CN115184943A - Terahertz radar detection method and system based on photon technology - Google Patents
Terahertz radar detection method and system based on photon technology Download PDFInfo
- Publication number
- CN115184943A CN115184943A CN202210705255.2A CN202210705255A CN115184943A CN 115184943 A CN115184943 A CN 115184943A CN 202210705255 A CN202210705255 A CN 202210705255A CN 115184943 A CN115184943 A CN 115184943A
- Authority
- CN
- China
- Prior art keywords
- signal
- optical
- frequency
- terahertz
- receiving
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/4802—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/483—Details of pulse systems
- G01S7/484—Transmitters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/483—Details of pulse systems
- G01S7/486—Receivers
- G01S7/487—Extracting wanted echo signals, e.g. pulse detection
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/491—Details of non-pulse systems
- G01S7/4911—Transmitters
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/491—Details of non-pulse systems
- G01S7/493—Extracting wanted echo signals
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Electromagnetism (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The invention discloses a terahertz radar detection method and a system based on a photon technology, wherein a wavelength selection module is used for selecting two comb teeth, one of the comb teeth is divided into an upper path and a lower path, a baseband signal inhibits the modulation of a carrier single-side band on the comb teeth on the upper path of light to obtain a sweep frequency optical signal, and then the sweep frequency optical signal and the light frequency are combed into a composite optical signal by the other comb teeth; a part of the composite optical signal is converted into a terahertz signal by a photoelectric detector and then radiated into a target environment, a receiving unit receives a target echo signal and then down-converts the signal by a harmonic mixer to obtain a baseband echo signal, and the baseband echo signal modulates a down-path comb tooth to obtain a received optical signal; and the received optical signal and the other part of the composite optical signal are sent to a coherent receiving module to realize coherent receiving, an intermediate frequency signal carrying target information is obtained, and the detected target information can be extracted through an algorithm. According to the terahertz radar signal receiving device, photon generation and real-time coherent reception of terahertz radar signals are achieved through the same reference source synchronous optical frequency comb and the harmonic mixer, the radar system parameters are flexible and adjustable, and the anti-interference capability is strong.
Description
Technical Field
The invention relates to a radar detection method, in particular to a micro terahertz radar detection method and system based on a photon technology.
Background
The multi-dimensional high-resolution radar is widely applied to the military and civil fields, and has respective advantages when working in different frequency bands based on the electromagnetic wave scattering characteristic and the medium propagation characteristic. Related technologies of microwave frequency band radar are widely developed, and the terahertz frequency band radar is limited by the development of terahertz devices, in particular to a terahertz radar system which covers a wide terahertz frequency spectrum space, is flexible and adjustable in working wave band and can process and analyze signals in real time and at high precision. Currently, a terahertz Radar system is mainly implemented based on frequency doubling and up-conversion of a microwave baseband signal, but is limited by the problems of potential intermodulation/harmonic interference, impedance matching, amplitude/phase nonlinearity and the like when a current radio frequency amplification, frequency doubling, frequency mixing and transmission link carry the functions of generation, sampling, processing and the like of a broadband signal, and the performance of the terahertz Radar system is seriously affected (see [ m.caris, s.stanko, s.palm, et al.300ghz Radar for high resolution SAR and ISAR applications.2015 1uth International Radar symposium, dresden,2015,577-580 ]). Thanks to the rapid development of microwave photon technology, the optical domain generation, transmission and processing of microwave signals can solve the problem that the traditional electric domain can not be processed, such as photon frequency mixing, photon frequency doubling, photon true delay, photon coherent reception and the like, so as to overcome the electronic bottleneck problem of the traditional radar, improve the technical performance, provide a new technical support, and become the key technology of the next generation of radar (see [ Ghelfi P, laghezza F, scotti F, et al. A full photonic-based coherent radar system [ J ] Nature,2014,507 (7492): 341-345 ]. Particularly, the bottleneck problem limiting the development of the terahertz radar can be solved based on the photon technology. Technologies such as broadband radar detection signal generation based on photon frequency doubling technology and broadband radar echo signal real-time receiving and processing based on photon frequency mixing technology have been used in new radar receiving technologies (see Zhang F, guo Q, zhang Y, et al, photonics-based real-time and high-resolution ISAR imaging of non-coherent target [ J ]. Chinese Optics Letters,2017,15 (11): 112801.). However, the scheme for realizing terahertz radar signal generation based on the photon frequency doubling technology at present has the following problems: 1) The frequency multiplication factor for realizing optical frequency multiplication based on a special modulator is limited and cannot be flexibly adjusted; 2) Because of the overlapping of the high-order sidebands, it is difficult to achieve spurious-free terahertz band signal generation. 3) The signal generation mode limits that most radar signal receiving schemes are difficult to receive broadband target echo signals through coherent reception.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method overcomes the defects in the prior art, realizes generation of a terahertz radar transmitting signal with a reconfigurable waveband through selection of optical frequency comb teeth, and realizes real-time orthogonal deskew of a terahertz radar echo signal based on clock synchronization locking and photon coherent receiving technology. The system is flexible and adjustable, and the anti-interference performance is excellent.
The invention specifically adopts the following technical scheme to solve the technical problems:
first, an optical frequency comb generator generates a repetition frequency f LO The optical frequency comb signal is amplified and then sent to a wavelength selection module, the wavelength selection module selects two comb teeth with different frequencies from the optical frequency comb signal respectively, one comb tooth is divided into an upper path and a lower path, and a baseband signal f LFM The method comprises the steps that carrier single-sideband modulation is suppressed on an upper comb optical signal to obtain a sweep optical signal, and the sweep optical signal and another comb optical signal are combined into a composite optical signal; after the composite optical signal is divided into two paths, one path of composite optical signal is converted into frequency (M + N) f through a radar transmitting unit LO +f LFM And radiating the terahertz signal into a target environment (M, N are integers); the method comprises the following steps that a radar receiving unit receives a terahertz radar echo signal, then the terahertz radar echo signal is subjected to down-conversion through a harmonic mixer to obtain a baseband receiving signal, and the baseband receiving signal is amplified through a low-noise amplifier and then modulates a comb tooth optical signal of a next path to obtain a receiving modulation optical signal; and the received modulated optical signal and the other path of composite optical signal are sent to a coherent receiving module to realize coherent reception, an intermediate frequency signal carrying target information is obtained, and the intermediate frequency signal is analyzed through an algorithm to obtain the detection target information.
Preferably, the optical-frequency comb generator may be a mode-locked laser, a femtosecond laser, a micro-ring optical-frequency comb generator, or an externally modulated optical-frequency comb generator; wherein the fundamental frequency and optical frequency comb repetition frequency f of the harmonic mixer LO And the optical frequency comb generator and the harmonic mixer are synchronized by the same reference signal.
Further, the wavelength selection module is specifically a light beam shaper, a dual laser injection locking device, an optical filter and the like; the positions of two comb teeth with different frequencies can be controlled by controlling the working state of the wavelength selection module, and then the working waveband of the terahertz signal, namely the terahertz signal (M + N) f is coarsely regulated and controlled LO +f LFM Medium size of M + N.
Further, the baseband signal f LFM Is not influenced by the repetition frequency f of the optical frequency comb signal LO By controlling the baseband signal f LFM The working frequency and the bandwidth of the terahertz signal can be finely adjusted.
The following technical scheme can be obtained according to the same invention concept:
a terahertz radar detection system based on photonic technology, comprising:
an optical frequency comb generator for generating a frequency interval of f LO The optical frequency comb signal of (a);
the reference signal source is used for generating reference signals for the optical frequency comb generator and the receiving unit;
the optical amplifier is used for amplifying the optical frequency comb signal generated by the optical frequency comb generator;
the wavelength selection module is used for respectively selecting two comb tooth signals with different frequencies from the optical frequency comb signals and respectively outputting the two comb tooth signals;
the first optical coupler is used for dividing a comb optical signal into an upper path and a lower path, and respectively sending the upper path and the lower path to the first electro-optical modulator and the second electro-optical modulator;
baseband signal source for generating a frequency f LFM The baseband chirp signal of (1);
the first electro-optical modulator is used for modulating a baseband signal to a comb optical signal input to the first electro-optical modulator to obtain a sweep frequency optical signal;
the second optical coupler is used for combining the frequency sweeping optical signal and the other comb tooth signal output by the wavelength selection module into a composite optical signal, dividing the composite optical signal into an upper path and a lower path, sending the upper path composite optical signal to the transmitting unit, and sending the lower path composite optical signal serving as a reference optical signal to one input end of the coherent receiving module;
the transmitting unit is used for converting the composite optical signal into a terahertz signal and radiating the terahertz signal to a target environment;
a receiving unit; the system comprises a receiver, a processing unit and a processing unit, wherein the receiver is used for receiving a terahertz radar echo signal and converting the terahertz radar echo signal into a baseband receiving signal through down-conversion;
the low noise amplifier is used for amplifying the baseband receiving signal;
the second electro-optical modulator is used for modulating the baseband receiving signal amplified by the low-noise amplifier to the comb-teeth optical signal input to the second electro-optical modulator to obtain a receiving modulation optical signal and sending the receiving modulation optical signal to the other receiving end of the coherent receiving module;
the coherent receiving module is used for realizing coherent fusion detection of the reference optical signal and the receiving modulation optical signal in an optical domain to obtain two paths of orthogonal intermediate frequency signals carrying target information;
and the acquisition processing module is used for performing analog-to-digital conversion on the two paths of orthogonal intermediate frequency signals, performing radar digital signal processing and extracting target information.
Further, the transmitting unit includes:
the unidirectional carrier detector is used for converting the composite optical signal into a terahertz signal;
the terahertz emission amplifier is used for amplifying the terahertz signal output by the unidirectional carrier detector;
the terahertz transmitting antenna is used for transmitting the amplified terahertz signal to obtain a terahertz radar detection signal;
further, the receiving unit includes:
the terahertz receiving antenna is used for receiving a terahertz radar echo signal;
the terahertz receiving amplifier is used for amplifying the terahertz radar echo signal received by the terahertz receiving antenna;
the harmonic mixer is used for down-converting the terahertz radar echo signal into a baseband receiving signal;
preferably, the optical frequency comb generator may be a mode-locked laser, a femtosecond laser, a micro-ring optical frequency comb generator, an external modulation optical frequency comb generator, or the like; wherein the fundamental frequency and optical frequency comb repetition frequency f of the harmonic mixer LO And the optical frequency comb generator and the harmonic mixer are synchronized by the same reference signal.
Further, the wavelength selection module is embodied as a light beam shaper, a dual laser injection locking, an optical filter, and the like.
Further, the first electro-optical modulator is a double parallel mach-zehnder modulator, and the second electro-optical modulator is a mach-zehnder modulator, a phase modulator, a double parallel modulator, or the like.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1) The signal generation part realizes the adjustment of the working waveband of the terahertz radar signal based on the frequency selection of the optical frequency comb, can flexibly realize the adjustment of the terahertz radar signal in the terahertz waveband width based on the rich frequency spectrum characteristics of the optical frequency comb, and has no limitation of the radar working bandwidth by the repetition frequency of the optical frequency comb.
2) The signal receiving part of the invention realizes the terahertz radar echo signal receiving by combining the harmonic mixer with the optical coherence technology, can realize the coherent receiving of broadband terahertz signals in the optical domain, and can effectively inhibit system noise and image frequency interference signals.
3) The invention provides reference signals for the optical frequency comb generator and the harmonic mixer simultaneously based on a single high-performance reference signal, and ensures that the fundamental frequency signal participating in down-conversion of the harmonic mixer is strictly coherent with the terahertz radar signal, thereby ensuring the strictly coherent reception of the radar echo signal and improving the stability and the signal-to-noise ratio of a radar system.
Drawings
FIG. 1 is a schematic diagram of a terahertz radar system of the present invention;
FIG. 2 is a block diagram of one embodiment of a terahertz radar of the present invention;
FIG. 3 is a schematic diagram of a spectrum and a signal generated at a corresponding node in the terahertz radar system shown in FIG. 2;
the spectrum distribution of the output optical signal of the mode-locked laser is corresponded by A, the spectrum distribution of the composite optical signal is corresponded by B, the spectrum distribution of the emission signal of the terahertz radar is corresponded by C, the spectrum distribution of the base band echo signal is corresponded by D, the spectrum distribution of the radar receiving optical signal is corresponded by E, the spectrum diagram of the reference composite optical signal fused with the radar receiving optical signal is corresponded by F, and the spectrum of the intermediate frequency signal in a complex form is corresponded by G.
Detailed Description
Aiming at the defects of the prior art, the method is based on rich spectrum components of an optical frequency comb, the generation of a band-reconfigurable terahertz radar signal is realized through a wavelength selection technology, the down-conversion of a terahertz radar echo signal is realized based on a stable reference signal, and the coherent reception of the radar echo signal is realized based on a photon coherent reception method. The radar has the advantages of flexible and adjustable working parameters, real-time and high-efficiency signal processing and strong anti-stray capacity.
The terahertz radar detection system based on the photon technology specifically comprises, as shown in fig. 1, the following components: the device comprises an optical frequency comb generator, an optical amplifier, a wavelength selection module, a baseband signal source, a reference signal source, a first electro-optical modulator, a second electro-optical modulator, a 1 x 2 optical coupler (OC 1), a 2 x 2 optical coupler (OC 2), a transmitting unit, a receiving unit, a coherent receiving module, an acquisition processing module, a Low Noise Amplifier (LNA) and the like.
First, an optical frequency comb generator generates a repetition frequency f LO The optical frequency comb signal is amplified by an optical amplifier and then sent to a wavelength selection module, the wavelength selection module selects two comb tooth optical signals with different frequencies from the optical frequency comb signal respectively, one comb tooth optical signal is divided into an upper path and a lower path, and a baseband signal f generated by a baseband signal source LFM The method comprises the steps that single-sideband modulation of a carrier is suppressed on an upper comb tooth optical signal passing through a first electro-optical modulator to obtain a frequency sweeping optical signal, and the frequency sweeping optical signal and another comb tooth optical signal are combined into a composite optical signal; after the composite optical signal is divided into two paths, one path of composite optical signal is converted into a frequency of (M + N) f through a radar transmitting unit LO +f LFM And radiating the terahertz signal into a target environment (M, N are integers); the radar receiving unit receives the terahertz radar echo signal, down-converts the terahertz radar echo signal through the harmonic mixer to obtain a baseband receiving signal, and modulates the next comb tooth optical signal through the second electro-optical modulator after the baseband receiving signal is amplified through the low-noise amplifier to obtain a receiving modulation optical signal; the receiving modulation optical signal and the other path of composite optical signal are sent to a coherent receiving module to realize coherent receiving, and an intermediate frequency signal carrying target information is obtained.
To facilitate understanding of the public, the technical solution of the present invention is further described in detail by a specific embodiment.
It should be noted that the second electro-optical modulator may adopt various modulator types, and preferably, the embodiment selects a mach-zehnder modulator scheme; the optical frequency comb generator can adopt various devices, and a mode-locked laser is selected in the embodiment; the wavelength selection module can adopt various devices, and the embodiment prefers a beam shaper.
As shown in fig. 2, the terahertz radar system of the present embodiment includes: the optical fiber signal receiving and transmitting system comprises 1 mode-locked laser, 1 optical amplifier, 1 beam shaper, 1 baseband signal source, 1 reference signal source, 1 double parallel Mach-Zehnder modulator (double parallel MZM), 1 Mach-Zehnder modulator (MZM), 1 x 2 optical coupler (OC 1), 1 x 2 optical coupler (OC 2), 1 unidirectional carrier detector (UTC-PD), 2 terahertz amplifiers (TTA, TRA), 2 terahertz antennas (Tx, rx), 1 harmonic mixer, 1 Low Noise Amplifier (LNA), 1 coherent receiving module and 1 acquisition and processing module.
The terahertz radar detection system firstly refers to a signal source with the output frequency f LO The reference signal is input to the clock input end of the mode-locked laser to enable the mode-locked laser to work in a mode-locked state, and the output frequency interval of the mode-locked mode laser is f LO The optical frequency comb signal of (1), the spectrum of which is shown as A in FIG. 3, wherein f C Is an optical carrier. The optical frequency comb signal is sent into an optical amplifier for amplification, then sent into a beam shaper, a filter response curve of the beam shaper is set, and the two output ends of the beam shaper respectively output the frequency f C -Mf LO And f C +Nf LO One of the two comb-teeth optical signals is selected to be sent into a 1X 2 optical coupler to be divided into an upper path and a lower path, and the upper path and the lower path are divided into two paths by a comb-tooth f C +Nf LO For example. The comb signals are sent to a double parallel Mach-Zehnder modulator, and the frequency generated by a baseband signal source is f LFM ＝f 0 The baseband linear frequency modulation signal of + kt (T is more than or equal to 0 and less than or equal to T) carries out carrier-restraining single-sideband modulation on the comb optical signal through a double-parallel Mach-Zehnder modulator, wherein f 0 Obtaining a swept-frequency optical signal for the initial frequency of the baseband chirp signal, k is the chirp rate, and T is the period, where the swept-frequency optical signal is a positive-order swept-frequency sideband or a negative-order swept-frequency sideband, and here, the positive-order swept-frequency sideband is taken as an example, and the instantaneous frequency is f C +Nf LO +f LFM The time domain can be represented as:
S T (t)＝Aexp[j2π(f C +Nf LO +f 0 +0.5kt)t] (0≤t≤T) (1)
where A is the signal electric field amplitude. The frequency sweep optical signal and the frequency are f C -M f LO The optical signals of the comb teeth are combined into a path through a 2 multiplied by 2 optical coupler to obtain a composite optical signal,the composite optical signal spectrum is shown at B of figure 3. The 2 x 2 optical coupler divides the composite optical signal into two paths, one path is used as a transmitting optical signal and sent to the transmitting unit, and the other path is used as a reference optical signal and sent to an optical input end of the coherent receiving module. After the light-terahertz signal conversion of the transmitting signal transmitted into the transmitting unit is completed through the one-way carrier detector, the obtained terahertz signal is transmitted into a Terahertz Transmitting Amplifier (TTA) to be amplified, and the amplified terahertz signal is transmitted into a terahertz transmitting antenna (Tx) to be transmitted and radiated to a target environment as a terahertz radar transmitting signal. The spectrogram of the terahertz radar transmission signal is shown in C of FIG. 3. The terahertz radar receiving method comprises the steps that a terahertz radar transmitting signal meeting a target is reflected to obtain a terahertz radar echo signal, the terahertz radar echo signal is received through a terahertz receiving antenna (Rx) of a receiving unit, amplified through a Terahertz Receiving Amplifier (TRA) and sent to a harmonic mixer. The other path of reference signal output by the reference signal source is input to a fundamental frequency input port of a harmonic mixer of the receiving unit, frequency multiplication is carried out in the harmonic mixer to obtain a frequency (M + N) f LO The harmonic terahertz signal is mixed with the terahertz radar echo signal to obtain a down-converted baseband receiving signal, and the frequency spectrum of the down-converted baseband receiving signal is shown as D in fig. 3. The time domain can be represented as:
S Tr (t)＝Bexp[j2π(f 0 (t-τ)+0.5k(t-τ) 2 )] (0≤t≤T) (2)
wherein, B is the amplitude of the electric field of the signal, and tau is the time delay of the echo signal of the terahertz radar relative to the emission signal of the terahertz radar. The baseband receiving signal is amplified by a low-noise amplifier and then the instantaneous frequency is adjusted to be f by a Mach-Zehnder modulator C +Nf LO The received modulated optical signal is obtained, and its spectral diagram is shown as E in fig. 3, and its time domain can be expressed as:
S R (t)＝A- 1 exp[j2π((f C +Nf LO -f 0 )(t-τ)-0.5k(t-τ) 2 )]+A 0 exp[j2π((f C +Nf LO )(t-τ))]+A 1 exp[j2π((f C +Nf LO +f 0 )(t-τ)+0.5k(t-τ) 2 )(0≤t≤T) (3)
wherein A- 1 、A 0 And A 1 The amplitude of the sideband signal electric field is negative first order, carrier wave and positive first order. The received optical signal is sent to the other optical receiving end of the coherent receiving module, the received optical signal and the reference optical signal are fused in the optical domain, and the positive first-order sideband of the received optical signal coincides with the reference optical signal, and the spectrum of the received optical signal is shown as F in fig. 3. The instantaneous frequency difference of the overlapped part is kt t, after the receiving optical signal and the reference optical signal are coherently received in the coherent receiving module, two orthogonal intermediate frequency signals can be obtained at two output ends of the coherent receiving module, and the intermediate frequency electrical signal can be represented as:
i.e. two orthogonal components S of the intermediate frequency signal carrying the target information I (t)、S Q (t), where φ is the phase information of the intermediate frequency signal, corresponding to a complex form of the signal:
S IF (t)＝S I (t)+jS Q (t)＝Cexp[j2πkτt+jφ] (0≤t≤T) (5)
and C is the amplitude of the complex intermediate frequency signal, and after the intermediate frequency signal is subjected to analog-to-digital conversion, information such as target distance, speed, scattering characteristics and the like can be obtained based on a radar signal processing algorithm, and the frequency spectrum of the intermediate frequency signal is shown as G in fig. 2.
According to the scheme, the optical frequency comb generator is locked by the same clock source, and a fundamental frequency signal is provided for the harmonic mixer, so that good coherence of a radar system can be ensured; the flexible adjustment of the working wave band of the terahertz radar can be realized by selecting different comb teeth of the optical frequency comb; and based on a photon coherent receiving scheme, the radar system is ensured to work in a terahertz wave band, and meanwhile, real-time coherent receiving is realized, so that a complex intermediate frequency signal is obtained. Compared with a real intermediate frequency signal, the real intermediate frequency signal has one more dimension of information and has stronger capability of resisting image frequency interference. The overall receiver signal-to-noise ratio can also be greatly improved.
Finally, it should be noted that the above-mentioned list is only a specific embodiment of the present invention. The present invention is not limited to the above embodiments, and many variations are possible. All modifications which can be derived or suggested by the person skilled in the art from the present disclosure are to be considered within the scope of the present invention.
Claims (9)
1. A terahertz radar detection method based on a photon technology is characterized by comprising the following steps:
first, an optical frequency comb generator generates a repetition frequency f LO The optical frequency comb signal selects two comb tooth optical signals with different frequencies from the optical frequency comb signal, wherein one comb tooth optical signal is divided into an upper path and a lower path, and a baseband signal f LFM The method comprises the steps that carrier single-sideband modulation is suppressed on an upper comb optical signal to obtain a sweep optical signal, and the sweep optical signal and another comb optical signal are combined into a composite optical signal; after the composite optical signal is divided into two paths, one path of composite optical signal is converted into a frequency of (M + N) f through a radar transmitting unit LO +f LFM Radiating the terahertz signal into a target environment, wherein M and N are integers; generating a terahertz radar echo signal after encountering a target, receiving the terahertz radar echo signal, then performing down-conversion on the terahertz radar echo signal through a harmonic mixer to obtain a baseband receiving signal, amplifying the baseband receiving signal, and then modulating a next comb tooth optical signal to obtain a receiving modulated optical signal; and receiving the modulated optical signal and the other path of composite optical signal to realize coherent reception, obtaining an intermediate frequency signal carrying target information, and analyzing the intermediate frequency signal to obtain detection target information.
2. The method of claim 1, wherein said optical-frequency comb generator is a mode-locked laser, a femtosecond laser, a micro-ring optical-frequency comb generator, or an externally-modulated optical-frequency comb generator; wherein the fundamental frequency and optical frequency comb repetition frequency f of the harmonic mixer LO And the optical frequency comb generator and the harmonic mixer are synchronized by the same reference signal.
3. The method of claim 1, wherein said selecting two different frequency comb optical signals from the optical-frequency comb signal is performed by optical beam shaper, twin laser injection locking, orThe optical filter selects the wavelength to realize; the working waveband of the terahertz signal, namely the terahertz signal (M + N) f, is coarsely adjusted by controlling the positions of two comb teeth with different frequencies LO +f LFM The size of M + N.
4. Method according to claim 1, characterized in that the method is performed by controlling the baseband signal f LFM The working frequency and the bandwidth of the terahertz signal are finely adjusted.
5. A terahertz radar detection system based on photon technology is characterized by comprising:
an optical frequency comb generator for generating a repetition frequency f LO The optical frequency comb signal of (a);
the reference signal source is used for generating a reference signal for the optical frequency comb generator and the receiving unit;
the optical amplifier is used for amplifying the optical frequency comb signal generated by the optical frequency comb generator;
the wavelength selection module is used for respectively selecting two comb tooth optical signals with different frequencies from the optical frequency comb signals and respectively outputting the two comb tooth optical signals;
the first optical coupler is used for dividing one comb optical signal into an upper path and a lower path, and respectively transmitting the upper path and the lower path to the first electro-optical modulator and the second electro-optical modulator;
baseband signal source for generating a frequency f LFM A baseband signal of (a);
the first electro-optical modulator is used for modulating a baseband signal to a comb optical signal input to the first electro-optical modulator to obtain a sweep frequency optical signal;
the second optical coupler is used for combining the swept-frequency optical signal and the other comb-tooth signal output by the wavelength selection module into a composite optical signal, dividing the composite optical signal into an upper path and a lower path, sending the upper path of the composite optical signal to the transmitting unit, and sending the lower path of the composite optical signal serving as a reference optical signal to one input end of the coherent receiving module;
the transmitting unit is used for converting the composite optical signal into a terahertz signal and radiating the terahertz signal to a target environment;
a receiving unit; the system comprises a receiver, a processing unit and a processing unit, wherein the receiver is used for receiving a terahertz radar echo signal and converting the terahertz radar echo signal into a baseband receiving signal through down-conversion; the low noise amplifier is used for amplifying the baseband receiving signal;
the second electro-optical modulator is used for modulating the baseband receiving signal amplified by the low-noise amplifier to the comb-teeth optical signal input to the second electro-optical modulator to obtain a receiving modulation optical signal and sending the receiving modulation optical signal to the other receiving end of the coherent receiving module;
the coherent receiving module is used for realizing coherent fusion detection of the reference optical signal and the receiving modulation optical signal in an optical domain to obtain two paths of orthogonal intermediate frequency signals carrying target information;
and the acquisition processing module is used for performing analog-to-digital conversion on the two paths of orthogonal intermediate frequency signals, performing radar digital signal processing and extracting target information.
6. The system of claim 5, wherein the transmitting unit comprises:
the unidirectional carrier detector is used for converting the composite optical signal into a terahertz signal;
the terahertz emission amplifier is used for amplifying the terahertz signal output by the unidirectional carrier detector;
the terahertz transmitting antenna is used for transmitting the amplified terahertz signals to obtain terahertz radar detection signals;
the receiving unit includes:
the terahertz receiving antenna is used for receiving a terahertz radar echo signal;
the terahertz receiving amplifier is used for amplifying the terahertz radar echo signal received by the terahertz receiving antenna;
and the harmonic mixer is used for down-converting the terahertz radar echo signal into a baseband receiving signal.
7. The system of claim 5, wherein the optical-frequency comb generator is a mode-locked laser, a femtosecond laser, a micro-ring optical-frequency comb generator, or an externally modulated optical-frequency comb generator; wherein the fundamental frequency of the harmonic mixerWith optical frequency comb repetition frequency f LO And the optical frequency comb generator and the harmonic mixer are synchronized by the same reference signal.
8. The system of claim 5, wherein the wavelength selective module is an optical beam shaper, a twin laser, or an optical filter.
9. The system of claim 5, wherein the first electro-optical modulator is a dual parallel mach-zehnder modulator, and the second electro-optical modulator is a mach-zehnder modulator, a phase modulator, or a dual parallel modulator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210705255.2A CN115184943A (en) | 2022-06-21 | 2022-06-21 | Terahertz radar detection method and system based on photon technology |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210705255.2A CN115184943A (en) | 2022-06-21 | 2022-06-21 | Terahertz radar detection method and system based on photon technology |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115184943A true CN115184943A (en) | 2022-10-14 |
Family
ID=83515105
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210705255.2A Pending CN115184943A (en) | 2022-06-21 | 2022-06-21 | Terahertz radar detection method and system based on photon technology |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115184943A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116466354A (en) * | 2023-06-20 | 2023-07-21 | 之江实验室 | Wave band reconfigurable microwave photon radar detection method and system |
| CN117741594A (en) * | 2024-02-19 | 2024-03-22 | 中国科学院空天信息创新研究院 | Interference device and method for distributed cooperative ISAR detection system |
| CN118174115A (en) * | 2024-05-13 | 2024-06-11 | 武汉中科锐择光电科技有限公司 | Photon frequency synthesizer for improving terahertz frequency stability |
-
2022
- 2022-06-21 CN CN202210705255.2A patent/CN115184943A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116466354A (en) * | 2023-06-20 | 2023-07-21 | 之江实验室 | Wave band reconfigurable microwave photon radar detection method and system |
| CN116466354B (en) * | 2023-06-20 | 2023-09-12 | 之江实验室 | Wave band reconfigurable microwave photon radar detection method and system |
| CN117741594A (en) * | 2024-02-19 | 2024-03-22 | 中国科学院空天信息创新研究院 | Interference device and method for distributed cooperative ISAR detection system |
| CN117741594B (en) * | 2024-02-19 | 2024-04-30 | 中国科学院空天信息创新研究院 | Interference device and method for distributed cooperative ISAR detection system |
| CN118174115A (en) * | 2024-05-13 | 2024-06-11 | 武汉中科锐择光电科技有限公司 | Photon frequency synthesizer for improving terahertz frequency stability |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111538028B (en) | Polarization multiplexing microwave photon radar detection method and system based on photon sampling | |
| CN113253286B (en) | Coherent microwave photon radar detection method and system based on injection locking frequency multiplication | |
| Ghelfi et al. | Photonics in radar systems: RF integration for state-of-the-art functionality | |
| CN115184943A (en) | Terahertz radar detection method and system based on photon technology | |
| CN114720947B (en) | Terahertz radar detection method and system based on photon frequency doubling technology | |
| CN112327276B (en) | Photon sampling chip oriented to microwave photon radar and application system thereof | |
| CN111751812B (en) | Microwave photon time division multiplexing MIMO radar detection method and system | |
| CN109387833B (en) | MIMO radar detection method and device based on microwave photon orthogonal difference frequency multiplexing | |
| CN113114380B (en) | Microwave photon radar detection method and system based on photon sampling and coherent reception | |
| CN110221292B (en) | Microwave photon multiband radar imaging system and method | |
| CN108802698A (en) | Radar detection method, device based on microwave photon frequency multiplication and quadrature demodulation | |
| CN110289931B (en) | Radio frequency storage method and device based on microwave photon channelization | |
| CN111580071B (en) | Orthogonal demodulation receiving method and device for dual-band linear frequency modulation radar | |
| CN115032611B (en) | Distributed terahertz radar detection system and method based on photon technology | |
| Cao et al. | Photonic deramp receiver for dual-band LFM-CW radar | |
| Peng et al. | A photonics-based coherent dual-band radar for super-resolution range profile | |
| CN114047507B (en) | Microwave-laser radar integrated chip, application system and detection method | |
| CN113721202B (en) | Microwave photon radar detection method and device based on broadband spectrum sensing | |
| Onori et al. | A 0–40 GHz RF tunable receiver based on photonic direct conversion and digital feed-forward lasers noise cancellation | |
| CN114355382A (en) | Microwave photon MIMO radar transmitting and receiving system | |
| CN116626693A (en) | Coherent microwave photon radar detection method and system based on photon frequency multiplication | |
| CN116338592A (en) | Microwave photon radar system and detection method based on photon mixing technology | |
| CN112285732A (en) | Photon-assisted Doppler radar detection method and device | |
| US20230324504A1 (en) | Integrated photonics millimeter wave (mmw) radar communication system based on analog phase modulation scheme | |
| Ragheb et al. | Photonics-based multi-band/multi-mode radar signal generation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |