Publication: Sistema de caracterización automática de láseres de semiconductor y aplicación a láseres en anillo
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2010-10
Defense date
2010-10-29
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Abstract
El trabajo realizado durante el presente proyecto fin de carrera ha consistido en la automatización de la adquisición de datos de los diferentes instrumentos utilizados en un laboratorio de investigación optoelectrónico. Se han desarrollado diversos interfases software, para obtener los parámetros característicos de un láser de semiconductor, como son la curva de potencia óptica frente a corriente (curva P-I), la caracterización del ruido de fase. Estos interfases han sido utilizados para la caracterización de los láseres en anillo diseñados en la Universidad Carlos III de Madrid y fabricados en la plataforma europea de InP JePPIX. Las medidas realizadas sobre estos dispositivos son la curva P-I, el espectro óptico y el espectro eléctrico. Los resultados obtenidos, durante la medida de la curva P-I, han permitido verificar que los dispositivos operan como láser, obteniendo sus corrientes umbrales. Adicionalmente, la medida característica en diferentes tipos de estructuras (asimétricas y simétricas), ha permitido identificar que en los anillos asimétricos con múltiples absorbentes saturables se puede influir en la competición de modos que se contrapropagan en un anillo. Y mediante la polarización de cada uno de los absorbentes saturables independientemente, se ha demostrado que se puede compensar o aumentar el efecto que producen las asimetrías de la cavidad. Por otra parte, las medidas realizadas sobre el anillo simétrico han permitido observar como al aumentar la tensión inversa del absorbente saturable ambas direcciones pasan a presentar potencias semejantes, sugiriendo que el dispositivo entra en un modo de operación de colisión de pulsos entre los modos que se contrapropagan. Por el contrario, si en el anillo asimétrico se polarizaban los dos absorbentes saturables siempre se ha obtenido un modo dominante según la corriente aplicada. Con la medida del espectro óptico se ha ampliado la información de los dispositivos, obteniéndose información del número de modos de emisión y de la separación entre modos. Este último dato está relacionado con la longitud del resonador óptico. En los láseres en anillo, la tasa de repetición es inversa a la longitud del resonador L, según c/nL. Según las medidas realizadas en el anillo asimétrico se obtiene una tasa de 12.73 GHz y en el láser en anillo simétrico 15.52GHz. Finalmente, las medidas realizadas del espectro eléctrico han requerido amplificar la señal óptica. Los amplificadores ópticos disponibles eran dos EDFAs y un SOA disponible en el laboratorio. Sin embargo, el SOA era un dispositivo optimizado para generar efectos no lineales, y por tanto los resultados obtenidos para esta medida no son los esperados. En un futuro estudio será necesaria la adquisición de un SOA lineal para realizar un correcto análisis del ruido de fase. ____________________________________________________________________________________________________________
This end of degree project has been the automation the data acquisition from different instruments, which are used in optoelectronic research laboratory. Two interfaces are developed in this project. These interfaces are a useful tool to obtain the characteristic parameters of a semiconductor laser. The first of these interfaces allows measurement of optical power curve versus current (P-I curve) and the second interface is used for the characterization of phase noise. These interfaces have been used for the characterization of ring lasers. These ring lasers were designed at the University Carlos III of Madrid and manufactured in the European platform InP JePPIX. The measurements made in these lasers are the P-I curve, the optical spectrum and the electrical spectrum. The results obtained with the P-I curve, allowed to verify that the devices operate as lasers. In addition, the P-I curve was performed in different types of structures (asymmetric and symmetric). These measures has identified that the competition between modes which propagate in opposite directions can be modified in asymmetric rings with multiple saturable absorber. In the asymmetric ring laser always appears a dominant mode when both saturable absorbers are biased. Moreover, the polarization of each saturable absorber independently has proved that the effect of the asymmetries of the cavity can be reduced or increased. On the other hand, if the inverse tension of symmetric ring laser was increased, the modes of opposite directions acquired the same power. This suggests that the device enters a mode of operation of pulse collision between modes which propagate in opposite directions. The measurement of the optical spectrum provides more information about the device, as he number of emission modes and the separation between modes. This last fact is related to the length of the optical resonator. In a ring laser, the repetition rate is the inverse of a laser resonator length L, as c/nL. In the results, the rate for the asymmetric ring laser was 12.73 GHz and the rate in the symmetric ring laser was 15.52 GHz. Finally, the electric spectrum measurements are requires amplifying the optical signal. The optical amplifiers available in the laboratory were two EDFAs and a SOA. For measuring the electric spectrum was used a SOA which was available in the laboratory. However, the SOA was a device optimized to generate nonlinear effects. Because of this, the results for this measure weren´t expected. In the future study, a linear SOA will be requires to perform an accurate analysis of the phase noise.
This end of degree project has been the automation the data acquisition from different instruments, which are used in optoelectronic research laboratory. Two interfaces are developed in this project. These interfaces are a useful tool to obtain the characteristic parameters of a semiconductor laser. The first of these interfaces allows measurement of optical power curve versus current (P-I curve) and the second interface is used for the characterization of phase noise. These interfaces have been used for the characterization of ring lasers. These ring lasers were designed at the University Carlos III of Madrid and manufactured in the European platform InP JePPIX. The measurements made in these lasers are the P-I curve, the optical spectrum and the electrical spectrum. The results obtained with the P-I curve, allowed to verify that the devices operate as lasers. In addition, the P-I curve was performed in different types of structures (asymmetric and symmetric). These measures has identified that the competition between modes which propagate in opposite directions can be modified in asymmetric rings with multiple saturable absorber. In the asymmetric ring laser always appears a dominant mode when both saturable absorbers are biased. Moreover, the polarization of each saturable absorber independently has proved that the effect of the asymmetries of the cavity can be reduced or increased. On the other hand, if the inverse tension of symmetric ring laser was increased, the modes of opposite directions acquired the same power. This suggests that the device enters a mode of operation of pulse collision between modes which propagate in opposite directions. The measurement of the optical spectrum provides more information about the device, as he number of emission modes and the separation between modes. This last fact is related to the length of the optical resonator. In a ring laser, the repetition rate is the inverse of a laser resonator length L, as c/nL. In the results, the rate for the asymmetric ring laser was 12.73 GHz and the rate in the symmetric ring laser was 15.52 GHz. Finally, the electric spectrum measurements are requires amplifying the optical signal. The optical amplifiers available in the laboratory were two EDFAs and a SOA. For measuring the electric spectrum was used a SOA which was available in the laboratory. However, the SOA was a device optimized to generate nonlinear effects. Because of this, the results for this measure weren´t expected. In the future study, a linear SOA will be requires to perform an accurate analysis of the phase noise.
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Keywords
Optoelectrónica, Láser, Desarrollo de software, Semiconductores