Low-power-consumption MZ interferometer and low-speed phase shifter based on silicon-based SOI chip
By designing a carrier dispersion phase shifter on a silicon-based SOI chip and canceling the terminal matching resistance, high stability and low power consumption of low-speed phase modulation are achieved, and the stability and power consumption problems of existing low-speed phase shifters during temperature changes are solved.
Patent Information
- Application Number
- CN202422825179.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-08-26
- Estimated Expiration
- 2034-11-19
AI Technical Summary
Existing low-speed phase shifters have poor stability when the temperature changes in the external ambient temperature and have high power consumption, making it difficult to meet high stability requirements such as quantum state modulation.
A carrier dispersion phase shifter based on a silicon-based SOI chip is used to perform P-type and N-type doping on both sides of the ridge optical waveguide and cancel the terminal matching resistance between the electrodes to achieve a maximum impedance and extremely small current, ensuring the temperature stability of the phase shifter and low power consumption.
A phase shifter with high stability and low power consumption in low-speed phase modulation scenarios is realized, improving the temperature stability of the phase shifter and reducing power consumption.
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Figure CN223271832U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of integrated optics, in particular to a low-speed phase shifter based on a silicon-based SOI chip and a low-power MZ interferometer realized by using the same. Background Art
[0002] Optical phase modulation is involved in many fields, including optical communications, optical sensing, and quantum communications. By combining optical phase modulation with optical structures such as interferometers, it is possible to modulate dimensions such as intensity and polarization. Phase modulation generally involves high-speed phase modulation and low-speed phase modulation. High-speed phase modulation is typically used directly for encoding, while low-speed phase modulation is often used in scenarios such as adjusting the bias point of an interferometer.
[0003] With the development of photonic integration technology, on-chip low-speed phase modulators have become a key component. In the prior art, when low-speed phase modulation is required, those skilled in the art will usually use thermally tuned phase shifters as low-speed phase shifters. For example, in the design of optical computing network chips, thermally tuned phase shifters are formed by utilizing the thermo-optical effect of materials to be used as low-speed phase shifters. In this case, with the help of the high thermo-optical coefficient of silicon waveguides, a thermo-optical phase shifter is realized by adding a heating resistor above the waveguide. The heating resistor is energized to generate heat to change the temperature of the waveguide below, thereby changing the effective refractive index of the waveguide, thereby causing a phase shift in the optical signal in the waveguide.
[0004] The advantage of this low-speed phase shifter based on thermal effects is very low loss, with half-wave power consumption of approximately tens of milliwatts. However, because it uses thermal tuning to generate phase shift, changes in the ambient temperature will cause changes in the waveguide temperature, resulting in poor phase stability. Furthermore, the process of generating phase shift through resistive heating inevitably generates power consumption. The greater the required phase shift, the higher the power consumption. Currently, general low-speed phase shifter technology solutions are moving towards low power consumption, but due to the thermal effect, stability remains a challenge.
[0005] Currently, conventional low-speed phase shifters mostly use thermal effects. The working state of the phase shifter is affected by the external ambient temperature. Changes in ambient temperature will affect the current thermal balance of the phase shifter. As the chip temperature changes, the phase shift of the phase shifter also changes accordingly. The stability is poor and it is difficult to meet the requirements of scenarios with high stability requirements such as quantum state modulation. Utility Model Content
[0006] To address the aforementioned issues in the prior art, the present invention proposes a low-speed phase shifter based on a silicon-on-insulator (SOI) chip, as well as a low-power MZ interferometer implemented with this low-speed phase shifter. This invention breaks away from the inherent assumption that carrier-dispersion phase shifters are typically suitable for high-speed modulation scenarios and makes unique improvements to the existing carrier-dispersion phase shifter structure. In particular, the parallel resistor is no longer required in the carrier-dispersion phase shifter, enabling it to exhibit high impedance and extremely low current in low-speed modulation scenarios, achieving extremely low power consumption. At the same time, it can maintain a constant temperature during operation, thereby achieving higher stability.
[0007] The first aspect of the present invention relates to a low-speed phase shifter based on a silicon-based SOI chip, which includes a silicon-based substrate and a ridge optical waveguide, a first electrode, and a second electrode formed on the silicon-based substrate;
[0008] The low-speed phase shifter is of carrier dispersion type, and no terminal matching resistor is provided between the first electrode and the second electrode.
[0009] Furthermore, a first slab region and a second slab region are formed on both sides of the ridge type optical waveguide respectively;
[0010] The first slab region is doped with a P-type, and the second slab region is doped with an N-type.
[0011] Furthermore, the first electrode is an S electrode, and the second electrode is a GND electrode;
[0012] The first flat plate region is located on the side close to the first electrode;
[0013] The second flat plate region is located on the side close to the second electrode.
[0014] Furthermore, the ridge type optical waveguide includes a first optical waveguide portion and a second optical waveguide portion that are symmetrical;
[0015] The first optical waveguide portion is lightly P-type doped and is close to the first electrode;
[0016] The second optical waveguide portion is lightly N-type doped and is close to the second electrode.
[0017] Furthermore, the first electrode is connected to the silicon in the first plate region through an ohmic contact, and the second electrode is connected to the silicon in the second plate region through an ohmic contact.
[0018] Furthermore, the first electrode is connected to a negative level, and the second electrode is connected to a zero level.
[0019] A second aspect of the present invention relates to a low-power MZ interferometer, which includes a beam splitter, an optical waveguide, a beam combiner and a phase shifter, wherein the phase shifter is the above-mentioned low-speed phase shifter.
[0020] Furthermore, the MZ interferometer is based on a silicon-based SOI chip.
[0021] Furthermore, the input end of the beam splitter is connected to the input optical waveguide; the first output end of the beam splitter and the input end of the phase shifter, and the output end of the phase shifter and the first input end of the beam combiner are connected through optical waveguides; the second output end of the beam splitter and the second input end of the beam combiner are connected through optical waveguides.
[0022] Preferably, the silicon-based SOI chip is a 220nm chip. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings.
[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0025] Figure 1 The schematic diagram of the structure of the carrier dispersion phase shifter in the prior art is shown;
[0026] Figure 2 The schematic diagram shows the structural principle of the low-speed phase shifter based on silicon-based SOI chip of the present invention;
[0027] Figure 3 Schematically shows a cross-sectional view of a low-speed phase shifter based on a silicon-based SOI chip of the present invention;
[0028] Figure 4 An example of the low-power MZ interferometer of the present invention is schematically shown. DETAILED DESCRIPTION
[0029] Hereinafter, 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 to fully convey the spirit of the present invention to those skilled in the art to which the present invention belongs. Therefore, the present invention is not limited to the embodiments disclosed herein.
[0030] The carrier dispersion modulator is based on the carrier dispersion effect. It has a high bandwidth, but it also has problems such as high loss and large size. Therefore, it is usually used in high-speed modulation scenarios in the existing technology, but not in low-speed modulation scenarios. In order to achieve traveling wave modulation of high-speed electrical signals and optical signals, the terminals of the modulator need to be impedance matched, such as Figure 1 As shown, a matching resistor is provided between the S electrode and the GND electrode.
[0031] The main reason for the high losses in carrier dispersion modulators is their long length, primarily due to the need to reduce the drive voltage. While reducing the modulator length reduces losses, the high-speed drive voltage increases, significantly increasing the difficulty of achieving high-speed drive. Furthermore, as the drive voltage increases, the modulator's power consumption rises rapidly, generating excessive heat that can affect system stability. Therefore, while the stability of a carrier dispersion modulator will be improved compared to conventional low-speed phase shifters based on thermal effects, the losses and power consumption will be significantly increased.
[0032] In general, current on-chip phase modulators have difficulty balancing stability, loss, and power consumption. To address this issue, this utility model proposes a low-speed phase shifter based on a silicon-on-insulator (SOI) chip, which can simultaneously exhibit high stability and low power consumption during operation.
[0033] Figure 2-3 The schematic diagram and cross-sectional view of the low-speed phase shifter based on silicon-based SOI chip of the present invention are respectively shown.
[0034] like Figure 2 As shown, the low-speed phase shifter of the present invention is a phase shifter based on a silicon-based SOI chip, which includes a silicon-based substrate, and a ridge-type optical waveguide and a first electrode and a second electrode located on both sides of the ridge-type optical waveguide are formed on the silicon-based substrate.
[0035] See also Figure 3 A first slab region and a second slab region are formed on both sides of the ridge type optical waveguide.
[0036] The first plate region is located on the side close to the first electrode, and P-type doping is performed in the plate region.
[0037] The second plate region is located on the side close to the second electrode, and N-type doping is performed in the plate region.
[0038] The ridge type optical waveguide has a first optical waveguide portion and a second optical waveguide portion that are symmetrical, wherein the first optical waveguide portion is relatively closer to the first electrode, and the second optical waveguide portion is relatively closer to the second electrode.
[0039] In the present invention, the first optical waveguide portion and the second optical waveguide portion are lightly P-doped and N-doped respectively to serve as static preset carriers in the waveguide.
[0040] On this basis, the first electrode is connected to the silicon in the first plate region as a P-type doping region through an ohmic contact, and the second electrode is also connected to the silicon in the second plate region as an N-type doping region through an ohmic contact.
[0041] In the present invention, the first electrode and the second electrode may be respectively set as an S electrode and a GND electrode to respectively receive a negative level signal and a zero level signal in an external driving signal.
[0042] To ensure high stability and low power consumption for low-speed phase modulation applications, the present invention, unlike conventional carrier-dispersive phase shifters, eliminates the need for parallel resistors. Specifically, the present invention eliminates a terminal matching resistor between the first and second electrodes.
[0043] The process of the phase shifter of the present invention performing low-speed phase modulation on an optical signal is described below to better understand the working principle of the present invention.
[0044] When an optical signal is input into the phase shifter from the optical waveguide, an external driver applies a zero-level signal to the second electrode and a negative-level signal to the first electrode, thereby realizing a bias voltage in the carrier dispersion phase shifter and providing a negative bias drive signal from the first electrode to the second electrode.
[0045] At this point, the statically pre-set carriers in the ridge waveguide drift under the negative bias drive signal, reducing the carrier concentration inside the waveguide. Since the carrier concentration within the waveguide determines its effective refractive index, controlling the magnitude of the negative bias drive signal can alter the effective refractive index.
[0046] Therefore, when a light signal passes through the optical waveguide in the phase shifter, it will produce a phase shift due to the interaction with the carriers. By applying different bias voltages to the phase shifter, the effective refractive index of the optical waveguide is changed, and ultimately different phase shifts can be produced on the light signal, thereby achieving phase modulation of the light signal.
[0047] During the phase modulation process, the carriers preset in the optical waveguide are extracted from the optical waveguide. At the same time, since the phase shifter of the present invention does not have a parallel resistor, it will show a large impedance (>10 6Ω) and extremely low current, so the power consumption generated by the phase shifter during operation is extremely small and negligible. Even though reducing the modulator length results in an increase in the driving voltage, the additional power consumption remains negligible due to its extremely high impedance. Compared with existing thermally tuned phase shifters used for low-speed phase modulation, the low-speed phase shifter of the utility model can maintain a constant temperature during operation and eliminate heat exchange with the environment, thereby achieving higher stability.
[0048] Figure 4 An example of a low-power MZ interferometer of the present invention is shown, which includes a beam splitter, an optical waveguide and a beam combiner, and a phase shifter is provided on the optical arm between the beam splitter and the beam combiner.
[0049] In the present invention, the MZ interferometer is in the form of a silicon-based SOI chip, in which the ports of each component are connected through an optical waveguide, that is, the input end of the beam splitter is connected to the input optical waveguide, the first output end of the beam splitter and the input end of the phase shifter, as well as the output end of the phase shifter and the first input end of the combiner are connected through an optical waveguide, and the second output end of the beam splitter and the second input end of the combiner are connected through an optical waveguide.
[0050] In a preferred example, the MZ interferometer can be implemented based on a 220 nm SOI chip.
[0051] According to the present invention, the phase shifter in the MZ interferometer will adopt the above-mentioned low-speed phase shifter based on silicon-based SOI chip, thereby ensuring its high stability and low power consumption performance during operation.
[0052] Specifically, when the optical signal enters the MZ interferometer through the optical waveguide, it is first evenly divided into two beams (both with power I0) in the beam splitter, and output from the first and second output ports of the beam splitter to enter the upper optical arm and the lower optical arm respectively.
[0053] In the upper optical arm, the optical signal passes through the phase shifter and is phase-modulated before entering the combiner through the first input port of the combiner, while the optical signal in the lower optical arm enters the combiner through the second input port.
[0054] When an optical signal passes through a phase shifter, a driver connects the first and second electrodes of the phase shifter. By applying a voltage U to both electrodes, the voltage level at the first electrode drops below that at the second. This bias voltage then draws the carriers in the phase shifter's optical waveguide out of the waveguide, reducing the carrier concentration and increasing the effective refractive index. Consequently, the optical signal in the upper optical arm undergoes additional phase modulation by the phase shifter, resulting in different phases between the two arms, for example, a phase difference φ(U). This phase difference is controlled by the voltage U output by the driver.
[0055] The two optical signals with phase difference interfere with each other in the combiner and are finally output at the output port of the combiner. The output optical power is I=2I0+2I0cos(φ(U)).
[0056] Although the present invention has been described above through specific embodiments in conjunction with the accompanying drawings, it is easy for those skilled in the art to recognize that the above embodiments are merely exemplary and are 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-speed phase shifter based on a silicon-based SOI chip, comprising a silicon-based substrate and a ridge optical waveguide, a first electrode, and a second electrode formed on the silicon-based substrate; It is characterized by: The low-speed phase shifter is of carrier dispersion type, and no terminal matching resistor is provided between the first electrode and the second electrode.
2. The low-speed phase shifter according to claim 1, wherein: A first slab region and a second slab region are respectively formed on both sides of the ridge type optical waveguide; The first plate region is doped with P type, and the second plate region is doped with N type.
3. The low-speed phase shifter according to claim 2, wherein: The first electrode is an S electrode, and the second electrode is a GND electrode; The first flat plate region is located on the side close to the first electrode; The second flat plate region is located on the side close to the second electrode.
4. The low-speed phase shifter according to claim 3, wherein: The ridge type optical waveguide comprises a first optical waveguide portion and a second optical waveguide portion that are symmetrical; The first optical waveguide portion is lightly P-type doped and is close to the first electrode; The second optical waveguide portion is lightly N-type doped and is close to the second electrode.
5. The low-speed phase shifter according to claim 4, wherein: The first electrode is connected to the silicon in the first slab region through an ohmic contact, and the second electrode is connected to the silicon in the second slab region through an ohmic contact.
6. The low-speed phase shifter according to claim 5, wherein: The first electrode is connected to a negative potential, and the second electrode is connected to a zero potential.
7. A low-power MZ interferometer, comprising a beam splitter, an optical waveguide, a beam combiner, and a phase shifter; It is characterized by: The phase shifter is a low-speed phase shifter according to any one of claims 1 to 6.
8. The MZ interferometer according to claim 7, wherein: The MZ interferometer is based on a silicon-based SOI chip.
9. The MZ interferometer according to claim 7, wherein: The input end of the beam splitter is connected to the input optical waveguide; The first output end of the beam splitter and the input end of the phase shifter, and the output end of the phase shifter and the first input end of the beam combiner are connected via optical waveguides; The second output end of the beam splitter is connected to the second input end of the beam combiner through an optical waveguide.
10. The MZ interferometer according to claim 8, wherein: The silicon-based SOI chip is a 220nm chip.