Saxena, Bhavaye2014-10-302014-10-3020142014http://hdl.handle.net/10393/31766http://dx.doi.org/10.20381/ruor-6615Frequency and intensity noise are characterized for Erbium-Doped Fiber and Brillouin random lasers based on Rayleigh distributed feedback mechanism. We propose a theoretical model for the frequency noise of an Er-doped fiber random lasers using the property of random phase modulations from multiple scattering points in ultra-long fibers. We find that the Rayleigh feedback suppresses the noise at higher frequencies by introducing a Lorentzian envelope over the thermal frequency noise of a long fiber cavity. The theoretical model and measured frequency noise agree quantitatively with two fitting parameters. A similar model, which also includes additional acoustic fluctuations and a distributed gain profile in the fiber, has been speculated for the Brillouin random laser. These random laser exhibits a frequency noise level of < 6 Hz^2/Hz at 2 kHz, which is lower than what is found in conventional narrow-linewidth EDF fiber lasers and Nonplanar Ring Laser oscillators (NPRO) by a factor of 166 and 2 respectively.enRandom LaserFiber OpticsFrequency NoiseThesis