CN203587230U - Optical-fiber delay line phase-controlled coherent-light detection system - Google Patents
Optical-fiber delay line phase-controlled coherent-light detection system Download PDFInfo
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- CN203587230U CN203587230U CN201320674518.4U CN201320674518U CN203587230U CN 203587230 U CN203587230 U CN 203587230U CN 201320674518 U CN201320674518 U CN 201320674518U CN 203587230 U CN203587230 U CN 203587230U
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Abstract
The utility model discloses an optical-fiber delay line phase-controlled coherent-light detection system. An output end of an optical-fiber laser of the coherent-light detection system is connected with an input end of an optical-fiber spliter; a first output end of the optical-fiber spliter is connected with one input end of a modulator, the other input end of the modulator is connected with an external RF signal generator, and an output end of the modulator is connected with one input end of an optical-fiber combiner; a second output end of the optical-fiber spliter is connected with the other input end of the optical-fiber combiner; an optical-fiber delay line is serially connected between the output end of the modulator and the one input end of the input end of the modulator, or the optical-fiber delay line is serially connected between the second output end of the optical-fiber spliter and the other input end of the optical-fiber combiner; and an output end of the optical-fiber combiner is connected with an input end of a photoelectric detector. Phase control can be realized through the optical-fiber delay line, and a phase difference between reference light and a signal light branch is compensated to improve receiving sensitivity, the signal to noise ratio and system output stability.
Description
Technical field
The utility model relates to optical communication field, is specifically related to a kind of coherent light detection system of fibre delay line phase control.
Background technology
The develop rapidly of laser and optical fiber technology, makes coherent light communication realize again important leap, not only at optical communication field, is widely used, and at other field, also has very wide application as sensing, signal processing etc.Due to good filtering performance, the advantage such as band efficiency is high, receiving sensitivity is high, become the effective means that meets communication terminal high request, solves optical communication bottleneck.Its output signal of coherent light detection system (referring to Fig. 1) meets:
the condition that this formula is set up is frequency and the phase relation that flashlight is identical with wavefront necessary maintenance on whole detector photosurface of reference light.Press detection mode, coherent light detection system can be divided into zero-difference detection and heterodyne detection.When flashlight and reference light frequency not etc., i.e. ω
s-ω
l, be referred to as heterodyne detection at ≠ 0 o'clock; When both equate, i.e. ω
s-ω
l, be referred to as zero-difference detection at=0 o'clock.The detection sensitivity of homodyne is than the high 3dB of heterodyne, and laser is homology, laser characteristics parameter and optical match are convenient to control, whether for meet coherent light, survey the necessary condition that output signal formula is set up, or in order to adopt the more zero-difference detection of high-efficient simple, between holding signal light and reference light, vital effect has all been played in the consistent realization for coherent light detection of phase place and the lifting of performance.Yet in the process of conventional laser signal of communication transmission, have light path difference, will inevitably can introduce certain phase place and change, in the consistent situation of laser frequency, final result of detection will depend on the variation of phase place.Along with two ways of optical signals phase differential changes between 0～2 π, coherent detection output signal can produce fluctuation, and the parameters such as stability of the receiving sensitivity of system, signal to noise ratio (S/N ratio) and output signal are by the impact being subject in various degree.How to carry out the control of phase place, become the key that signal transmission receives.Because light frequency is high, its concrete phase place cannot accurately be controlled, and by the mapping relations of phase place and time, adopts the transmission time to control to substitute phase control relatively simply too much.
Utility model content
Technical problem to be solved in the utility model is to provide a kind of coherent light detection system of fibre delay line phase control, it can pass through control phase, and the phase differential between compensate for reference light and flashlight branch road improves when system output stability of receiving sensitivity, noise.
For addressing the above problem, the utility model is achieved through the following technical solutions:
The coherent light detection system of fibre delay line phase control, is mainly comprised of fiber laser, optical fiber splitter, modulator, fibre delay line, optical fiber combiner and photodetector; Wherein the output terminal of fiber laser and the input end of optical fiber splitter are connected; The first output terminal of optical fiber splitter connects an input end of modulator, and another input end of this modulator is connected with outside RF signal generator, and the output terminal of this modulator connects an input end of optical fiber combiner; The second output terminal of optical fiber splitter connects another input end of optical fiber combiner; Fibre delay line is serially connected between the output terminal of modulator and an input end of optical fiber combiner or fibre delay line is serially connected between the second output terminal of optical fiber splitter and another input end of optical fiber combiner; The output terminal of optical fiber combiner connects the input end of photodetector.
In order to regulate two tributary signal luminous powers, to select suitable splitting ratio, on the first output terminal of optical fiber splitter and on the second output terminal, be connected to attenuator described in said system.
In said system, centered by described fiber laser, frequency is the single-frequency laser of 1550nm.
In said system, described optical fiber combiner is polarization-maintaining fiber coupler.
In said system, on the output terminal of described photodetector, be also connected to spectrum analyzer and oscillograph.
Compared with prior art, the utility model adopts external modulation method, in Laser emission light path, realize signal modulation, reduce many unfavorable factors that laserresonator instantaneous process brings, guarantee the frequency stability of laser instrument, be conducive to improve modulation rate, increase transmission range, be convenient to the processing of phase control simultaneously.And adopt polarization-maintaining fiber coupler to close road mixing to two paths of signals, the polarization state of two paths of signals is consistent, be conducive to reduce the output signal fluctuating that polarization fluctuation brings.This is, one of core improvement of the present utility model is in coherent light detection system, to adopt fibre delay line to carry out phase control, improved traditional randomness without mixed frequency signal phase differential in the coherent detection system of phase control, greatly improved the determinacy of coherent detection signal output, by the phase transition that is difficult to accurately to control, be to control the time, by conditioning signal, transmitting light path comes control phase to postpone, compensation is inevitably phase place variation in transmitting procedure, phase differential between fine adjustment signal light and reference light, make the two ways of optical signals that participates in mixing meet certain phase relation, be conducive to improve mixing efficiency and detection sensitivity, promoted the performance that coherent light is surveyed, strengthen its using value in optical fiber communication.
Accompanying drawing explanation
Fig. 1 is coherent light detection principle figure;
Fig. 2 is a kind of coherent light detection system schematic diagram of fibre delay line phase control;
Fig. 3 is the coherent light detection system schematic diagram of another kind of fibre delay line phase control.
Embodiment
Embodiment 1:
As shown in Figure 2, it is mainly comprised of fiber laser, optical fiber splitter, modulator, fibre delay line, polarization-maintaining fiber coupler and photodetector a kind of coherent light detection system of fibre delay line phase control.Wherein the output terminal of fiber laser and the input end of optical fiber splitter are connected.The first output terminal of optical fiber splitter connects an input end of modulator, and another input end of this modulator is connected with outside RF signal generator, and the output terminal of this modulator connects an input end of polarization-maintaining fiber coupler through fibre delay line.The second output terminal of optical fiber splitter directly connects another input end of polarization-maintaining fiber coupler.The output terminal of polarization-maintaining fiber coupler connects photodetector.
Centre frequency is that the laser signal that the single-frequency laser of 1550nm produces is divided into two-way through 1 * 2 optical fiber splitter, and a road, as flashlight branch road, is connected with the input end of modulator, and the rf signal of outside input is connected with another input end of modulator.The input end of the output terminal incoming fiber optic lag line of modulator.Another road that optical fiber splitter separates is as with reference to light branch road, and as phase reference, the modulated signal of this signal and fibre delay line output accesses polarization-maintaining fiber coupler simultaneously, and its output terminal is connected with photodetection module.
In order to regulate two tributary signal luminous powers, to select suitable splitting ratio, in the utility model preferred embodiment, on the first output terminal of described optical fiber splitter and/or on the second output terminal, be connected to attenuator.In addition, on the output terminal of photodetector, being also connected to spectrum analyzer carries out tracking measurement to radio frequency signal frequency domain and/or is connected to oscillograph to radio frequency signal waveform is shown.
The coherent light detection method of the fibre delay line phase control that above-mentioned detection system realizes, comprises the steps:
(1) adopt fiber laser to produce continuous laser beam; In the utility model preferred embodiment example, described laser beam is produced by the single-frequency laser of centre frequency 1550nm;
(2) optical branching device is divided into two-way by laser beam by the laser beam producing in step (1), forms flashlight and reference light in coherent light detection; Can on the first output terminal of optical fiber splitter and/or on the second output terminal, add attenuator more as required, regulate two tributary signal luminous powers, to select suitable splitting ratio;
(3) laser beam of flashlight branch road interacts in modulator with the radiofrequency signal of outside input, realizes the loading of information;
(4) the flashlight branch road laser beam of load information, incoming fiber optic lag line Dui Gai road signal postpones, transmission light path to signal is controlled, thereby realize the control and compensation to phase place, with reference to reference light phase place, to obtain being applicable to the phase differential of optimal detection, improve relevant mixing efficiency and receiving sensitivity;
(5) the two branch road light signals that obtain certain phase differential enter the mixing that is concerned with of optical fiber combiner; In the utility model preferred embodiment case, optical fiber combiner adopts polarization-maintaining fiber coupler, to keep the consistent of two branch road light signal polarization states;
(6) signal of photodetection module after to mixing carries out light signal to the conversion of electric signal, and adopts spectrum analyzer radio frequency signal frequency domain is carried out to tracking measurement and adopt oscillograph to show the radiofrequency signal waveform of photodetector output.
Embodiment 2:
As shown in Figure 3, it is mainly comprised of fiber laser, optical fiber splitter, modulator, fibre delay line, optical fiber combiner and photodetector a kind of coherent light detection system of fibre delay line phase control.Wherein the output terminal of fiber laser and the input end of optical fiber splitter are connected.The first output terminal of optical fiber splitter connects an input end of modulator, and another input end of this modulator is connected with outside RF signal generator, and the output terminal of this modulator directly connects an input end of optical fiber combiner.The second output terminal of optical fiber splitter connects another input end of optical fiber combiner by fibre delay line.The output terminal of optical fiber combiner connects photodetector.
Centre frequency is that the laser signal that the single-frequency laser of 1550nm produces is divided into two-way through 1 * 2 optical fiber splitter, and a road, as flashlight branch road, is connected with the input end of modulator, and the rf signal of outside input is connected with another input end of modulator.The input end of the output terminal incoming fiber optic lag line of modulator.Another road that optical fiber splitter separates is as with reference to light branch road, and as phase reference, the modulated signal of this signal and fibre delay line output accesses polarization-maintaining fiber coupler simultaneously, and its output terminal is connected with photodetection module.
In order to regulate two tributary signal luminous powers, to select suitable splitting ratio, in the utility model preferred embodiment, on the first output terminal of described optical fiber splitter and/or on the second output terminal, be connected to attenuator.In addition, on the output terminal of photodetector, being also connected to spectrum analyzer carries out tracking measurement to radio frequency signal frequency domain and/or is connected to oscillograph to radio frequency signal waveform is shown.
The coherent light detection method of the fibre delay line phase control that above-mentioned detection system realizes, comprises the steps:
(1) adopt fiber laser to produce continuous laser beam; In the utility model preferred embodiment example, described laser beam is produced by the single-frequency laser of centre frequency 1550nm;
(2) optical branching device is divided into two-way by laser beam by the laser beam producing in step (1), forms flashlight and reference light in coherent light detection; Can on the first output terminal of optical fiber splitter and/or on the second output terminal, add attenuator more as required, regulate two tributary signal luminous powers, to select suitable splitting ratio;
(3) laser beam of flashlight branch road interacts in modulator with the radiofrequency signal of outside input, realizes the loading of information;
(4) laser beam of reference light branch road, incoming fiber optic lag line Dui Gai road signal postpones, transmission light path to signal is controlled, thereby realize the control and compensation to phase place, the light phase of contrast signal light branch road, to obtain being applicable to the phase differential of optimal detection, improve relevant mixing efficiency and receiving sensitivity;
(5) the two branch road light signals that obtain certain phase differential enter the mixing that is concerned with of optical fiber combiner; In the utility model preferred embodiment case, optical fiber combiner adopts polarization-maintaining fiber coupler, to keep the consistent of two branch road light signal polarization states;
(6) signal of photodetection module after to mixing carries out light signal to the conversion of electric signal, and adopts spectrum analyzer radio frequency signal frequency domain is carried out to tracking measurement and adopt oscillograph to show the radiofrequency signal waveform of photodetector output.
Claims (5)
1. the coherent light detection system of fibre delay line phase control, is characterized in that: mainly fiber laser, optical fiber splitter, modulator, fibre delay line, optical fiber combiner and photodetector, consist of; Wherein the output terminal of fiber laser and the input end of optical fiber splitter are connected; The first output terminal of optical fiber splitter connects an input end of modulator, and another input end of this modulator is connected with outside RF signal generator, and the output terminal of this modulator connects an input end of optical fiber combiner; The second output terminal of optical fiber splitter connects another input end of optical fiber combiner; Fibre delay line is serially connected between the output terminal of modulator and an input end of optical fiber combiner or fibre delay line is serially connected between the second output terminal of optical fiber splitter and another input end of optical fiber combiner; The output terminal of optical fiber combiner connects the input end of photodetector.
2. the coherent light detection system of fibre delay line phase control according to claim 1, is characterized in that: on the first output terminal of described optical fiber splitter He on the second output terminal, be connected to attenuator.
3. the coherent light detection system of fibre delay line phase control according to claim 1, is characterized in that: centered by described fiber laser, frequency is the single-frequency laser of 1550nm.
4. the coherent light detection system of fibre delay line phase control according to claim 1, is characterized in that: described optical fiber combiner is polarization-maintaining fiber coupler.
5. the coherent light detection system of fibre delay line phase control according to claim 1, is characterized in that: on the output terminal of described photodetector, be also connected to spectrum analyzer and/or oscillograph.
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| CN103575408A (en) * | 2013-10-29 | 2014-02-12 | 桂林电子科技大学 | Coherent light detection system and method for optical fiber delay line phase control |
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| CN103575408A (en) * | 2013-10-29 | 2014-02-12 | 桂林电子科技大学 | Coherent light detection system and method for optical fiber delay line phase control |
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