Search results for "nonlinear effects"
showing 6 items of 6 documents
Flat supercontinuum generation pumped by amplified noise-like pulses from a figure-eight erbium-doped fiber laser
2017
The conditions to obtain noise-like pulses (NLPs) from a figure-eight fiber laser (F8L) and their application for supercontinuum (SC) generation in the anomalous dispersion regime are reported. The F8L is designed to remove the undesired low-intensity background radiation from pulse emission, generating NLPs with a 3 dB spectral bandwidth of 17.43 nm at the fundamental repetition frequency of 0.8 MHz. After amplification, NLPs reach a maximum average power of 9.2 mW and 123.32 nm spectral bandwidth. By controlling the amplifier pump power, flat SC generation is demonstrated through both a 800 m long spool of SMF-28 fiber and a piece of 5 m long highly nonlinear optical fiber. The results de…
Enhancement of electron spin lifetime in GaAs crystals: the benefits of dichotomous noise
2013
The electron spin relaxation process in n-type GaAs crystals driven by a fluctuating electric field is investigated. Two different sources of fluctuations are considered: (i) a symmetric dichotomous noise and (ii) a Gaussian correlated noise. Monte Carlo numerical simulations show, in both cases, an enhancement of the spin relaxation time by increasing the amplitude of the external noise. Moreover, we find that the electron spin lifetime versus the noise correlation time: (i) increases up to a plateau in the case of dichotomous random fluctuations, and (ii) shows a nonmonotonic behaviour with a maximum in the case of bulks subjected to a Gaussian correlated noise.
Electron dynamical response in InP semiconductors driven by fluctuating electric fields
2015
Abstract The complexity of electron dynamics in low-doped n-type InP crystals operating under fluctuating electric fields is deeply explored and discussed. In this study, we employ a multi-particle Monte Carlo approach to simulate the non-linear transport of electrons inside the semiconductor bulk. All possible scattering events of hot electrons in the medium, the main details of the band structure, as well as the heating effects, are taken into account. The results presented in this study derive from numerical simulations of the electron dynamical response to the application of a sub-Thz electric field, fluctuating for the superimposition of an external source of Gaussian correlated noise.…
Sub-200-kHz single soliton generation in a long ring Er-fiber laser with strict polarization control by using twisted fiber
2020
Abstract In the present work we demonstrate a novel single-soliton ultra-low pulse repetition frequency passively mode-locked erbium-doped fiber laser. We mitigate the residual linear birefringence of fiber by fiber twist to achieve a strict control of polarization. For mode-locking the nonlinear polarization rotation (NPR) was used. Special technique was applied to reduce the overdriving of NPR that allows the generation of single soliton in ultra-long cavity. The strict control of polarization yields a stable relation between the polarization state of the pulses propagating in the cavity and the regimes of generation. A 192.12-kHz train of soliton pulses was obtained with pulse duration o…
Whispering Gallery Modes: Advanced Photonic Applications
2019
Los micro-resonadores basados en Whispering Gallery Modes (WGMs) han atraido un gran interés en las últimas décadas debido a su fuerte confinamiento de la luz. Tales micro-resonadores pueden ser fabricados con diferentes geometrías y materiales. Estos micro-resonadores exhiben factores de calidad Q altos y volúmenes modales pequeños, lo que permite realizar un gran número de estudios y aplicaciones, como por ejemplo el estudio de efectos no-lineales ópticos. La delgada anchura spectral que presentan las resonancias WGM permite la medida de pequeñas perturbaciones de los parámetros de los micro-resonadores, con un límite de detección bajo. Esta tesis proporciona la caracterización experiment…
Microwave response of bulk MgB2 samples of different granularity
2006
The microwave response of three high-density bulk MgB2 samples has been investigated in the linear and nonlinear regimes. The three samples, characterized by different mean size of grains, have been obtained by reactive infiltration of liquid Mg in powdered B preforms. The linear response has been studied by measuring the microwave surface impedance; the nonlinear response by detecting the power radiated by the sample at the second-harmonic frequency of the driving field. Our results suggest that bulk MgB2 prepared by the liquid Mg infiltration technique is particularly promising for manufacturing resonant cavities operating at microwave frequencies.