High-integration low-power-consumption phase shifter based on silicon-based SOI chip and MZ interferometer

Abstract

The utility model provides a high-integration low-power-consumption phase shifter based on a silicon-based SO I chip, and an on-chip integrated low-power-consumption MZ interferometer realized by using the phase shifter. The current carrier dispersion type phase shifter breaks through the inherent thought that a parallel matching resistor needs to be configured in the current carrier dispersion type phase shifter, and a parallel resistor is not arranged in the current carrier dispersion type phase shifter any more, so that the current carrier dispersion type phase shifter can show large impedance and extremely low current, extremely low power consumption can be generated in the working process, the temperature of the current carrier dispersion type phase shifter is ensured to be unchanged, high stability is achieved, and the service life of the current carrier dispersion type phase shifter is prolonged. The method is especially suitable for direct-current conditions. Besides, the comb-shaped design is adopted on the modulation electrode, so that the space utilization rate can be effectively improved, and particularly, compared with the existing straight-strip-shaped design, under the condition of the same equivalent phase shift length, the phase shifter disclosed by the utility model is lower in overall area, and the integration level of the device can be remarkably improved.

Description

Technical Field

[0001] The utility model relates to the field of integrated optics, in particular to a highly integrated low-power phase shifter based on a silicon-based SOI chip, and an on-chip integrated low-power MZ interferometer realized by using the same. Background Art

[0002] Phase shifters play a vital role in optical communications. As optical communications develop towards integration and low power consumption, optimizing the power consumption of phase shifters has become a research hotspot. The following two types of phase shifters (or electro-optical modulators) are primarily used in photonic integrated chips:

[0003] One type is a thermally tuned phase shifter, which is used in applications such as DC bias. This requires the system to maintain a stable phase for a long time, as the drive voltage supplied to the phase shifter remains constant or changes infrequently. For example, patent document CN218037581U discloses a thermally tuned 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. This heating resistor generates heat, which changes the refractive index of the underlying waveguide, thereby creating a phase shift.

[0004] The advantage of this low-speed phase shifter is its relatively low power consumption, which is only tens of milliwatts per half-wave. However, because it uses thermal tuning to generate phase shift, the phase retention stability is poor. Furthermore, the phase shift generated by resistor heating inevitably consumes power; the greater the required phase shift, the higher the power consumption.

[0005] The other is the carrier dispersion modulator, which is used in high-speed modulation applications. In this phase shifter, with the help of external reverse modulation signal excitation, the carriers in the waveguide area are extracted from the waveguide area, causing the effective refractive index of the waveguide to change, thereby changing the phase of the optical signal. Figure 1 As shown, a 50Ω or 100Ω terminal matching resistor is usually set at one end of the modulation electrode of the carrier dispersion modulator to match the impedance of the signal source to improve the bandwidth of the modulator.

[0006] The advantages of carrier dispersion modulators are higher bandwidth (usually reaching tens of GHz) and better stability compared to thermally tuned phase shifters, but they have the significant disadvantage of high power consumption. Utility Model Content

[0007] In response to the above-mentioned problems existing in the prior art, the present invention proposes a highly integrated, low-power phase shifter based on a silicon-based SOI chip, and an on-chip integrated, low-power MZ interferometer realized by using this phase shifter. The present invention breaks through the inherent thinking that a parallel matching resistor needs to be configured in a carrier dispersion type phase shifter, and no longer sets a parallel resistor in the carrier dispersion type phase shifter, so that it can exhibit large impedance and extremely small current, thereby generating extremely small power consumption during operation, ensuring that its own temperature remains unchanged, thereby achieving high stability, and is particularly suitable for DC working conditions. In addition, the present invention can effectively improve space utilization by adopting a comb-shaped design on the modulation electrode, especially compared with the existing straight strip design. Under the condition of the same equivalent phase shift length, the overall area of ​​the phase shifter of the present invention is lower, which can significantly improve the device integration.

[0008] The first aspect of the utility model relates to a highly integrated, low-power phase shifter based on a silicon-based SOI chip, which comprises a silicon-based substrate and a ridge optical waveguide, a first electrode, and a second electrode formed on the silicon-based substrate;

[0009] The phase shifter is of carrier dispersion type, and no terminal matching resistor is provided between the first electrode and the second electrode;

[0010] The first electrode and the second electrode are in a comb shape, and the comb teeth of the first electrode and the second electrode are arranged to cross each other.

[0011] Furthermore, the optical waveguide is a ridge waveguide, and a bending region exists in a waveguide portion distributed between the comb teeth of the first electrode and the second electrode, and the bending region has a preset bending radius.

[0012] Furthermore, the first electrode is an S electrode, and the second electrode is a GND electrode;

[0013] A first slab region and a second slab region are respectively formed on both sides of the ridge type optical waveguide;

[0014] The first flat plate region is located on the side close to the first electrode;

[0015] The second flat plate region is located on the side close to the second electrode.

[0016] Furthermore, the ridge type optical waveguide includes a first optical waveguide portion and a second optical waveguide portion that are symmetrical;

[0017] The first optical waveguide portion is lightly P-type doped and is close to the first electrode;

[0018] The second optical waveguide portion is lightly N-type doped and is close to the second electrode;

[0019] The first slab region is doped with a P-type, and the second slab region is doped with an N-type.

[0020] 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.

[0021] Furthermore, the first electrode is connected to a negative level, and the second electrode is connected to a zero level.

[0022] A second aspect of the present invention relates to an on-chip integrated 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 phase shifter.

[0023] Furthermore, the MZ interferometer is based on a silicon-based SOI chip.

[0024] 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.

[0025] Preferably, the silicon-based SOI chip is a 220nm chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The specific implementation of the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] 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.

[0028] Figure 1 The present invention schematically shows a carrier dispersion phase shifter in the prior art;

[0029] Figure 2 The schematic diagram shows the structure principle diagram of the highly integrated low-power phase shifter based on silicon-based SOI chip of the present invention;

[0030] Figure 3 Schematically shows a cross-sectional view of a highly integrated, low-power phase shifter based on a silicon-based SOI chip according to the present invention;

[0031] Figure 4An example of an on-chip integrated low-power MZ interferometer of the present invention is schematically shown. DETAILED DESCRIPTION

[0032] 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.

[0033] Figure 2-3 The structural principle diagram and cross-sectional diagram of the highly integrated low-power phase shifter based on silicon-based SOI chip of the present invention are respectively shown, which is a carrier dispersion type.

[0034] like Figure 2 As shown, the phase shifter of the present invention is a phase shifter based on a silicon-based SOI chip, which includes a silicon-based substrate, a ridge-type optical waveguide formed on the silicon-based substrate, and a first electrode and a second electrode located on both sides of the ridge-type optical waveguide.

[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, the present invention, unlike conventional carrier-dispersive phase shifters, eliminates the need for parallel resistors. Specifically, the present invention eliminates the need for a terminal matching resistor between the first and second electrodes.

[0043] In addition, if Figure 2 As shown, unlike the conventional straight strip design, the first electrode and the second electrode of the present invention are both designed to have a comb-like structure 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.

[0044] Because the optical waveguide is formed between the first and second electrodes, a corresponding bend region exists in the portion of the optical waveguide located between the comb teeth of the first and second electrodes. In the present invention, to reduce losses in the optical waveguide, an appropriate bend radius can be preset in the bend region to allow the extension direction of the optical waveguide to change in a smooth transition.

[0045] The process of phase modulation of an optical signal by the phase shifter of the present invention is described below to better understand the working principle of the present invention.

[0046] When an optical signal is input into the phase shifter from an 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, i.e., providing a negative bias drive signal from the first electrode to the second electrode.

[0047] 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.

[0048] 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.

[0049] 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 small current, so the power consumption generated by the phase shifter during this working process is extremely small and can be ignored. Even if the driving voltage will increase when the modulator length is reduced, the additional power consumption can still be ignored due to its extremely large impedance. Compared with the existing thermally tuned phase shifters used for low-speed phase modulation, the phase shifter of the present invention can ensure that its own temperature remains unchanged during operation, and there is no heat exchange with the environment, thereby achieving higher stability performance, and is particularly suitable for operation under DC conditions. In addition, the comb-shaped electrode design structure can effectively improve space utilization, especially compared with the existing straight strip design, under the same equivalent phase shift length, the overall area of ​​the phase shifter of the present invention is lower, which can significantly improve the device integration.

[0050] 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.

[0051] 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.

[0052] In a preferred example, the MZ interferometer can be implemented based on a 220 nm SOI chip.

[0053] According to the present invention, the phase shifter in the MZ interferometer will adopt the above-mentioned highly integrated low-power phase shifter based on silicon-based SOI chip, thereby ensuring its high stability and low power consumption performance during operation.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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)).

[0058] 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 highly integrated, low-power phase shifter based on a silicon-based SOI chip, comprising a silicon-based substrate, a ridge optical waveguide, a first electrode, and a second electrode formed on the silicon-based substrate; It is characterized by: The phase shifter is of carrier dispersion type, and no terminal matching resistor is provided between the first electrode and the second electrode; Furthermore, the first electrode and the second electrode are in a comb shape, and the comb teeth of the first electrode and the second electrode are arranged to cross each other.

2. The highly integrated, low-power phase shifter according to claim 1, wherein: The optical waveguide is a ridge-type optical waveguide, and a bending region is present in a portion of the optical waveguide distributed between the comb teeth of the first electrode and the second electrode. The bending region has a preset bending radius.

3. The highly integrated, low-power phase shifter according to claim 2, wherein: The first electrode is an S electrode, and the second electrode is a GND electrode; A first slab region and a second slab region are respectively formed on both sides of the ridge type optical waveguide; 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 highly integrated, low-power phase shifter according to claim 3, wherein: The ridge type optical waveguide includes a symmetrical first optical waveguide portion and a second optical waveguide portion, wherein the first optical waveguide portion is lightly P-type doped and close to the first electrode, and the second optical waveguide portion is lightly N-type doped and close to the second electrode; The first slab region is doped with a P-type, and the second slab region is doped with an N-type.

5. The highly integrated, low-power 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 highly integrated, low-power 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. An on-chip, 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 highly integrated, low-power phase shifter according to any one of claims 1 to 6.

8. The low-power MZ interferometer according to claim 7, wherein: The MZ interferometer is based on a silicon-based SOI chip.

9. The low-power 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 low-power MZ interferometer according to claim 8, wherein: The silicon-based SOI chip is a 220nm chip.

Images