Electro-optic modulator, optical chip, and integrated chip

Abstract

An electro-optical modulator, an optical chip and an integrated chip. The electro-optical modulator is arranged on the surface of a substrate (01), and the electro-optical modulator comprises: an optical waveguide layer (002) arranged above the substrate (01), a modulation electrode (003) arranged above the optical waveguide layer (002), and a metal electrode (004) arranged above the modulation electrode (003) and electrically connected with the modulation electrode (003); a first end of the metal electrode (004) is coupled with a radio frequency driver to receive a modulation signal input by the radio frequency driver, and the modulation electrode (003) is used for electro-optically modulating the optical waveguide layer (002) based on the modulation signal; and a second end of the metal electrode (004) is coupled to a direct current voltage end for inputting a voltage signal and providing a bias voltage for the radio frequency driver through the metal electrode (004). The electro-optical modulator multiplexes the metal electrode (004), without the need to arrange a complex peripheral circuit, thereby reducing the cost, reducing the size of the electro-optical modulator, and being conducive to the miniaturization of the equipment.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of electro-optical modulation, and in particular to an electro-optical modulator, an optical chip and an integrated chip. BACKGROUND

[0002] With the development of optical communication technology, optical networks have been popularized in communication, for example, more and more users use fiber broadband to surf the Internet. When using fiber broadband to surf the Internet, an electro-optical modulator needs to be deployed, wherein the electro-optical modulator can be used to modulate an electrical signal onto an optical signal.

[0003] The existing modulation electrode design in the electro-optical modulator adopts a single-ended AC coupling mode, which needs to set up peripheral circuits such as capacitors and inductors for signal processing. The structure is complex, and the size is large and the cost is high, which is not conducive to the miniaturization of the device. SUMMARY

[0004] Embodiments of the present application provide an electro-optical modulator, an optical chip and an integrated chip, which solve the problems of complex peripheral circuit, high cost and large size of the electro-optical modulator.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: the first aspect of the embodiments of the present application provides an electro-optical modulator, which is arranged on the surface of a substrate, and comprises: an optical waveguide layer arranged above the substrate; a modulation electrode arranged above the optical waveguide layer; and a metal electrode arranged above the modulation electrode and electrically connected with the modulation electrode; a first end of the metal electrode is coupled with a radio frequency driver; wherein the metal electrode is used to receive a modulation signal input by the radio frequency driver, and the modulation electrode is used to perform electro-optical modulation on the optical waveguide layer based on the modulation signal; a second end of the metal electrode is coupled to a direct current voltage end, the direct current voltage end is used to input a voltage signal, and the metal electrode is used to provide a bias voltage for the radio frequency driver. Thus, the modulation electrode is electrically connected with the signal output end of the radio frequency driver through the metal electrode, the voltage signal input by the direct current voltage end can be received through the metal electrode, and the metal electrode and the direct current voltage end are coupled, so that the metal electrode can be multiplexed to supply power to the radio frequency driver. The electro-optical modulator multiplexes the metal electrode, and uses an open circuit direct current coupling mode to supply power to the driver of the electro-optical modulator, without the need to set up a complex peripheral circuit, thereby reducing the cost, and at the same time reducing the size of the electro-optical modulator, which is conducive to the miniaturization of the device.

[0006] [According to Rule 91, corrected on 10.08.2020]

[0007] In an alternative implementation, the optical waveguide layer comprises: an electro-optic crystal layer parallel to the substrate, the electro-optic crystal layer being provided with the modulation electrode and the ridge waveguide on a side away from the substrate, the modulation electrode being arranged on both sides of the ridge waveguide, and the modulation electrode being configured to perform electro-optic modulation on the optical wave transmitted by the ridge waveguide. In this way, a capacitance is formed between the modulation electrodes, and an electric field can be formed by capacitive coupling to perform electro-optic modulation on the optical wave transmitted by the ridge waveguide.

[0008] In an alternative implementation, the electro-optic modulator further comprises: an insulating layer arranged on the surface of the substrate, the optical waveguide layer and the modulation electrode being arranged in the insulating layer, and the insulating layer being provided with an opening on the surface of the modulation electrode, and the metal electrode being arranged at the opening. In this way, the modulation electrode is arranged in the insulating layer to avoid short circuiting of the modulation electrode.

[0009] In an alternative implementation, the optical waveguide layer comprises: a first branch and a second branch arranged symmetrically, the input end of the first branch being coupled to the input end of the second branch, and the output end of the first branch being coupled to the output end of the second branch, the first end of the modulation electrode being coupled to the input end of the first branch and the input end of the second branch, and the second end of the modulation electrode being coupled to the output end of the first branch and the output end of the second branch; the first end of the modulation electrode being coupled to the signal output end of the radio frequency driver, the second end of the modulation electrode being connected to a terminal resistance, and the second end of the modulation electrode being coupled to the direct current voltage end, wherein the optical signals output by the first branch and the second branch are in opposite phases. In this way, a push-pull modulation mode is realized, and the modulation efficiency is improved.

[0010] In an alternative implementation, the modulation electrode comprises: a first electrode pair and a second electrode pair, the first electrode pair being arranged symmetrically on both sides of the first branch, and the second electrode pair being arranged symmetrically on both sides of the second branch. In this way, the first electrode pair and the second electrode pair can be modulated with the first branch and the second branch, respectively. In addition, the modulation electrode adopts a symmetric structure, can realize non-chirp modulation, and can guarantee the transmission quality of the signal.

[0011] In an alternative implementation, the first end of the first electrode pair is connected to a signal output end of the radio frequency driver, the second end of the first electrode pair is connected to the first end of the second electrode pair, and the second end of the second electrode pair is connected to the direct current voltage end; the first branch and the second branch each include a first part and a second part, the first part of the first branch and the first part of the second branch are opposite to each other, and the second part of the first branch and the second part of the second branch are opposite to each other; the first electrode pair is arranged on both sides of the first part of the first branch, the second electrode pair is arranged on both sides of the second part of the second branch, the polarization directions of the first branch and the second branch are opposite to each other, the direction of the electric field applied by the first electrode pair on the first branch is the same as the direction of the electric field applied by the second electrode pair on the second branch. Thus, during operation, the radio frequency signal is first loaded onto the first electrode pair of the electro-optical modulator through the signal output end of the radio frequency driver, and then loaded onto the second electrode pair of the electro-optical modulator. The first electrode pair, the second electrode pair, and the third electrode pair are connected in series, so that the directions of the electric fields applied by the first electrode pair and the second electrode pair on the first branch and the second branch are the same. Since the polarization directions of the first branch and the second branch are opposite to each other, the phase of the light signals finally output by the first branch and the second branch is opposite, so that the push-pull modulation mode is realized without introducing a peripheral circuit, the modulation efficiency is improved, and the size of the electro-optical modulator is reduced.

[0012] In an alternative implementation, the modulation electrode further comprises: a third electrode pair, a first end of the first electrode pair is connected to the signal output end of the radio frequency driver, a second end of the first electrode pair is connected to a first end of the second electrode pair, a first end of the third electrode pair is connected to a second end of the second electrode pair, and a second end of the third electrode pair is connected to the direct current voltage end; the first branch and the second branch comprise: a first portion, a second portion and a third portion which are distributed in an S shape and parallel to each other, and the second portion is located between the first portion and the third portion; the first electrode pair is arranged on both sides of the first portion of the first branch, the second electrode pair is arranged on both sides of the second portion of the second branch, and the third electrode pair is arranged on both sides of the third portion of the first branch; wherein the direction of the electric field applied by the first electrode pair on the first branch is opposite to the direction of the electric field applied by the second electrode pair on the second branch, the direction of the electric field applied by the third electrode pair on the third modulation arm is opposite to the direction of the electric field applied by the second electrode pair on the second branch, and the polarization directions of the first branch and the second branch are the same. Thus, during operation, the radio frequency signal is first loaded onto the first electrode pair of the electro-optical modulator through the signal output end of the radio frequency driver, the first portion of the second branch is not loaded with an electric field, then the light path and the electric field follow a 180° turn with the modulation arm, the radio frequency signal is loaded onto the second electrode pair of the electro-optical modulator, at this time, the second portion of the first branch is not loaded with an electric field, then the light path and the electric field follow another 180° turn with the modulation arm, the radio frequency signal is loaded onto the third electrode pair of the electro-optical modulator, and the third portion of the second branch is not loaded with an electric field. The direction of the electric field of the first electrode pair and the second electrode pair is opposite, and the direction of the electric field of the third electrode pair and the second electrode pair is opposite. Since the polarization directions of the first branch and the second branch are the same, the phase of the light signals output by the first branch and the second branch is opposite, thus the push-pull modulation mode is realized without introducing peripheral circuits, the modulation efficiency is improved, and the size of the electro-optical modulator is reduced.

[0013] In an alternative implementation, the first ends of the first electrode pair and the second electrode pair are respectively connected to signal output ends of the radio frequency driver, the second ends of the first electrode pair and the second electrode pair are both connected with resistors, the first electrode pair comprises a first electrode and a second electrode, the second electrode pair comprises a third electrode and a fourth electrode, the first electrode and the second electrode are for example located on both sides of the first branch and the second branch, the third electrode and the fourth electrode are for example located between the first branch and the second branch, the first electrode, the second electrode, the third electrode and the fourth electrode can adopt an input mode of S+S-, S-S+, so that the electric field direction of the first electrode pair applied on the first branch and the electric field direction of the second electrode pair applied on the second branch are opposite, and the polarization directions of the first branch and the second branch are the same. Thus, the first electrode and the second electrode pair adopt a parallel connection mode, the electric field directions of the first electrode pair and the second electrode pair can be changed by adjusting the positive and negative connection mode of the first electrode pair and the second electrode pair, so that the phase of the light signals finally output by the first branch and the second branch are opposite, i.e. the push-pull modulation mode is realized, the modulation efficiency is improved, and the size of the electro-optical modulator is reduced.

[0014] In an alternative implementation, the first ends of the first electrode pair and the second electrode pair are respectively connected to signal output ends of the radio frequency driver, the second ends of the first electrode pair and the second electrode pair are both connected with resistors, the first electrode pair comprises a first electrode and a second electrode, the second electrode pair comprises a third electrode and a fourth electrode, the first electrode and the second electrode are for example located on both sides of the first branch and the second branch, the third electrode and the fourth electrode are for example located between the first branch and the second branch, the first electrode, the second electrode, the third electrode and the fourth electrode can adopt an input mode of S+S-, S+S-, the electric field direction of the first electrode pair applied on the first branch and the electric field direction of the second electrode pair applied on the second branch are the same, and the polarization directions of the first branch and the second branch are opposite. Thus, the first electrode and the second electrode pair adopt a parallel connection mode, the electric field directions of the first electrode pair and the second electrode pair can be made the same, and the polarization directions of the first branch and the second branch, so that the phase of the light signals finally output by the first branch and the second branch are opposite, i.e. the push-pull modulation mode is realized, the modulation efficiency is improved, and the size of the electro-optical modulator is reduced.

[0015] In a second aspect of the present application, an optical chip is provided, comprising a substrate and an electro-optical modulator as described above, the electro-optical modulator being arranged on a surface of the substrate. Thus, the optical chip adopts the electro-optical modulator described above, which is advantageous for reducing the size of the optical chip and facilitating the co-sealing with other chips.

[0016] In an alternative implementation, the optical chip further comprises: an input waveguide connected with the input end of the electro-optical modulator, and an output waveguide connected with the output end of the electro-optical modulator. In this way, the optical signal to be modulated can be input through the input waveguide, and the modulated optical signal can be output through the output waveguide.

[0017] In an alternative implementation, the optical chip further comprises: a photoelectric detector connected with the output waveguide through a connecting waveguide, and configured to detect the modulated optical signal. In this way, by arranging the photoelectric detector, a small-size and low-cost optical chip with high integration of transceiver can be obtained.

[0018] In a third aspect, the present application provides an integrated chip, comprising: an electrical chip, and an optical chip as described above, wherein the electrical chip is arranged on the surface of the optical chip, and the electrical chip is connected with the optical chip by soldering. In this way, by using the soldering connection mode, the circuit can be simplified, and meanwhile, the optical chip has a small size, thereby reducing the size of the integrated chip. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 An equivalent circuit diagram of an electro-optical modulator;

[0020] Figure 2 An equivalent circuit diagram of an electro-optical modulator provided by an embodiment of the present application;

[0021] Figure 3 An equivalent circuit diagram of an electro-optical modulator provided by an embodiment of the present application;

[0022] Figure 3a An X-cut structure diagram of an electro-optical modulator provided by an embodiment of the present application;

[0023] [Corrected according to Rule 91 on 10.08.2020]

[0024] Figure 3b A Z-cut structure diagram of an electro-optical modulator provided by an embodiment of the present application;

[0025] Figure 3c A Y-cut structure diagram of an electro-optical modulator provided by an embodiment of the present application;

[0026] Figure 3d An electric hysteresis loop diagram of a lithium niobate material provided by an embodiment of the present application;

[0027] Figure 4 An equivalent circuit diagram of another electro-optical modulator provided by an embodiment of the present application;

[0028] Figure 5An equivalent circuit diagram of another electro-optical modulator provided by an embodiment of the present application;

[0029] Figure 6 An equivalent circuit diagram of another electro-optical modulator provided by an embodiment of the present application;

[0030] Figure 7 A structural schematic diagram of an optical chip provided by an embodiment of the present application;

[0031] Figure 8 A structural schematic diagram of an integrated chip;

[0032] Figure 9 A structural schematic diagram of an integrated chip provided by an embodiment of the present application. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings.

[0034] Hereinafter, the terms "first", "second", etc. are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0035] In addition, in the present application, the orientation terms such as "upper", "lower", etc. are defined with respect to the orientation of the components shown in the drawings, and it should be understood that these directional terms are relative concepts, which are used for relative description and clarification, and can be changed accordingly according to the change of the orientation of the components placed in the drawings.

[0036] The present application provides an electro-optical modulator, which can be used as a conversion interface for converting from an electrical domain to an optical domain in an optical network, and is used in a communication system.

[0037] It should be noted that the optical network refers to a wide area network, a metropolitan area network or a newly built large-scale local area network using optical fibers as the main transmission medium.

[0038] Figure 1 A structural schematic diagram of an electro-optical modulator. It should be noted that the electro-optical modulator is usually a semiconductor device, Figure 1 An equivalent circuit diagram of the semiconductor device. As Figure 1 shown, the electro-optical modulator includes a first branch 202 and a second branch 201 symmetrically arranged, the input end of the first branch 202 and the input end of the second branch 201 are connected, and the output end of the first branch 202 and the output end of the second branch 201 are connected.

[0039] The electro-optical modulator is, for example, a Mach-Zehnder modulator, which divides the input light into two equal signals and inputs the signals into a first branch 202 and a second branch 201 respectively. The first branch 202 and the second branch 201 are made of electro-optical material, for example, lithium niobate, whose refractive index changes with the size of the externally applied electric signal.

[0040] The first branch 202 and the second branch 201 are provided with a first metal layer 101 and a second metal layer 103 on both sides, and a third metal layer 102 is arranged between the first branch 202 and the second branch 201. The first metal layer 101 and the third metal layer 102 form a first electrode pair, and the second metal layer 103 and the third metal layer 102 form a second electrode pair.

[0041] The input side of the electro-optical modulator is provided with, for example, a radio frequency input end 11 and a direct current input end 12. The radio frequency input end 11 (i.e. the driver output end of the electro-optical modulator) is used to input an alternating current electric signal of high frequency modulation to the first electrode pair and the second electrode pair, and the direct current input end 12 is used to input a direct current bias electric signal to the driver of the electro-optical modulator.

[0042] The signal output end 11 of the radio frequency driver is connected to the first electrode pair and the second electrode pair through a capacitor 111, which is used to filter out the direct current signal. The direct current voltage end 12 is connected to the modulation electrode of the electro-optical modulator through an inductor 121, which is used to filter out the high frequency signal.

[0043] The modulation signal input by the direct current voltage end 12 can be coupled to the first branch 202 and the second branch 201 through the capacitor 111 structure formed by the first electrode pair and the second electrode pair respectively.

[0044] In the above embodiment, the first electrode pair and the second electrode pair are, for example, an alternating current bias electrode. In order to realize that only the high frequency alternating current signal is input to the modulator and only the direct current signal is input to the driver 11, the capacitor 111, the inductor 121 and other peripheral circuits are arranged between the signal output end 11 of the radio frequency driver, the direct current voltage end 12 and the first electrode pair and the second electrode pair of the electro-optical modulator, so as to obtain the direct current signal and the high frequency alternating current signal respectively. The peripheral circuit structure is complex, and the device size is large, which is not conducive to the miniaturization of the equipment.

[0045] Figure 8 A structure schematic diagram of an integrated chip is provided in the present application. As shown in the figure, the integrated chip comprises a substrate 01, and an optical chip 02 and an electric chip 03 arranged on the substrate. The optical chip 02 is, for example, a Mach-Zehnder modulator. Figure 8 The electric chip 03 is, for example, a radio frequency driver. The optical chip 02 and the electric chip 03 are arranged on the substrate 01 through a through hole 04. Figure 1The electro-optic modulator shown is relatively large, and the optical chip 02 and the electrical chip 03 are connected by wires.

[0046] This application provides an electro-optic modulator. Figure 2 This is a schematic diagram of an electro-optic modulator provided in an embodiment of this application. Figure 3 An equivalent circuit diagram of an electro-optic modulator provided in an embodiment of this application is shown. Figure 2 , Figure 3 As shown, the electro-optic modulator includes: an optical waveguide layer 002 formed on a substrate 01, a modulation electrode 003 disposed on the optical waveguide layer 002, and a metal electrode 004 disposed on the modulation electrode 003 and electrically connected to the modulation electrode 003.

[0047] The first end of the metal electrode 004 is coupled to the signal output terminal 11 of the radio frequency driver.

[0048] The metal electrode 004 is used to receive the modulation signal input by the radio frequency driver, and the modulation electrode is used to perform electro-optic modulation on the optical waveguide layer based on the modulation signal.

[0049] The second end of the metal electrode 004 is coupled to the DC voltage terminal 12, which is used to input voltage signals and provides bias voltage to the RF driver through the metal electrode 004.

[0050] It should be noted that the RF driver includes at least an RF signal output terminal and a bias voltage terminal. The RF signal output terminal is coupled to the modulation electrode 003, for example, through the metal electrode 004. The RF signal output terminal can output an RF signal to the metal electrode 004, and the modulation electrode 003 is used to perform electro-optic modulation on the optical waveguide layer based on the modulation signal. The bias voltage input terminal can be coupled to the metal electrode 004 to receive the bias voltage output from the DC voltage terminal through the metal electrode 004, thereby powering the RF driver.

[0051] The specific configuration of the radio frequency signal output terminal and the bias voltage input terminal is existing technology for those skilled in the art, and will not be described in detail here.

[0052] like Figure 3 As shown, the metal electrodes 004 are continuously arranged, while the different modulation electrodes 003 are discontinuous. Therefore, the high-frequency modulation signal input to the RF driver can be loaded onto the waveguide through the modulation electrodes 003 and terminated at the terminating resistor 104. The DC voltage signal transmitted at the DC voltage terminal 12 can pass through the metal electrodes 004 to provide the bias voltage required for the operation of the RF driver.

[0053] In operation, the DC voltage terminal 12 supplies power to the radio frequency driver through the metal electrode, so that the radio frequency driver starts to work, and then the radio frequency driver outputs a modulation signal, the metal electrode 004 receives the modulation signal input by the radio frequency driver, and the modulation electrode 003 performs electro-optical modulation on the optical waveguide layer based on the modulation signal.

[0054] The electro-optical modulator provided by the embodiments of the present application is coupled with the signal output terminal of the radio frequency driver through the metal electrode, can receive the voltage signal input by the DC voltage terminal through the metal electrode, and is coupled with the DC voltage terminal, so that the metal electrode can be multiplexed to supply power to the radio frequency driver. The electro-optical modulator multiplexes the metal electrode, adopts an open-circuit DC coupling mode to supply power to the driver of the electro-optical modulator, does not need to set a complex peripheral circuit, reduces the cost, simultaneously reduces the size of the electro-optical modulator, and is beneficial to the miniaturization of equipment.

[0055] As shown in Figure 2 The optical waveguide layer 002 includes an electro-optical crystal layer 005 parallel to the substrate, and a ridge waveguide 006 arranged on the side of the electro-optical crystal layer 005 away from the substrate, and the modulation electrode 003 is arranged on both sides of the ridge waveguide 006, and the modulation electrode 003 is used for performing electro-optical modulation on the light wave transmitted by the ridge waveguide 006. Therefore, the modulation electrode 003 forms a capacitor, and an electric field can be formed between the modulation electrodes 003 in a capacitive coupling mode, so as to perform electro-optical modulation on the light wave transmitted by the ridge waveguide 006.

[0056] [Corrected according to Rule 91 on 10.08.2020]

[0057] It should be noted that the electro-optical crystal layer 005 and the ridge waveguide 006 can be integrally formed. The material of the electro-optical crystal layer 005 and the ridge waveguide 006 is, for example, an electro-optical material, and specifically lithium niobate, and the refractive index of which changes with the size of the external applied electric signal.

[0058] The material of the substrate 01 is, for example, silicon (Si), the surface of the substrate 01 is provided with an insulating layer 02, for example, a silicon dioxide material, and the optical waveguide layer 002 and the modulation electrode 003 are arranged in the insulating layer 02.

[0059] In some other embodiments of the present application, referring to Figure 2 The insulating layer on the surface of the modulation electrode is provided with an opening, and the metal electrode 004 is arranged at the opening.

[0060] Therefore, arranging the modulation electrode 003 in the insulating layer can avoid short circuit

[0061] As shown in Figure 3As shown, the optical waveguide layer includes: a first branch 202 and a second branch 201 symmetrically arranged (i.e., Figure 2 The ridge waveguide 006 in the middle, the first branch 202 and the second branch 201 are provided with modulation electrodes on both sides ( Figure 3 (10, 20).

[0062] The input terminal of the first branch 202 is connected to the input terminal of the second branch 201, and the output terminal of the first branch 202 is connected to the output terminal of the second branch 201.

[0063] The modulation electrodes are respectively disposed on both sides of the first branch 202 and the second branch 201, and are used to modulate the electric field around the first branch 202 and the second branch 201, so that the optical signals output by the first branch 202 and the second branch 201 are out of phase. The first end of the modulation electrode is coupled to the input terminal 21 of the first branch 202 and the second branch 201, and the second end of the modulation electrode is coupled to the output terminal 22 of the first branch 202 and the second branch 201. The second end of the modulation electrode is connected to a terminating resistor 104.

[0064] The terminating resistor 104 can be two resistors connected in series, with a resistance value of, for example, 32.5 ohms.

[0065] The phase directions of the first branch 202 and the second branch 201 being opposite include: the polarization directions of the first branch 202 and the second branch 201 being the same, and the direction of the electric field applied to the first branch 202 and the second branch 201 by the modulation electrode can be adjusted so that the electric field directions of the first branch 202 and the second branch 201 are opposite, so that the phase directions of the first branch 202 and the second branch 201 are opposite.

[0066] Alternatively, the modulation electrodes have the same direction of the external electric field applied to the first branch 202 and the second branch 201, and the polarization directions of the first branch 202 and the second branch 201 are opposite, so that the phase directions of the first branch 202 and the second branch 201 are opposite.

[0067] The first branch 202 and the second branch 201 are made of electro-optic materials, specifically lithium niobate, whose refractive index varies with the magnitude of the externally applied electrical signal.

[0068] This application embodiment does not limit the polarization direction of the first branch 202 and the second branch 201. In one implementation of this application, the first branch 202 and the second branch 201 can be as follows: Figure 2 As shown, a structure for transmitting light along the Y direction is fabricated on a Z-cut lithium niobate substrate.

[0069] In another implementation of the present application, the first branch 202 and the second branch 201 can also be made to transmit light along the Z direction on an X-cut lithium niobate substrate as shown in FIG. 3. Figure 3a

[0070] In another implementation of the present application, the first branch 202 and the second branch 201 can also be made to transmit light along the X direction on a Z-cut lithium niobate substrate as shown in FIG. 4. Figure 3b

[0071] In another implementation of the present application, the first branch 202 and the second branch 201 can also be made to transmit light along the Z direction on a Y-cut lithium niobate substrate as shown in FIG. 5. Figure 3c

[0072] It should be noted that lithium niobate is also a good ferroelectric material, and has the characteristics of spontaneous polarization and applied electric field polarization. Figure 3d As shown in FIG. 6, it is a hysteresis loop of the lithium niobate material, the horizontal coordinate is the applied electric field intensity E, the vertical coordinate is the polarization intensity P, and Ps is the polarization direction of the lithium niobate material under the corresponding polarization intensity. When the lithium niobate material is applied with a reverse electric field, the direction of the spontaneous polarization has a tendency to reverse, and when the applied electric field is strong enough, the ions will overcome the potential barrier and jump from one equilibrium position to another, so that the polarization direction is reversed, and the change trajectory is along curve 1. At this time, the electric field intensity is reduced, and the polarization intensity changes along another curve 2, which is called the hysteresis loop. When the electric field is reduced to zero, the spontaneous polarization still exists, at this time the polarization direction changes from point A to point B, that is, the polarization direction is reversed. Continue to apply a voltage in the reverse direction, and when the field strength reaches a certain value, the polarization intensity will be zero, and this voltage value is called the coercive field strength Ec.

[0073] In the embodiment of the present application, the second branch 201 of the electro-optical modulator can be polarized by applying a pulse voltage, so that the polarization directions of the first branch 202 and the second branch 201 are opposite. For example, the radio frequency signal can be first loaded to the first branch 202 of the modulator, and the direction of the electric field loaded is as shown by the arrow in FIG. 7. Figure 2 The direction of the applied electric field is opposite to the "+Z" direction, and after being loaded to 1 / 2 of the equivalent modulation zone length, the electric field is converted to the second branch 201, and the polarization direction of "+Z" is as shown by the arrow, downward, and the electric field direction does not change, so that the polarization directions of the first branch 202 and the second branch 201 are opposite.

[0074] ​​​In addition, the electro-optical modulator further comprises a signal output end 11 of a radio frequency driver (i.e., a driver output end of the electro-optical modulator) connected to the first end of the modulation electrode and used for inputting a modulation signal, and a direct current voltage end 12 connected to the second end of the modulation electrode through the terminal resistor 104 and used for inputting a direct current bias signal to the driver of the electro-optical modulator.

[0075] In operation, the input light wave is split into two equal beams at a Y branch after passing through the input end of the electro-optical modulator and is transmitted through the first branch 202 and the second branch 201, respectively. Since the first branch 202 and the second branch 201 are made of electro-optical material, the refractive index of which changes with the strength of the applied electric field, the two light signals have a phase difference when reaching the second Y branch.

[0076] The radio frequency signal input by the signal output end 11 of the radio frequency driver is directly coupled to the modulation electrode for electro-optical modulation. The phase difference of the light signal can be changed by adjusting the strength of the electric field, thereby achieving modulation of the light signal. Finally, the radio frequency signal is terminated on the terminal resistor 104. At the same time, a direct current bias voltage can be loaded on the terminal resistor 104 to supply power to the driver of the electro-optical modulator.

[0077] The signal output end 11 of the radio frequency driver and the direct current voltage end 12 of the electro-optical modulator are located at the two ends of the modulation electrode. The modulation electrode adopts open set direct current coupling. Compared with the traditional single-terminal alternating current coupling, no filter devices such as capacitors 111 and inductors 121 are required, and the peripheral circuit is greatly simplified. On the premise of ensuring that the performance of the electro-optical modulator is not affected, the integration of the electro-optical modulator can be further improved, the difficulty of high-density packaging layout and the wiring pressure are effectively reduced, and the chip is beneficial to sealing. In addition, the modulation electrode adopts a symmetrical structure and can achieve non-chirp modulation, thereby ensuring the transmission quality of the signal.

[0078] In addition, the electro-optical modulator adopts a push-pull mode for modulation, so that the phase directions of the first branch 202 and the second branch 201 are opposite, thereby improving the modulation efficiency.

[0079] The specific structure of the modulation electrode is not limited in the embodiments of the present application. In one implementation manner of the present application, as shown in Figure 2 the modulation electrode comprises a first electrode pair 20 and a second electrode pair 10, the first electrode pair 20 is arranged on the two sides of the first branch 202, and the second electrode pair 10 is arranged on the two sides of the second branch 201.

[0080] In an implementation form of the application, the polarization directions of the first branch 202 and the second branch 201 are opposite, and the electric field direction applied on the first branch 202 by the first electrode pair 20 is the same as the electric field direction applied on the second branch 201 by the second electrode pair 10. The electro-optical modulator realizes the modulator driving in a push-pull manner.

[0081] For example, as shown in Figure 2 , the first electrode pair 20 and the second electrode pair 10 are connected in series. The first end of the first electrode pair 20 is connected to the signal output end 11 of the radio frequency driver, the second end of the first electrode pair 20 is connected to the first end of the second electrode pair 10, the second end of the second electrode pair 10 is connected with a resistor, and the second end of the second electrode pair 10 is connected to the direct current voltage end 12.

[0082] Next, referring to Figure 2 , the first branch 202 and the second branch 201 each include a first part and a second part, and the first part of the first branch 202 and the first part of the second branch 201 are opposite, and the second part of the first branch 202 and the second part of the second branch 201 are opposite.

[0083] The first electrode pair 20 is arranged on both sides of the first part of the first branch 202, and the second electrode pair 10 is arranged on both sides of the second part of the second branch 201. The polarization directions of the first branch 202 and the second branch 201 are opposite, and the electric field direction applied on the first branch 202 by the first electrode pair 20 is the same as the electric field direction applied on the second branch 201 by the second electrode pair 10.

[0084] In operation, the radio frequency signal is loaded onto the first electrode pair 20 of the electro-optical modulator through the signal output end 11 of the radio frequency driver, and the first electrode pair 20 applies the electric field direction on the first part of the first branch 202 as shown by the arrow, downward, at this time, the first part of the second branch 201 is not loaded with electric field. Then the radio frequency signal is loaded onto the second electrode pair 10 of the electro-optical modulator, and the second electrode pair 10 applies the electric field direction on the second part of the second branch 201 which is the same as the electric field direction applied on the first branch 202 by the first electrode pair 20, at this time, the second part of the first branch 202 is not loaded with electric field. At this time, because the polarization directions of the first branch 202 and the second branch 201 are opposite, the light signals output by the first branch 202 and the second branch 201 are opposite in phase, realizing the push-pull modulation mode and improving the modulation efficiency.

[0085] For another example, as shown in Figure 4As shown, the first electrode pair 20 and the second electrode pair 10 are connected in parallel. The first end of the first electrode pair 20 and the first end of the second electrode pair 10 are connected to the signal output end 11 of the RF driver, the second end of the first electrode pair 20 and the second end of the second electrode pair 10 are connected to the DC voltage end 12 via resistors, and the second end of the first electrode pair 20 and the second end of the second electrode pair 10 are connected to the terminal resistor 104. The polarization directions of the first branch 202 and the second branch 201 are opposite.

[0086] The signal output end 11 of the RF driver is provided with a set of differential inputs, and the first electrode pair 20 and the second electrode pair 10 each include a first electrode and a second electrode. The first electrode of the first electrode pair 20 is located on the upper side of the first branch 202, the second electrode of the first electrode pair 20 is located on the lower side of the first branch 202, the first electrode of the second electrode pair 10 is located on the upper side of the second branch 201, and the second electrode of the second electrode pair 10 is located on the lower side of the second branch 201.

[0087] The first electrode of the first electrode pair 20 is connected to the positive pole of the signal output end 11 of the RF driver, and the second electrode of the first electrode pair 20 is connected to the negative pole of the signal output end 11 of the RF driver. The first electrode of the second electrode pair 10 is connected to the positive pole of the signal output end 11 of the RF driver, and the second electrode of the second electrode pair 10 is connected to the negative pole of the signal output end 11 of the RF driver. The electric field direction of the first electrode pair 20 applied to the first branch 202 is the same as the electric field direction of the second electrode pair 10 applied to the second branch 201.

[0088] In operation, the RF signal is loaded onto the first electrode pair 20 and the second electrode pair 10 of the electro-optical modulator via the signal output end 11 of the RF driver. The electric field direction of the first electrode pair 20 applied to the first branch 202 is downward as indicated by the arrow, and the electric field direction of the second electrode pair 10 applied to the second branch 201 is downward as indicated by the arrow. Since the polarization directions of the first branch 202 and the second branch 201 are opposite, the light signals output by the first branch 202 and the second branch 201 are in opposite phases. Finally, the RF signal is terminated on the terminal resistor 104.

[0089] In another implementation of the present application, the polarization directions of the first branch 202 and the second branch 201 are the same, and the electric field direction of the first electrode pair 20 applied to the first branch 202 is opposite to the electric field direction of the second electrode pair 10 applied to the second branch 201. The electro-optical modulator is driven in a push-pull mode.

[0090] As Figure 5As shown, the electro-optical modulator comprises: a first electrode pair 20, a second electrode pair 10 and a third electrode pair 30, and the first electrode pair 20. The second electrode pair 10 and the third electrode pair 30 are connected in series. Wherein, the first end of the first electrode pair 20 is connected with the signal output end 11 of the radio frequency driver, the second end of the first electrode pair 20 is connected with the first end of the second electrode pair 10, the first end of the third electrode pair 30 is connected with the second end of the second electrode pair 10, the second end of the third electrode pair 30 is connected with a resistance, and the second end of the second electrode pair 10 is connected with the direct current voltage end 12.

[0091] The first branch 202 and the second branch 201 are both S-shaped distributed, and the first branch 202 and the second branch 201 comprise: a first part, a second part and a third part which are parallel to each other, and the second part is located between the first part and the third part. Wherein, the first electrode pair 20 is arranged on both sides of the first part of the first branch 202, the second electrode pair 10 is arranged on both sides of the second part of the second branch 201, and the third electrode pair 30 is arranged on both sides of the third part of the first branch 202. Wherein, the direction of the electric field applied by the first electrode pair 20 on the first branch 202 is opposite to the direction of the electric field applied by the second electrode pair 10 on the second branch 201, the direction of the electric field applied by the third electrode pair 30 on the third modulation arm is opposite to the direction of the electric field applied by the second electrode pair 10 on the second branch 201, the polarization direction of the first branch 202 is the same as the polarization direction of the second branch 201.

[0092] In operation, the radio frequency signal is loaded onto the first electrode pair 20 of the electro-optical modulator through the signal output end 11 of the radio frequency driver, and the first electrode pair 20 applies an electric field on the first part of the first branch 202 in the direction as shown by the arrow, downward. At this time, the first part of the second branch 201 is not loaded with an electric field. Then, after a 180° optical path and electric field turning, along with the turning of the waveguide and the electrode, the radio frequency signal is loaded onto the second electrode pair 10 of the electro-optical modulator, and the second electrode pair 10 applies an electric field on the second part of the second branch 201 in the direction as shown by the arrow, upward. At this time, the second part of the first branch 202 is not loaded with an electric field. Then, after a 180° optical path and electric field turning, along with the turning of the waveguide and the electrode, the radio frequency signal is loaded onto the third electrode pair 30 of the electro-optical modulator, and the third electrode pair 30 applies an electric field on the third part of the first branch 202 in the direction as shown by the arrow, downward. At this time, the third part of the second branch 201 is not loaded with an electric field, and finally the radio frequency signal is terminated on the terminal resistance 104.

[0093] In another implementation manner of the present application, as shown inFigure 6 As shown in another implementation of the present application, the first electrode pair and the second electrode pair 10 are connected in parallel. The signal output end 11 of the radio frequency driver is increased by a set of differential inputs, using the input mode of S+S-, the first end of the first electrode pair 20 and the second electrode pair 10 are respectively connected with the signal output end 11 of the radio frequency driver, the second end of the first electrode pair 20 and the second electrode pair 10 are both connected with a resistor, and the second end of the first electrode pair 20 and the second electrode pair 10 are respectively connected with the direct current voltage end 12, and the polarization directions of the first branch 202 and the second branch 201 are the same.

[0094] The first electrode pair 20 and the second electrode pair 10 respectively include a first electrode and a second electrode, wherein the first electrode of the first electrode pair 20 is located on the upper side of the first branch 202, the second electrode of the first electrode pair 20 is located on the lower side of the first branch 202, the first electrode of the second electrode pair 10 is located on the upper side of the second branch 201, and the first electrode of the second electrode pair 10 is located on the lower side of the second branch 201.

[0095] The first electrode of the first electrode pair 20 is connected with the positive pole of the signal output end 11 of the radio frequency driver, and the second electrode of the first electrode pair 20 is connected with the negative pole of the signal output end 11 of the radio frequency driver. The first electrode of the second electrode pair 10 is connected with the negative pole of the signal output end 11 of the radio frequency driver, and the second electrode of the second electrode pair 10 is connected with the positive pole of the signal output end 11 of the radio frequency driver. The electric field direction of the first electrode pair 20 applied on the first branch 202 is opposite to the electric field direction of the second electrode pair 10 applied on the second branch 201.

[0096] In operation, the radio frequency signal is loaded on the first electrode pair 20 and the second electrode pair 10 of the electro-optical modulator through the signal output end 11 of the radio frequency driver, the electric field direction of the first electrode pair 20 applied on the first branch 202 is downward as shown by the arrow, and the electric field direction of the second electrode pair 10 applied on the second branch 201 is upward as shown by the arrow, and since the polarization directions of the first branch 202 and the second branch 201 are the same, the light signals output by the first branch 202 and the second branch 201 are opposite in phase. Finally, the radio frequency signal is terminated on the terminal resistor 104.

[0097] In the above embodiments, it can be found by comparison that the electro-optical modulator has the characteristics of small size, no peripheral circuit, and suitable for hybrid packaging.

[0098] The embodiment of the present application also provides an optical chip, which can include a substrate 01, and an electro-optical modulator and other devices arranged on the substrate, and the other devices can be connected with the electro-optical modulator through a connecting waveguide.

[0099] Other devices can be at least one of laser diodes, semiconductor optical amplifiers, and photodetectors. It is understood that there can be multiple devices on the same substrate, and the devices can be connected in any desired connection order.

[0100] Figure 7 This is a schematic diagram of the structure of the optical chip provided in an embodiment of this application. Figure 7 As shown, the optical chip includes: a substrate 01, and an electro-optic modulator, an input waveguide 010, and an output waveguide 011 disposed on the substrate 01.

[0101] The embodiments of this application do not limit the material of the modulation electrode. In one implementation of this application, the material of the modulation electrode 003 is a metal material such as copper (Cu) or zinc (Zn).

[0102] In another implementation of this application, the modulation electrode 003 is made of transparent conductive oxide (TCO). TCO has high conductivity and low light absorption. Replacing Au as the lower electrode can further reduce the electrode distance, thereby increasing the electric field intensity in the optical field region and improving the modulation efficiency of the electro-optic modulator. Compared with conventional modulation electrodes, the chip length corresponding to the same phase modulation is shorter, which is beneficial to reducing the chip size.

[0103] The optical chip may also include, for example, a light source 014 and a photodetector 012. The light source 014 is disposed on the surface of the substrate 01, for example, in parallel with the silicon dioxide layer. The photodetector 012 is disposed on the surface of the silicon dioxide layer. The light source 014 is used to emit light, and the input waveguide 010 is used to transmit the light emitted by the light source 014 to the electro-optic modulator. The electro-optic modulator is used to modulate the light emitted by the light source 014. The photodetector 012 can be connected to the input terminal 011 of the electro-optic modulator 001 through the connecting waveguide 013. The photodetector 012 can detect the optical signal modulated by the electro-optic modulator.

[0104] This application also provides an integrated chip, including: an electrical chip, and an optical chip as described above.

[0105] The electro-optic modulator in this optical chip can be used as follows: Figure 2 , Figure 4 , Figure 5 or Figure 6 The structure shown indicates that the optical chip is small in size and can be encapsulated with the electrical chip by soldering.

[0106] like Figure 9 As shown, the electrical chip is disposed on the surface of the optical chip, and the electrical chip is soldered to the optical chip via solder balls.

[0107] The above description is only specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any change or replacement within the technical scope disclosed in the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. An electro-optic modulator, characterized in that, The electro-optic modulator is disposed on the surface of the substrate, and the electro-optic modulator includes: An optical waveguide layer disposed on the substrate; Modulation electrodes disposed on the optical waveguide layer; and A metal electrode disposed on the modulation electrode and electrically connected to the modulation electrode; The first end of the metal electrode is coupled to the radio frequency driver; The metal electrode is used to receive the modulation signal input by the radio frequency driver, and the modulation electrode is used to perform electro-optic modulation on the optical waveguide layer based on the modulation signal. The second end of the metal electrode is coupled to a DC voltage terminal, which is used to input a voltage signal and provides a bias voltage to the RF driver through the metal electrode. The metal electrodes are continuously arranged single units, and one metal electrode is connected to multiple modulation electrodes, which are spaced apart.

2. The electro-optic modulator according to claim 1, characterized in that, Also includes: An insulating layer is disposed on the surface of the substrate, the optical waveguide layer and the modulation electrode are located within the insulating layer, and an opening is provided on the insulating layer on the surface of the modulation electrode, and the metal electrode is formed at the opening.

3. The electro-optic modulator according to claim 1 or 2, characterized in that, The optical waveguide layer includes: an electro-optic crystal layer parallel to the substrate, and a ridge waveguide disposed on the side of the electro-optic crystal layer away from the substrate. The modulation electrodes are respectively disposed on both sides of the ridge waveguide, and the modulation electrodes are used to electro-optically modulate the optical waves transmitted in the ridge waveguide.

4. The electro-optic modulator according to claim 3, characterized in that, The ridge waveguide includes: a first branch and a second branch arranged symmetrically, the input terminals of the first branch and the second branch being coupled, the output terminals of the first branch and the second branch being coupled, the first end of the modulation electrode being coupled to the input terminals of the first branch and the second branch, and the second end of the modulation electrode being coupled to the output terminals of the first branch and the second branch; the first end of the modulation electrode is coupled to the signal output terminal of the RF driver, and the second end of the modulation electrode is connected to a terminating resistor, wherein the optical signals output by the first branch and the second branch are out of phase.

5. The electro-optic modulator according to claim 4, characterized in that, The modulation electrode includes a first electrode pair and a second electrode pair, wherein the first electrode pair is symmetrically disposed on both sides of the first branch, and the second electrode pair is symmetrically disposed on both sides of the second branch.

6. The electro-optic modulator according to claim 5, characterized in that, The optical waveguide layer is made of an electro-optic material. The electric field direction applied by the first electrode pair to the first branch is the same as the electric field direction applied by the second electrode pair to the second branch. The polarization directions of the first branch and the second branch are opposite.

7. The electro-optic modulator according to claim 6, characterized in that, The first end of the first electrode pair is connected to the signal output terminal of the radio frequency driver, the second end of the first electrode pair is connected to the first end of the second electrode pair, and the second end of the second electrode pair is connected to a terminating resistor. The first branch and the second branch each include: a first part and a second part, wherein the first part of the first branch and the first part of the second branch are opposite to each other, and the second part of the first branch and the second part of the second branch are opposite to each other; The first electrode pair is disposed on both sides of the first part of the first branch, and the second electrode pair is disposed on both sides of the second part of the second branch.

8. The electro-optic modulator according to claim 6, characterized in that, The first electrode pair and the first electrode pair are respectively connected to the signal output terminal of the radio frequency driver, and the second electrode pair and the second electrode pair are connected to a terminating resistor. The first electrode pair includes a first electrode and a second electrode, and the second electrode pair includes a third electrode and a fourth electrode. The first electrode and the second electrode are located on both sides of the first branch and the second branch, and the third electrode and the fourth electrode are located between the first branch and the second branch. The first electrode and the third electrode are connected to the positive terminal of the signal output terminal of the RF driver, and the second electrode and the fourth electrode are connected to the negative terminal of the signal output terminal of the RF driver.

9. The electro-optic modulator according to claim 5, characterized in that, The electric field applied by the first electrode pair to the first branch is in the opposite direction to the electric field applied by the second electrode pair to the second branch, and the polarization directions of the first branch and the second branch are the same.

10. The electro-optic modulator according to claim 9, characterized in that, The modulation electrode further includes: a third electrode pair, wherein a first end of the first electrode pair is connected to the signal output terminal of the radio frequency driver, a second end of the first electrode pair is connected to the first end of the second electrode pair, a first end of the third electrode pair is connected to the second end of the second electrode pair, and a terminating resistor is connected to the second end of the third electrode pair; The first branch and the second branch each include: a first part, a second part, and a third part that are S-shaped and parallel to each other, with the second part located between the first part and the third part; the first electrode pair is disposed on both sides of the first part of the first branch, the second electrode pair is disposed on both sides of the second part of the second branch, and the third electrode pair is disposed on both sides of the third part of the first branch; The electric field applied by the third electrode pair to the first branch is in the opposite direction to the electric field applied by the second electrode pair to the second branch.

11. The electro-optic modulator according to claim 9, characterized in that, The first ends of the first electrode pair and the second electrode pair are respectively connected to the signal output terminal of the radio frequency driver, and the second ends of the first electrode pair and the second electrode pair are each connected to a terminating resistor; The first electrode pair includes a first electrode and a second electrode, and the second electrode pair includes a third electrode and a fourth electrode. The first electrode and the second electrode are located on both sides of the first branch and the second branch, and the third electrode and the fourth electrode are located between the first branch and the second branch. The first electrode and the fourth electrode are connected to the positive terminal of the signal output terminal of the RF driver, and the second electrode and the third electrode are connected to the negative terminal of the signal output terminal of the RF driver.

12. The electro-optic modulator according to any one of claims 1-11, characterized in that, The modulation electrode is made of copper, zinc, or a transparent conductive oxide.

13. An optical chip, characterized in that, include: The substrate, and the electro-optic modulator as claimed in any one of claims 1-12, wherein the electro-optic modulator is disposed on the surface of the substrate.

14. The optical chip according to claim 13, characterized in that, It also includes an input waveguide and an output waveguide, wherein the input waveguide is connected to the input end of the optical waveguide layer, and the output waveguide is connected to the output end of the optical waveguide layer.

15. The optical chip according to claim 14, characterized in that, Also includes: A photodetector is connected to the output waveguide via a connecting waveguide, and the photodetector is used to detect modulated optical signals.

16. An integrated chip, characterized in that, include: An electrical chip, and an optical chip as described in any one of claims 13-15, wherein the electrical chip is disposed on the surface of the optical chip and is soldered to the optical chip via solder balls.

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