A high extinction ratio high-speed electro-optic modulator chip

Abstract

The present invention relates to the field of optical communication technology, and in particular to a high-extinction ratio high-speed electro-optic modulator chip, which includes: an arbitrary ratio power divider and a traveling wave electrode structure; the input end of the arbitrary ratio power divider is connected to a coupler, the output end of the arbitrary ratio power divider is connected to the traveling wave electrode structure, and the arbitrary ratio power divider and the traveling wave electrode structure are also respectively connected to a signal generator; the arbitrary ratio power divider receives a power control signal from a signal generator, adjusts the optical signal input by the coupler to two-way adjustment optical signals of a preset power ratio, and transmits the two-way adjustment optical signals to the traveling wave electrode structure; the traveling wave electrode structure receives a high-frequency microwave signal from a signal generator, modulates the adjustment optical signal according to the high-frequency microwave signal, and then transmits it. The power of the two-arm optical signal is adjusted by adjusting the different power distribution ratios of the two waveguides, thereby generating a relatively higher static extinction ratio and dynamic extinction ratio.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a high-extinction ratio and high-speed electro-optic modulator chip. Background Art

[0002] Electro-optic modulators use electric fields to control the transmission characteristics of optical signals. The basic principle is to change the optical properties of materials by applying an external electric field, thereby modulating the optical signal.

[0003] The optical structure of the Mach-Zehnder Electro-Optic Modulator (MZM) includes a beam splitter that divides the input optical signal into two arms, then applies an electric field to each arm for modulation, and finally recombines the optical signals of the two arms through a beam combining structure. Ideally, the optical signals of the two arms should be exactly the same to achieve the best modulation effect. However, in the actual manufacturing process, errors are inevitable. These errors will lead to inconsistent power distribution between the upper and lower arms, different waveguide losses, uneven materials, etc., which ultimately reduce the extinction ratio (ER) of the device.

[0004] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The main purpose of the present invention is to provide a high extinction ratio and high-speed electro-optic modulator chip, aiming to solve the technical problem in the prior art that the extinction ratio of the device is reduced due to manufacturing errors of the electro-optic modulator.

[0006] To achieve the above object, the present invention proposes a high extinction ratio high-speed electro-optic modulator chip, the high extinction ratio high-speed electro-optic modulator chip comprising: an arbitrary ratio power divider and a traveling wave electrode structure;

[0007] The input end of the arbitrary proportional power divider is connected to the coupler, the output end of the arbitrary proportional power divider is connected to the traveling wave electrode structure, and the arbitrary proportional power divider and the traveling wave electrode structure are also connected to a signal generator respectively;

[0008] The arbitrary ratio power divider is used to receive the power control signal of the signal generator, adjust the optical signal input by the coupler into two adjustment optical signals with preset power ratios, and transmit the two adjustment optical signals to the traveling wave electrode structure;

[0009] The traveling wave electrode structure is used to receive the high-frequency microwave signal from the signal generator, and modulate the adjustment optical signal according to the high-frequency microwave signal before transmitting it out.

[0010] Optionally, the arbitrary ratio power splitter comprises: a first beam splitter, a thermal adjustment structure and an electrical adjustment structure;

[0011] The input end of the first beam splitter is connected to the coupler, and the output end of the first beam splitter is respectively connected to the upper and lower arms of the thermal adjustment structure. The upper arm of the thermal adjustment structure is transmitted to the first modulation area of ​​the traveling wave electrode structure through the electrical adjustment structure, and the lower arm of the thermal adjustment structure is transmitted to the second modulation area of ​​the traveling wave electrode structure through the electrical adjustment structure.

[0012] Optionally, the heat adjustment structure includes: a first resistor, a second resistor, and first to fourth DC electrodes;

[0013] The first resistor is arranged on the first output waveguide of the first beam splitter, one end of the first resistor is electrically connected to the first DC electrode, and the other end of the first resistor is electrically connected to the second DC electrode;

[0014] The second resistor is arranged on the second waveguide of the first beam splitter, one end of the second resistor is electrically connected to the third DC electrode, and the other end of the second resistor is electrically connected to the fourth DC electrode.

[0015] Optionally, the traveling wave electrode structure comprises: a first ground electrode, a source electrode, and a second ground electrode arranged in sequence;

[0016] The first ground electrode is electrically connected to the second ground electrode, and a third resistor is further provided between the first ground electrode and the source electrode;

[0017] The source electrode receives the high-frequency microwave signal of the signal generator, generates a first electric field in a first modulation area between the source electrode and the first ground electrode, and generates a second electric field in a second modulation area between the source electrode and the second ground electrode;

[0018] The first electric field and the second electric field are in opposite directions.

[0019] Optionally, the traveling wave electrode structure further comprises: a plurality of microelectrode pairs;

[0020] Each of the microelectrode pairs is disposed between the source electrode and the first ground electrode and the second ground electrode.

[0021] Optionally, the arbitrary ratio power splitter comprises: second to sixth beam splitters and a second thermal adjustment structure;

[0022] The input end of the second beam splitter is connected to the coupler, the output end of the second beam splitter is connected to the input ends of the third beam splitter and the fourth beam splitter respectively, the output end of the third beam splitter is connected to the input end of the fifth beam splitter through the second thermal adjustment structure, the output end of the fourth beam splitter is connected to the input end of the sixth beam splitter through the second thermal adjustment structure, the output end of the fifth beam splitter is transmitted to the first modulation area of ​​the traveling wave electrode structure, and the output end of the sixth beam splitter is transmitted to the second modulation area of ​​the traveling wave electrode structure.

[0023] Optionally, the second heat adjustment structure includes: a fourth resistor, a fifth resistor, and fifth to eighth DC electrodes;

[0024] The fourth resistor is arranged on the first output waveguide of the third beam splitter, one end of the fourth resistor is electrically connected to the fifth DC electrode, and the other end of the fourth resistor is electrically connected to the sixth DC electrode;

[0025] The fifth resistor is arranged on the second output waveguide of the fourth beam splitter, one end of the fifth resistor is electrically connected to the seventh DC electrode, and the other end of the fifth resistor is electrically connected to the eighth DC electrode.

[0026] Optionally, the high extinction ratio high-speed electro-optic modulator chip further includes: a sixth resistor, a ninth DC electrode and a tenth DC electrode;

[0027] The sixth resistor is arranged between the arbitrary proportional power divider and the traveling wave electrode structure;

[0028] One end of the sixth resistor is electrically connected to the ninth DC electrode, and the other end of the sixth resistor is electrically connected to the tenth DC electrode.

[0029] Optionally, the high extinction ratio high-speed electro-optic modulator chip further comprises: a substrate layer, a buried layer, a thin-film lithium niobate and an upper cladding layer arranged in sequence from bottom to top;

[0030] The buried layer is arranged between the substrate layer and the thin film lithium niobate, the arbitrary proportion power divider and the traveling wave electrode structure are arranged in the upper cladding layer, and the upper cladding layer covers the top of the thin film lithium niobate.

[0031] In addition, to achieve the above-mentioned object, the present invention further provides an optical communication system, which includes the high extinction ratio and high-speed electro-optic modulator chip as described above.

[0032] One or more technical solutions proposed in this application have at least the following technical effects:

[0033] The present invention provides a high-extinction ratio high-speed electro-optic modulator chip, including: an arbitrary ratio power divider and a traveling wave electrode structure; the input end of the arbitrary ratio power divider is connected to a coupler, the output end of the arbitrary ratio power divider is connected to the traveling wave electrode structure, and the arbitrary ratio power divider and the traveling wave electrode structure are also respectively connected to a signal generator; the arbitrary ratio power divider is used to receive the power control signal of the signal generator, adjust the optical signal input by the coupler to two-way adjustment optical signals with a preset power ratio, and transmit the two-way adjustment optical signals to the traveling wave electrode structure; the traveling wave electrode structure is used to receive the high-frequency microwave signal of the signal generator, modulate the adjustment optical signal according to the high-frequency microwave signal and then transmit it. The present invention adjusts the power of the two-arm optical signal by adjusting the different power distribution ratios of the two waveguides, so that the power of the electro-optical modulation is balanced, and a relatively higher static extinction ratio and dynamic extinction ratio are generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0035] Figure 1 It is a schematic structural diagram of the first embodiment of the high extinction ratio high-speed electro-optic modulator chip of the present invention;

[0036] Figure 2 It is a schematic cross-sectional structure diagram of the first embodiment of the high extinction ratio high-speed electro-optic modulator chip of the present invention;

[0037] Figure 3 It is a schematic structural diagram of a second embodiment of a high extinction ratio high-speed electro-optic modulator chip of the present invention;

[0038] Figure 4 It is a schematic structural diagram of a third embodiment of a high extinction ratio high-speed electro-optic modulator chip of the present invention;

[0039] Figure 5 It is a schematic cross-sectional structure diagram of a third embodiment of a high extinction ratio high-speed electro-optic modulator chip of the present invention;

[0040] Figure 6 It is a schematic structural diagram of a fourth embodiment of a high extinction ratio high-speed electro-optic modulator chip of the present invention;

[0041] Figure 7 It is a schematic diagram of the dual-drive structure in the fourth embodiment of the high extinction ratio high-speed electro-optic modulator chip of the present invention.

[0042] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0043] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0046] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0047] The main solution of the embodiment of the present invention is: the high extinction ratio high-speed electro-optical modulator chip includes: an arbitrary proportion power divider and a traveling wave electrode structure; the input end of the arbitrary proportion power divider is connected to the coupler, the output end of the arbitrary proportion power divider is connected to the traveling wave electrode structure, and the arbitrary proportion power divider and the traveling wave electrode structure are also respectively connected to the signal generator; the arbitrary proportion power divider is used to receive the power control signal of the signal generator, adjust the optical signal input by the coupler into two adjustment optical signals with preset power ratios, and transmit the two adjustment optical signals to the traveling wave electrode structure; the traveling wave electrode structure is used to receive the high-frequency microwave signal of the signal generator, modulate the adjustment optical signal according to the high-frequency microwave signal and then transmit it out.

[0048] Integrated photonics has developed rapidly in recent years and is driving the development of next-generation classical and quantum photonic devices. By using photon signals with inherent high frequencies and low propagation losses in waveguides, integrated photonics achieves ultra-low energy consumption, wide bandwidth, and ultra-high density data communications, which is significantly better than traditional electronic communications in performance. As an advanced material, thin-film lithium niobate has become an ideal platform for integrated photonics. Its excellent electro-optical effect, high nonlinear coefficient, and wide bandwidth characteristics make it show great potential in the fields of optical communication, optical sensing, and quantum computing. Thin-film lithium niobate can not only achieve high-speed and efficient optical signal modulation, but also has the advantages of low power consumption and high integration, which promotes the development and application of high-performance photonic devices. Thin-film lithium niobate electro-optic modulator is a key device that is widely used in the fields of optical communication, optical signal processing, and quantum optics. Due to the excellent electro-optical effect and high nonlinear coefficient of thin-film lithium niobate materials, this modulator can achieve high-speed and efficient optical signal modulation. In addition, thin-film lithium niobate electro-optic modulators also have the characteristics of low power consumption and high integration, making them an important component for realizing high-performance photonic devices and complex photonic integrated circuits.

[0049] Electro-optic modulators use electric fields to control the transmission characteristics of optical signals, and play a vital role in optical communications, optical sensing, and photonic computing. The basic principle is to change the optical properties of materials by applying an external electric field, thereby modulating optical signals. Lithium niobate electro-optic modulators are one of the common types, which use the electro-optic effect of lithium niobate crystals to change the refractive index of the crystal under the action of an electric field to achieve optical signal modulation. Thin-film lithium niobate (TFLN) electro-optic modulators improve the performance and applicability of the modulator by preparing a thin film on the surface of the crystal and taking advantage of the structure and material advantages of the thin film. The advantages of thin-film lithium niobate include higher modulation speed, lower insertion loss, and on-chip integration, which make TFLN modulators have significant advantages in high-performance optoelectronic applications. Mach–Zehnder interferometer (MZI) electro-optic modulators based on TFLN have become a hot topic in academia and industry due to their high modulation bandwidth, miniaturized structure, and high efficiency.

[0050] The optical structure of the Mach-Zehnder electro-optic modulator includes a beam splitter that divides the input optical signal into two arms, then applies an electric field to the two arms for modulation, and finally recombines the optical signals of the two arms through a beam combining structure. Ideally, the optical signals of the two arms should be exactly the same to achieve the best modulation effect. However, in the actual processing and manufacturing process, errors are inevitable. These errors will lead to inconsistent power distribution between the upper and lower arms, different waveguide losses, uneven materials, etc., which ultimately reduce the extinction ratio of the device. The extinction ratio is an important parameter of the electro-optic modulator, which represents the ratio of the optical power output of the modulator in the "on" and "off" states. A high extinction ratio means that the modulator can effectively switch the optical signal from the "on" state to the "off" state, thereby achieving clearer signal modulation and lower bit error rate. In optical communication and optical signal processing applications, the quality of the extinction ratio directly affects the performance and reliability of the system. Therefore, optimizing the extinction ratio is one of the keys to improving the performance of electro-optic modulators.

[0051] For high-speed optical communication MZM, there are two extinction ratios of concern, static extinction ratio and dynamic extinction ratio. The static extinction ratio is measured under stable and ideal laboratory conditions, reflecting the performance of the modulator under a constant driving signal. The dynamic extinction ratio is measured when the modulator receives a high-frequency modulation signal of the actual operating frequency, reflecting the performance of the modulator under a real working environment. It represents the power ratio between the optical "on" state and the "off" state of the modulator under the action of a high-frequency modulation signal. The dynamic extinction ratio is closer to the actual application scenario and is an important indicator for evaluating the actual working performance of the modulator. Under ideal conditions, the static extinction ratio and the dynamic extinction ratio should be close to or equal. However, in actual applications, the dynamic extinction ratio is usually lower than the static extinction ratio. This is because high-frequency modulation signals introduce various dynamic effects, such as electro-optical effect hysteresis, poor frequency response, etc., which leads to a decrease in the dynamic extinction ratio. Although the static extinction ratio and the dynamic extinction ratio are two different indicators, MZ modulators with high static extinction ratios can usually perform better under actual high-frequency working conditions and provide higher dynamic extinction ratios. This gives it superior performance and reliability in optical communication applications that require high speed, large capacity, and low latency.

[0052] In a solution provided by the present application, the power of the optical signals in the two arms is regulated by adjusting the different power allocation ratios of the two waveguides, so that the power of the electro-optical modulation is balanced, resulting in a relatively higher static extinction ratio and dynamic extinction ratio.

[0053] Based on this, the present application embodiment provides a high extinction ratio high-speed electro-optic modulator chip, referring to Figure 1 , Figure 1 FIG. 1 is a schematic diagram of the structure of the first embodiment of the high extinction ratio high-speed electro-optic modulator chip of the present invention. Figure 1As shown, in this embodiment, the high extinction ratio high-speed electro-optic modulator chip includes: an arbitrary ratio power divider 10 and a traveling wave electrode structure 20. The input end of the arbitrary ratio power divider 10 is connected to a coupler (not shown in the figure), the output end of the arbitrary ratio power divider 10 is connected to the traveling wave electrode structure 20, and the arbitrary ratio power divider 10 and the traveling wave electrode structure 20 are also respectively connected to a signal generator (not shown in the figure).

[0054] It should be noted that the optical signal enters the thin-film lithium niobate ridge waveguide through the coupler, performs on-chip optical path transmission, and enters the arbitrary ratio power divider 10. The arbitrary ratio power divider 10 can be used to receive the power control signal of the signal generator, adjust the optical signal input by the coupler to two adjustment optical signals with preset power ratios, and transmit the two adjustment optical signals to the traveling wave electrode structure. The balance of the optical signal power received by the traveling wave electrode structure 20 is achieved by allocating different powers to the two output waveguides. The traveling wave electrode structure 20 can be used to receive the high-frequency microwave signal of the signal generator, modulate the adjustment optical signal according to the high-frequency microwave signal, and then transmit it out.

[0055] It should be understood that the power control signal can be an optical signal that is loaded into the waveguide by the radio frequency electrical signal using the electro-optical effect of lithium niobate according to a specific traveling wave electrode, and is specifically set by testing the power imbalance caused by process errors or hardware differences.

[0056] In a possible implementation, the arbitrary proportional power divider 10 includes: a first beam splitter 101, a thermal adjustment structure and an electrical adjustment structure; the input end of the first beam splitter 101 (the first waveguide 1011 in the figure) is connected to the coupler, and the output end of the first beam splitter (the second waveguide 1012 and the third waveguide 1013 in the figure) are respectively connected to the upper and lower arms of the thermal adjustment structure, the upper arm of the thermal adjustment structure is transmitted to the first modulation area of ​​the traveling wave electrode structure through the electrical adjustment structure, and the lower arm of the thermal adjustment structure is transmitted to the second modulation area of ​​the traveling wave electrode structure through the electrical adjustment structure.

[0057] Wherein, the thermal adjustment structure includes: a first resistor R1, a second resistor R2, and first to fourth DC electrodes (E1~E4); the first resistor R1 is arranged on the second waveguide 1012 of the first beam splitter 101, one end of the first resistor R1 is electrically connected to the first DC electrode E1, and the other end of the first resistor R1 is electrically connected to the second DC electrode E2; the second resistor R2 is arranged on the third waveguide 1013 of the first beam splitter 101, one end of the second resistor R2 is electrically connected to the third DC electrode E3, and the other end of the second resistor R2 is electrically connected to the fourth DC electrode E4.

[0058] Reference Figure 2 , Figure 2 The cross-sectional structure diagram of the first embodiment of the high extinction ratio high-speed electro-optic modulator chip of the present invention is shown. Using an x-cut thin-film lithium niobate wafer, the high extinction ratio high-speed electro-optic modulator chip includes a substrate layer 201, a low-refractive index buried layer 202, a thin-film lithium niobate 203 ridge waveguide structure, the electro-optic modulation region waveguide transmission direction is the y direction, and a low-refractive index upper cladding layer 204 laid on the thin-film lithium niobate material.

[0059] Among them, the substrate layer 201 is a silicon or quartz substrate with a thickness of 500 microns, the low refractive index buried layer 202 is silicon dioxide with a refractive index of 1.44 and a thickness of 2 microns, the ridge waveguide thickness of the thin film lithium niobate 203 is 180 nanometers, the thickness of the planar waveguide is 180 nanometers, and the low refractive index upper cladding 204 is silicon dioxide with a thickness of 1 micron.

[0060] Furthermore, the traveling wave electrode structure 20 includes: a first ground electrode 301 , a source electrode 302 , and a second ground electrode 303 arranged in sequence; the first ground electrode 301 is electrically connected to the second ground electrode 303 , and a third resistor R3 is further arranged between the first ground electrode 301 and the source electrode 302 .

[0061] It should be noted that the source electrode receives the high-frequency microwave signal of the signal generator, generates a first electric field in the first modulation area between the source electrode and the first ground electrode, and generates a second electric field in the second modulation area between the source electrode and the second ground electrode, wherein the directions of the first electric field and the second electric field are opposite.

[0062] It should be understood that the high-frequency microwave signal provided by the signal generator can be loaded onto each electrode in the above-mentioned traveling wave electrode structure 20 through a GSG (ground electrode-source electrode-ground electrode) high-frequency probe to achieve single-ended push-pull high-speed electro-optical modulation in the high-speed modulation area.

[0063] Furthermore, the traveling wave electrode structure 20 further includes: a plurality of micro-electrode pairs 304; each of the micro-electrode pairs is arranged between the source electrode 302 and the first ground electrode 301 and the second ground electrode 303 to improve the electro-optic modulation efficiency.

[0064] It should be noted that the electric adjustment structure is similar to the above-mentioned traveling wave electrode structure and can have GSG electrodes (corresponding to Figure 1The first electrically adjustable ground electrode 401, the electrically adjustable source electrode 402 and the second electrically adjustable ground electrode 403 in the figure are also similar in principle and function to the above-mentioned traveling wave electrode, which will not be described in detail here. At the same time, a 2*2 multimode interference (Multimode Interference, MMI) structure 107 can also be provided in the electrically adjustable structure and the traveling wave electrode structure. The fourth waveguide 1071 and the fifth waveguide 1072 at the input end of the multimode interference structure 107 are respectively connected to the two output waveguides of the first beam splitter (the second waveguide 1012 and the third waveguide 1013 in the figure), and the output bending waveguides of the multimode interference structure 107 (the sixth waveguide 1073 and the seventh waveguide 1074 in the figure) are respectively transmitted to the first modulation area and the second modulation area of ​​the traveling wave electrode structure. In order to realize the output capability of the optical signal after differential modulation, a 2*1 beam combining structure 108 is further provided at the rear end of the traveling wave electrode structure, and its input waveguides (the eighth waveguide 1081 and the ninth waveguide 1082 in the figure) are respectively connected to the output bending waveguides of the multimode interference structure 107, and the modulated optical signal is output through the output waveguide of the beam combining structure 108.

[0065] It should be understood that the above electrodes adopt a coplanar waveguide structure, the material is gold or copper, the thickness is 0.9 microns, the traveling wave electrode uses the electro-optical effect of lithium niobate to load the radio frequency electrical signal into the optical signal in the waveguide, and the electrode structure parameters are determined by simulation. The aspect ratio is calculated based on the resistance of 50Ω. The resistance material is nickel-chromium alloy.

[0066] Furthermore, the high extinction ratio high-speed electro-optic modulator chip also includes a thermal adjustment structure for achieving the 3dB bias operating point required for high-speed electro-optic modulation. The thermal adjustment structure includes: a sixth resistor R6, a ninth DC electrode E9 and a tenth DC electrode E10;

[0067] It should be noted that the sixth resistor R6 is disposed between the arbitrary ratio power divider 10 and the traveling wave electrode structure 20; one end of the sixth resistor R6 is electrically connected to the ninth DC electrode E9, and the other end of the sixth resistor R6 is electrically connected to the tenth DC electrode E10. The 3dB bias operating point required for high-speed electro-optical modulation is achieved by loading a DC bias current on the sixth resistor R6.

[0068] In this embodiment, the light from the light source enters the thin-film lithium niobate ridge waveguide through the on-chip optical coupling structure and enters the arbitrary ratio power divider. In the arbitrary ratio power divider: the optical signal is divided into two equal paths of light through the beam splitter, and is distributed to the upper and lower arms of the electrically adjustable structure through the first output waveguide and the second output waveguide. After passing through the multi-mode interference structure, it is output through the two output curved waveguides. The power ratio of the two output curved waveguides of the multi-mode interference structure can be adjusted through the thermal adjustment structure and the electrical adjustment structure, thereby realizing arbitrary ratio power division. The optical signal coming out of the two output curved waveguides enters the high-speed electro-optical modulation area. After the light of the upper and lower arm waveguides of the high-speed modulation area is electro-optically modulated, it is output through the waveguide after passing through the beam combining structure. The entire process realizes ultra-high extinction ratio and ultra-high-speed electro-optical modulation.

[0069] Reference Figure 3 , Figure 3 FIG. 1 is a schematic diagram of the structure of the second embodiment of the high extinction ratio high-speed electro-optic modulator chip of the present invention. Figure 3 As shown, in this embodiment, the same or similar contents as those of the first embodiment can be referred to the above introduction and will not be described in detail later.

[0070] In this embodiment, in order to realize the multi-input and multi-output optical waveguide capability of the electro-optical modulator, the above-mentioned 1*2 first beam splitter 101 can be replaced by a 2*2 MMI structure, and the above-mentioned 2*1 beam combining structure 108 can be replaced by a 2*2 MMI structure. At this time, the other thermal adjustment structures and electrical adjustment structures remain unchanged.

[0071] Reference Figure 4 , Figure 4 FIG. 1 is a schematic diagram of the structure of the third embodiment of the high extinction ratio high-speed electro-optic modulator chip of the present invention. Figure 4 As shown, in this embodiment, the same or similar contents as those in the above embodiment can be referred to the above introduction and will not be described in detail later.

[0072] In this embodiment, in order to realize the dual-drive high-speed modulation capability of the electro-optic modulator, the traveling wave electrode structure may include: an upper arm ground electrode 305, a positive signal electrode 306, a common ground electrode 307, a negative signal electrode 308, and a lower arm ground electrode 309 arranged in sequence. At this time, the electrical signal for modulating the optical signal is provided by the differential high-frequency microwave signal output by the signal generator. The thermal adjustment structure and the electrical adjustment structure in the arbitrary ratio power divider remain unchanged.

[0073] Further, refer to Figure 5 , Figure 5 It is a schematic cross-sectional structure diagram of the third embodiment of the high extinction ratio high-speed electro-optic modulator chip of the present invention.

[0074] Similar to the above solution, the high extinction ratio high-speed electro-optic modulator chip uses x-cut thin-film lithium niobate wafer. Figure 5 The high extinction ratio high-speed electro-optic modulator chip also includes a substrate layer 201, a low-refractive index buried layer 202, a thin-film lithium niobate 203 ridge waveguide structure, the electro-optic modulation region waveguide transmission direction is the y direction, and a low-refractive index upper cladding 204 laid on the thin-film lithium niobate material.

[0075] Reference Figure 6 , Figure 6 FIG. 4 is a schematic diagram of the structure of a fourth embodiment of a high extinction ratio high-speed electro-optic modulator chip according to the present invention. Figure 6 As shown, in this embodiment, the same or similar contents as those in the above embodiment can be referred to the above description and will not be described in detail later. The arbitrary ratio power divider may also include: second to sixth beam splitters and a second thermal adjustment structure; the input end of the second beam splitter 102 (refer to the tenth waveguide 1021 in the figure) is connected to the coupler, the output end waveguide of the second beam splitter 102 (refer to the eleventh waveguide 1022 and the twelfth waveguide 1023 in the figure) is connected to the input end of the third beam splitter 103 and the fourth beam splitter 104 respectively, and the output end of the third beam splitter 103 (refer to the thirteenth waveguide 1032 in the figure) is connected to the fifth beam splitter 103 through the second thermal adjustment structure. 5 is connected to the input end of the traveling wave electrode structure 20 (refer to the fourteenth waveguide 1051 in the figure), the output end of the fourth beam splitter 104 (refer to the fifteenth waveguide 1043 in the figure) is connected to the input end of the sixth beam splitter 106 (refer to the sixteenth waveguide 1062 in the figure) through the second thermal adjustment structure, the output end of the fifth beam splitter (refer to the seventeenth waveguide 1053 in the figure) is transmitted to the first modulation area of ​​the traveling wave electrode structure 20, and the output end of the sixth beam splitter (refer to the eighteenth waveguide 1063 in the figure) is transmitted to the second modulation area of ​​the traveling wave electrode structure.

[0076] It should be understood that the output end of the third beam splitter 103 (refer to the nineteenth waveguide 1033 in the figure) can also be connected to the input end of the fifth beam splitter 105 (refer to the twentieth waveguide 1052 in the figure) through the second thermal adjustment structure, and the output end of the fourth beam splitter 104 (refer to the twenty-first waveguide 1042 in the figure) can be connected to the input end of the sixth beam splitter 106 (refer to the twenty-second waveguide 1061 in the figure) through the second thermal adjustment structure.

[0077] The second thermal adjustment structure includes: a fourth resistor R4, a fifth resistor R5, and fifth to eighth DC electrodes; the fourth resistor R4 is arranged on the first output waveguide (i.e., the thirteenth waveguide 1032) of the third beam splitter 103, one end of the fourth resistor R4 is electrically connected to the fifth DC electrode E5, and the other end of the fourth resistor R4 is electrically connected to the sixth DC electrode E6; the fifth resistor R5 is arranged on the second waveguide (i.e., the fifteenth waveguide 1043) of the fourth beam splitter 104, one end of the fifth resistor R5 is electrically connected to the seventh DC electrode E7, and the other end of the fifth resistor R5 is electrically connected to the eighth DC electrode E8. The rest of the structure of the electro-optic modulator of this embodiment is similar to that of the first embodiment, and will not be described one by one here.

[0078] In this embodiment, the light from the light source enters the thin-film lithium niobate ridge waveguide through the on-chip optical coupling structure, and the optical signal is divided into two equal paths of light through the second beam splitter 102, and enters the upper and lower sub-MZ structures respectively through the third beam splitter 103 and the fourth beam splitter 104. The thirteenth waveguide 1032, the nineteenth waveguide 1033, the fourteenth waveguide 1051 and the twentieth waveguide 1052 constitute the upper sub-MZ structure, and the twenty-first waveguide 1042, the fifteenth waveguide 1043, the twenty-second waveguide 1061 and the sixteenth waveguide 1062 constitute the lower sub-MZ structure. The light of the upper sub-MZ structure is output from the beam splitter 105, and enters the upper arm waveguide of the high-speed modulation zone after passing through the seventeenth waveguide 1053. The light of the lower sub-MZ structure exits from the beam splitter 106, and enters the lower arm waveguide of the high-speed modulation zone after passing through the eighteenth waveguide 1063. After the light of the upper and lower arm waveguides of the high-speed modulation zone is electro-optically modulated, it passes through the beam combining structure 108 and is output through the twenty-third waveguide 1083. The entire process realizes an ultra-high extinction ratio through the sub-MZ structure and realizes high-speed electro-optical modulation through the high-speed modulation zone.

[0079] Further, please refer to Figure 7 , Figure 7 This is a schematic diagram of the dual-drive structure in the fourth embodiment of the high extinction ratio high-speed electro-optic modulator chip of the present invention. The specific implementation method is similar to the above embodiment.

[0080] In addition, in order to achieve the above-mentioned purpose, an embodiment of the present invention also proposes an optical communication system. Since the optical communication system includes the above-mentioned high extinction ratio and high-speed electro-optical modulator chip, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0081] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A high extinction ratio high-speed electro-optic modulator chip, characterized in that: The high extinction ratio high-speed electro-optic modulator chip comprises: an arbitrary proportion power divider and a traveling wave electrode structure; The input end of the arbitrary proportional power divider is connected to the coupler, the output end of the arbitrary proportional power divider is connected to the traveling wave electrode structure, and the arbitrary proportional power divider and the traveling wave electrode structure are also connected to a signal generator respectively; The arbitrary ratio power divider is used to receive the power control signal of the signal generator, adjust the optical signal input by the coupler into two adjustment optical signals with preset power ratios, and transmit the two adjustment optical signals to the traveling wave electrode structure; The traveling wave electrode structure is used to receive the high-frequency microwave signal from the signal generator, modulate the adjustment optical signal according to the high-frequency microwave signal and then transmit it out; Wherein, the arbitrary ratio power divider comprises: a first beam splitter, a thermal adjustment structure and an electrical adjustment structure; The input end of the first beam splitter is connected to the coupler, and the output end of the first beam splitter is respectively connected to the upper and lower arms of the thermal adjustment structure. The upper arm of the thermal adjustment structure is transmitted to the first modulation area of ​​the traveling wave electrode structure through the electrical adjustment structure, and the lower arm of the thermal adjustment structure is transmitted to the second modulation area of ​​the traveling wave electrode structure through the electrical adjustment structure.

2. The high extinction ratio high speed electro-optic modulator chip according to claim 1, characterized in that: The heat adjustment structure includes: a first resistor, a second resistor, and first to fourth DC electrodes; The first resistor is arranged on the first output waveguide of the first beam splitter, one end of the first resistor is electrically connected to the first DC electrode, and the other end of the first resistor is electrically connected to the second DC electrode; The second resistor is arranged on the second output waveguide of the first beam splitter, one end of the second resistor is electrically connected to the third DC electrode, and the other end of the second resistor is electrically connected to the fourth DC electrode.

3. The high extinction ratio high speed electro-optic modulator chip according to claim 2, characterized in that: The traveling wave electrode structure comprises: a first ground electrode, a source electrode, and a second ground electrode arranged in sequence; The first ground electrode is electrically connected to the second ground electrode, and a third resistor is further provided between the first ground electrode and the source electrode; The source electrode receives the high-frequency microwave signal of the signal generator, generates a first electric field in a first modulation area between the source electrode and the first ground electrode, and generates a second electric field in a second modulation area between the source electrode and the second ground electrode; The first electric field and the second electric field are in opposite directions.

4. The high extinction ratio high speed electro-optic modulator chip according to claim 3, characterized in that: The traveling wave electrode structure further comprises: a plurality of microelectrode pairs; Each of the microelectrode pairs is disposed between the source electrode and the first ground electrode and the second ground electrode.

5. The high extinction ratio high speed electro-optic modulator chip according to claim 1, characterized in that: The arbitrary ratio power splitter comprises: second to sixth beam splitters and a second thermal adjustment structure; The input end of the second beam splitter is connected to the coupler, the output end of the second beam splitter is connected to the input ends of the third beam splitter and the fourth beam splitter respectively, the output end of the third beam splitter is connected to the input end of the fifth beam splitter through the second thermal adjustment structure, the output end of the fourth beam splitter is connected to the input end of the sixth beam splitter through the second thermal adjustment structure, the output end of the fifth beam splitter is transmitted to the first modulation area of ​​the traveling wave electrode structure, and the output end of the sixth beam splitter is transmitted to the second modulation area of ​​the traveling wave electrode structure.

6. The high extinction ratio high speed electro-optic modulator chip according to claim 5, characterized in that: The second heat adjustment structure includes: a fourth resistor, a fifth resistor, and fifth to eighth DC electrodes; The fourth resistor is arranged on the first output waveguide of the third beam splitter, one end of the fourth resistor is electrically connected to the fifth DC electrode, and the other end of the fourth resistor is electrically connected to the sixth DC electrode; The fifth resistor is arranged on the second output waveguide of the fourth beam splitter, one end of the fifth resistor is electrically connected to the seventh DC electrode, and the other end of the fifth resistor is electrically connected to the eighth DC electrode.

7. The high extinction ratio high-speed electro-optic modulator chip according to any one of claims 1 to 6, characterized in that: The high extinction ratio high-speed electro-optic modulator chip further includes: a sixth resistor, a ninth DC electrode and a tenth DC electrode; The sixth resistor is arranged between the arbitrary proportional power divider and the traveling wave electrode structure; One end of the sixth resistor is electrically connected to the ninth DC electrode, and the other end of the sixth resistor is electrically connected to the tenth DC electrode.

8. The high extinction ratio high speed electro-optic modulator chip according to claim 1, characterized in that: The high extinction ratio high-speed electro-optic modulator chip also includes: a substrate layer, a buried layer, a thin-film lithium niobate and an upper cladding layer arranged in sequence from bottom to top; The buried layer is arranged between the substrate layer and the thin film lithium niobate, the arbitrary proportion power divider and the traveling wave electrode structure are arranged in the upper cladding layer, and the upper cladding layer covers the top of the thin film lithium niobate.

9. An optical communication system, characterized in that: The optical communication system comprises the high extinction ratio and high speed electro-optic modulator chip according to any one of claims 1 to 8.

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