Research On Novel Pulse Laser Based On SOA

With the development of modern science and the progress of technology, pulselaser plays a more important role in scientific research and industrial production, andhas been widely used in fields of optical fiber communication and optical fibersensors. More and more researchers pay attentions to the lasers based on the gainmedium of SOA. In this paper, we put forward a variety of novel pulse laser structuresbased on the SOA and we analyzed their realization mechanisms.Based on the nonlinear polarization rotation technique of the SOA, for the firsttime, we proposed the structure of self-mode locking laser. We analyzed the nonlinearpolarization rotation of the SOA which is the key elements of self-mode locking laser.By using the Stokes vector and the Mueller matrix, we analyze light polarization statein the SOA. we also analyzed the SOA numerical extension model of nonlinearpolarization rotation. Phenomenons of self-mode locking are boserved, and pulsedurations of30ns and50ns are achieved, with frequency repetitions are19.34MHzand9.67MHz respectively. We carry on the experiment and theoretical analysis forthe phenomenon of dimidiate frequency: the polarization rotation caused by the SOAleads to the change of output power and phenomenon of dimidiate frequencygenerates.We studied the theory of the dark pulse laser based on the group velocitydispersion and self phase modulation. By using the nonlinear Schrodinger equation,we anaylze bright and dark soliton conditions: bright solitons appear in anomalousdispersion regime, and dark solitons appear in normal dispersion regime. Based on theXGM and XPM character of the SOA, for the first time we proposed the structure ofpulse width tunable dark pulse laser based on the feedback cavity, by changing thelength of the feedback loop, with the same repetition frequency, we achieve darkpulses with the pulse width of4ns to22ns, and we analyzed the mechanisms of XPMand XGM in the SOA for realizing the dark pulse.Utilizing the switch features of the optical fiber loop mirror based on SOA, forthe first time we propose a F8L based on the optical fiber loop mirror to generatethree-level optical staircase waveform with frequency repetition of9MHz and33.4MHzand pulse widths of37ns and10ns respectively. By adjusting the polarization controllers in or out of the cavity, we found power ratio of ‘1’ code and ‘2’code can convert into the other.By changing the position of the SOA in the loop, we also find pulse widths changeaccordingly. Experiments and theoretical analysis demonstrate that pulses transmit onclockwise and counterclockwise directions produce the cross phase modulation and crossgain modulation in the SOA to turn on the switching window and form two pulses with thesame pulse widths.The two pulses compose the optical staircase waveform.