CN111682905B - BPSK modulation-based optical digital-to-analog conversion device and method - Google Patents
BPSK modulation-based optical digital-to-analog conversion device and method Download PDFInfo
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- H04B10/556—Digital modulation, e.g. differential phase shift keying [DPSK] or frequency shift keying [FSK]
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
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Abstract
An optical digital-to-analog conversion device based on BPSK modulation, comprising: a BPSK optical signal generating unit for generating and outputting a binary phase keying modulated optical signal; the modulation format conversion unit is connected with the BPSK optical signal generation unit and used for converting the input BPSK signal into an APSK modulation format and outputting the optical signal after format conversion; the balanced coherent detection unit is connected with the modulation format conversion unit and is used for demodulating the APSK modulated optical signal and outputting four electric signals with different amplitudes; and the laser generating unit is respectively connected with the BPSK optical signal generating unit and the balanced coherent detection unit and is used for emitting laser which is respectively used as an optical carrier required by the BPSK optical signal generating unit and the balanced coherent detection unit for modulating the optical signals and a local oscillator optical signal required by coherent detection. The invention realizes 2-bit optical digital-to-analog conversion based on BPSK modulation, is more suitable for long-distance optical fiber networks than common OOK modulated optical digital-to-analog conversion, and is beneficial to realizing a fully transparent optical network.
Description
Technical Field
The invention relates to the technical field of signal processing, in particular to an optical digital-to-analog conversion device and method based on BPSK modulation.
Background
All-optical signal processing has been successfully applied in many applications, including signal amplification, dispersion compensation, clock extraction, add/drop multiplexers, sampling and signal conversion, etc. Where optical digital to analog conversion (DA) technology is considered to be the basis for most operations, including packet switching and label processors, facilitating a completely transparent optical communication system. Most optical digital-to-analog converters currently use binary amplitude keying (OOK) modulation format optical signals for processing. Phase Shift Keying (PSK) modulation, however, is more tolerant of nonlinear distortion than OOK modulation and is often used for transmission over long distances in optical fibers. Therefore, it is not only easy to use
A low-cost and low-complexity optical digital-to-analog conversion device and method are to be developed.
Disclosure of Invention
In view of the above, the main object of the present invention is to provide an optical digital-to-analog conversion apparatus and method based on BPSK modulation, so as to partially solve at least one of the above technical problems.
In order to achieve the above object, as an aspect of the present invention, there is provided an optical digital-to-analog conversion apparatus based on BPSK modulation, comprising
A BPSK optical signal generating unit for generating and outputting a binary phase keying modulated optical signal;
the modulation format conversion unit is connected with the BPSK optical signal generation unit and used for converting the input BPSK signal into an APSK modulation format and outputting the optical signal after format conversion;
the balanced coherent detection unit is connected with the modulation format conversion unit and is used for demodulating the APSK modulated optical signal and outputting four electric signals with different amplitudes; the radio frequency signal output by the format conversion system is modulated onto an optical carrier and converted into an optical signal to be output;
and the laser generating unit is respectively connected with the BPSK optical signal generating unit and the balanced coherent detection unit and is used for emitting laser which is respectively used as an optical carrier required by the BPSK optical signal generating unit and the balanced coherent detection unit for modulating the optical signals and a local oscillator optical signal required by coherent detection.
Wherein, BPSK optical signal produces the unit and includes:
and the photoelectric modulator is used for modulating the input radio frequency signal onto an optical carrier through a BPSK modulation format.
Wherein the electro-optical modulator is a phase modulator or an intensity modulator.
Wherein the modulation format conversion unit includes:
the directional coupler is used for dividing an optical signal input to the waveguide into two paths according to a certain power ratio and transmitting the two paths of optical signals on the upper and lower waveguides;
the phase controller is used for acting on the upper path of waveguide output by the directional coupler and controlling the phase change of the optical signal, so that the phases of the upper path of optical signal and the lower path of optical signal at the output end are the same;
and the waveguide beam combiner is used for coupling the optical signals output by the upper path and the lower path of the directional coupler.
Wherein the splitting ratio of the directional coupler is 3: 1.
Wherein the balanced coherent detection unit comprises:
the 180-degree optical mixer is used for carrying out optical mixing on the signal light and the local oscillator light output by the modulation format conversion unit and outputting two paths of optical signals after the optical mixing;
and the balance detector is connected with the 180-degree optical mixer and is used for performing photoelectric conversion on the two paths of optical signals output by the balance detector and outputting radio-frequency signals.
Wherein the laser generating unit includes:
a laser transmitter for transmitting laser light;
and the input end of the optical splitter is connected with the laser transmitter, one output end of the optical splitter is connected with the directional coupler and is used for modulating the required optical carrier, and the other output end of the optical splitter is connected with the input end of the 180-degree frequency mixer and is used for coherently demodulating the required local oscillator light.
Wherein the wavelength and power of the optical carrier emitted by the laser emitter are within the working range of the optical splitter, the photoelectric modulator and the balance detector.
As another aspect of the present invention, a method for optical digital-to-analog conversion based on BPSK modulation is provided, which includes the following steps:
the laser generating unit emits laser, the laser is divided into two paths and then respectively input into the BPSK optical signal generating unit and the balanced coherent detection unit, and the laser is respectively used as an optical carrier required by the modulated optical signals of the two units and a local oscillator optical signal required by coherent detection;
the BPSK optical signal generating unit receives a digital radio frequency signal;
the BPSK optical signal generating unit modulates the digital radio frequency signal to an optical carrier through an optoelectronic modulator, the modulation format is BPSK modulation, and the digital radio frequency signal is output to the input end of the modulation format conversion unit;
the modulation format conversion unit divides the input optical signals into two paths according to a certain proportion through a directional coupler, controls the phase change of the two paths, enables the phases of the two paths of optical signals to be the same, and outputs signals in an APSK modulation format;
the balanced coherent detection unit carries out balanced coherent detection on the APSK optical signals output by the modulation format conversion unit, the optical signals are converted into radio frequency signals to form electric signals with four medium amplitudes, and the obtained signals are analog signals obtained after 2-bit optical digital-to-analog conversion.
Based on the above technical solution, the optical digital-to-analog conversion apparatus and method based on BPSK modulation according to the present invention have at least one of the following advantages over the prior art:
1. the invention realizes 2-bit optical digital-to-analog conversion based on BPSK modulation, is more suitable for long-distance optical fiber networks than common OOK modulated optical digital-to-analog conversion, and is beneficial to realizing a fully transparent optical network.
2. The invention realizes digital-to-analog conversion by using an optical method, breaks the bottleneck of electronic devices, is easy to integrate, and reduces the complexity and cost of the system.
Drawings
Fig. 1 is a schematic structural diagram of an optical digital-to-analog conversion device according to an embodiment of the present invention;
fig. 2 is a diagram of an operation mode of a modulation format conversion unit in the apparatus shown in fig. 1;
FIG. 3 is a graph of digital input versus analog output for the device of FIG. 1;
fig. 4 is a graph of the results of simulation output in the device shown in fig. 1.
In the above figures, the reference numerals have the following meanings:
1. a laser transmitter; 2. an optical splitter; 3. a photoelectric modulator; 4. a directional coupler; 5. a phase controller; 6. a waveguide combiner; 7. a 180 degree mixer; 8. a balanced detector.
Detailed Description
The invention discloses an optical digital-to-analog conversion device and method based on BPSK modulation, which utilize coherent detection and modulation format conversion technology to realize 2-bit digital-to-analog conversion in an optical domain, have simple assembly and easy integration and reduce the complexity of a system.
In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.
The invention provides an optical digital-to-analog conversion device, comprising: a BPSK optical signal generating unit for generating and outputting a binary phase keying modulated optical signal; the modulation format conversion unit is connected with the BPSK optical signal generation unit and used for converting the input BPSK signal into an APSK modulation format and outputting the optical signal after format conversion; and the balanced coherent detection unit is connected with the modulation format conversion unit and is used for demodulating the APSK modulated optical signal and outputting four electric signals with different amplitudes. The radio frequency signal output by the format conversion system is modulated onto an optical carrier and converted into an optical signal to be output; and the laser generating unit is respectively connected with the BPSK optical signal generating unit and the balanced coherent detection unit and is used for emitting laser which is respectively used as an optical carrier required by the modulated optical signals of the two units and a local oscillator optical signal required by coherent detection.
Fig. 1 is a schematic structural diagram of an optical digital-to-analog conversion apparatus according to an embodiment of the present invention, and as shown in fig. 1, the BPSK optical signal generating unit includes: and an optical-electrical modulator 3 for modulating the input radio-frequency signal onto an optical carrier by a BPSK modulation format. The modulator may be a phase modulator or an intensity modulator.
The modulation format conversion unit includes: the directional coupler 4 is used for dividing an optical signal input to the waveguide into two paths according to a certain power ratio and transmitting the two paths of optical signals on the upper and lower waveguides; the phase controller 5 is used for acting on the upper waveguide output by the directional coupler and controlling the phase change of the optical signal, so that the phases of the upper and lower optical signals at the output end are the same; and the waveguide beam combiner 6 is used for coupling the optical signals output by the directional coupler 4 in the upper path and the lower path.
In an exemplary embodiment of the invention, the splitting ratio of the directional coupler 4 is 1: 3.
The balanced coherent detection unit comprises: the 180-degree optical mixer 7 is used for performing optical mixing on the signal light and the local oscillator light output by the modulation format conversion unit and outputting two paths of optical signals after the optical mixing; and the balance detector 8 is connected with the 180-degree optical mixer 7 and is used for performing photoelectric processing on the two paths of optical signals output by the balance detector and outputting radio-frequency signals.
The laser generating unit includes: a laser transmitter 1 for transmitting laser light; and the input end of the optical splitter 2 is connected with the laser transmitter 1, one output end of the optical splitter is connected with the directional coupler 4 and is used for modulating the required optical carrier, and the other output end of the optical splitter is connected with the input end of the 180-degree mixer 7 and is used for coherently demodulating the local oscillator optical signal.
The invention also discloses a digital-to-analog conversion method applying the device, which comprises the following steps:
the laser transmitter 1 transmits a laser signal;
laser emitted by the laser emitter 1 is divided into 2 paths after passing through the optical splitter 2, and the 2 paths are respectively used as an optical carrier signal required by the modulator 3 and a local oscillator optical signal required by coherent detection;
the photoelectric modulator 3 receives the digital radio frequency signal, modulates the digital radio frequency signal onto an optical carrier through the photoelectric modulator 3, and outputs the digital radio frequency signal to the input end of the directional coupler 4, wherein the modulation format is BPSK modulation;
the directional coupler 5 couples the input optical signal 1: the splitting ratio of 3 is divided into an upper path and a lower path, the phase change of the two paths is controlled by a phase controller 6, so that the phases of the two paths of optical signals are the same, the two paths of optical signals are synthesized into one path of output by an optical waveguide beam combiner, and the output optical signal is a signal in an APSK modulation format, as shown in FIG. 2;
inputting the output optical signal in the APSK modulation format as signal light to one end of a 180-degree optical mixer 7, inputting the other output light of the optical splitter 2 as local oscillation light to the other input end of the 180-degree optical mixer 7, and outputting two paths of mixed optical signals;
the balanced detector 8 performs photoelectric conversion on the two paths of mixed optical signals, and demodulates the APSK signals according to the principle of balanced coherent detection. Fig. 3 shows normalized amplitude values of output analog signals corresponding to different digital signals, where "00" corresponds to "3", the amplitude is the largest, "01" corresponds to "1", "10" corresponds to "-1", and "11" corresponds to "-3", which means that 2-bit optical digital-to-analog conversion is realized. Fig. 4 shows an example in which the input digital signal sequence is "11101011", and the output result of the present apparatus is high-frequency filtered by a low-pass filter to obtain a smoother analog signal curve.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. An optical digital-to-analog conversion device based on BPSK modulation, comprising:
a BPSK optical signal generating unit for generating and outputting a binary phase keying modulated optical signal;
the modulation format conversion unit is connected with the BPSK optical signal generation unit and used for converting the input BPSK signal into an APSK modulation format and outputting the optical signal after format conversion;
the balanced coherent detection unit is connected with the modulation format conversion unit and is used for demodulating the APSK modulated optical signal and outputting four electric signals with different amplitudes; the radio frequency signal output by the format conversion system is modulated onto an optical carrier and converted into an optical signal to be output;
and the laser generating unit is respectively connected with the BPSK optical signal generating unit and the balanced coherent detection unit and is used for emitting laser which is respectively used as an optical carrier required by the BPSK optical signal generating unit and the balanced coherent detection unit for modulating the optical signals and a local oscillator optical signal required by coherent detection.
2. The optical digital-to-analog conversion apparatus according to claim 1, wherein the BPSK optical signal generating unit includes:
and the photoelectric modulator is used for modulating the input radio frequency signal onto an optical carrier through a BPSK modulation format.
3. Optical digital-to-analog conversion device according to claim 2, characterized in that the electro-optical modulator is a phase modulator or an intensity modulator.
4. The optical digital-to-analog conversion apparatus according to claim 1, wherein the modulation format conversion unit includes:
the directional coupler is used for dividing an optical signal input to the waveguide into two paths according to a certain power ratio and transmitting the two paths of optical signals on the upper and lower waveguides;
the phase controller is used for acting on the upper path of waveguide output by the directional coupler and controlling the phase change of the optical signal, so that the phases of the upper path of optical signal and the lower path of optical signal at the output end are the same;
and the waveguide beam combiner is used for coupling the optical signals output by the upper path and the lower path of the directional coupler.
5. The optical digital-to-analog conversion device of claim 4, wherein the splitting ratio of the directional coupler is 3: 1.
6. The optical digital-to-analog conversion device according to claim 1, wherein the balanced coherent detection unit comprises:
the 180-degree optical mixer is used for carrying out optical mixing on the signal light and the local oscillator light output by the modulation format conversion unit and outputting two paths of optical signals after the optical mixing;
and the balance detector is connected with the 180-degree optical mixer and is used for performing photoelectric conversion on the two paths of optical signals output by the balance detector and outputting radio-frequency signals.
7. The optical digital-to-analog conversion device according to claim 1, wherein the laser generating unit includes:
a laser transmitter for transmitting laser light;
and the input end of the optical splitter is connected with the laser transmitter, one output end of the optical splitter is connected with the directional coupler and is used for modulating the required optical carrier, and the other output end of the optical splitter is connected with the input end of the 180-degree frequency mixer and is used for coherently demodulating the required local oscillator light.
8. The optical digital-to-analog conversion device of claim 7, wherein the wavelength and power of the optical carrier emitted by the laser emitter are within the operating range of the optical splitter, the electro-optic modulator and the balanced detector.
9. A method for implementing optical digital-to-analog conversion by using the optical digital-to-analog conversion device of any one of claims 1 to 8, comprising the steps of:
the laser generating unit emits laser, the laser is divided into two paths and then respectively input into the BPSK optical signal generating unit and the balanced coherent detection unit, and the laser is respectively used as an optical carrier required by the two units to modulate optical signals and a local oscillator optical signal required by coherent detection;
the BPSK optical signal generating unit receives a digital radio frequency signal;
the BPSK optical signal generating unit modulates the digital radio frequency signal to an optical carrier through an optoelectronic modulator, the modulation format is BPSK modulation, and the digital radio frequency signal is output to the input end of the modulation format conversion unit;
the modulation format conversion unit divides the input optical signals into two paths according to a certain proportion through a directional coupler, controls the phase change of the two paths, enables the phases of the two paths of optical signals to be the same, and outputs signals in an APSK modulation format;
the balanced coherent detection unit carries out balanced coherent detection on the APSK optical signals output by the modulation format conversion unit, the optical signals are converted into analog radio frequency signals to form electric signals with four amplitudes, and the obtained signals are analog signals obtained after 2-bit optical digital-to-analog conversion.
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| CN102317856A (en) * | 2009-02-16 | 2012-01-11 | 瑞典爱立信有限公司 | Optical digital-to-analog conversion |
| US8441383B1 (en) * | 2011-03-11 | 2013-05-14 | Rockwell Collins, Inc. | Photonic digital-to-analog conversion (DAC) based on RSOAs |
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| CN110266396A (en) * | 2019-06-21 | 2019-09-20 | 上海交通大学 | A kind of optics PAM-4 signal receiver and full light quantization method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107769783B (en) * | 2017-11-08 | 2020-12-15 | 中国科学院半导体研究所 | Multi-mode digital-to-analog converter |
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| CN102317856A (en) * | 2009-02-16 | 2012-01-11 | 瑞典爱立信有限公司 | Optical digital-to-analog conversion |
| US8441383B1 (en) * | 2011-03-11 | 2013-05-14 | Rockwell Collins, Inc. | Photonic digital-to-analog conversion (DAC) based on RSOAs |
| GB2540744A (en) * | 2015-07-16 | 2017-02-01 | Ew Simulation Tech Ltd | Photonic Digital-to-Analogue Converter |
| CN110266396A (en) * | 2019-06-21 | 2019-09-20 | 上海交通大学 | A kind of optics PAM-4 signal receiver and full light quantization method |
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| Title |
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