Date of Award


Degree Type


Degree Name

Master of Science



First Advisor

Arash Mafi

Committee Members

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.