CN1673769A - Double-optical fibre circular cascade laser warning device - Google Patents

Double-optical fibre circular cascade laser warning device Download PDF

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Publication number
CN1673769A
CN1673769A CN 200410022119 CN200410022119A CN1673769A CN 1673769 A CN1673769 A CN 1673769A CN 200410022119 CN200410022119 CN 200410022119 CN 200410022119 A CN200410022119 A CN 200410022119A CN 1673769 A CN1673769 A CN 1673769A
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Prior art keywords
fiber
fiber ring
ring
single fiber
optical
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CN 200410022119
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CN1332224C (en
Inventor
周晓军
白晓明
曾钦勇
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University of Electronic Science and Technology of China
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University of Electronic Science and Technology of China
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    • 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
    • G01S7/4804—Auxiliary means for detecting or identifying lidar signals or the like, e.g. laser illuminators
    • 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
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4818—Constructional features, e.g. arrangements of optical elements using optical fibres

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Optics & Photonics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Lasers (AREA)

Abstract

The double fiber ring cascading laser alarm has feedback unit comprising two cascade fiber rings to replace the feedback unit comprising single fiber ring in available technology, and the two fiber rings have length in integral number times. By means of the temporary storage of the fiber ring and power re-distribution of the fiber coupler, the degressive pulse sequence the fore stage of the fiber ring outputs may have its power re-distributed to improve the frequency domain characteristic of the output pulse sequence. Therefore, the double fiber ring cascading laser alarm of the present invention has the features of obvious characteristic frequency of output pulse sequence, less cross-talk between optical windows and high system precision. The present invention may be used in laser orientation distinction, location and other military reconnaissance fields.

Description

A kind of dual fiber ring cascade laser warning device
Technical field:
The invention belongs to the photoelectron technology field, it is particularly related to the laser warning technology.
Background technology
As everyone knows, utilize laser warning technology identification enemy to threaten and the threat orientation, can protect our visual plant and other platform effectively.Therefore, the laser warning Study on Technology is subjected to paying close attention to widely.Existing frequency coding laser warning system utilizes fiber optic loop feedback unit output pulse frequency identification optical antenna.Fig. 1 is this warning system structural representation, and it is by optical antenna direction identification sensing head (hemisphere sensing head) 1, fiber coupler 6, n single fiber ring: 2 1, 2 2..., 2 n(n is the number of optical antenna in the direction identification sensing head 1, and each single fiber ring is output terminal and the input end composition that the two ends of optical fiber is connected to fiber coupler 6), bank of filters 4 is formed.This warning system principle of work is: hemisphere sensing head 1 has the direction recognition capability, and the light pulse that i optical antenna of hemisphere sensing head receives is through respective feedback unit 2 i, obtain one and have characteristic frequency f iPulse train.f iBe the characteristic quantity of this optical antenna, utilize this characteristic quantity can distinguish optical antenna.The light pulse sequence of feedback unit output is converted to electric signal through photodiode 3, send into bank of filters 4, if pulse sequence frequency is identical with predeterminated frequency in the bank of filters 4, then corresponding signal processing circuit will have signal output, thereby determine that optical antenna receives the laser situation.[see document: Poisel; Hans (Dachau, DE); Trommer; Gert (Munich, DE) .Laser warning sensorwith frequency-coded position information.United States Patent, Patent Number:5,025,148.June 18,1991].
Fig. 2 has provided the feedback unit structural representation of above-mentioned laser warning system.It is to link to each other with input end 7 with the output terminal 8 of optical fiber with fiber coupler 6, make the part output light signal of fiber coupler 6 feed back to fiber coupler 6 input ends and be re-used as input signal, like this, at the light pulse sequence that output terminal 9 obtains having interval equal time, intensity is successively decreased successively, shown in Fig. 3 (b), the frequency of the light pulse sequence of this output is determined by the fiber optic loop length L.Though single fiber optic loop feedback unit shown in Figure 2 can convert the pulse train with characteristic frequency among Fig. 3 (b) to input pulse (shown in Fig. 3 (a)) to.But the frequency spectrum of its output pulse sequence (as shown in Figure 4) shows, at characteristic frequency f iAnd between the frequency multiplication, having continuous optical power value, this easily crosstalks adjacent optical antenna features frequency, promptly differentiates the signal that belonged to i optical antenna originally through the bandpass filter group, but is being mingled with the signal of adjacent optical antenna i-1 or i+1.The reason that this phenomenon occurs is: the amplitude of output optical pulse differs greatly shown in Fig. 3 (b), and the amplitude of pulse drops to 0 rapidly, and this moment, pulse train was not proper periodic pulse signal.Though increase the interval of adjacent optical antenna features frequency, the influence that can reduce to crosstalk, it has but reduced the number of optical window, has reduced the precision of system.
Summary of the invention
The task of patent of the present invention provides a kind of dual fiber ring cascade laser warning device, and it has number, the alarm precision of raising, the circuit characteristic of simple that increases optical window.
A kind of dual fiber ring cascade laser warning device provided by the invention, it comprises: direction identification sensing head 1, fiber coupler 6, n single fiber ring: 2 1, 2 22 n(n is the number of optical antenna in the direction identification sensing head 1, and each single fiber ring is output terminal and the input end composition that the two ends of optical fiber is connected to fiber coupler 6), bank of filters 4; It is characterized in that it also comprises n single fiber ring: 2 1', 2 2' ... 2 n', described n single fiber ring: 2 1', 2 2' ..., 2 n' be serially connected in direction sensing head 1 and the single fiber ring 2 corresponding respectively with it 1, 2 22 nBetween, single fiber ring 2 1' with 2 1, 2 2' with 2 2... 2 n' with 2 nForm n group fiber optic loop cascade feedback unit, single fiber ring 2 1The length of ' middle optical fiber is its corresponding single fiber ring 2 1The N of the length of middle optical fiber is (N 〉=2, N is a positive integer) doubly, and is same, single fiber ring 2 2' ... 2 n' the length of optical fiber be respectively corresponding single fiber ring 2 22 nOptical fiber length N doubly.
Need to prove n single fiber ring 2 1, 2 22 nIn in each ring the length of optical fiber depend on the characteristic frequency f that its corresponding optical antenna is default 1, f 2..., f n
Essence of the present invention is to replace forming feedback unit by single fiber optic loop in the prior art with the feedback unit that the dual fiber ring cascade constitutes, and the fiber lengths of two fiber optic loop of described dual fiber ring relation is the integral multiple relation.In Fig. 6, the fiber lengths of fiber optic loop 12 is N times of fiber optic loop 14 fiber lengths.
The innovation of a kind of dual fiber ring cascade laser warning device provided by the invention is: the feedback unit that constitutes with the dual fiber ring cascade replaces forming feedback unit by single fiber optic loop in the prior art.Its principle is to utilize storage of fiber optic loop transient state and the heavy distribution function of fiber coupler power, the pulse train of successively decreasing of prime fiber optic loop output, carries out power and redistributes, and the output pulse sequence frequency domain characteristic is improved.In the amplitude difference of improving on the time domain between the output pulse, the pulse height that slows down decline rate increases the output pulse number, makes output pulse sequence more near the feature of periodic signal.Be that theoretical analysis is carried out in innovation of the present invention below:
As shown in Figure 5, coupling coefficient is that the optical fiber of k is bad, impulse response with Hibert space vector A represent [see document: Wang Xu, Hu Li. a kind of novel non-OFDL theoretical analysis that wait to postpone. University of Electronic Science and Technology's journal, 1992 (8): 28～33]:
A＝[a 0，a 1，…，a i…] T
In the formula:
a 1 = k i = 0 ( 1 - k ) 2 k i - 1 i > 0 - - - ( 1 )
Be normalized to Σ i = 0 ∞ a i = 1 .
The delay interval of ∵ fiber optic loop 14 is T, and the fiber lengths of fiber optic loop 12 is N times of fiber optic loop 14 fiber lengths,
The delay interval of ∴ fiber optic loop 12 is NT (N is a positive integer), makes two fiber optic loop eigenvectors be respectively A=[a 0, a 1..., a i... ] T, B=[b 0, b 1..., b i... ] T, the time interval with fiber optic loop 12 is expressed as signal B '=[b that the time interval is T with signal phasor earlier 1', b 2' ..., b i' ... ], promptly
b k ( m + 1 ) - 1 ′ = Σ k = 0 N - 1 ( b m ′ ) = b m b i ′ = 0 , i ≠ N ( m + 1 ) - 1 - - - ( 2 )
Then the light impulse photoresponse C of whole feedback system is:
C = B Π ^ N A = B ′ Π ^ A
That is:
C m = Σ i = 0 k ( m + 1 ) - 1 b i ′ a k ( m + 1 ) - 1 - i - - - ( 3 )
When input optical pulse power is P 0The time, by dual fiber ring cascade impulse response C, obtaining cascaded optical fiber ring output optical pulse sequence luminous power is P=CP 0=[c 0, c 1..., c 2... ] TP 0Two fiber optic loop coupling mechanisms of choose reasonable coefficient can make output pulse sequence P very near the periodic signal feature.
In sum, can reach a conclusion: the feedback unit that the present invention adopts the dual fiber ring cascade to constitute can make output pulse sequence very near the periodic signal feature after replacing in the prior art forming feedback unit by single fiber optic loop.
Good effect of the present invention is embodied in:
(1) on the time domain, cascaded optical fiber ring feedback unit output pulse amplitude decline rate is slack-off, obtains longer pulse train under the situation of having only a light pulse input equally;
(2) on the frequency domain, the characteristic frequency performance that has solved a fiber optic loop feedback unit output optical pulse is not outstanding, and electronic circuit is separated difficult frequently problem.
Therefore, dual fiber ring cascade laser warning device provided by the invention is compared with existing single fiber ring laser warning device, the characteristic frequency with output pulse sequence obviously, be difficult for producing between the optical window crosstalk, characteristics that system accuracy is high.
Description of drawings
Fig. 1 is existing single fiber ring feedback unit laser warning system architecture synoptic diagram
Wherein, the 1st, hemisphere sensing head, 2 1, 2 2..., 2 nThe single fiber ring is by single fiber ring 2 1, 2 2..., 2 nForm feedback unit, the 3rd, photodiode, the 4th, bandpass filter group, f 1, f 2..., f nBe characteristic frequency, A 1, A 2..., A nIt is the output signal of bandpass filter group.
Fig. 2 is existing single optical fibre delay loop structural representation
Wherein, the 5th, optical fiber, the 6th, fiber coupler, the 7th, the input end of fiber coupler 6, the 8th, the output terminal that fiber coupler 6 is connected with optical fiber, the 9th, the signal output part of fiber coupler 6, L are fiber optic loop length.
Fig. 3 is existing single fiber optic loop input, output pulse synoptic diagram
Wherein, figure (a) is the fiber optic loop input pulse, and figure (b) is fiber optic loop output pulse, and among the figure, t is the time, P indicating impulse intensity.
Fig. 4 is existing single fiber optic loop output pulse Fourier transformation spectrogram
Fig. 5 is a kind of dual fiber ring cascade laser warning apparatus structure synoptic diagram of the present invention
Wherein, the 1st, hemisphere sensing head, 2 1', 2 2' ..., 2 n' and 2 1, 2 2..., 2 nBe the single fiber ring, by single fiber ring 2 1', 2 2' ..., 2 n' and 2 1, 2 2..., 2 nForm the feedback tuple, the 3rd, photodiode, the 4th, bandpass filter group, f 1, f 2..., f nBe characteristic frequency, A 1, A 2..., A nIt is the output signal of bandpass filter group.
Fig. 6 is a dual fiber ring cascade feedback unit structural representation of the present invention
Wherein, the 10, the 15th, connect optical fiber, the 12, the 14th, fiber optic loop, the 11, the 13rd, fiber coupler.
Fig. 7 is the output pulse normalization luminous power comparison diagram of existing single fiber ring laser warning device and dual fiber ring cascade laser warning device
Fig. 8 is the spectrogram of dual fiber ring cascade feedback unit output pulse sequence of the present invention
Embodiment
A kind of dual fiber ring cascade laser warning device
Two cascaded optical fiber ring feedback units connect optical fiber, fiber optic loop, fiber coupler and all can adopt the permanent communication of Sichuan light company limited product as shown in Figure 6,2 * 2 fiber couplers that the said firm produces, and it is little to have the loss of insertion error, the characteristics that added losses are low.
Select the coupling coefficient of fiber coupler 10 to be: k 1=0.46, the coupling coefficient of fiber coupler 12 is: k 2=0.38, input optical pulse intensity is normalized to 1.
Obtain the light impulse response A of two fiber optic loop, B by (1) formula:
A＝[0.46?0.292?0.134?0.062?0.028?0.013?0.006…]
B＝[0.38?0.384?0.146?0.0555?0.021?0.008?0.003…]
By (2) formula and A, B obtains the impulse response of cascaded optical fiber ring:
C＝[0.1748?0.1768?0.1780?0.1376?0.1033?0.0714?0.05060.0340?0.0237?0.0158?0.0110?0.0073?0.0051?0.0034?0.00230.0015?0.0011?0.0007?0.0005?0.0003…]
Cascaded optical fiber ring input optical pulse power is under 1 the situation, will export the normalization of pulse power value:
C′＝[0.9989?1.0104?1.0171?0.7864?0.5901?0.4082?0.28910.1945?0.1355?0.0904?0.0627?0.0417?0.0289?0.0192?0.01330.0088?0.0061?0.0041?0.0028?0.0019…]
Performance evaluation: use under two fiber optic loop cascade situations of the present invention, first three output pulse amplitude is almost equal, and succeeding impulse also descends slow than the pulse train of a fiber optic loop output significantly.Under the light pulse situation that obtains greater than normalization luminous power 0.007, two cascaded optical fiber rings have 17 pulse outputs, and single fiber optic loop has only 8 pulse outputs.Both output pulse sequences more as shown in Figure 7; Its frequency spectrum as shown in Figure 8, as can be seen, the luminous power between the various crest frequencies reduces to 0 rapidly, and the width of the shared frequency band of each characteristic frequency is significantly less than single fiber optic loop.
Dual fiber ring cascade laser warning device provided by the invention is compared with existing single fiber ring laser warning device, have characteristic frequency obviously, be difficult for producing between the optical window crosstalk, characteristics that system accuracy is high, it can be used for the association areas such as military surveillance of laser azimuth identification and location.

Claims (1)

1, a kind of dual fiber ring cascade laser warning device, it comprises: direction identification sensing head (1), fiber coupler (6), n single fiber ring: 2 1, 2 2... 2 n(n is the number of optical antenna in the direction identification sensing head (1), and each single fiber ring is output terminal and the input end composition that the two ends of optical fiber is connected to fiber coupler (6)), bank of filters (4); It is characterized in that it also comprises n single fiber ring: 2 1', 2 2' ... 2 n', described n single fiber ring: 2 1', 2 2' ..., 2 n' be serially connected in direction sensing head (1) and the single fiber ring 2 corresponding respectively with it 1, 2 2... 2 nBetween, single fiber ring 2 1' with 2 1, 2 2' with 2 2... 2 n' with 2 nForm n group fiber optic loop cascade feedback unit, single fiber ring 2 1The length of ' middle optical fiber is its corresponding single fiber ring 2 1The N of the length of middle optical fiber is (N 〉=2, N is a positive integer) doubly, and is same, single fiber ring 2 2' ... 2 n' the length of optical fiber be respectively corresponding single fiber ring 2 2... 2 nOptical fiber length N doubly.
CNB2004100221195A 2004-03-25 2004-03-25 Double-optical fibre circular cascade laser warning device Expired - Fee Related CN1332224C (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106199504A (en) * 2016-07-05 2016-12-07 中北大学 A kind of method that laser azimuth is attacked in acquisition in non-imaged type laser warning device
CN107504864A (en) * 2017-08-04 2017-12-22 南京理工大学 A kind of comprehensive laser engineered net shaping construction method
CN107748398A (en) * 2017-11-16 2018-03-02 西安方元明科技股份有限公司 A kind of laser warning device

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3323828C2 (en) * 1983-07-01 1986-01-16 Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn Laser warning sensor
FR2618456B1 (en) * 1987-07-24 1990-08-17 Centre Nat Etd Spatiales METHOD AND DEVICE FOR THE CONTINUOUS SPREADING OF FRAGILE FIBERS
SE9100916L (en) * 1991-03-27 1992-09-28 Nobeltech Electronics Ab Laser Detector
CN2340032Y (en) * 1998-09-30 1999-09-22 王启华 Laser network monitoring alarming device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106199504A (en) * 2016-07-05 2016-12-07 中北大学 A kind of method that laser azimuth is attacked in acquisition in non-imaged type laser warning device
CN107504864A (en) * 2017-08-04 2017-12-22 南京理工大学 A kind of comprehensive laser engineered net shaping construction method
CN107504864B (en) * 2017-08-04 2019-09-13 南京理工大学 A kind of comprehensive laser engineered net shaping construction method
CN107748398A (en) * 2017-11-16 2018-03-02 西安方元明科技股份有限公司 A kind of laser warning device

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