The Role of Rayleigh Backscattering of Coherent Light in the Mode Dynamics of Random DFB Fiber Lasers

Abstract

I would like to thank my advisor Jean Pierre von der Weid, whose teaching capabilities go far beyond optics and photonics. I learned to be curious about every tiny detail, which not often, but occasionally, hides incredible answers, revealed only to those who persist in being curious.To all my colleagues and friends from the photonics laboratory at PUC-Rio, who were always there to help and happy to discuss about all the interesting phenomena we witnessed over the years.To my wife, who enlightens my days with joy and love, being the best life-partner any man could ask for.To my mother, for her unlimited love and support, and for encouraging me along each and every step of the way.To my brother. My uttermost example of integrity, who has always chosen the path made of principles, that leads to character.Without them, this work would not have been possible. To all my family and friends, who directly or indirectly contributed to this work.This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -Brasil (CAPES) -Finance Code 001. And I would also like to thank the Brazilian agency CNPq for the financial support.

Mode-Locked Fiber Lasers for Optical Time-Domain Reflectometry and Sensing

“…In this work, demonstrates that when inserted in a ring, SOAs can simultaneously work as a gain medium and modulator in fiber laser configurations. In our lab, we use a SOA model SOA1013SXS [66] with FWHM bandwidth measured to be of 33-nm (see figure 2.6(a)) for an injection current of 425-mA [67]. Figure 2.7 shows the measured gain for bias currents varying from 0 to 400 mA.…”

“…For currents higher than I T the SOA provides gain to the input signal, however, further increase in the driving current gives less gain, thus, a gain saturation with driving current is observed. The results shown in Figure 2.7, a low power input signal had to be used, with input power of -20-dBm (small signs) [67]. For large signals, SOA saturates for smaller injection currents and consequently operates with gain compression.…”

“…Generally, RFL incorporate one optical amplifier and a fixed distributed reflector [19]. By using fiber optics as the random laser medium multiple scatters as shown in Works in the literature have reported random fiber lasers using localized (SOA) gain combined with Rayleigh scattering in single mode fibers [19,67]. Another works in the literature also reported random fiber lasers using distributed gain (Raman or EDF) [18,96].…”

“…27 Energy levels and carrier concentrations for a p-type and an n-type semiconductor [63]. 29 [67], and (b) its fiber-coupled packaged mount [66]. 30 12.…”

“…Confinement is caused by the difference in refractive index between the core and cladding structures, which retain light in the direction transverse to propagation. The benefits of using optical fibers as a medium for random laser action go far beyond reducing the complexity of the spatial emission, which, in this case, assumes an almost Gaussian beam[19, 20,67,96].…”