A control method for a low-power thermo-optic MZI structure device

Abstract

The present invention discloses a regulation method for a low-power thermo-optic MZI structure device. The regulation method includes: respectively setting the two phase-shift arms of the thermo-optic MZI structure device as a phase-biased arm and a working arm; scanning the voltage of the working arm to find the position of the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port, and judging the offset direction of the static characteristic curve; selecting the working point of the thermo-optic MZI structure device according to the position of the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port on the static characteristic curve. The method of the present invention can effectively reduce the influence of factors such as process errors and external temperature changes on the selection of the working point, and further effectively reduce the power consumption of the device. The thermo-optic MZI structure device is more suitable for constructing large-scale network devices.

Description

Technical Field

[0001] The field of the present invention relates to the field of silicon-based optoelectronic integration, and particularly to a method for regulating a low-power thermo-optic MZI structure device. Background Art

[0002] With the development of integrated silicon-based optoelectronic technology, silicon-based integrated optical switching devices are also developing towards large-scale and multi-port numbers. On-chip integrated thermo-optic effect devices, with simple device structures, process processing, and drive control, have become the preferred devices for constructing large-scale on-chip integrated systems. However, thermo-optic effect devices often consume relatively large power. For example, the power consumption of a general thermo-optic device with an MZI structure is about 20 - 30 mW. This brings great challenges to the driving and heat dissipation of high-density large-scale chips containing hundreds of such devices, such as optical computing and optical switching.

[0003] The thermo-optic MZI structure is widely used to construct large-scale integrated optoelectronic system devices. The thermo-optic MZI structure ( Figure 1 ) usually includes two beam splitters and two phase shift arms with thermal electrodes. By heating the waveguide through the thermal electrodes, the refractive index of the optical waveguide material is changed, so as to achieve the purpose of controlling the phase difference between the two phase shift arms of the MZI structure. For an ideal equal-arm MZI structure, in the initial state, the optical energy is output from one port ( Figure 1 ). The output optical power at the Cross port shows that the 0V voltage point corresponds to the maximum voltage value point on the static characteristic curve ( Figure 2 ). The output optical power of the Bar port is complementary to that of the Cross port. Only the situation of the Cross port is described here. As the voltage increases, the phase difference between the two arms is positively correlated with the voltage, and the output optical energy at the Cross port changes non-linearly and periodically ( Figure 2 ). In the ideal case, taking Figure 2 points A and B in it as the working points of the optical switch can achieve the maximum extinction ratio with the minimum power consumption, which is called the ideal working state.

[0004] However, due to semiconductor process errors, the initial state of the optical switch of the MZI structure often fluctuates near the ideal situation and cannot be accurately in the ideal state, that is, the intersection point of the static curve and the Y-axis is not the peak value. In practical engineering applications, points B and C in Figure 2 are often selected as the working points of the switch unit. According to the formula:

[0005] W = U 2 / R

[0006] When the thermal resistance remains unchanged, compared with the ideal operating state, it will bring a large amount of power consumption. Especially in an array device composed of a large number of optical switch units, the disadvantage of high power consumption will be particularly obvious, directly limiting the scale of array integration and posing huge challenges to the driving and heat dissipation of the array chip. Although researchers have developed different methods to reduce power consumption for MZI-structured optical switch devices made of different materials, such as designing deep etching isolation grooves, etc., this greatly increases the process complexity of the chip. Summary of the Invention

[0007] In view of this, the present invention proposes a method for regulating a low-power thermo-optic MZI-structured device.

[0008] To achieve the above-mentioned invention purpose, the technical solution of the present invention is: The present invention proposes a method for regulating a low-power thermo-optic MZI-structured device, and the regulation method includes the following steps:

[0009] Step S1, set the two phase shift arms of the thermo-optic MZI-structured device as a phase bias arm and a working arm respectively;

[0010] Step S2, scan the voltage of the working arm, find the position of the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port, and judge the offset direction of the static characteristic curve;

[0011] Step S3, select the working point of the thermo-optic MZI-structured device according to the position of the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port on the static characteristic curve.

[0012] Further, the phase bias arm regulates the overall working point of the thermo-optic MZI-structured device by setting a fixed bias voltage; the working arm is used to switch the voltage between the working voltage points of the thermo-optic MZI-structured device to achieve the function of optical path switching.

[0013] Further, judging the offset direction of the static characteristic curve includes: moving along the positive direction of the phase change coordinate axis is called the positive bias state, and moving along the negative direction of the phase change coordinate axis is called the negative bias state.

[0014] Further, the specific content of step S3 is:

[0015] If the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port is on the positive half-axis of the static characteristic curve, directly select the first voltage maximum point of the Cross port and its adjacent voltage minimum point, or the first voltage minimum point of the Bar port and its adjacent voltage maximum point as the working point;

[0016] If the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port is on the negative half-axis of the static characteristic curve, a voltage is applied to the phase bias arm to make the voltage maximum point or the voltage minimum point appear on the positive half-axis. Then, the first voltage maximum point of the Cross port and its adjacent voltage minimum point, or the first voltage minimum point of the Bar port and its adjacent voltage maximum point are selected as the working points.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: Compared with the prior art in which the first maximum value (Cross port) or minimum value (Bar port) point is abandoned as the working point due to process errors and other factors, in the present invention, the two phase shift arms of the MZI structure are set to have different functions, and the working arm can select a working point with a smaller voltage by adjusting the voltage on the bias arm, effectively reducing the influence of factors such as process errors and external temperature changes on the selection of the working point, and thus effectively reducing the overall power consumption of the device. Therefore, through the regulation method of the present invention, the thermo-optic MZI structure is more conducive to constructing a large-scale integrated array. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a schematic diagram of the thermo-optic MZI structure;

[0020] Figure 2 It is the static characteristic curve of the output optical power of the Cross port;

[0021] Figure 3 It is the flowchart of the method of the present invention;

[0022] Figure 4 It is a schematic diagram of setting the phase shift arm in the thermo-optic MZI structure in the method of the present invention;

[0023] Figure 5 It is a schematic diagram of the voltage peak point in the positive bias state in the method of the present invention;

[0024] Figure 6 It is a schematic diagram of the voltage peak point in the negative bias state in the method of the present invention. Specific Embodiments

[0025] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0026] The terms used in the present invention are for the purpose of describing particular embodiments only and are not intended to limit the present invention. The singular forms "a", "the", and "said" used in the present invention and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0027] It should be understood that although the terms first, second, third, etc. may be used in the present invention to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to a determination".

[0028] The present invention will be described in detail below with reference to the accompanying drawings. Without conflict, the features in the following embodiments and implementation manners may be combined with each other.

[0029] As Figure 3 shown, the present invention proposes a method for regulating a low-power thermo-optic MZI structure device to reduce the overall power consumption of the thermo-optic MZI structure device. The regulation method specifically includes the following steps:

[0030] Step S1, set the two phase shift arms of the thermo-optic MZI structure device as a phase bias arm and a working arm respectively.

[0031] Further, as Figure 3 shown, the phase bias arm regulates the overall operating point of the thermo-optic MZI structure device by setting a fixed bias voltage; the working arm is used to switch the voltage between the operating voltage points of the thermo-optic MZI structure device to achieve the function of optical path switching.

[0032] Step S2, scan the voltage of the working arm, find the position of the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port, and judge the offset direction of the static characteristic curve.

[0033] Specifically, under the influence of process errors or other factors, the static characteristic curve of the thermo-optic MZI structure device will no longer be in an ideal state. On the static characteristic curve, it shows a shift along the phase change coordinate axis in the positive or negative direction. Among them, the shift along the phase change coordinate axis in the positive direction is called the positive bias state, and the shift along the phase change coordinate axis in the negative direction is called the negative bias state. By scanning the voltage of the working arm, the offset direction can be determined.

[0034] Step S3: Select the working point of the thermo-optic MZI structure device according to the position of the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port on the static characteristic curve.

[0035] Specifically, if the first voltage maximum point of the above Cross port or the first voltage minimum point of the Bar port is on the positive half-axis of the static characteristic curve, directly select the first voltage maximum point of the Cross port and its adjacent voltage minimum point, or the first voltage minimum point of the Bar port and its adjacent voltage maximum point as the working point.

[0036] If the first voltage maximum point of the above Cross port or the first voltage minimum point of the Bar port is on the negative half-axis of the static characteristic curve, apply a voltage to the phase bias arm to make the voltage maximum point or voltage minimum point appear on the positive half-axis, and then select the first voltage maximum point of the Cross port and its adjacent voltage minimum point, or the first voltage minimum point of the Bar port and its adjacent voltage maximum point as the working point.

[0037] Exemplarily, as Figure 5 shown, the first voltage maximum point of the above Cross port or the first voltage minimum point of the Bar port is on the positive half-axis of the static characteristic curve, that is, in the positive bias state. Point A is the peak point, then select points A and B as the working voltages of the thermo-optic MZI structure device. As Figure 6 shown by the solid line in, the first voltage maximum point of the above Cross port or the first voltage minimum point of the Bar port is on the negative half-axis of the static characteristic curve, that is, in the negative bias state. Point A is located on the negative axis of the coordinate axis and cannot be used as a working point. At this time, apply a voltage to the phase bias arm, which can move point A to the positive axis ( Figure 6 shown by the dotted line in), and at this time point A' can be used as the working point of the switching unit. In this way, only a very small voltage needs to be applied to the phase bias arm to enable the working arm to select the two points A' and B' with smaller voltages as the working points. This is of great significance for constructing large-scale arrays using thermo-optic switches.

[0038] Embodiment 1

[0039] Take the silicon-based thermo-optic switch unit as an example to illustrate the working principle of the present invention. The silicon-based thermo-optic switch unit consists of two 2×2 MMI devices and two thermo-optic phase-shifting arms. The devices are fabricated on an SOI wafer with a top silicon thickness of 220 nm and a silicon waveguide etched to a depth of 70 nm. The length of the phase-shifting arm is 100 μm, the thermo-electrode is of the same length as the phase-shifting arm, and the resistance is 465 Ω.

[0040] In the positive bias state, without other operations, just select a suitable operating point.

[0041] In the negative bias state, it is impossible to select the maximum value point with the minimum voltage as the operating point. In the prior art, generally points B and C are selected as the operating points ( Figure 6 ), with voltages of 2 V and 3.5 V respectively, power consumptions of 8.6 mW and 26.3 mW respectively, and the total power consumption is 34.9 mW.

[0042] Applying a voltage of about 1 V to the phase bias arm can change the static characteristic curve of the device to the positive bias state. At this time, select A’ and B’ as the operating points ( Figure 6 ), with voltages of 0.5 V and 3 V respectively, power consumptions of 0.53 mW and 19.3 mW respectively, the power consumption on the bias arm is 2 mW, and the total power consumption is 21.83 mW.

[0043] Compared with the prior art, the power consumption is reduced by 13.07 mW, and the reduction value is 37.4% of the power consumption of the traditional method.

[0044] In summary, the present invention proposes to endow the two phase-shifting arms of the thermo-optic MZI structure with different functions of drive control and phase bias respectively. The purpose is to enable the selection of two operating points with relatively small voltages on the working arm through the regulation of the phase bias arm. Compared with the traditional working mode of the thermo-optic MZI structure, the method proposed by the present invention can effectively reduce the influence of factors such as process errors and external temperature changes on the selection of the operating point, and thus effectively reduce the power consumption of the device. It is more suitable for constructing large-scale network devices.

[0045] After considering the specification and the content disclosed herein, those skilled in the art will readily think of other embodiments of the present application. The present application aims to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include the common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and examples are only regarded as exemplary.

[0046] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. A method for regulating a low-power thermo-optic MZI structure device, characterized in that, The regulation method includes the following steps: Step S1: Set the two phase-shift arms of the thermo-optic MZI structure device as the phase-offset arm and the working arm respectively; Step S2: Scan the voltage of the working arm, find the position of the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port, and judge the offset direction of the static characteristic curve; Step S3: Select the working point of the thermo-optic MZI structure device according to the position of the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port on the static characteristic curve; Among them, step S3 is specifically: If the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port is on the positive half-axis of the static characteristic curve, directly select the first voltage maximum point of the Cross port and its adjacent voltage minimum point, or the first voltage minimum point of the Bar port and its adjacent voltage maximum point as the working point; If the first voltage maximum point of the Cross port or the first voltage minimum point of the Bar port is on the negative half-axis of the static characteristic curve, apply a voltage to the phase-offset arm to make the voltage maximum point or the voltage minimum point appear on the positive half-axis, and then select the first voltage maximum point of the Cross port and its adjacent voltage minimum point, or the first voltage minimum point of the Bar port and its adjacent voltage maximum point as the working point.

2. The regulation method of the low-power thermo-optic MZI structure device according to claim 1, wherein The phase-offset arm regulates the overall working point of the thermo-optic MZI structure device by setting a fixed bias voltage; the working arm is used to switch the voltage between the working voltage points of the thermo-optic MZI structure device to achieve the function of optical path switching.

3. The regulation method of the low-power thermo-optic MZI structure device according to claim 1, characterized in that Judging the offset direction of the static characteristic curve includes: Moving along the positive direction of the phase change coordinate axis is called the positive bias state, and moving along the negative direction of the phase change coordinate axis is called the negative bias state.

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