Research On Multi-Parameter Sensor Network For Fiber Ring Cavity Ring-Down

In daily life,the pollution of water resources and the ravages of smog have brought great harm to the living environment of human beings.The national government has also spent enormous manpower and resources.The detection of liquid and air environments is necessary.In the field of scientific research,some studies have been done on the detection of solution concentration,relative humidity and haze,but most of them use chemical methods,which easily change the properties of the substance to be tested,and the measurement of optical methods does not change the medium to be tested.Relevant nature.In this paper,a multi-parameter sensor network structure for fiber ring cavity ring-down is proposed.The liquid environment is simulated by sucrose solution,and the smog environment is simulated by cigarette smoke.Simultaneous sensing measurement of solution concentration,relative humidity and smoke concentration is realized.Pollution and air pollution testing provide an effective reference.In optical fiber ring cavity ring-down parameter in sensor network structure,this paper analyzes the coupler in optical fiber ring cavity ring-down system spectral ratio and erbium doped fiber amplifier parameters on fiber optic devices such as selection,choose the 2 Vpp,1 KHz,14μs pulse width,0.5% duty cycle of the pulse signal as modulation signal,1550 nm distributed feedback semiconductor laser source,99:1 ratio of the coupler,2 m long erbium fiber of erbium-doped fiber amplifier.At the same time,the design of double dislocation mazer interference structure,optical fiber aligned gas chamber and moisture preparation system are introduced in detail.The principle of double misalignment mazer sensor measurement,the process of making the misalignment structure and the selection of the parameters of the misalignment structure are described in detail.The structure of optical fiber aligned gas chamber,alignment principle of self-focusing lens and relative humidity preparation system are also introduced.The structure of the network is composed of several ring cavities in series one by one,in which a sensing unit is inserted in each ring cavities,and optical fiber delay lines of different lengths are set between the ring cavities to separate the sensing results of different parameters in time(i.e.,time division multiplexing),so as to achieve the purpose of multi-parameter simultaneous measurement.In the process of experiment implementation,the output results of each ring cavity parameter sometimes cannot be completely separated,but there is still crossover.Therefore,in order to avoid the aliasing of periodic output signals in the time domain,optical fiber rings of different lengths are set in each ring cavity,that is,the cavity length of each sensing unit is different,so that the output results can be effectively separated in the frequency domain after Fourier transform(i.e.,frequency division multiplexing),and then the change of each physical quantity is measured with 3dB bandwidth.Finally,TDM/FDM mixed multiplexing technology was used to realize simultaneous sensing measurement of fiber ring cavity oscillation with multiple parameters such as solution concentration,relative humidity and smoke concentration.