CN210894894U - High-integration electro-optical modulator - Google Patents
High-integration electro-optical modulator Download PDFInfo
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- CN210894894U CN210894894U CN201921790140.8U CN201921790140U CN210894894U CN 210894894 U CN210894894 U CN 210894894U CN 201921790140 U CN201921790140 U CN 201921790140U CN 210894894 U CN210894894 U CN 210894894U
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Abstract
The utility model provides an electro-optical modulator, the modulator is on modulating carrier signal to the linearly polarized light, can accomplish the coupling of optic fibre and waveguide, at the in-process of optic fibre and waveguide coupling, there is the light of a small part to leak out from the coupling point department in the coupling point department of light waveguide second Y branch, these leak the light and pass through input control module behind signal processing as the input of bias voltage control, control module exports modulation voltage and carries out signal processing, with the loading to the modulator on and change the bias voltage of modulator, realize the bias modulation. The utility model relates to a highly integrated electro-optic modulator, with bias voltage circuit integrated to the modulator inside, no longer use the beam splitter to carry out beam split simultaneously, but carry out the detection and analysis as the input of bias voltage control through the leak light of optic fibre and waveguide coupling in-process, reduced the volume, reduced insertion loss, improved output.
Description
Technical Field
The utility model belongs to the technical field of the optical communication technique and specifically relates to an electro-optical modulator of high integration degree.
Background
The lithium niobate electro-optic modulator mainly adopts the coupling of optical fibers and waveguides to realize the modulation of signals, and has the advantages of high bandwidth, low insertion loss, low voltage, stable working performance and the like, so that the lithium niobate electro-optic modulator becomes a mainstream modulator applied to the fields of radio frequency millimeter wave communication, high-speed long-distance optical communication and the like at present. However, due to the non-linear characteristic of the lithium niobate electro-optical modulator, the modulator is susceptible to the influence of factors such as external environment temperature and an external electric field, so that a transmission characteristic curve drifts, and at the moment, a modulation signal deviates from an optimal working point, and the stability of the modulation signal of the modulator is finally influenced. In order to ensure the stability of the modulation signal, a common technique is to add a bias control device at the outer end of the modulator, and the stability of the signal is ensured by the bias control device. The current common bias control method is a light splitting method, and the method is that a beam splitter with a certain proportion of light splitting function is additionally arranged at the output end of a modulator, one beam with a larger proportion (99%) of the beam splitter is used as an output signal, one beam with a smaller proportion (1%) of the beam splitter is used as a detection signal and is connected to an electric control component, and then a corresponding algorithm is matched to realize the automatic control of a bias point. Although simple and intuitive, the method has large insertion loss and volume.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide an electro-optical modulator of high integration to solve the too high and too big problem of volume of current bias voltage control method insertion loss.
In order to achieve the above object, the present invention provides an electro-optical modulator with high integration, which includes a modulation module and a bias circuit;
the modulation module includes:
the optical fiber coupler comprises a light source, a radio frequency connector and a modulator, wherein linearly polarized light output by the light source is input into the modulator, the radio frequency connector performs photoelectric conversion on the linearly polarized light to form a carrier signal, and the modulator modulates the carrier signal onto the linearly polarized light to complete the coupling of an optical fiber and a waveguide;
the bias circuit is integrated within the modulator, comprising:
the first signal processing module is positioned at the second Y-branch coupling point of the modulator to detect the leaked light at the coupling point and perform signal processing on the leaked light to form a detection signal;
the control module is connected with the first signal processing module and used for receiving the detection signal after analog-to-digital conversion, judging whether the modulator works at the optimal working point or not and outputting modulation voltage when the modulator does not work at the optimal working point;
and the second signal processing module is connected with the control module and the modulator and used for receiving the modulation voltage and carrying out signal processing so as to load the modulation voltage on the modulator and change the bias voltage of the modulator.
Optionally, the radio frequency connector is a V-shaped connector.
Optionally, the linearly polarized light is divided into two signals with the same frequency and phase through a first Y branch of the modulator, and the two signals are coupled and output through a second Y branch.
Optionally, the second signal processing module includes an oscillator, a digital-to-analog converter, an adder, and an amplifier, the oscillator is connected to the control module and configured to generate a pilot signal of 1KHz and 0.1V, the pilot signal is used to adjust an optimal operating point of the modulator, the digital-to-analog converter is connected to the control module and configured to receive the modulation voltage and perform digital-to-analog conversion on the modulation voltage, the adder superimposes the modulation voltage after digital-to-analog conversion with the pilot signal, and the amplifier amplifies the superimposed signal and loads the superimposed signal onto an electrode of the modulator.
Optionally, the first signal processing module includes a detector, a filter, and an analog-to-digital converter, where the detector is configured to detect the leakage light and perform photoelectric conversion on the leakage light to form an electrical signal, and the filter and the analog-to-digital converter sequentially perform filtering and analog-to-digital conversion on the electrical signal to form the detection signal.
The utility model provides an among the electro-optical modulator, the modulator is on modulating carrier signal to the linear polarization light, can accomplish the coupling of optic fibre and waveguide, at optic fibre and waveguide coupling's in-process, there is the light of a small part to leak out from the coupling point department at the coupling point department of light waveguide second Y branch, these leak the light and pass through input control module behind signal processing as the input of bias voltage control, control module output modulation voltage carries out signal processing, and the bias voltage of modulator is changed on loading to the modulator, realize the bias modulation. The utility model discloses inside with bias voltage circuit integration to the modulator, no longer use the beam splitter to carry out beam split simultaneously, but the leakage light through optic fibre and waveguide coupling in-process carries out the analysis by detection as the input of bias voltage control, can automatic tracking and lock the best operating point of electro-optic modulator, makes output signal not change along with external environment temperature's change, has reduced the volume, has reduced insertion loss, has improved output.
Drawings
Fig. 1 is a schematic structural diagram of an electro-optical modulator with high integration level according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be described in more detail with reference to the drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in simplified form and are not to precise scale, and are provided for convenience and clarity in order to facilitate the description of the embodiments of the present invention.
As shown in fig. 1, the present embodiment provides an electro-optic modulator MZM with high integration, including a modulation module and a bias circuit;
the modulation module comprises a light source LD, a radio frequency connector RF and a modulator MZM, wherein the light source LD is a polarization-maintaining light source LD and can output linearly polarized light with high stability and narrow line width and input the linearly polarized light into the modulator MZM, the radio frequency connector RF adopts a V-shaped connector to perform photoelectric conversion on the linearly polarized light to form a carrier signal, and the modulator MZM modulates the carrier signal onto the linearly polarized light to complete the coupling of an optical fiber and a waveguide; in the process of coupling the optical fiber and the waveguide, the linearly polarized light is divided into two paths of signals with the same frequency and phase through a first Y branch of the modulator MZM, the two paths of signals are coupled and output through a second Y branch, and a small part of light leaks out from a coupling point through the coupling point of the second Y branch of the optical waveguide;
the bias circuit is integrated within the modulator, comprising:
a first signal processing module, located at a second Y-branch coupling point of the modulator MZM, including a detector PD, a filter BMF, and an analog-to-digital converter a/D, where the detector PD is configured to detect the leakage light and perform photoelectric conversion on the leakage light to form an electrical signal, and the filter BMF and the analog-to-digital converter a/D sequentially perform filtering (filtering out mixed signals) and analog-to-digital conversion on the electrical signal to form the detection signal;
the control module CPU is connected with the first signal processing module, is used as a central processing unit to complete the regulation and control of the functions of the whole system, is used for receiving a detection signal after analog-to-digital conversion, and judges whether the modulator MZM works at the optimal working point or not, if the modulator MZM works at the optimal working point through the signal, the bias control is not modulated any more, if the modulator MZM does not work at the optimal working point through the judgment, the control module CPU outputs modulation voltage, and particularly, the stable control of the bias point of the electro-optic modulator MZM is realized through monitoring the change condition of the output light power of the modulator MZM;
a second signal processing module connected to the control module CPU and the modulator MZM, and including an oscillator OSC, a digital-to-analog converter D/a, a summer SUM, and an amplifier AMP, the oscillator OSC being connected to the control module CPU, for generating a pilot signal of 1KHz, 0.1V, for adjusting the optimum operating point of said modulator MZM, said digital-to-analog converter D/A being connected to said control module CPU, for receiving the modulation voltage (which may also be understood as an adjustment value) and for digital-to-analog converting the modulation voltage, the adder SUM superimposes the modulation voltage after digital-to-analog conversion with the pilot signal (pulse signal), the amplifier AMP amplifies the superimposed signal and applies the amplified signal to an electrode of the modulator MZM to change a bias voltage of the modulator MZM.
Since the bias circuit is integrated inside the modulator and the whole bias control operation is completed inside the modulator, it should be noted that in the leakage of the second Y-branch coupling point, there may be stray light such as natural light and peripheral light, which may be radiated from the leakage point and may affect the detection of the system on the signal, and therefore, the leakage point needs to be shielded by structural sealing to prevent the stray light from affecting the system.
The embodiment also provides a method for electro-optical modulation by the high-integration electro-optical modulator MZM, which includes:
step 1: initializing a control module CPU;
step 2: the method comprises the steps that a control module CPU obtains an optimal bias point of a modulator MZM, an ideal average light power value corresponding to the optimal bias point is measured, an ideal bias voltage of the modulator MZM is determined through a step-variable algorithm, and the ratio R of first-order partial derivatives and second-order partial derivatives of the ideal average light power corresponding to the ideal bias voltage is calculated;
the control module CPU obtains each bias voltage of the modulator MZM mainly through scanning, and the scanning voltage is divided into two steps of rough scanning and fine scanning. Coarse scanning, namely scanning from the maximum bias voltage to the minimum bias voltage by using 0.002-0.02V (large step size) as a step size by the controller; then, the selected step length is 0.001-0.002V (small step length) to carry out fine scanning, and the accurate optimal bias voltage value is determined.
And step 3: obtaining an average light power value output by the modulator MZM in real time, and calculating to obtain a ratio R' of a first-order partial derivative and a second-order partial derivative of the bias voltage corresponding to the average light power at the moment;
and 4, step 4: judging whether the average light power value is equal to the ideal average light power value or not and whether R and R' are equal or not, if any one is not equal, outputting an adjusting voltage through a variable step length algorithm, and loading the adjusting voltage onto a modulator MZM; if they are not equal, it is proved that the modulator MZM is at the best working point.
It will be appreciated that the step-size-varying algorithm obtains an accurate target value by selecting an appropriate step size. When the measured signal is far away from the target value, a larger step length can be selected for measurement, so that the measured signal can be conveniently and quickly close to the target value, and if the measured signal is closer to the target value, a smaller step length is given, so that the control precision is improved.
In summary, in the embodiment of the present invention, in the electro-optical modulator, the modulator modulates the carrier signal to the linearly polarized light, so as to complete the coupling between the optical fiber and the waveguide, and in the coupling process between the optical fiber and the waveguide, there is a small amount of light leaking from the coupling point at the second Y-branch coupling point of the optical waveguide, and these leaked lights are input to the control module after signal processing as the input of the bias control, and the control module outputs the modulation voltage and performs signal processing, so as to load the modulator and change the bias voltage of the modulator, thereby implementing the bias modulation. The utility model discloses inside with bias voltage circuit integration to the modulator, no longer use the beam splitter to carry out beam split simultaneously, but the leakage light through optic fibre and waveguide coupling in-process carries out the analysis by detection as the input of bias voltage control, can automatic tracking and lock the best operating point of electro-optic modulator, makes output signal not change along with external environment temperature's change, has reduced the volume, has reduced insertion loss, has improved output.
The above description is only for the preferred embodiment of the present invention, and does not limit the present invention. Any technical personnel who belongs to the technical field, in the scope that does not deviate from the technical scheme of the utility model, to the technical scheme and the technical content that the utility model discloses expose do the change such as the equivalent replacement of any form or modification, all belong to the content that does not break away from the technical scheme of the utility model, still belong to within the scope of protection of the utility model.
Claims (5)
1. An electro-optical modulator with high integration level is characterized by comprising a modulation module and a bias circuit;
the modulation module includes:
the optical fiber coupler comprises a light source, a radio frequency connector and a modulator, wherein linearly polarized light output by the light source is input into the modulator, the radio frequency connector performs photoelectric conversion on the linearly polarized light to form a carrier signal, and the modulator modulates the carrier signal onto the linearly polarized light to complete the coupling of an optical fiber and a waveguide;
the bias circuit is integrated within the modulator, comprising:
the first signal processing module is positioned at the second Y-branch coupling point of the modulator to detect the leaked light at the coupling point and perform signal processing on the leaked light to form a detection signal;
the control module is connected with the first signal processing module and used for receiving the detection signal after analog-to-digital conversion, judging whether the modulator works at the optimal working point or not and outputting modulation voltage when the modulator does not work at the optimal working point;
and the second signal processing module is connected with the control module and the modulator and used for receiving the modulation voltage and carrying out signal processing so as to load the modulation voltage on the modulator and change the bias voltage of the modulator.
2. The high integration electro-optic modulator of claim 1, wherein the radio frequency connector is a V-connector.
3. The high-integration electro-optic modulator of claim 1, wherein the linearly polarized light is split into two signals with the same frequency and phase by a first Y-branch of the modulator, and coupled out by a second Y-branch.
4. The high-integration electro-optic modulator of claim 1, wherein the second signal processing module comprises an oscillator, a digital-to-analog converter, an adder and an amplifier, the oscillator is connected to the control module for generating a pilot signal of 1KHz and 0.1V, the pilot signal is used for adjusting an optimal operating point of the modulator, the digital-to-analog converter is connected to the control module for receiving the modulation voltage and performing digital-to-analog conversion on the modulation voltage, the adder adds the modulation voltage after digital-to-analog conversion and the pilot signal, and the amplifier amplifies the added signal and loads the added signal on an electrode of the modulator.
5. The high-integration electro-optic modulator of claim 1, wherein the first signal processing module comprises a detector for detecting the leakage light and photoelectrically converting the leakage light to form an electrical signal, a filter and an analog-to-digital converter for sequentially filtering and analog-to-digital converting the electrical signal to form the detection signal.
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| CN201921790140.8U CN210894894U (en) | 2019-10-23 | 2019-10-23 | High-integration electro-optical modulator |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110609400A (en) * | 2019-10-23 | 2019-12-24 | 广西师范大学 | High-integration electro-optical modulator and electro-optical modulation method |
| CN111711487A (en) * | 2020-07-04 | 2020-09-25 | 中国电子科技集团公司第三十四研究所 | Automatic bias working point control system based on temperature drift compensation |
-
2019
- 2019-10-23 CN CN201921790140.8U patent/CN210894894U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110609400A (en) * | 2019-10-23 | 2019-12-24 | 广西师范大学 | High-integration electro-optical modulator and electro-optical modulation method |
| CN111711487A (en) * | 2020-07-04 | 2020-09-25 | 中国电子科技集团公司第三十四研究所 | Automatic bias working point control system based on temperature drift compensation |
| CN111711487B (en) * | 2020-07-04 | 2023-05-02 | 中国电子科技集团公司第三十四研究所 | Offset working point automatic control system based on temperature drift compensation |
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