Desarrollo de un transmisor óptico para redes de acceso. / Development of an optical transmitter for access networks.

Zoireff, Gustavo (2015) Desarrollo de un transmisor óptico para redes de acceso. / Development of an optical transmitter for access networks. Integration Project in Telecommunications Engineering, Universidad Nacional de Cuyo, Instituto Balseiro.

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Abstract in Spanish

En este trabajo se realizó el diseño, fabricación y puesta en marcha de un transmisor óptico para redes de acceso o sistemas de radio sobre fibra. Inicialmente se analizaron la teoría de operación y el modelo de láseres de semiconductor tipo DFB (Distributed Feedback). Luego, se estudiaron diferentes circuitos adaptadores de impedancia y de polarización para la implementación de la modulación directa de la corriente del láser. En principio, se construyeron, caracterizaron y ensayaron diferentes adaptadores de componentes discretos que permitían modular hasta frecuencias del orden de las decenas de megahertz, pero fue necesario optar por otra implementación basada en líneas de transmisión de microtira para poder modular con señales de anchos de banda del orden del gigahertz. Para generar la señal de modulación se diseñó en una FPGA un conformador de pulsos digital. A continuación, se diseñó y fabricó un conversor digital-analógico de 4 bits con sus correspondientes circuitos de acondicionamiento de señal para excitar la entrada de modulación del transmisor. Finalmente, se ensambló y se ensayó el transmisor óptico con un fotodetector comercial. Se logró obtener una tasa de transmisión de 100 Mbps, utilizando pulsos digitales con el formato de modulación On-Off Keying codicado a NRZ.

Abstract in English

This work decribes the design, manufacturing and start up of an optical transmitter for access networks or radio-over-fiber systems. In the first place, they were analyzed the operation theory and the model of semiconductor DFB (Distributed-Feedback) lasers. Next, severals impedance matching and bias networks were studied for direct modulation of the current applied to the laser. To begin with, they were built, characterized and tested different kinds of matching networks with lumped elements, which accomplished to modulate up to frequencies about tens of megahertz. However, it was necessary to choose another implementation based on microstrip transmission lines to achieve modulated signals with gigahertz-bandwidth. To generate the modulation signal it was carried out a digital pulse shaper in an FPGA. Then, a 4 bit digital-to-analog converter was designed and set up, including their appropriate signal conditioning circuits to excite the transmitter's modulation input. Finally, the optical transmitter was assembled and tested with a commercial photodetector. A 100 Mbps transmission bit rate was achieved, using digital pulses with On-Off Keying NRZ-coded modulation scheme.

Item Type:Thesis (Integration Project in Telecommunications Engineering)
Keywords:Telecommunication systems; Sistemas de telecomunicación; Optical systems; Sistemas ópticos; Optical fibers; Fibras ópticas; Optoelectronic devices; Dispositivos optoelectrónicos; Data transmission; Transmisión de datos; Lasers; Láseres [Optical transmitters; Transmisores ópticos; Access networks; Redes de acceso; Direct modulation; Modulación directa; Impedance matching networks; Redes de adaptación de impedancias]
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Subjects:Ingeniería en telecomunicaciones > Comunicaciones ópticas
Divisions:Gcia. de área de Investigación y aplicaciones no nucleares > Laboratorio de investigación aplicada en Telecomunicaciones
ID Code:791
Deposited By:Tamara Cárcamo
Deposited On:08 Aug 2019 15:49
Last Modified:08 Aug 2019 15:49

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