Publication: Characterization of integrable photonic sources of pulsed light via mode-locked ring laser diode
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2011-12
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2011-12-14
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Abstract
El presente proyecto ha consistido en el estudio en profundidad de una serie de láseres en anillo enganchados en fase, integrados en una placa de circuito. Los láseres en anillo de semiconductor son una fuente atractiva de pulsos ópticos para los sistemas fotónicos integrados que necesitan componentes compactos y económicos, necesarios para un desarrollo comercial exitoso. Además, estos diodos láser pueden ser integrados junto con otros componentes ópticos en el mismo circuito, lo que reduce su tamaño, las pérdidas y el precio. El hecho de que sean láseres enganchados en fase contribuye a generar pulsos cortos de luz a una determinada tasa de repetición, por lo que los láseres de anillo son una gran fuente de luz para muchas aplicaciones, especialmente en el área de las comunicaciones. Tres interfaces software han sido desarrollados para interactuar con los instrumentos presentes en el laboratorio para automatizar las medidas que se han tomado. El objetivo era medir parámetros típicos de los láseres en estudio: la curva de potencia óptica frente a la intensidad (curva PI), el espectro de radiofrecuencia junto con su ruido de fase y la autocorrelación de los pulsos de luz presentes en la guía onda de salida del láser. También se ha incluido la medida del espectro óptico para completar los resultados. Los resultados obtenidos de la curva PI han permitido determinar la corriente umbral de los diodos láser en anillo y los distintos regímenes de trabajo. Las medidas del espectro óptico y de radiofrecuencia han contribuido a establecer la hipótesis de funcionamiento en modos enganchados en fase, y este hecho ha sido corroborado por el estudio de autocorrelación de los pulsos emitidos. Por último, algunos resultados muy interesantes pueden ser extraídos de estas últimas medidas sobre una estructura de anillo láser simétrico con dos secciones SOA y un absorbente saturable. En primer lugar, se ha corroborado que el régimen de modos enganchados en fase se induce a través de una polarización inversa en el contacto del absorbente saturable, apareciendo pulsos de luz ultracortos bien definidos. En segundo lugar, se ha demostrado que la forma y el ancho de estos pulsos se puede controlar a través de la polarización asimétrica de sus dos secciones de ganancia. La tasa de repetición del láser simétrico es de 14,98 GHz y se han obtenido pulsos de entre 1 y 2 picosegundos de ancho temporal. Los mejores resultados incluso ofrecen un ancho de pulso temporal por debajo de 1 ps con un perfil lorentziano, que es un hecho muy interesante. ______________________________________________________________________________________________________________________________
The present project has consisted in the in-depth study of a series of mode-locked ring lasers integrated in a circuit board. Semiconductor ring lasers are an attractive source of optical pulses for photonic integrated systems which need compact and cheap components, required for a successful commercial development. Furthermore, these diode lasers can be integrated together with other optical components in the same circuit, thus reducing size, losses and price. Mode-locking contributes to generate short light pulses at a given repetition rate, making ring lasers a great source for many applications, especially in the communications area. Three software interfaces have been developed to interact with the instruments present in the laboratory to automate the measurements that have been taken. The objective was to measure typical parameters of the lasers under study: the curve of optical power versus intensity (PI curve), the radio frequency spectrum together with its phase noise and the autocorrelation of the emitted light pulses at the output waveguide of the lasers. It has also been included the measurement of the optical spectrum to complete the results. The obtained results of the PI curve have allowed determining the lasing threshold of the diode ring lasers and different working regimes. Optical and radio frequency spectrum measurements have contributed to establish the hypothesis of mode-locking functioning, and this fact has been corroborated by the autocorrelation study of the emitted pulses. Finally, some very interesting results can be extracted from these last measurements over a symmetric ring laser structure with two SOA sections and a saturable absorber. In first place, it has been corroborated that the mode-locking regime is induced through a reverse bias in the saturable absorber contact, appearing well-defined ultrashort light pulses. Secondly, it has been proved that the shape and width of these pulses can be controlled throughout the asymmetric biasing of its two gain sections. The measured repetition rate of the symmetric laser is of 14.98 GHz and pulses between 1 and 2 picoseconds have been obtained. The best results even offer a temporal pulse width under 1 ps with a Lorentzian profile shape, which is a very interesting issue.
The present project has consisted in the in-depth study of a series of mode-locked ring lasers integrated in a circuit board. Semiconductor ring lasers are an attractive source of optical pulses for photonic integrated systems which need compact and cheap components, required for a successful commercial development. Furthermore, these diode lasers can be integrated together with other optical components in the same circuit, thus reducing size, losses and price. Mode-locking contributes to generate short light pulses at a given repetition rate, making ring lasers a great source for many applications, especially in the communications area. Three software interfaces have been developed to interact with the instruments present in the laboratory to automate the measurements that have been taken. The objective was to measure typical parameters of the lasers under study: the curve of optical power versus intensity (PI curve), the radio frequency spectrum together with its phase noise and the autocorrelation of the emitted light pulses at the output waveguide of the lasers. It has also been included the measurement of the optical spectrum to complete the results. The obtained results of the PI curve have allowed determining the lasing threshold of the diode ring lasers and different working regimes. Optical and radio frequency spectrum measurements have contributed to establish the hypothesis of mode-locking functioning, and this fact has been corroborated by the autocorrelation study of the emitted pulses. Finally, some very interesting results can be extracted from these last measurements over a symmetric ring laser structure with two SOA sections and a saturable absorber. In first place, it has been corroborated that the mode-locking regime is induced through a reverse bias in the saturable absorber contact, appearing well-defined ultrashort light pulses. Secondly, it has been proved that the shape and width of these pulses can be controlled throughout the asymmetric biasing of its two gain sections. The measured repetition rate of the symmetric laser is of 14.98 GHz and pulses between 1 and 2 picoseconds have been obtained. The best results even offer a temporal pulse width under 1 ps with a Lorentzian profile shape, which is a very interesting issue.
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Láser, Optoelectrónica, Instrumentación, Circuitos integrados