Date of Award
Master of Science
George Hanson, Chiu-Tai Law, Guangwu Xu
Four Wave Mixing, Multimode, Nonlinear, Optical Fiber, Raman Scattering
Nonlinear processes in optical fibers can affect data transmission and power carried by
optical fibers and can limit the bandwidth and the capacity of optical communications.
On the other hand nonlinear phenomena could be utilized to build in-fiber all-optical
light sources and amplifiers. In this thesis new peaks inside an optical fiber have been
generated using nonlinear processes. An intense green pump laser has been launched
into a short fiber and specific modes have been excited to generate two new peaks in
red and blue wavelengths, where two pump photons are annihilated to create two new
photons in red and blue. The generated peaks are shifted far from pump; therefore
they are less polluted by pump and Raman induced noises. The phase matching
condition and the photon-flux rate for spontaneous and stimulated FWM have been
studied both theoretically and experimentally for a commercial grade SMF-28 fiber.
In low power and spontaneous regime new peaks are generated from quantum vacuum
noise. Using the same pump laser for a long fiber, up to 21 new peaks spanning from
green to Infrared have been generated. These peaks are equally spaced by 13THz.
Generation of a Raman cascade spanning the wavelength range of 523 to 1750 nm
wavelength range, in a standard telecommunication graded-index multimode optical
fiber has been reported. Despite the highly multimode nature of the pump, the Raman
peaks are generated in specific modes of the fiber, confirming substantial beam cleanup
during the stimulated Raman scattering process.
Pourbeyram Kaleibar, Hamed, "Nonlinear Processes in Multi-Mode Optical Fibers" (2014). Theses and Dissertations. 481.