Investigation Of Multi-functional Fiber Signal Processing Devices Under Magnetic Field Control

Integration of multiple functions into a single device is an important means to reduce the cost of all-optical signal processing devices.As a good example,all-optical 3R regenerator integrates the functions of re-amplification,re-shaping and re-timing together.The fiber-based four-wave mixing effect can be used to achieve optically controllable3 R signal processing.By further applying magneto-optical effect to the fiber-based devices,the device performance and control flexibility can be improved.The main contents and innovations are listed as follows:1.The noise characteristics of fiber optical parametric amplifier(FOPA)are investigated,including the shot noise,amplified quantum noise,pump amplified spontaneous emission(ASE)transfer noise,and so on.The in-band and out-of-band noises for the pump are respectively represented by the input optical signal-to-noise ratios of the pump(OSNRP)and the equivalent signal OSNR(OSNRs).Then the noise figure of FOPA is measured directly by optical domain method.It is shown that the NF decreases with the increase of OSNRP or OSNRs until the minimum noise figure of 4.3 dB is achieved when OSNRP?35dB or OSNRs? 25 dB.The experimental results are in good agreement with the simulation.2.The influences of pump in-band ASE noise on the performance of fiber optical parametric regenerator(FOPR)are analyzed.The regeneration performance is significantly degraded when the pump OSNR is smaller than 19.6dB,while the effect of pump in-band ASE noise can be neglected when the pump OSNR exceeds 35 dB.Then a clock offset pump regeneration scheme is proposed.Experiment result shows that for a 10 Gb/s degraded signal with a Q value of 7.13,the Q value after regeneration can be increased to 10.16,and the optical receiver sensitivity can be increased by 3.1dB.3.The oscillation starting of the optical parametric oscillator(FOPO)is achieved by the method of injecting ASE noise into the fiber loop.A 10 GHz optical clock signal is extracted with the phase jitter value of 0.025 UI.Experiment result shows that,by putting a line polarizer into the fiber loop,the degree of polarization(DOP)of the output optical clock signal can be increased from 37.94% to 99.61%.4.The magnetic control mechanism of the all-fiber Sagnac structure is theoretically analyzed,and then the magneto-optical modulation experiment is carried out.Experiment result shows that,under a 177 Gs magnetic field,the modulation degree of the magneto-optical modulator can reach 17.05 dB with good repeatability.On the basis of magneto-optical modulation,a pump signal is introduced to carry out the optically controlled switch experiment.Under the control of a pump with the peak launch power of 28.2dBm,the extinction ratio for the optically controlled switch can reach 25.8dB.By further applying a 177 Gs magnetic field,the extinction ratio of the optically controlled switch can be increased by 0.7dB.5.A fiber based multifunctional integrated signal processing device is developed.By appropriately switching the optical path,the device can act as fiber optical parametric amplifier(FOPA),fiber optical parametric regenerator(FOPR),fiber optical parametric oscillator(FOPO)or fiber optical parametric magneto-optical switch(FOPS).The major performance parameters have been tested and verified by a third party.