: a common ground electrode 10 .

[0158] The upper arm traveling wave electrode structure includes: a positive signal electrode 11 and an upper arm ground electrode 11 - 3 .

[0159] The lower arm traveling wave electrode structure includes: a negative signal electrode 12 and a lower arm ground electrode 12 - 3 .

[0160] The microelectrode structure includes an upper arm microelectrode structure 11 - 4 and a lower arm microelectrode structure 12 - 4 .

[0161] Each of the upper arm microelectrode structures 11-4 is respectively arranged between the positive signal electrode 11 and the upper arm ground electrode 11-3 and between the positive signal electrode 11 and the common ground electrode 10, and each of the lower arm microelectrode structures 12-4 is respectively arranged between the negative signal electrode 12 and the lower arm ground electrode 12-3 and between the negative signal electrode 12 and the common ground electrode 10.

[0162] For ease of understanding, refer to Figure 8 To explain, Figure 8 This is a cross-sectional schematic diagram of the first structure in the third embodiment of the broadband differential drive electro-optic modulator chip of the present application. Figure 8In the figure, the low refractive index buried layer 204 is arranged between the substrate layer 203 and the thin film lithium niobate ridge waveguide structure 205. The thin film lithium niobate ridge waveguide structure 205 is a structure having a ridge waveguide, and the ridge waveguide includes the upper arm waveguide 201 and the lower arm waveguide 202. The polarization direction shown can be the polarization direction of the ferroelectric domain of the lithium niobate crystal. The low refractive index upper cladding layer 206 is laid on the thin film lithium niobate ridge waveguide structure 205. The microelectrode structure E is between the upper arm ground electrode 11-3 and the upper arm waveguide 201, the upper arm waveguide 201 is between the microelectrode structure E and the microelectrode structure F, the positive signal electrode 11 is between the microelectrode structure F and the microelectrode structure G, the common ground electrode 10 is between the microelectrode structure H and the microelectrode structure I, the lower arm waveguide 202 is between the microelectrode structure I and the microelectrode structure J, the negative signal electrode 12 is between the microelectrode structure J and the microelectrode structure K, the microelectrode structure L is between the microelectrode structure K and the lower arm ground electrode 12-3, and each electrode structure adopts a coplanar waveguide structure. The microelectrode structure E, the microelectrode structure F, the microelectrode structure G, and the microelectrode structure H are all upper arm microelectrode structures 11-4; the microelectrode structure I, the microelectrode structure J, the microelectrode structure K, and the microelectrode structure L are all lower arm microelectrode structures 12-4.

[0163] In this embodiment, the polarization direction of the ferroelectric domain of the lithium niobate crystal can be reversed. When the polarization direction of the ferroelectric domain is reversed, the direction of the electro-optical effect of the lithium niobate crystal is also reversed along with the polarization direction.

[0164] In the basic modulation area, the positive signal electrode 11 and the upper arm ground electrode 11 - 3 form the upper arm basic differential electric field based on the upper arm differential signal, and the negative signal electrode 12 and the common ground electrode 10 form the lower arm basic differential electric field based on the lower arm differential signal.

[0165] It should be noted that for the upper arm traveling wave electrode structure. The two upper arm differential electrical signals are loaded onto the positive signal electrode 11 through the GSSG probe, generating an upper arm basic differential electric field from the upper positive signal electrode to the upper arm ground electrode 11-3 (i.e., S+ to G), and the optical signal in the upper arm waveguide 201 is affected by the upper arm differential electric field. For the lower arm traveling wave electrode structure. The two lower arm differential electrical signals are loaded onto the negative signal electrode 12 and the common ground electrode 10 through the GSSG probe, generating a lower arm basic differential electric field from the common ground electrode 10 to the negative signal electrode 12 (i.e., G to S-), and the optical signal in the lower arm waveguide 202 is affected by the lower arm differential electric field.

[0166] In the basic modulation region, the upper arm waveguide 201 is in the upper arm basic differential electric field, and the lower arm waveguide 202 is in the lower arm basic differential electric field.

[0167] In a specific implementation, the upper arm waveguide 201 is in the upper arm basic differential electric field and is also in the electrode pair of the upper arm microelectrode structure 11-4. The lower arm waveguide 202 is in the lower arm basic differential electric field and is also in the electrode pair of the lower arm microelectrode structure 12-4. Based on this, the electro-optical effect of the upper arm waveguide 201 and the lower arm waveguide 202 in the basic modulation area can be enhanced, thereby improving the modulation efficiency.

[0168] It is understandable that in the basic modulation region, the upper arm basic differential electric field where the upper arm waveguide 201 is located and the lower arm basic differential electric field where the lower arm waveguide 202 is located are in opposite directions, so that the electro-optic modulator works in the push-pull mode in the basic modulation region.

[0169] In a first feasible implementation manner, the electro-optical frequency domain equalizer includes: a same polarity modulation region, a transition region, and a reverse polarity modulation region.

[0170] In the same polarity modulation region, the upper arm waveguide 201 is in the upper arm basic differential electric field, and the lower arm waveguide 202 is in the lower arm basic differential electric field.

[0171] In the transition zone, the upper arm waveguide 201 is bent and enters between the positive signal electrode 11 and the common ground electrode 10 in the reverse polarity modulation zone, and the lower arm waveguide 202 is bent and enters between the negative signal electrode 12 and the lower arm ground electrode 12-3 in the reverse polarity modulation zone.

[0172] In the reverse polarity modulation region, the upper arm waveguide 201 is in the first differential electric field formed by the positive signal electrode 11 and the common ground electrode 10, and the lower arm waveguide 202 is in the second differential electric field formed by the negative signal electrode 12 and the lower arm ground electrode 12-3.

[0173] It should be noted that the upper arm waveguide 201 in the same polarity modulation zone is in the upper arm basic differential electric field pointed from the positive signal electrode 11 to the upper arm ground electrode 11-3, and enters the reverse polarity modulation zone after bending in the transition zone. The upper arm waveguide 201 in the reverse polarity modulation zone is in the first differential electric field formed by the positive signal electrode 11 pointing to the common ground electrode 10, thereby realizing the reversal of the differential electric field in which the upper arm waveguide 201 is located.

[0174] It can be understood that the lower arm waveguide 202 in the same polarity modulation area is in the lower arm basic differential electric field pointing from the common ground electrode 10 to the negative signal electrode 12, and enters the reverse polarity modulation area after bending in the transition area. The lower arm waveguide 202 in the reverse polarity modulation area is in the second differential electric field pointing from the lower arm ground electrode 12-3 to the negative signal electrode 12, thereby achieving the reversal of the differential electric field in which the lower arm waveguide 202 is located. Since the directions of the first differential electric field and the second differential electric field are opposite, the electro-optical modulator can be operated in the push-pull mode in the reverse polarity modulation area. In this way, the electrical modulator can be operated in the push-pull mode in the reverse polarity modulation area.

[0175] It should be noted that when a high-frequency microwave signal (i.e., a differential signal) is loaded, since the differential electric field of the upper arm waveguide 201 is switched from the upper arm basic differential electric field to the first differential electric field of the opposite direction, and the differential electric field of the lower arm waveguide 202 is switched from the lower arm basic differential electric field to the second differential electric field of the opposite direction, the influence of the electro-optical frequency domain equalizer on the phase of the optical signal in the upper arm waveguide 201 and the lower arm waveguide 202 is the influence of the same polarity modulation area on the phase of the optical signal, minus the influence of the opposite polarity modulation area on the phase of the optical signal, so that the intensity change in the high frequency band is higher than that in the low frequency band, thereby compensating for the phenomenon that the electro-optical bandwidth decreases in the high frequency band due to the increase in microwave transmission loss in the high frequency band through the electro-optical frequency domain equalizer, thereby achieving an increase in the electro-optical bandwidth, broadening the electro-optical bandwidth, and enabling the electro-optical modulator to perform broadband modulation.

[0176] In a second possible implementation, refer to Fig. 9 , Fig. 9 This is a second structural diagram of the third embodiment of the broadband differential drive electro-optic modulator chip of the present application. Under this embodiment, the difference from the first feasible embodiment mentioned above is that in the basic modulation area and the same polarity modulation area, the upper arm waveguide 201 is in the upper arm basic differential electric field formed by the positive signal electrode 11 and the common ground electrode 10, and the lower arm waveguide 202 is in the lower arm basic differential electric field formed by the negative signal electrode 12 and the lower arm ground electrode 12-3.

[0177] The upper arm waveguide 201 in the transition region bends toward between the positive signal electrode 11 and the upper arm ground electrode 11 - 3 in the reverse polarity modulation region. In the reverse polarity modulation region, the upper arm waveguide 201 is in the first differential electric field formed by the positive signal electrode 11 and the upper arm ground electrode 11 - 3.

[0178] The lower arm waveguide 202 in the transition region bends toward between the negative signal electrode 12 and the common ground electrode 10 in the reverse polarity modulation region. In the reverse polarity modulation region, the lower arm waveguide 202 is in the second differential electric field formed by the negative signal electrode 12 and the common ground electrode 10 .

[0179] This implementation can also improve the electro-optic bandwidth and broaden the electro-optic bandwidth so that the electro-optic modulator can perform broadband modulation. The relevant description can refer to the first feasible implementation described above and will not be repeated here.

[0180] In a third possible implementation, refer to Fig.10 , Fig.10 The third structural diagram of the third embodiment of the broadband differential drive electro-optic modulator chip of the present application. Under this embodiment, the difference from the first feasible embodiment is that in the transition zone, the upper arm waveguide 201 is bent between the negative signal electrode 12 and the common ground electrode 10 in the reverse polarity modulation zone, and in the reverse polarity modulation zone, the upper arm waveguide 201 is in the first differential electric field formed by the negative signal electrode 12 and the common ground electrode 10; the lower arm waveguide 202 is bent between the positive signal electrode 11 and the upper arm ground electrode 11-3 in the reverse polarity modulation zone, and in the reverse polarity modulation zone, the lower arm waveguide 202 is in the second differential electric field formed by the positive signal electrode 11 and the upper arm ground electrode 11-3.

[0181] Among them, in this embodiment, the first differential electric field may be consistent with the lower arm basic differential electric field formed by the negative signal electrode 12 and the common ground electrode 10, and the second differential electric field may be the upper arm basic differential electric field formed by the positive signal electrode 11 and the upper arm ground electrode 11-3.

[0182] This implementation can also improve the electro-optic bandwidth and broaden the electro-optic bandwidth so that the electro-optic modulator can perform broadband modulation. For related descriptions, please refer to the second embodiment above and will not be repeated here.

[0183] In a fourth possible implementation, referring to 11, Fig.11 This is a fourth structural diagram of the third embodiment of the broadband differential drive electro-optic modulator chip of the present application.

[0184] In this implementation, the electro-optical frequency domain equalizer includes: a same polarity modulation area and an opposite polarity modulation area.

[0185] The electrode pair of the upper arm microelectrode structure 11 - 4 includes: a first upper arm microelectrode 11 - 41 and a second upper arm microelectrode 11 - 42.

[0186] The electrode pair of the lower arm microelectrode structure 12 - 4 includes: a first lower arm microelectrode 12 - 41 and a second lower arm microelectrode 12 - 42 .

[0187] In the basic modulation area and the same polarity modulation area, each of the first upper arm microelectrodes 11-41 is connected to the positive signal electrode 11, each of the second upper arm microelectrodes 11-42 is connected to the upper arm ground electrode 11-3, each of the first lower arm microelectrodes 12-41 is connected to the common ground electrode 10, and each of the second lower arm microelectrodes 12-42 is connected to the negative signal electrode 12.

[0188] In the reverse polarity modulation zone, each of the first upper arm microelectrodes 11-41 is connected to the upper arm ground electrode 11-3, each of the second upper arm microelectrodes 11-42 is connected to the positive signal electrode 11, each of the first lower arm microelectrodes 12-41 is connected to the negative signal electrode 12, and each of the second lower arm microelectrodes 12-42 is connected to the common ground electrode 10.

[0189] In the reverse polarity modulation area, the upper arm basic differential electric field forms the first differential electric field in the opposite direction after passing through the first upper arm microelectrode 11 - 41 and the second upper arm microelectrode 11 - 42 .

[0190] It should be noted that in the basic modulation area and the same polarity modulation area, the electric field direction of each upper arm microelectrode structure 11-4 is the same as the direction of the upper arm basic differential electric field, from the positive signal electrode 11 to the upper arm ground electrode 11-3, and the electric field direction of each lower arm microelectrode structure 12-4 is the same as the direction of the lower arm basic differential electric field, from the common ground electrode 10 to the negative signal electrode 12.

[0191] It can be understood that in the reverse polarity modulation zone, each first upper arm microelectrode 11-41 is connected to the upper arm ground electrode 11-3, and each second upper arm microelectrode 11-42 is connected to the positive signal electrode 11. A first differential electric field can be formed in the reverse polarity modulation zone, pointing from the second upper arm microelectrode 11-42 to the first upper arm microelectrode 11-41. The first differential electric field is opposite to the direction of the upper arm basic differential electric field, thereby switching the differential electric field in which the upper arm waveguide 201 is located from the upper arm basic differential electric field to the first differential electric field in the opposite direction.

[0192] It should be noted that, in the reverse polarity modulation zone, each first lower arm microelectrode 12-41 is connected to the negative signal electrode 12, and each second lower arm microelectrode 12-42 is connected to the common ground electrode 10. A second differential electric field can be formed in the reverse polarity modulation zone, pointing from the second lower arm microelectrode 12-42 to the first lower arm microelectrode 12-41. The second differential electric field is opposite in direction to the lower arm basic differential electric field, thereby switching the differential electric field in which the lower arm waveguide 202 is located from the lower arm basic differential electric field to a second differential electric field in the opposite direction.

[0193] It should be noted that, since the differential electric field where the upper arm waveguide 201 is located is switched from the upper arm basic differential electric field to the first differential electric field in the opposite direction, and the differential electric field where the lower arm waveguide 202 is located is switched from the lower arm basic differential electric field to the second differential electric field in the opposite direction, combined with the description of the above embodiment, it can be seen that under this implementation, the electro-optical bandwidth can be improved, thereby broadening the electro-optical bandwidth, so that the electro-optical modulator can perform broadband modulation.

[0194] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the broadband differential drive electro-optic modulator chip of the present application. More simple transformations based on this technical concept are all within the protection scope of the present application.

[0195] In addition, the present application also proposes an optical communication system, which includes the broadband differential drive electro-optic modulator chip described above.

[0196] Other embodiments or specific implementations of the optical communication system of the present application may refer to the above-mentioned embodiment of the broadband differential drive electro-optic modulator chip, which will not be described in detail here.

[0197] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A broadband differential drive electro-optic modulator chip, characterized in that: The broadband differential drive electro-optic modulator chip comprises: an electrode structure, an upper arm waveguide, a lower arm waveguide and an electro-optic frequency domain equalizer; A differential electric field formed by multiple differential signals exists in the electrode structure; The upper arm waveguide and the lower arm waveguide are respectively in differential electric fields in opposite directions; In the electro-optical frequency domain equalizer, the directions of the differential electric fields of the upper arm waveguide and the lower arm waveguide are reversed; The broadband differential drive electro-optic modulator chip further includes: a basic modulation area; The basic modulation area is a modulation area without the electro-optical frequency domain equalizer; The electrode structure comprises: an upper arm traveling wave electrode structure and a lower arm traveling wave electrode structure; The upper arm traveling wave electrode structure forms an upper arm basic differential electric field in the basic modulation area; The lower arm traveling wave electrode structure forms a lower arm basic differential electric field in the basic modulation area; Wherein, the direction of the upper arm basic differential electric field is opposite to the direction of the lower arm basic differential electric field; In the basic modulation region, the upper arm waveguide is in the upper arm basic differential electric field, and the lower arm waveguide is in the lower arm basic differential electric field; In the electro-optical frequency domain equalizer, the upper arm waveguide is in a first differential electric field, and the direction of the first differential electric field is opposite to the direction of the upper arm basic differential electric field; In the electro-optical frequency domain equalizer, the lower arm waveguide is in a second differential electric field, and the direction of the second differential electric field is opposite to the direction of the lower arm basic differential electric field; The broadband differential drive electro-optic modulator chip further comprises: a plurality of micro-electrode structures provided with electrode pairs; Each of the micro-electrode structures is respectively arranged in the upper arm traveling wave electrode structure and the lower arm traveling wave electrode structure; The direction of the electric field formed by the electrode pairs of each microelectrode structure is parallel to the direction of the upper arm basic differential electric field and / or the lower arm basic differential electric field; The upper arm waveguide is arranged in the electrode pair of the micro-electrode structure in the upper arm traveling wave electrode structure; The lower arm waveguide is arranged in the electrode pair of the micro-electrode structure in the lower arm traveling wave electrode structure.

2. The broadband differential drive electro-optic modulator chip according to claim 1, characterized in that: The upper arm traveling wave electrode structure comprises: an upper arm positive signal electrode and an upper arm negative signal electrode; The lower arm traveling wave electrode structure comprises: a lower arm positive signal electrode and a lower arm negative signal electrode; The microelectrode structure comprises: an upper arm microelectrode structure and a lower arm microelectrode structure; Each of the upper arm microelectrode structures is disposed between the upper arm positive signal electrode and the upper arm negative signal electrode, and each of the lower arm microelectrode structures is disposed between the lower arm positive signal electrode and the lower arm negative signal electrode; In the basic modulation area, the upper arm positive signal electrode and the upper arm negative signal electrode form the upper arm basic differential electric field based on the upper arm differential signal, and the lower arm positive signal electrode and the lower arm negative signal electrode form the lower arm basic differential electric field based on the lower arm differential signal; In the basic modulation region, the upper arm waveguide is disposed in an electrode pair of each upper arm microelectrode structure, and the lower arm waveguide is disposed in an electrode pair of each lower arm microelectrode structure.

3. The broadband differential drive electro-optic modulator chip according to claim 2, characterized in that: The electro-optical frequency domain equalizer comprises: a same polarity modulation region, a transition region and a reverse polarity modulation region; In the same polarity modulation area, the upper arm waveguide is in the upper arm basic differential electric field, and the lower arm waveguide is in the lower arm basic differential electric field; In the transition region, the upper arm waveguide is bent and enters between the lower arm positive signal electrode and the lower arm negative signal electrode in the reverse polarity modulation region, and the lower arm waveguide is bent and enters between the upper arm positive signal electrode and the upper arm negative signal electrode in the reverse polarity modulation region; In the reverse polarity modulation area, the upper arm waveguide is located in the lower arm basic differential electric field formed by the lower arm positive signal electrode and the lower arm negative signal electrode after bending, and the lower arm waveguide is located in the upper arm basic differential electric field formed by the upper arm positive signal electrode and the upper arm negative signal electrode after bending; Among them, in the reverse polarity modulation area, the first differential electric field is the lower arm basic differential electric field, and the second differential electric field is the upper arm basic differential electric field.

4. The broadband differential drive electro-optic modulator chip according to claim 2, characterized in that: The electro-optical frequency domain equalizer comprises: a same polarity modulation area and a reverse polarity modulation area; The electrode pair of the upper arm microelectrode structure includes: a first upper arm microelectrode and a second upper arm microelectrode; The electrode pair of the lower arm microelectrode structure includes: a first lower arm microelectrode and a second lower arm microelectrode; In the basic modulation area and the same polarity modulation area, each of the first upper arm microelectrodes is connected to the upper arm positive signal electrode, each of the second upper arm microelectrodes is connected to the upper arm negative signal electrode, each of the first lower arm microelectrodes is connected to the lower arm positive signal electrode, and each of the second lower arm microelectrodes is connected to the lower arm negative signal electrode; In the reverse polarity modulation area, each of the first upper arm microelectrodes is connected to the upper arm negative signal electrode, each of the second upper arm microelectrodes is connected to the upper arm positive signal electrode, each of the first lower arm microelectrodes is connected to the lower arm negative signal electrode, and each of the second lower arm microelectrodes is connected to the upper arm positive signal electrode; In the reverse polarity modulation area, the upper arm basic differential electric field passes through the first upper arm microelectrode and the second upper arm microelectrode to form the first differential electric field in the opposite direction; In the reverse polarity modulation region, the lower arm basic differential electric field forms the second differential electric field with the opposite direction after passing through the first lower arm microelectrode and the second lower arm microelectrode.

5. The broadband differential drive electro-optic modulator chip according to claim 1, characterized in that: The electrode structure further comprises: a common ground electrode; The upper arm traveling wave electrode structure includes: a positive signal electrode and an upper arm ground electrode The lower arm traveling wave electrode structure comprises: a negative signal electrode and a lower arm ground electrode; The microelectrode structure comprises: an upper arm microelectrode structure and a lower arm microelectrode structure; Each of the upper arm microelectrode structures is respectively arranged between the positive signal electrode and the upper arm ground electrode and between the positive signal electrode and the common ground electrode, and each of the lower arm microelectrode structures is respectively arranged between the negative signal electrode and the lower arm ground electrode and between the negative signal electrode and the common ground electrode; In the basic modulation area, the positive signal electrode and the upper arm ground electrode form the upper arm basic differential electric field based on the upper arm differential signal, and the negative signal electrode and the common ground electrode form the lower arm basic differential electric field based on the lower arm differential signal; In the basic modulation region, the upper arm waveguide is in the upper arm basic differential electric field, and the lower arm waveguide is in the lower arm basic differential electric field.

6. The broadband differential drive electro-optic modulator chip as claimed in claim 5, characterized in that: The electro-optical frequency domain equalizer comprises: a same polarity modulation region, a transition region and a reverse polarity modulation region; In the same polarity modulation area, the upper arm waveguide is in the upper arm basic differential electric field, and the lower arm waveguide is in the lower arm basic differential electric field; In the transition region, the upper arm waveguide is bent and enters between the positive signal electrode and the common ground electrode in the reverse polarity modulation region, and the lower arm waveguide is bent and enters between the negative signal electrode and the lower arm ground electrode in the reverse polarity modulation region; In the reverse polarity modulation region, the upper arm waveguide is in the first differential electric field formed by the positive signal electrode and the common ground electrode, and the lower arm waveguide is in the second differential electric field formed by the negative signal electrode and the lower arm ground electrode.

7. The broadband differential drive electro-optic modulator chip according to claim 5, characterized in that: The electro-optical frequency domain equalizer comprises: a same polarity modulation area and a reverse polarity modulation area; The electrode pair of the upper arm microelectrode structure includes: a first upper arm microelectrode and a second upper arm microelectrode; The electrode pair of the lower arm microelectrode structure includes: a first lower arm microelectrode and a second lower arm microelectrode; In the basic modulation area and the same polarity modulation area, each of the first upper arm microelectrodes is connected to the positive signal electrode, each of the second upper arm microelectrodes is connected to the upper arm ground electrode, each of the first lower arm microelectrodes is connected to the common ground electrode, and each of the second lower arm microelectrodes is connected to the negative signal electrode; In the reverse polarity modulation area, each of the first upper arm microelectrodes is connected to the upper arm ground electrode, each of the second upper arm microelectrodes is connected to the positive signal electrode, each of the first lower arm microelectrodes is connected to the negative signal electrode, and each of the second lower arm microelectrodes is connected to the common ground electrode; In the reverse polarity modulation area, the upper arm basic differential electric field passes through the first upper arm microelectrode and the second upper arm microelectrode to form the first differential electric field in the opposite direction; In the reverse polarity modulation region, the lower arm basic differential electric field forms the second differential electric field with the opposite direction after passing through the first lower arm microelectrode and the second lower arm microelectrode.

8. An optical communication system, characterized in that: The optical communication system comprises the broadband differential drive electro-optic modulator chip according to any one of claims 1 to 7.

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