CN211959218U - Photoelectric quantization device based on light injection semiconductor laser - Google Patents

Abstract

The utility model belongs to the field of microwave photonics, and in order to solve the problem of low quantization precision existing in the existing optical quantization scheme, a photoelectric quantization device based on light injection semiconductor laser and a method thereof are disclosed, comprising a main laser, an optical attenuator, a first Polarization controller, intensity modulator, analog electrical signal source to be tested, sample and hold circuit, second polarization controller, optical circulator, semiconductor laser, photodetector, power divider, filter array. By means of main laser injection, the semiconductor laser works in a single-cycle oscillation state; the output microwave frequency after photoelectric conversion is related to the light injection intensity, and the mapping from "the amplitude of the signal to be measured" to "the instantaneous frequency of the output microwave" is realized; photoelectric detection The output of the converter is input to the filter array with different bandwidths through the power divider for frequency domain processing to directly realize the quantization and classification. The main advantages of the utility model are: high quantification precision, simple system device and strong controllability.

Description

A photoelectric quantization device based on light injection semiconductor laser

technical field

The utility model discloses a photoelectric quantization device based on light injection semiconductor laser and a method thereof, which relate to the fields of communication, radar and microwave photonics.

Background technique

An analog-to-digital converter (ADC) usually includes three parts: sampling, quantization and encoding, and is widely used in communications, radar, signal processing, and image processing. Due to the limitation of electron carrier mobility, the development of traditional electrical ADC has encountered a bottleneck, which limits the further improvement of its performance. Therefore, researchers have proposed a variety of photonic technology-based optical ADCs to overcome this electronic bottleneck. At present, the research on the sampling part in the optical ADC has been relatively in-depth, and some schemes have been applied. In comparison, there is less research work on quantization and coding, and most schemes still use the electrical method.

At present, the most classic quantization scheme based on photonic technology is to use the transmission response multiplication relationship between multiple Mach-Zehnder modulators (MZM, Mach-Zehnder modulators) connected in parallel for amplitude quantization (see [H.F.Taylor, "An optical analog -to-digital converter-design and analysis", IEEE Journal of Quantum Electronics, vol. 15, no. 4, pp. 210-216, 1979]). However, this scheme requires multiple electro-optic modulators to be cascaded or connected in parallel, the system structure is complex, and the quantization accuracy is limited by the half-wave voltage accuracy of the modulator, making it difficult to achieve high-precision quantization and classification. H.Zmuda and others from the University of Florida used analog electrical signals to drive wavelength-tunable lasers to change the wavelength of the laser's output light, and then used optical filters, scattering gratings or converging lenses to disperse optical signals of different wavelengths to different wavelengths. position, hierarchical quantification by photodetection at the corresponding position (see [H. Zmuda, "Analog-to-digital conversion using high-speed photonic processing", in International Symposium on Optical Science and Technology, 2001, San Diego, United States ]). The low tuning speed of the wavelength tunable laser in this scheme, the nonlinearity that may occur in the tuning process, and the low precision of the optical domain filtering greatly limit the sampling rate and quantization accuracy. The common disadvantage of the existing quantization schemes based on photonic technology is that the quantization accuracy is low, and it is difficult to further improve.

Utility model content

The main purpose of the present utility model is to provide a photoelectric quantization device and method based on light injection semiconductor laser, so as to solve the shortcoming of low quantization accuracy existing in the existing photoquantization scheme, and has the advantages of high speed, high quantization accuracy, simple structure and low cost. and easy-to-implement advantages.

In order to achieve the above purpose, the utility model provides a photoelectric quantization device based on light injection semiconductor laser, comprising: a main laser, an optical attenuator, a first polarization controller, an intensity modulator, an analog electrical signal source to be measured, a sample-and-hold Circuit, second polarization controller, optical circulator, semiconductor laser, photodetector, power divider, parallel filter array;

The optical circulator is provided with a port, b port, and c port;

The intensity modulator is provided with an optical input end, a radio frequency input end, and an optical output end;

The photodetector is provided with an input end and an output end;

The parallel filter array is provided with an input end and an output end;

The power divider is provided with an input end and N output ends, and the optical signal is imported from the input end of the power divider and distributed into N branches and exported from the N output ends. A filter is connected, and the filters in the N branches together form the parallel filter array, wherein N is the number of output ends of the power divider;

The main laser, the optical attenuator, the first polarization controller, the intensity modulator, the second polarization controller, and the port a of the optical circulator are connected in sequence through an optical fiber; the port b of the optical circulator is connected to the semiconductor laser; The c port of the detector is connected to the input end of the photodetector; the analog electrical signal source to be tested, the sample and hold circuit, and the RF input end of the intensity modulator are connected in sequence; the output end of the photodetector is connected to the input end of the power divider; The output end of the power divider is connected with the input end of the parallel filter array; the output end of the parallel filter array is used as the output end of the photoelectric quantization device.

Further, the semiconductor laser is a single-mode distributed feedback semiconductor laser or a distributed Bragg reflection laser without an isolator at the output end.

Further, the semiconductor laser works in a single-cycle oscillation state, the lower limit of the oscillation frequency of the semiconductor laser operating in the single-cycle oscillation state is denoted as f _L , and the upper limit is denoted as f _H , and the tuning range of the single-cycle oscillation frequency of the semiconductor laser is f _L ~ f _H , and the tuning bandwidth is denoted as B, then B=f _H -f _L is satisfied.

Further, the parallel filter array includes N parallel band-pass filters, whose pass-band frequency ranges are (f _L , f _H ), (f _L , f _H -B/N), . . . , (f _L ,f _H -(N-1)B/N).

The operating steps of the above-mentioned photoelectric quantization device for injecting light into a semiconductor laser are as follows:

Step 1. The continuous optical signal generated by the main laser is input to the intensity modulator through the optical attenuator and the first polarization controller, and the insertion loss of the intensity modulator is minimized by controlling the first polarization controller; the bias voltage of the intensity modulator is set Make it work at the linear point; control the second polarization controller to make the injection into the semiconductor laser the highest efficiency; set the output frequency of the main laser and change the light injection intensity by controlling the optical attenuator to make the semiconductor laser work in a single-cycle oscillation state, The tuning range of the single-cycle oscillation frequency of the semiconductor laser is f _L ~ f _H , and the single-cycle oscillation frequency is linearly related to the light injection intensity; the optical signal output by the semiconductor laser generates a single-frequency microwave signal after the photodetector beat frequency, and its frequency is equal to the single-cycle oscillation frequency;

Step 2. The microwave signal output by the analog electrical signal source to be tested is sampled and held by the sample and hold circuit, and then input to the radio frequency end of the intensity modulator to control the light injection intensity, and the amplitude change of the microwave signal to be tested is mapped to step 1. The frequency change of the single-frequency microwave signal output by the photodetector; the output of the photodetector is input to the parallel filter array after passing through the power divider. The parallel filter array includes N parallel bandpass filters, and the passband frequency ranges are in order (f _L ,f _H ), (f _L ,f _H -B/N),…,(f _L ,f _H -(N-1)B/N); depending on the output microwave frequency, the signal will pass through the corresponding The quantization level of the input signal can be determined by judging the position of the band-pass filter through which the signal passes.

The "minimum" in "minimizing the insertion loss of the intensity modulator by controlling the first polarization controller" in the above scheme refers to the minimum value of the insertion loss of the used intensity modulator. "Highest" in "the efficiency of injection into the semiconductor laser is maximized by controlling the second polarization controller" is the maximum value of the efficiency of the semiconductor laser used.

The above letter symbols are only marks made to facilitate the description of the relationship between different components, and can also be replaced by other symbols. The letters themselves do not limit the shape of the structure.

Beneficial effects: The utility model provides a photoelectric quantization device and method based on light injection semiconductor laser. Different from the existing quantization schemes based on photonic technology, this scheme utilizes the single-cycle oscillation state of light injected into the semiconductor laser, and realizes the mapping from "the amplitude of the signal to be measured" to the "instantaneous frequency of the output microwave". Quantitative grading is directly realized. Due to the wide tuning range of the single-cycle oscillation frequency of the optical injection semiconductor laser, the high tuning rate and the high filtering accuracy in the electrical domain, the photoelectric quantization device and method proposed by the present invention have the advantages of high speed, high precision, simple system device and strong controllability. advantage.

Description of drawings

1 is a schematic structural diagram of a photoelectric quantization device based on light injection semiconductor lasers in the present utility model;

Fig. 2 is a graph showing the relationship between light injection intensity and output microwave frequency in a photoelectric quantization device based on light injection semiconductor laser;

Figure 3 is a waveform diagram of the output signal after the analog electrical signal source to be tested passes through the sample-and-hold circuit;

FIG. 4 is a graph showing the instantaneous frequency and quantization result of the output microwave signal.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present utility model more clearly understood, the present utility model will be further described in detail below with reference to the accompanying drawings.

A photoelectric quantization device based on light injection semiconductor laser, as shown in FIG. 1, FIG. 1 is a schematic structural diagram of the photoelectric quantization device based on light injection semiconductor laser, including: a main laser 1, an optical attenuator 2, a first polarization controller 3. Intensity modulator 4, analog electrical signal source to be measured 5, sample and hold circuit 6, second polarization controller 7, optical circulator 8, semiconductor laser 9, photodetector 10, power divider 11, parallel filter array 12;

The main laser 1, the optical attenuator 2, the first polarization controller 3, the intensity modulator 4, the second polarization controller 7, and the port a of the optical circulator 8 are connected in sequence through optical fibers; the port b of the optical circulator 8 is connected in sequence. Connected to the semiconductor laser 9; the c port of the optical circulator 8 is connected to the input end of the photodetector 10; the analog electrical signal source 5 to be tested, the sample and hold circuit 6, and the radio frequency input end of the intensity modulator 4 are connected in sequence; The output end of the power divider 10 is connected to the input end of the power divider 11; the output end of the power divider 11 is connected to the input end of the parallel filter array 12; the output end of the parallel filter array 12 is used as the output end of the photoelectric quantization device.

The optical circulator is provided with a port, b port, and c port;

The intensity modulator is provided with an optical input end, a radio frequency input end and an output end;

The photodetector is provided with an input end and an output end;

An input end and an output end are arranged on the parallel filter array;

The power divider is provided with an input end and N output ends, and the optical signal is imported from the input end of the power divider and distributed into N parallel branches and exported from the N output ends. All are connected with filters, and the filters in the N branches together form the parallel filter array, wherein N is the number of output ends of the power divider;

Further, the semiconductor laser is a single-mode distributed feedback semiconductor laser or a distributed Bragg reflection laser without an isolator at the output end.

Further, the semiconductor laser (9) works in a single-cycle oscillation state, the lower limit of the oscillation frequency of the semiconductor laser working in the single-cycle oscillation state is denoted as f _L , and the upper limit is denoted as f _H , and the single-cycle oscillation frequency tuning range of the semiconductor laser is f _L to f _H , and the tuning bandwidth is denoted as B, then B=f _H -f _L is satisfied. ).

Further, the parallel filter array includes N parallel band-pass filters, whose pass-band frequency ranges are (f _L , f _H ), (f _L , f _H -B/N), . . . , (f _L ,f _H -(N-1)B/N).

FIG. 1 is only a schematic diagram of the connection relationship between various technical features of the device of the present solution, and the shapes of the components in FIG. 1 are only schematic representations thereof, and do not constitute limitations on their shapes and structures.

The specific working principle of the photoelectric quantization device based on the light injection semiconductor laser and the method thereof involved in the present utility model is as follows:

The utility model is mainly based on the single-cycle oscillation nonlinear dynamic state of the light injection semiconductor laser. The frequency detuning and optical injection intensity parameters between the main laser and the semiconductor laser are set, so that the optical injection semiconductor laser system works in a single-cycle oscillation state. At this time, the output optical signal of the semiconductor laser presents a self-sustained single-frequency intensity oscillation; the output signal is photodetected. After the beat frequency, a single-frequency microwave signal can be generated, and the frequency is equal to the single-cycle oscillation frequency. For a given frequency detuning between the main laser and the semiconductor laser, increasing the light injection intensity, the single-cycle oscillation frequency increases approximately linearly. The output of the analog electrical signal source to be tested is loaded onto the intensity modulator after sampling and holding operation to modulate the instantaneous light injection intensity. Therefore, the frequency of the microwave signal output by the photodetector, that is, the single-cycle oscillation frequency, will change with the change of the output signal amplitude of the analog electrical signal source to be measured, and the mapping from "the amplitude of the signal to be measured" to the "instantaneous frequency of the output microwave" is realized. . The output of the photodetector is input to the parallel filter array through the power divider, wherein the passband frequency ranges of the N parallel band-pass filters are (f _L , f _H ), (f _L , f _H -B/N) ,...,(f _L ,f _H -(N-1)B/N); according to the difference of the output microwave frequency of the photodetector, the signal will pass through one or more corresponding bandpass filters to determine the band passed by the signal. The quantization level of the input signal can be determined by passing the filter position. Specifically, taking 4-bit quantization as an example, the amplitude of the electrical signal when the output microwave frequency is f _H -B/4 is selected as the first decision amplitude A _1th , and when the signal amplitude is greater than A _1th , the first decision amplitude of the parallel filter is A 1th . The output is marked as "1", and the output is marked as "0"; when the output microwave frequency is f _H -B/2, the electrical signal amplitude is _selected as the first judgment amplitude A _2th , when the signal amplitude is greater than A _2th , the parallel The second output of the filter is denoted as "1", and smaller than A _2th is denoted as "0"; and so on, the amplitude of the electrical signal when the output microwave frequency is f _H -B is selected as the fourth decision amplitude A _4th , when the signal When the amplitude is greater than A _4th , the fourth output of the parallel filter is recorded as "1", and less than A _4th is recorded as "0". Therefore, when the amplitude of the electrical signal to be measured is greater than A _1th , the quantized output is denoted as (1111); correspondingly, when the amplitude of the electrical signal to be measured is between A _2th ～A _1th , A _3th ～A _2th , A _4th ～A Between the _3th , the quantized output corresponds to (0111), (0011), and (0001) respectively.

The operating steps of the above-mentioned photoelectric quantization device for injecting light into a semiconductor laser are as follows:

Step 1. The continuous optical signal generated by the main laser 1 is input to the intensity modulator 4 through the optical attenuator 2 and the first polarization controller 3, and the insertion loss of the intensity modulator 4 is minimized by controlling the first polarization controller 3; setting the intensity The bias voltage of the modulator 4 makes it work at a linear point; the efficiency of the injection into the semiconductor laser 9 is the highest by controlling the second polarization controller 7; the output frequency of the main laser 1 is set and the light injection intensity is changed by controlling the optical attenuator 2 So that the semiconductor laser 12 works in a single-cycle oscillation state, the tuning range of the single-cycle oscillation frequency of the semiconductor laser 12 is f _L to f _H , and the single-cycle oscillation frequency is linearly related to the light injection intensity; the optical signal output by the semiconductor laser 12 passes through The photodetector 10 generates a single-frequency microwave signal after the beat frequency, and its frequency is equal to the single-cycle oscillation frequency.

Step 2. The microwave signal output by the analog electrical signal source 5 to be tested is sampled and held by the sample and hold circuit 6 and then input to the radio frequency end of the intensity modulator 4 to control the light injection intensity, and the amplitude change of the microwave signal to be measured is mapped as In step 1, the frequency change of the single-frequency microwave signal output by the photodetector 10; the output of the photodetector 10 is input to the parallel filter array 12 after passing through the power divider 11, and the parallel filter array 12 includes N parallel bandpass filters. , its passband frequency range is (f _L , f _H ), (f _L , f _H -B/N), ..., (f _L , f _H -(N-1)B/N); according to the output microwave Depending on the frequency, the signal will pass through one or more corresponding band-pass filters, and the quantization level of the input signal can be determined by judging the position of the band-pass filter through which the signal passes.

In order to verify the effect of the technical solution of the present utility model, experimental verification is carried out. In the experiment, the wavelength of the main laser 1 is 1552.870nm, and the output power is 13.5dBm; the semiconductor laser 9 is a commercial single-mode distributed feedback semiconductor laser, and its free-running wavelength and power are 1552.915nm and 4.98dBm, respectively. The main laser 1 and the semiconductor laser 9 has a frequency difference of 5.6GHz. The optical attenuator 2 is set to make the slave laser work in a single-cycle oscillation state. Figure 2 shows the relationship between the light injection intensity and the output microwave frequency of the photoelectric quantization device based on the light injection semiconductor laser: as the light injection intensity increases, the single-cycle oscillation The frequency, that is, the output microwave frequency of the photodetector 10, increases approximately linearly from f _L =9.6 GHz to f _H =22.1 GHz, and the tuning range is B = 12.5 GHz. The intensity modulator 4 is a Mach-Zehnder modulator with a bandwidth of 10 GHz, biased at the linear point. The microwave signal output by the analog electrical signal source 5 to be tested is sampled and held by the sample and hold circuit 6 to output a multi-level step signal, which is replaced by the signal shown in FIG. 3 in the experiment. The signal shown in FIG. 3 is loaded on the intensity modulator 4, so that the instantaneous frequency of the output microwave varies with the amplitude of the signal to be measured. Figure 4 is a graph of the instantaneous frequency of the output microwave signal, and the four state values of the instantaneous frequency of the microwave are 13.8, 20.8, 17.3, and 10.3 GHz, respectively. N=4 is selected, and the passband frequency ranges of the four band-pass filters of the parallel filter array 12 are set to be 9.6-22.1 GHz, 9.6-18.975 GHz, 9.6-15.85 GHz and 9.6-12.725 GHz, respectively. The output microwave signal of the photodetector 10 is input to the parallel filter array 12 after passing through the power divider 11; according to the difference of the output microwave frequency, the signal will pass through one or more corresponding band-pass filters to determine the band-pass through which the signal passes. The position of the filter can determine the quantization level of the input signal. Figure 4 shows the quantization levels corresponding to the four state values of the microwave instantaneous frequency, and the corresponding encoding results are "0011", "1111", "0111" and "0001" in sequence, that is, 4-bit photoelectric quantization is realized. .

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention, and are not intended to limit the present invention. In the utility model, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims (3)

1. a photoelectric quantization device based on light injection semiconductor laser, is characterized in that, comprises: main laser (1), optical attenuator (2), first polarization controller (3), intensity modulator (4), waiting for Measuring analog electrical signal source (5), sample and hold circuit (6), second polarization controller (7), optical circulator (8), semiconductor laser (9), photodetector (10), power divider (11) ), a parallel filter array (12); The optical circulator is provided with a port, b port, and c port; The intensity modulator is provided with an optical input end, a radio frequency input end, and an optical output end; The photodetector is provided with an input end and an output end; The parallel filter array is provided with an input end and an output end; The power divider is provided with an input end and N output ends. The optical signal is imported from the input end of the power divider and distributed into N branches and derived from the N output ends. Each branch in the N branches All are connected with filters, and the filters in the N branches together form the parallel filter array, wherein N is the number of output ends of the power divider; The main laser (1), the optical attenuator (2), the first polarization controller (3), the intensity modulator (4), the second polarization controller (7), and the a port of the optical circulator (8) pass through The optical fibers are connected in sequence; the b port of the optical circulator (8) is connected to the semiconductor laser (9); the c port of the optical circulator (8) is connected to the input end of the photodetector (10); the analog electrical signal source to be measured ( 5) The radio frequency input ends of the sample and hold circuit (6) and the intensity modulator (4) are connected in sequence; the output end of the photodetector (10) is connected to the input end of the power divider (11); the power divider (11) ) output end is connected with the input end of the parallel filter array (12); the output end of the parallel filter array (12) is used as the output end of the photoelectric quantization device. 2. a kind of photoelectric quantization device based on light injection semiconductor laser according to claim 1, it is characterized in that, described semiconductor laser (9) is the single-mode distributed feedback semiconductor laser or distributed Bragg with no isolator at the output end Reflective laser. 3. a kind of photoelectric quantization device based on light injection semiconductor laser according to claim 1, is characterized in that, described semiconductor laser (9) works in the single-cycle oscillation state, and the semiconductor laser works at the oscillation frequency of the single-cycle oscillation state The lower limit is denoted as f _L , the upper limit is denoted as f _H , the single-cycle oscillation frequency tuning range of the semiconductor laser is f _L to f _H , and the tuning bandwidth is denoted as B, then B=f _H -f _L is satisfied.

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