Estudo do desempenho de filtros acústicos-ópticos sintonizáveis como componentes biestáveis e sua utilização na criptografia em redes ópticas

• Ano de defesa: 2009
• Autor(a) principal: Sabóia, Karlo David Alves
• Orientador(a): Sombra, Antônio Sérgio Bezerra
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Ótica; Criptografia; Optics; Bistability
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/13670

The performance of acoustic-optic tunable filters (AOTF) as a bistable component, applied to cryptography in optical networks, has been studied with analytical and numerical methods. Initial investigations of such filters highlighted their main transmissions, and analyzed their behavior by nonlinear effects with formation of optical bistability when a feedback was introduced in the system. Subsequently, it was proposed the use of an AOTF device, together with simultaneous modulation of ultrashort pulses by position (PPM) and amplitude (PAM), for generation of a cryptographic system for application in optical networks. Numerical simulations were performed using the Runge-Kutta fourth order method. The results for the study of bistability showed the dependence of the hysteresis curve with respect to the product of coupling constant by the length of the device and the conversion power-coupling constant factor (G). It was shown that the range of bistability varies significantly with both G and the product of coupling constant by the length of the device. The variation of the product of coupling constant by the length of the device directly increases the size of the bistability range while the increase in G causes the bistability occurrence for initial powers to decrease. The results obtained in the study of the AOTF as a cryptographer showed that it is possible to define a pair of parameters, called PPM/PAM pair, directly related to the modulations used in the process, which will serve as key to communications between two users in an optical network. The device would be used to encode and decode data.