Broadband light modulation chip with reconfigurable frequency response

Abstract

The invention provides a broadband optical modulation chip with reconfigurable frequency response, which can be applied to the technical field of optoelectronic integration and optical communication. The chip comprises a traveling wave electrode used for transmitting an electric signal, and an optical waveguide used for transmitting an optical signal and located in a gap of the traveling wave electrode, the multi-mode interferometer is connected to the two ends of the optical waveguide and used for carrying out beam combination and beam splitting operation on the optical signals; the grating is used for coupling light into or out of the modulator and is connected with the multimode interferometer; the terminal resistor is connected to the tail end of the traveling wave electrode, and the two ends of the terminal resistor are connected with the signal electrode and the ground electrode of the traveling wave electrode respectively; the heater is located right above the terminal resistor, the two sides of the heater are connected with the conductive metal respectively and led out to a bonding pad on the surface layer of the chip, and the bonding pad is used for applying regulation and control voltage to the heater.

Description

Technical Field

[0001] This invention relates to the fields of optoelectronic integration and optical communication technology, and more specifically to a frequency-response reconfigurable broadband optical modulation chip. Background Technology

[0002] With the continued rapid development of IoT, big data, and AI technologies, the demand for data traffic across industries is escalating at an unprecedented rate. Against this backdrop, traditional electrical interconnect technologies, while dominating the communications field in the past due to their high maturity, low cost, and widespread availability, now face serious challenges. In high-frequency signal transmission scenarios, the skin effect and parasitic effects severely limit further improvements in the speed and bandwidth of electrical interconnect devices, making it difficult to meet the ever-increasing data transmission demands.

[0003] Given the limitations of traditional electrical interconnection technology, optoelectronic integration technology, with its significant advantages such as high speed, low power consumption, resistance to electromagnetic interference, and large bandwidth, is gradually emerging as a strong candidate to replace traditional electrical interconnection technology, and its application prospects in the field of communication are becoming increasingly broad.

[0004] In optical interconnect systems, electro-optic modulators are key components ensuring high-speed, high-efficiency signal transmission. Their core function is to accurately convert electrical signals into optical signals, and they effectively meet the requirements of high-speed, low-drive-voltage applications. However, current optoelectronic integrated systems still face some unresolved issues in practical applications. Due to the low modulation efficiency of common materials, the length of electro-optic modulators is typically on the order of a few millimeters. According to transmission line theory, when the electrode size is close to or even exceeds the wavelength of the applied electrical signal, the lumped model no longer applies. Therefore, most modulators currently used in optoelectronic integration employ traveling-wave electrode designs to adapt to these unique transmission conditions.

[0005] Furthermore, the degree of impedance matching optimization directly determines the overall performance of a communication system, whether for individual optoelectronic integrated modulator devices or the entire transmitter system link. Impedance mismatch in the driver source or load can trigger a series of serious problems, such as signal reflection, reduced power transmission efficiency, and signal distortion. These problems not only reduce the transmitter's bandwidth but also significantly degrade the performance of the entire communication system. Therefore, how to achieve flexible impedance adjustment to effectively reduce signal reflection and thus improve the overall system performance has become a crucial issue that cannot be ignored and urgently needs to be addressed in the current development of optoelectronic integration technology. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the challenge of precise impedance matching in existing optoelectronic technologies, this invention provides a broadband optical modulation chip with reconfigurable frequency response. By using a thermistor material, a thermistor heater is integrated on top of the terminating resistor. The resistive characteristics of a metal with a specific temperature coefficient are utilized to achieve flexible adjustment of the terminating impedance. By changing the voltage, the resistance value can be dynamically calibrated within a reasonable matching range, ensuring that the modulator electrodes always achieve low reflection impedance matching with the driving circuit, thereby optimizing signal integrity and suppressing energy return interference.

[0008] (II) Technical Solution

[0009] To address the aforementioned technical problems, embodiments of the present invention propose a frequency-response reconfigurable broadband optical modulation chip.

[0010] According to a first aspect of the present invention, a frequency-response reconfigurable broadband optical modulation chip is provided, comprising: a traveling-wave electrode for transmitting an electrical signal, including a signal electrode and a ground electrode, located above a waveguide layer; an optical waveguide located in the gap between the traveling-wave electrode, the optical waveguide being used to transmit an optical signal; a multimode interferometer connected to both ends of the optical waveguide for performing beam combining and beam splitting operations on the optical signal; a grating connected to the multimode interferometer, the grating being used to couple light into or out of the modulator; a terminating resistor connected to the end of the traveling-wave electrode, the two ends of the terminating resistor being connected to the signal electrode and the ground electrode of the traveling-wave electrode, respectively; by adjusting the resistance value of the terminating resistor, the impedance of the traveling-wave electrode can be adjusted, thereby realizing the modulation of the intensity of the modulated electrical signal carried by the traveling-wave electrode; and a heater located directly above the terminating resistor, both sides of the heater being connected to conductive metal and led out to pads on the surface of the chip, the pads being used to apply a control voltage to the heater.

[0011] In some exemplary embodiments, the terminating resistor is made of a thermistor material, and the resistance of the terminating resistor can change with temperature; the thermistor material includes at least one of a negative temperature coefficient thermistor, a positive temperature coefficient thermistor, a metal thermistor, or a thermistor alloy.

[0012] In some exemplary embodiments, the traveling wave electrode, the metal connecting the terminating resistor, and the metal connecting the heater are made of a conductive metal material; the conductive metal material includes at least one of copper or aluminum.

[0013] In some exemplary embodiments, the heater is made of an electrically heating material that generates heat when an electric current passes through it; the electrically heating material includes at least one of titanium nitride, tungsten, or platinum.

[0014] In some exemplary embodiments, the heater is connected to independent pads on the chip surface via metal wires to form a voltage application path. By applying different voltages to the pads, the heater generates corresponding heat, thereby changing the resistance value of the terminal resistor and realizing the reconfigurable frequency response characteristics of the chip.

[0015] In some exemplary embodiments, the traveling wave electrode is a coplanar waveguide type, the traveling wave electrode is connected to the ground electrode at the end, and the terminating resistor is connected between the signal electrode and the ground electrode; or when the traveling wave electrode is a coplanar slot type, the terminating resistor is directly connected between the signal electrode and the ground electrode.

[0016] In some exemplary embodiments, the optical waveguide path is kept at a distance from the terminating resistor and heater, and the wiring avoids heat source areas.

[0017] In some exemplary embodiments, by optimizing the geometric parameters of the traveling wave electrode, it is possible to adapt to different system impedance requirements; wherein the geometric parameters include at least one of electrode width, electrode spacing, or electrode shape.

[0018] In some exemplary embodiments, the modulator is a Mach-Zehnder type electro-optic modulator; the Mach-Zehnder type electro-optic modulator includes at least one of a silicon-based optical modulator, a heterogeneously integrated lithium niobate modulator, a barium titanate modulator, or a lead zirconate titanate modulator.

[0019] In some exemplary embodiments, a thermal insulation layer is disposed between the terminating resistor and the optical waveguide, the thermal insulation layer being made of at least one of silicon dioxide or silicon nitride.

[0020] (III) Beneficial Effects

[0021] As can be seen from the above technical solution, the frequency-response reconfigurable broadband optical modulation chip provided by the embodiments of the present invention has at least the following beneficial effects:

[0022] (1) By using a thermistor material, a thermistor material heater is integrated on the top layer of the terminal resistor. The resistance characteristics of the metal with a specific temperature coefficient are used to achieve flexible adjustment of the terminal impedance. By changing the voltage, the resistance value can be dynamically calibrated within a reasonable matching range, ensuring that the modulator electrode always achieves low reflection impedance matching with the drive circuit, thereby optimizing signal integrity and suppressing energy echo interference.

[0023] (2) The adjustable terminal resistor electro-optic modulator can flexibly adjust the modulator terminal impedance in actual testing or application of the modulator. When it is necessary to minimize microwave reflection, the terminal resistor can be precisely calibrated to the system characteristic impedance value to achieve low-loss signal transmission across the entire frequency band. Appropriately reducing the resistance value can deliberately introduce the peak gain effect and improve the compensation gain of high-frequency components, thereby selectively expanding the equivalent bandwidth while maintaining signal integrity.

[0024] (3) By using the dynamic adjustable mechanism of the terminating resistor, the system-level coordinated optimization of the impedance of the driving circuit, modulator, and terminating resistor is achieved, which fundamentally solves the limitations of traditional static impedance matching, enabling the entire signal transmission link to adapt to changes in working state and environment, thereby comprehensively improving the overall performance of the communication system. This achieves maximum power transmission, optimized bandwidth and signal quality, reduced noise and interference, and improved overall performance of the link system. Attached Figure Description

[0025] The above-described features, other objects, and advantages of the present invention will become clearer from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0026] Figure 1 The schematic diagram illustrates the structure of a broadband optical modulation chip with reconfigurable frequency response of coplanar slot traveling wave electrodes according to an embodiment of the present invention.

[0027] Figure 2 The schematic diagram illustrates the terminal resistor and heater cross-sectional structure of a broadband optical modulation chip with reconfigurable frequency response of coplanar slot traveling wave electrodes according to an embodiment of the present invention.

[0028] Figure 3 The schematic diagram illustrates the structure of a broadband optical modulation chip with reconfigurable frequency response of a coplanar waveguide-type traveling-wave electrode according to an embodiment of the present invention.

[0029] Figure label:

[0030] 1-Traveling wave electrode; 2-Optical waveguide; 3-Multimode interferometer; 4-Grate; 5-Terminal resistor; 6-Heater. Detailed Implementation

[0031] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0033] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0034] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0035] Figure 1 The schematic diagram illustrates the structure of a broadband optical modulation chip with reconfigurable frequency response of coplanar slot traveling wave electrodes according to an embodiment of the present invention. Figure 2 The diagram illustrates the terminating resistor and heater cross-sectional structure of a broadband optical modulation chip with reconfigurable frequency response of coplanar slot traveling wave electrodes according to an embodiment of the present invention.

[0036] like Figure 1 and Figure 2 As shown, a frequency-response reconfigurable broadband optical modulation chip according to an embodiment of the present invention includes: a traveling-wave electrode for transmitting electrical signals, including a signal electrode and a ground electrode, located above a waveguide layer; an optical waveguide located in the gap between the traveling-wave electrodes, used for transmitting optical signals; a multimode interferometer connected to both ends of the optical waveguide, used for beam combining and splitting optical signals; a grating connected to the multimode interferometer, used for coupling light into or out of the modulator; a terminating resistor connected to the end of the traveling-wave electrode, the two ends of the terminating resistor being connected to the signal electrode and the ground electrode of the traveling-wave electrode, respectively; by adjusting the resistance value of the terminating resistor, the impedance of the traveling-wave electrode can be adjusted, thereby realizing the control of the modulation electrical signal intensity carried by the traveling-wave electrode; a heater located directly above the terminating resistor, with conductive metal connected to both sides of the heater and led out to pads on the chip surface, the pads being used to apply a control voltage to the heater. The heater is connected to independent pads on the chip surface via metal wires at both ends, forming a voltage application path. By applying different voltages to the pads, the heater generates corresponding heat, thereby changing the resistance value of the terminal resistor and realizing the reconfigurable frequency response of the chip.

[0037] In embodiments of the present invention, the traveling wave electrode is a coplanar groove with a width of 100-150 μm, a spacing of 5-30 μm, and a length of 2000-3000 mm. By optimizing the geometric parameters of the traveling wave electrode, it can adapt to different system impedance requirements, and adjust relevant parameters to achieve a specific characteristic impedance. The geometric parameters include at least one of electrode width, electrode spacing, or electrode shape. For example, the characteristic impedance can be increased by appropriately increasing the spacing of the traveling wave electrodes; the characteristic impedance can be reduced by increasing the electrode width. If better velocity matching between the traveling wave electrode and the optical waveguide is required, techniques such as T-shaped tracks can be used to increase the design freedom of the traveling wave electrode, allowing for a wider range of microwave refractive index variation.

[0038] In embodiments of the present invention, the optical waveguide should be a ridge waveguide, and its structural parameters need to be comprehensively optimized at the system level, including modulation efficiency, optical field constraint, loss, and process tolerance. The typical width can be 350~500nm, and specific transmission wavelengths can be achieved by adjusting the waveguide width. For example, for the C-band of a silicon photonic modulator, the waveguide width is typically set to 500nm. The waveguide length can be 2000~3000mm to achieve better modulation results.

[0039] In embodiments of the present invention, for coplanar slot traveling-wave electrodes, the optical waveguide should be kept as far away as possible from the heater and terminating resistor. During wiring, heat sources should be avoided as much as possible to prevent them from affecting the modulator. A multimode interferometer can be used for beam combining before the terminating resistor, and then the waveguide can be used to guide the light out from under the traveling-wave electrode, avoiding the terminating resistor. Additionally, thermal insulation material can be used near the terminating resistor to isolate the resistor from the waveguide region, improving the wavelength stability of the modulator over a wide temperature range.

[0040] In embodiments of the present invention, the modulator is a Mach-Zehnder type electro-optic modulator, realizing the modulation process from electrical signal to optical signal. For coplanar slot traveling-wave electrodes, they are mainly used in silicon modulators based on plasmon dispersion effects achieved through silicon waveguide doping. Two waveguides are placed between the traveling-wave electrodes, and during doping, two pn junctions are connected back-to-back to form a series push-pull modulator. For coplanar waveguide traveling-wave electrodes, they are primarily used in lithium niobate modulators, barium titanate modulators, lead zirconate titanate modulators, etc., based on electro-optic effects achieved through heterogeneous integration in silicon-based material systems. Two waveguides are placed between two gaps, and each waveguide generates opposite phase changes when a signal is applied. For example, for coplanar slot traveling-wave electrodes, a silicon-optical single-ended push-pull modulator with coplanar slot electrodes can be used.

[0041] In some exemplary embodiments, the terminating resistor is made of a thermistor material whose resistance can change with temperature. The thermistor material includes at least one of a negative temperature coefficient thermistor, a positive temperature coefficient thermistor, a metal thermistor, or a thermistor alloy.

[0042] In some exemplary embodiments, the traveling wave electrode, the metal connecting the terminating resistor, and the metal connecting the heater are made of a conductive metal material; the conductive metal material includes at least one of copper or aluminum.

[0043] In some exemplary embodiments, the heater is made of an electrically conductive heating material, which generates heat when an electric current passes through it; the electrically conductive heating material includes at least one of titanium nitride, tungsten, or platinum.

[0044] For example, the resistance of the terminating resistor changes significantly after heating. These materials include, but are not limited to, negative temperature coefficient thermistors, positive temperature coefficient thermistors, metal thermistors, and thermistor alloys. A heater is placed above the terminating resistor; the heater material includes, but is not limited to, titanium nitride, tungsten, and platinum. This material exhibits significant heat generation when current flows through it. By applying different voltages to the heater pads, the heater temperature is changed, thereby altering the terminating resistance.

[0045] In embodiments of the present invention, the value of the terminating resistor is set near the target resistance value. For a single-ended modulator, the terminating resistor value is set at approximately 50Ω, and for a differential modulator, the terminating resistor value is set at approximately 100Ω. The specific target value should be based on a comprehensive evaluation of the output impedance of the driver source, transmission line characteristics, and load requirements to ensure the formation of a low-reflection path. For specific systems, the value needs to be set according to relevant requirements, taking into account factors such as channel bandwidth and noise margin.

[0046] Figure 3 The schematic diagram illustrates the structure of a broadband optical modulation chip with reconfigurable frequency response of a coplanar waveguide-type traveling-wave electrode according to an embodiment of the present invention.

[0047] like Figure 3 As shown, a broadband optical modulation chip with reconfigurable frequency response of a coplanar waveguide-type traveling-wave electrode according to an embodiment of the present invention and Figure 1 Compared to the traveling wave electrode, which is a coplanar waveguide type, the traveling wave electrode is connected to the ground electrode at the end, and the terminating resistor is connected between the signal electrode and the ground electrode.

[0048] The frequency-response reconfigurable broadband optical modulation chip according to embodiments of the present invention achieves dynamic optimization of modulator performance by combining a thermal tuning mechanism with impedance matching technology. Its core principle lies in integrating a thin-film resistor with a specific temperature coefficient at the traveling wave electrode termination of the modulator and applying an adjustable voltage via a micro-heater. When the heater voltage changes, the temperature gradient causes a change in the resistance value, thereby adjusting the termination impedance state in real time. This design overcomes the limitation of traditional fixed resistors being unable to adapt to process fluctuations or high-frequency parasitic parameters. In practical applications and testing, by continuously changing the heater voltage and simultaneously acquiring two sets of key performance indicators—the bandwidth and eye diagram of the electro-optic modulator—the optimal matching resistor can be determined. When it is necessary to minimize microwave reflection, the termination resistor is precisely calibrated to the system characteristic impedance value, achieving low-loss signal transmission across the entire frequency band. Alternatively, the termination resistance can be appropriately reduced to introduce a gain peak effect, thereby increasing the compensation gain of high-frequency components and selectively expanding the bandwidth while maintaining signal integrity.

[0049] Those skilled in the art will understand that the features described in the various embodiments of the present invention can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments of the present invention can be combined and / or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

Claims

1. A frequency-response reconfigurable broadband optical modulation chip, characterized in that, include: Traveling wave electrodes, used to transmit electrical signals, include signal electrodes and ground electrodes, and are located above the waveguide layer; An optical waveguide is located in the gap between the traveling wave electrodes, and the optical waveguide is used to transmit optical signals; A multimode interferometer, connected to both ends of the optical waveguide, is used to perform beam combining and beam splitting operations on the optical signal; A grating, connected to the multimode interferometer, is used to couple light into or out of the modulator; A terminating resistor is connected to the end of the traveling wave electrode, and the two ends of the terminating resistor are respectively connected to the signal electrode and the ground electrode of the traveling wave electrode. By adjusting the resistance value of the terminating resistor, the impedance of the traveling wave electrode can be adjusted, thereby realizing the control of the modulation signal strength carried by the traveling wave electrode. A heater is located directly above the terminating resistor. Conductive metal is connected to both sides of the heater and leads out to pads on the chip surface. The pads are used to apply a control voltage to the heater.

2. The frequency-response reconfigurable broadband optical modulation chip according to claim 1, characterized in that, The terminating resistor is made of a thermistor material, and its resistance value can change with temperature. The thermistor material includes at least one of the following: negative temperature coefficient thermistor, positive temperature coefficient thermistor, metal thermistor, or thermistor alloy.

3. The frequency-response reconfigurable broadband optical modulation chip according to claim 1, characterized in that, The traveling wave electrode, the metal connected to the terminating resistor, and the metal connected to the heater are made of a conductive metal material. The conductive metallic material includes at least one of copper or aluminum.

4. The frequency-response reconfigurable broadband optical modulation chip according to claim 1, characterized in that, The heater is made of an electrically conductive heating material, and the heater generates heat when an electric current passes through it. The heating element is composed of at least one of titanium nitride, tungsten, or platinum.

5. The frequency-response reconfigurable broadband optical modulation chip according to claim 1, characterized in that, The heater is connected to independent pads on the chip surface via metal wires at both ends, forming a voltage application path. By applying different voltages to the pads, the heater generates corresponding heat, thereby changing the resistance value of the terminal resistor and realizing the reconfigurable frequency response of the chip.

6. The frequency-response reconfigurable broadband optical modulation chip according to claim 1, characterized in that, The traveling wave electrode is a coplanar waveguide type, and the traveling wave electrode is connected to the ground electrode at its end. The terminating resistor is connected between the signal electrode and the ground electrode; or When the traveling wave electrode is a coplanar slot type, the terminating resistor is directly connected between the signal electrode and the ground electrode.

7. The frequency-response reconfigurable broadband optical modulation chip according to claim 1, characterized in that, The optical waveguide path maintains an isolation distance from the terminating resistor and heater, and the wiring avoids the heat source area.

8. The frequency-response reconfigurable broadband optical modulation chip according to claim 1, characterized in that, By optimizing the geometric parameters of the traveling wave electrode, it is possible to adapt to different system impedance requirements. The geometric parameters include at least one of electrode width, electrode spacing, or electrode shape.

9. The frequency-response reconfigurable broadband optical modulation chip according to claim 1, characterized in that, The modulator is a Mach-Zehnder type electro-optic modulator; The Mach-Zehnder type electro-optic modulator includes at least one of a silicon-based optical modulator, a heterogeneously integrated lithium niobate modulator, a barium titanate modulator, or a lead zirconate titanate modulator.

10. The frequency-response reconfigurable broadband optical modulation chip according to claim 1, characterized in that, A thermal insulation material layer is disposed between the terminating resistor and the optical waveguide, and the material of the thermal insulation material layer includes at least one of silicon dioxide or silicon nitride.

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