High-integration low-power-consumption phase shifter and stable phase modulation method
By employing comb-shaped electrodes and a design without parallel resistors in a carrier dispersive phase shifter, combined with a ridge-type optical waveguide and doped regions, low-power, high-stability phase modulation is achieved, suitable for DC operating conditions, and improving device integration and space utilization.
Patent Information
- Application Number
- CN202411659082.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2026-05-19
AI Technical Summary
Existing carrier-dispersive phase shifters have high power consumption and poor stability in high-speed modulation applications, while thermally tuned phase shifters have poor phase stability and high power consumption in low-speed applications.
Design a carrier dispersive phase shifter that employs a comb-shaped electrode structure without parallel matching resistors. Combined with a ridge-type optical waveguide and a doped region, phase modulation is achieved through negative voltage bias driving, thus avoiding increased power consumption.
It achieves low power consumption and high stability phase modulation, is suitable for DC operating conditions, and improves device integration and space utilization.
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Figure CN122068283A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of integrated optics, and more specifically to a highly integrated and low-power phase shifter, and a phase-stabilized modulation method implemented using the phase shifter. Background Technology
[0002] Phase shifters play a crucial role in optical communication. Currently, optical communication is developing towards integration and low power consumption, making power optimization of phase shifters a hot research topic. In photonic integrated chips, the following two types of phase shifters (or electro-optic modulators) are mainly involved:
[0003] One type is the thermally tunable phase shifter, used in applications such as DC bias, where the driving voltage supplied to the phase shifter remains constant or changes at a low frequency, requiring the phase shifter to maintain phase stability for a long period. For example, patent document CN218037581U discloses a thermally tunable phase shifter based on the thermo-optical effect of materials for use in optical computing network chips. In this thermo-optical phase shifter, a heating resistor is placed above the optical waveguide; the phase shift is achieved by changing the refractive index of the waveguide below through the heating resistor's heating.
[0004] The advantage of this type of low-speed phase shifter is its relatively low power consumption, with a half-wave power consumption of approximately tens of milliwatts. However, because it uses a thermally tuned method to generate the phase shift, the stability of phase maintenance is relatively poor. Furthermore, power consumption is inevitably generated during the phase shift process caused by resistor heating; the larger the required phase shift, the higher the power consumption.
[0005] Another type is the carrier-dispersive modulator, used in high-speed modulation applications. In this phase shifter, with the excitation of an external reverse modulation signal, carriers in the waveguide region are extracted from the waveguide region, causing a change in the effective refractive index of the waveguide, thereby altering the phase of the optical signal. For example... Figure 1 As shown, a 50Ω or 100Ω terminating resistor is usually set at one end of the modulation electrode of the carrier dispersive modulator to match the impedance of the signal source, thereby improving the bandwidth of the modulator.
[0006] The advantages of carrier dispersive modulators are high bandwidth (typically reaching tens of GHz) and better stability compared to thermally tuned phase shifters, but they have the significant disadvantage of high power consumption. Summary of the Invention
[0007] To address the aforementioned problems in existing technologies, this invention proposes a highly integrated and low-power phase shifter, and a phase-stabilized modulation method based on this phase shifter. It breaks away from the conventional thinking that carrier-dispersive phase shifters require parallel matching resistors, eliminating the need for such resistors and allowing the phase shifter to exhibit high impedance and extremely low current. This results in minimal power consumption during operation, maintaining a constant temperature and achieving high stability, particularly suitable for DC applications. Furthermore, the invention employs a comb-like design on the modulation electrodes, effectively improving space utilization. Compared to existing linear designs, it requires a smaller overall phase shifter area for the same equivalent phase shift length, significantly increasing device integration.
[0008] Specifically, the first aspect of the present invention relates to a low-power phase-stabilized modulation method, which includes a modulation step of introducing an optical signal into the optical waveguide of a phase shifter and applying a bias voltage to the phase shifter to modulate the phase of the optical signal.
[0009] The phase shifter is a carrier-dispersive type and also includes a substrate, a first electrode, and a second electrode. The optical waveguide, the first electrode, and the second electrode are formed on the substrate.
[0010] Wherein, the first electrode and the second electrode are comb-shaped, and the comb teeth of the first electrode and the second electrode are arranged to cross each other;
[0011] Furthermore, no terminating resistor is provided between the first electrode and the second electrode.
[0012] Furthermore, the optical waveguide is a ridge waveguide, and there is a bending region in the optical waveguide portion distributed between the comb teeth of the first electrode and the second electrode, the bending region having a preset bending radius.
[0013] Furthermore, the phase shifter also includes a first slab region and a second slab region located on both sides of the ridge waveguide, wherein the first slab region is a P-type doped region and is close to the first electrode side, and the second slab region is an N-type doped region and is close to the second electrode side.
[0014] The ridge-type optical waveguide includes a first optical waveguide portion and a second optical waveguide portion. The first optical waveguide portion is lightly p-type doped and located near the first electrode side, while the second optical waveguide portion is lightly n-type doped and located near the second electrode side.
[0015] Furthermore, the first electrode is connected to the first slab region via an ohmic contact, and the second electrode is connected to the second slab region via an ohmic contact.
[0016] Furthermore, in the modulation step, the bias voltage is formed by applying a zero level to the second electrode while simultaneously applying a negative level to the first electrode; and / or, the bias voltage is a DC voltage.
[0017] A second aspect of the present invention relates to a highly integrated, low-power phase shifter, comprising a substrate, and an optical waveguide, a first electrode, and a second electrode formed on the substrate;
[0018] The first electrode and the second electrode are comb-shaped, and the comb teeth of the first electrode and the second electrode are arranged to cross each other.
[0019] No terminating resistor is provided between the first electrode and the second electrode.
[0020] Furthermore, the optical waveguide is a ridge waveguide, and there is a bending region in the optical waveguide portion distributed between the comb teeth of the first electrode and the second electrode, the bending region having a preset bending radius.
[0021] Furthermore, a first slab region doped with P-type is formed on the side of the ridge waveguide near the first electrode, and a second slab region doped with N-type is formed on the side of the ridge waveguide near the second electrode.
[0022] Furthermore, the ridge-type optical waveguide includes a first optical waveguide portion and a second optical waveguide portion. The first optical waveguide portion is lightly p-type doped and located near the first electrode side, while the second optical waveguide portion is lightly n-type doped and located near the second electrode side.
[0023] Furthermore, the first electrode is connected to the first slab region via an ohmic contact, and the second electrode is connected to the second slab region via an ohmic contact.
[0024] Furthermore, the first electrode is an S electrode, and the second electrode is a GND electrode. Attached Figure Description
[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 A carrier-dispersive phase shifter in the prior art is schematically illustrated;
[0028] Figure 2 The schematic diagram illustrates the structural principle of the highly integrated, low-power phase shifter of the present invention.
[0029] Figure 3 A cross-sectional view of the highly integrated, low-power phase shifter of the present invention is shown schematically. Detailed Implementation
[0030] In the following description, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example in order to fully convey the spirit of the invention to those skilled in the art. Therefore, the invention is not limited to the embodiments disclosed herein.
[0031] Figure 2-3 The schematic diagram and cross-sectional view of the highly integrated low-power phase shifter of the present invention are shown respectively. It is a carrier dispersion type.
[0032] like Figure 2 As shown, the phase shifter of the present invention includes a substrate, on which a ridge waveguide is formed, and a first electrode and a second electrode are located on both sides of the ridge waveguide. The substrate is preferably a silicon-based substrate.
[0033] See Figure 3 A first slab region and a second slab region are formed on both sides of the ridge-type optical waveguide.
[0034] The first slab region is located on the side closest to the first electrode, and P-type doping is performed in this slab region.
[0035] The second slab region is located on the side closer to the second electrode, and N-type doping is performed in this slab region.
[0036] The ridge-type optical waveguide has a first optical waveguide section and a second optical waveguide section, wherein the first optical waveguide section is relatively closer to the first electrode, and the second optical waveguide section is relatively closer to the second electrode.
[0037] In this invention, the first optical waveguide portion and the second optical waveguide portion are lightly doped with P and N, respectively, to serve as static pre-loaded carriers within the waveguide.
[0038] Based on this, ohmic contacts can be used to form connections between the first electrode and the first slab region, and between the second electrode and the second slab region. For example, when the phase shifter uses a silicon substrate, the first electrode can be connected to silicon in the first slab region, which is a P-type doped region, via an ohmic contact, and the second electrode can be connected to silicon in the second slab region, which is an N-type doped region, via an ohmic contact.
[0039] In this invention, the first electrode and the second electrode can be set as the S electrode and the GND electrode, respectively, to receive the negative level signal and the zero level signal in the external driving signal.
[0040] To ensure the phase shifter operates with high stability and low power consumption, unlike existing carrier-dispersive phase shifters, this invention eliminates the need for a parallel resistor in the carrier-dispersive phase shifter structure. That is, in the carrier-dispersive phase shifter of this invention, no terminating resistor is provided between the first electrode and the second electrode.
[0041] In addition, such as Figure 2 As shown, unlike the conventional straight strip design, the first electrode and the second electrode of the present invention are both designed as comb-like structures with at least one comb tooth, and the comb teeth of the first electrode and the second electrode are arranged to cross each other to form a complementary structure.
[0042] Since the optical waveguide is formed between the first and second electrodes, a bending region will correspondingly exist in the portion of the optical waveguide distributed between the comb teeth of the first and second electrodes. In this invention, to reduce losses in the optical waveguide, an appropriate bending radius can be preset in the bending region so that the extension direction of the optical waveguide changes in a smooth transition manner.
[0043] To better understand the present invention, a method for achieving phase-stable modulation using the phase shifter of the present invention is described below.
[0044] When an optical signal is input into the phase shifter from the optical waveguide, an external drive applies a zero-level signal to the second electrode and a negative-level signal to the first electrode, thereby realizing the bias voltage in the carrier dispersive phase shifter and providing a negative bias drive signal from the first electrode to the second electrode.
[0045] At this point, the statically preset charge carriers in the ridge waveguide will drift under the influence of the negative bias driving signal, resulting in a decrease in the charge carrier concentration inside the waveguide. Since the charge carrier concentration inside the waveguide determines its effective refractive index, the effective refractive index can be changed by controlling the magnitude of the negative bias driving signal.
[0046] Therefore, when an optical signal passes through the optical waveguide in a phase shifter, a phase shift occurs due to the interaction with charge carriers. By applying different bias voltages to the phase shifter and changing the effective refractive index of the optical waveguide, different phase shifts can ultimately be generated in the optical signal, thereby achieving phase modulation of the optical signal.
[0047] During the aforementioned phase modulation process, the pre-set charge carriers within the optical waveguide are extracted. Simultaneously, since the phase shifter of this invention does not contain a parallel resistor, it exhibits extremely high impedance (>10).6 With its extremely low impedance (Ω) and negligible current, the phase shifter generates minimal power consumption during operation. Even when reducing the modulator length leads to an increase in drive voltage, the additional power consumption remains negligible due to its extremely high impedance. Therefore, compared to existing thermally tuned phase shifters for low-speed phase modulation, the phase shifter (chip) of this invention maintains a constant temperature during operation, eliminating heat exchange with the environment and achieving higher stability, making it particularly suitable for operation under DC conditions. Furthermore, the use of a comb-shaped electrode design on the modulation electrode effectively improves the space utilization of the phase shifter chip. In particular, compared to existing linear designs, the overall area of the phase shifter of this invention is lower for the same equivalent phase shift length, significantly improving device integration.
[0048] Although the present invention has been described above with reference to the accompanying drawings and specific embodiments, those skilled in the art will readily recognize that the above embodiments are merely exemplary and used to illustrate the principles of the present invention. They do not limit the scope of the present invention. Those skilled in the art can make various combinations, modifications and equivalent substitutions to the above embodiments without departing from the spirit and scope of the present invention.
Claims
1. A low-power phase-stabilized modulation method, comprising a modulation step of introducing an optical signal into the optical waveguide of a phase shifter and applying a bias voltage to the phase shifter to modulate the phase of the optical signal; The phase shifter is a carrier-dispersive type and also includes a substrate, a first electrode, and a second electrode. The optical waveguide, the first electrode, and the second electrode are formed on the substrate. in, The first electrode and the second electrode are comb-shaped, and the comb teeth of the first electrode and the second electrode are arranged to cross each other. Furthermore, no terminating resistor is provided between the first electrode and the second electrode.
2. The phase-stabilized modulation method as described in claim 1, wherein, The optical waveguide is a ridge waveguide, and there is a bending region in the portion of the optical waveguide distributed between the comb teeth of the first electrode and the second electrode, the bending region having a preset bending radius.
3. The phase-stabilized modulation method as described in claim 2, wherein, The phase shifter also includes a first slab region and a second slab region located on both sides of the ridge waveguide. The first slab region is a P-type doped region and is close to the first electrode side, and the second slab region is an N-type doped region and is close to the second electrode side. The ridge-type optical waveguide includes a first optical waveguide portion and a second optical waveguide portion. The first optical waveguide portion is lightly p-type doped and located near the first electrode side, while the second optical waveguide portion is lightly n-type doped and located near the second electrode side.
4. The phase-stabilized modulation method as described in claim 3, wherein, The first electrode is connected to the first slab region via an ohmic contact, and the second electrode is connected to the second slab region via an ohmic contact.
5. The phase-stabilized modulation method as described in claim 4, wherein, In the modulation step, the bias voltage is formed by applying a zero level to the second electrode and a negative level to the first electrode simultaneously. And / or, the bias voltage is a DC voltage.
6. A highly integrated, low-power phase shifter, comprising a substrate, and an optical waveguide, a first electrode, and a second electrode formed on the substrate; The first electrode and the second electrode are comb-shaped, and the comb teeth of the first electrode and the second electrode are arranged to cross each other. No terminating resistor is provided between the first electrode and the second electrode.
7. The phase shifter as claimed in claim 6, wherein, The optical waveguide is a ridge waveguide, and there is a bending region in the portion of the optical waveguide distributed between the comb teeth of the first electrode and the second electrode, the bending region having a preset bending radius.
8. The phase shifter as claimed in claim 7, wherein, The ridge waveguide has a first slab region doped with P-type formed on the side near the first electrode, and a second slab region doped with N-type formed on the side near the second electrode. The ridge-type optical waveguide includes a first optical waveguide portion and a second optical waveguide portion. The first optical waveguide portion is lightly p-type doped and located near the first electrode side, while the second optical waveguide portion is lightly n-type doped and located near the second electrode side.
9. The phase shifter as claimed in claim 8, wherein, The first electrode is connected to the first slab region via an ohmic contact, and the second electrode is connected to the second slab region via an ohmic contact.
10. The phase shifter as claimed in any one of claims 6-9, wherein, The first electrode is an S electrode, and the second electrode is a GND electrode.