Date of Completion
nonlinear optics, fiber optics, supercontinuum, short pulse, optical communications
Niloy K. Dutta
Field of Study
Doctor of Philosophy
The dramatic progress in optical communication is attributed to the development of wavelength-division multiplexing and time-division multiplexing technologies, which employ broadband light source and ultrashort optical pulses respectively to carry signals in optical fibers. Supercontinuum generation is the spectral broadening of narrow-band incident pulses by the propagation through optical waveguides made of nonlinear materials. In this PhD dissertation, I show the design of a tapered lead-silicate optical fiber for supercontinuum generation. The physical mechanisms of optical pulse evolution are explained, which involve various nonlinear optical effects including self-phase and cross-phase modulation, stimulated Raman scattering, four-wave mixing, modulation instability and optical soliton dynamics. I have also proposed planar waveguides with longitudinally varying structure to manage chromatic dispersion, and numerically simulated the generation of (1) broadband and (2) flat octave-spanning supercontinuum output. The coherence property and noise sensitivity of supercontinuum are also investigated in this dissertation, which depend strongly on pumping conditions. A hybrid mode-locked erbium-doped fiber ring laser, which combines rational harmonic active mode-locking technique and graphene saturable absorber, has been designed and experimentally demonstrated to produce optical pulse train. Compared to active mode-locking configuration, the hybrid scheme narrows the pulse width significantly at a high repetition rate of 20 GHz.
Hu, Hongyu, "Nonlinear Optical Processes for Spectral Broadening and Short Pulse Generation" (2017). Doctoral Dissertations. 1353.