CN109244823B - Chaotic laser generation method and system with hidden high-bandwidth and time-delay labels - Google Patents
Chaotic laser generation method and system with hidden high-bandwidth and time-delay labels Download PDFInfo
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- CN109244823B CN109244823B CN201811305714.8A CN201811305714A CN109244823B CN 109244823 B CN109244823 B CN 109244823B CN 201811305714 A CN201811305714 A CN 201811305714A CN 109244823 B CN109244823 B CN 109244823B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/005—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping
- H01S5/0085—Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping for modulating the output, i.e. the laser beam is modulated outside the laser cavity
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/12—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
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Abstract
The invention provides a chaotic laser generation method and system with a hidden high-bandwidth and time-delay label. A phase modulation module and a time delay optical fiber interferometer are sequentially added into a feedback cavity of a traditional external cavity semiconductor laser. And performing photoelectric conversion and amplification on the output chaotic laser to be used as radio frequency input of a phase modulator to form a self-chaotic phase modulation structure. The method has the beneficial effects of simultaneously realizing the generation of the broadband chaotic laser, the hiding of the time delay label and the symmetrical amplitude distribution.
Description
Technical Field
The invention relates to a broadband chaotic laser generation scheme, in particular to a chaotic laser generation method and system with a hidden high-bandwidth and time-delay label.
Background
The chaotic laser has important application in the fields of secret communication, high-speed physical random number generation, high-resolution anti-interference radar detection and the like. The wide-band wide-amplitude chaotic laser is used as a carrier wave for hiding information, and then chaotic synchronization is used for carrying out information demodulation, so that the encrypted communication of high-speed information can be realized; due to the characteristics of high bandwidth and large amplitude noise-like of the chaotic laser, the chaotic laser is used as a new generation of physical entropy source to solve the problem of insufficient real-time generation rate of physical random numbers; the radar system is constructed by using the broadband chaotic laser as a signal source, so that the range resolution of target detection can be effectively improved.
The external cavity semiconductor laser becomes the most common light source for chaotic laser generation and application due to the advantages of simple structure, convenient operation, easy integration and the like. However, after intensive research, the researchers found that the chaotic laser generated by the external cavity semiconductor laser has some defects that (1) the external cavity semiconductor laser has obvious relaxation oscillation, and the main energy of the chaotic laser is concentrated near the relaxation oscillation frequency from the observation of a power spectrum, thereby limiting the effective bandwidth and the flatness of the power spectrum; (2) due to the existence of external cavity resonance, an obvious correlation peak appears on the generated autocorrelation curve of the chaotic signal at the external cavity period, and the characteristic is called as a time delay label; (3) the chaotic laser generated by the external cavity semiconductor laser has unbalanced amplitude oscillation, and the amplitude distribution is obviously asymmetric. The presence of these defects limits practical applications. In secret communication, the bandwidth of chaotic laser is only several GHz due to relaxation oscillation, and the limited bandwidth can limit the transmission rate of chaotic optical communication; meanwhile, the time delay characteristic reveals the length of an external cavity, so that an interception party can reconstruct a chaotic carrier signal by using the key structure information, further crack transmitted information and weaken the safety of a communication system. In physical random number generation, the limited entropy source bandwidth limits the rate at which physical random numbers are generated; the randomness and the balance ratio of 0 and 1 bit are respectively deteriorated by the time delay characteristic and the asymmetrical amplitude distribution, and complex subsequent processing needs to be utilized for optimization. In the aspect of radar detection, limited bandwidth limits the improvement of the detection distance resolution of the chaotic laser; the time delay feature also reduces the security and anti-interference capability of the radar system.
Disclosure of Invention
Aiming at the problems, the invention provides a method for generating broadband chaotic laser. The chaotic signal generated by the method has a high-broadband power spectrum and symmetrical amplitude distribution, and the time delay label can be effectively inhibited.
In order to achieve the above object, the present invention provides a method for generating chaotic laser with high bandwidth and hidden delay label, specifically, a phase modulation module and a delay interferometer are sequentially added in a feedback loop of a traditional External Cavity Semiconductor Laser (ECSL); the output light of the time delay interferometer is divided into two paths: one path of light is used as feedback light and is injected back to the laser after passing through the attenuator; the other path is further divided into two sub-paths: a sub-circuit is converted into an electric domain chaotic signal through a photoelectric detector, and the electric domain chaotic signal is amplified by an amplifier and then is used as the radio frequency input of the phase modulation module to form self-chaotic phase modulation; and the other sub-path is used as the finally generated broadband chaotic laser.
Preferably, the output light of the DFB laser passes through an optical circulator and then is input into a phase modulation module for electro-optic phase modulation, and the output light of the phase modulation module is input into a time-delay interferometer composed of two sections of optical fibers with different lengths.
Preferably, the output of the time-delay interferometer is split into two parts via an optical coupler.
Preferably, one path of output of the time-delay interferometer passes through the attenuator and the optical circulator and then is injected back to the laser to serve as a feedback optical signal.
Preferably, the phase modulation module is a common electro-optical phase modulator.
Preferably, the phase modulation module may employ a mach-zehnder modulator (MZM) or an electro-optic phase modulator.
Preferably, the time-delay interferometer may be a mach-zehnder interferometer (MZI), a polarization interferometer, a Sagnac interferometer, a Michelson interferometer or a Fabry-Perot interferometer.
Meanwhile, the invention also provides a chaotic laser generating system with a hidden high-bandwidth and time-delay label, which comprises a first signal loop and a second signal loop: the first signal loop comprises a DFB laser, an optical circulator, a phase modulator, a time delay interferometer and an optical attenuator; the second signal loop is a radio frequency signal loop formed by a photoelectric detector and an electronic amplifier;
the output light of the DFB laser passes through an optical circulator and then is input into a phase modulator for electro-optic phase modulation, the output light of the phase modulator is input into a time delay interferometer composed of two sections of optical fibers with different lengths, and the output of the time delay interferometer is divided into two parts by an optical coupler; one part of the light beam passes through the attenuator and the optical circulator in sequence and then is injected back to the laser to be used as a feedback optical signal; the other part is divided into two sub-optical signals through the optical coupler again: one sub-circuit is used as the finally generated broadband chaotic laser, and the other sub-circuit is converted into an electric signal through a photoelectric detector and then is amplified through an electronic amplifier to be used as the radio frequency input of the phase modulator.
Drawings
FIG. 1 is a schematic structural view of the present invention.
Fig. 2 a power spectrum of a chaotic signal generated by a general ECSL.
Fig. 3 shows a scheme for generating a power spectrum of a chaotic signal.
Fig. 4 shows the amplitude distribution of a chaotic signal generated by a general ECSL.
Fig. 5 shows the amplitude distribution of the chaotic signal generated by the proposed scheme of the present invention.
Fig. 6 the general ECSL generates an autocorrelation function of the chaotic signal.
Fig. 7 illustrates the time-delay mutual information of chaotic signals generated by a general ECSL.
Fig. 8 shows the permutation entropy of the chaotic signal generated by the general ECSL.
Fig. 9 shows a scheme for generating an autocorrelation function of a chaotic signal.
Fig. 10 shows a scheme for generating time-delay mutual information of chaotic signals.
FIG. 11 shows a scheme for generating permutation entropy of chaotic signals.
In the figure: DFB: a DFB laser; PM: a phase modulator; OC: an optical circulator; PC, polarization controller; FC: a fiber coupler; PD: a photodetector; amp is an electronic amplifier; DL: an optical fiber delay line; VOA: a variable optical attenuator.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the embodiments of the present invention are described in further detail below with reference to the accompanying drawings.
As shown in fig. 1, the solution proposed by the present invention comprises a first signal loop and a second signal loop: the first signal loop consists of a DFB laser, an optical circulator, a phase modulator and a time delay interferometer MZI; the second signal loop is a radio frequency signal loop formed by a photoelectric detector and an electronic amplifier.
The output light of the DFB laser passes through an optical circulator and then is input into a phase modulator for electro-optic phase modulation, the output light of the phase modulator is input into a time delay interferometer composed of two sections of optical fibers with different lengths, and the output of the time delay interferometer is divided into two parts by an optical coupler. One part of the light beam passes through the attenuator and the optical circulator in sequence and then is injected back to the laser to be used as a feedback optical signal; the other part is divided into two optical signals through the optical coupler again: one path of the chaotic laser is used as finally generated broadband chaotic laser, and the other path of the chaotic laser is converted into an electric signal through a photoelectric detector and then is amplified by an electronic amplifier to be used as radio frequency input of a phase modulator.
The broadband chaotic laser generation scheme provided by the invention has the following benefits: (1) the broadband spectrum has high bandwidth and high spectrum flatness; (2) the time delay characteristic of the external cavity semiconductor laser caused by external cavity feedback is eliminated; (3) the symmetry of the amplitude distribution is significantly improved. Therefore, when the method is applied to secret communication, the transmission rate and the safety of the chaotic carrier can be improved. The broadband chaos is applied to random numbers and serves as a physical entropy source of a random number generator, the rate of generating the random numbers can be increased, and a complex post-processing method is not needed to eliminate the influence of time delay characteristics. In addition, the distance resolution of radar detection can be improved by adopting the broadband chaotic signal, and meanwhile, the safety and the anti-interference capability of a radar system are improved by eliminating the time delay characteristic.
Examples
Fig. 2-5 show the implementation of bandwidth enhancement and amplitude distribution improvement of chaotic laser. We use 80% of the energy of the power spectrum as the effective bandwidth. As shown in fig. 2, in general, the chaotic signal generated by ECSL has an effective bandwidth of only several GHz because the main frequency components are concentrated near the relaxation oscillation frequency. As shown in fig. 3, the power spectrum is obviously broadened and the effective bandwidth is increased to 26GHz by the scheme of the present invention. Furthermore, the effective bandwidth in the results here is mainly limited by the bandwidth of the electronics (photodetector and cable) in the experiment. Therefore, when an electronic device with a higher bandwidth is used, the bandwidth of the actual chaotic signal is wider. In addition, as shown in fig. 4, the amplitude distribution function of the chaotic signal output by the conventional ECSL shows a significant asymmetry, which is particularly reflected in that the oscillation amplitude is not symmetric about the mean value. As shown in fig. 5, the amplitude distribution of the chaotic signal generated by the scheme of the present invention is significantly improved, and exhibits a symmetrical distribution like gaussian distribution.
Fig. 6-11 show the implementation of the time-delay label elimination, and we use the autocorrelation function (ACF), the time-Delay Mutual Information (DMI), and the Permutation Entropy (PE) to compare the elimination results. As shown in fig. 6 to 8, for chaotic signals generated by general ECSL, a significant correlation peak occurs at the feedback delay. As shown in fig. 9-11, the delay characteristic of the external cavity feedback is effectively eliminated by the proposed scheme of the present invention.
In summary, the broadband chaotic laser generation scheme provided by the invention has the following benefits: (1) the broadband spectrum has high bandwidth and high spectrum flatness; (2) the time delay characteristic of the external cavity semiconductor laser caused by external cavity feedback is eliminated; (3) the symmetry of the amplitude distribution is significantly improved. Therefore, when the method is applied to secret communication, the transmission rate and the safety of the chaotic carrier can be improved. The broadband chaos is applied to random numbers and serves as a physical entropy source of a random number generator, the rate of generating the random numbers can be increased, and a complex post-processing method is not needed to eliminate the influence of time delay characteristics. In addition, the distance resolution of radar detection can be improved by adopting the broadband chaotic signal, and meanwhile, the safety and the anti-interference capability of a radar system are improved by eliminating the time delay characteristic.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.
The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (5)
1. A chaotic laser generation method for hiding a high-bandwidth and time-delay label is characterized by comprising a first signal loop and a second signal loop: the first signal loop comprises a DFB laser, an optical circulator, a phase modulator, a time delay interferometer and an optical attenuator; the second signal loop is a radio frequency signal loop formed by a photoelectric detector and an electronic amplifier; in a feedback loop of a conventional External Cavity Semiconductor Laser (ECSL), the phase modulator and the time delay interferometer are sequentially added, specifically including: the output light of the DFB laser passes through a polarization controller PC1 and then passes through an optical circulator, then is input into the phase modulator for electro-optic phase modulation, and the output light of the phase modulator is input into the time-delay interferometer; the output light of the time-delay interferometer is divided into two paths through an optical coupler FC 3: one path of feedback light is fed back to the optical circulator after passing through the attenuator and is further injected back to the DFB laser to serve as a feedback light signal; the other path is further divided into two sub-optical signals through the optical coupler again: a sub-circuit is converted into an electric domain chaotic signal after passing through the photoelectric detector, and the electric domain chaotic signal is amplified by an electronic amplifier and then is used as the radio frequency input of the phase modulator to form self-chaotic phase modulation; the other sub-path is used as a finally generated broadband chaotic signal; the delay interferometer is a delay interferometer with a double-arm structure, wherein the delay interferometer is composed of an optical fiber coupler FC1, a polarization controller PC2, an optical fiber delay line DL and an optical fiber coupler FC2, one arm of the delay interferometer passes through the optical fiber delay line DL, and the other arm of the delay interferometer passes through the polarization controller PC 2.
2. The method for generating the chaotic laser with the high bandwidth and the hidden time delay label according to claim 1, wherein the time delay interferometer is composed of two sections of optical fibers with different lengths.
3. The method for generating the chaotic laser with high bandwidth and hidden time delay label according to claim 1, wherein the phase modulator is a Mach-Zehnder modulator (MZM) or an electro-optic phase modulator.
4. The method of claim 1, wherein the delay interferometer is a Mach-Zehnder interferometer (MZI), a polarization interferometer, a Sagnac interferometer, a Michelson interferometer, or a Fabry-Perot interferometer.
5. A chaotic laser generation system with hidden high-bandwidth and time-delay labels is characterized by comprising a first signal loop and a second signal loop: the first signal loop comprises a DFB laser, an optical circulator, a phase modulator, a time delay interferometer and an optical attenuator; the second signal loop is a radio frequency signal loop formed by a photoelectric detector and an electronic amplifier;
the output light of the DFB laser passes through a polarization controller PC1, then passes through an optical circulator, and then is input into a phase modulator for electro-optic phase modulation, the output light of the phase modulator is input into a time delay interferometer composed of two sections of optical fibers with different lengths, and the output light of the time delay interferometer is divided into two paths through an optical coupler FC 3: one path of feedback light is fed back to the optical circulator after passing through the attenuator and is injected back to the DFB laser to serve as a feedback light signal; the other path is further divided into two sub-optical signals through the optical coupler again: a sub-circuit is converted into an electric domain chaotic signal after passing through the photoelectric detector, and the electric domain chaotic signal is amplified by an electronic amplifier and then is used as the radio frequency input of the phase modulator to form self-chaotic phase modulation; the other sub-path is used as finally generated broadband chaotic laser;
the delay interferometer is a delay interferometer with a double-arm structure, wherein the delay interferometer is composed of an optical fiber coupler FC1, a polarization controller PC2, an optical fiber delay line DL and an optical fiber coupler FC2, one arm of the delay interferometer passes through the optical fiber delay line DL, and the other arm of the delay interferometer passes through the polarization controller PC 2.
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| CN110112646B (en) * | 2019-04-17 | 2020-08-28 | 电子科技大学 | Method and system for generating chaos laser signal with hidden time delay label |
| CN110571641B (en) * | 2019-08-27 | 2020-10-27 | 太原理工大学 | Method and device for suppressing chaotic time delay by using broadband spontaneous emission quantum noise |
| CN111653932A (en) * | 2020-05-14 | 2020-09-11 | 太原理工大学 | Chaotic laser device based on light injection amplified spontaneous emission suppression time delay |
| CN113595729B (en) * | 2021-04-21 | 2023-08-08 | 电子科技大学 | Multi-path physical random number generation method and system based on broadband laser chaotic source |
| CN115037374B (en) * | 2022-04-28 | 2023-07-07 | 苏州大学 | Broadband double-path polarized chaotic laser generation method and device |
| CN117199991B (en) * | 2023-06-30 | 2024-07-12 | 无锡芯光互连技术研究院有限公司 | Chaotic laser, multi-optical path introducing assembly and integrated chip thereof |
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