Development of photonic integrated circuit techniques for widely tunable Mid-IR sources based on quantum cascade lasers
- Autores: Luis Jorge Orbe Nava
- Directores de la Tesis: Guillermo Carpintero del Barrio (dir. tes.)
- Lectura: En la Universidad Carlos III de Madrid ( España ) en 2015
- Idioma: inglés
- Tribunal Calificador de la Tesis: Tadao WAGATSUMA (presid.), Horacio Lamela Rivera (secret.), Sebastian Lourdudoss (voc.)
- Programa de doctorado: Programa Oficial de Doctorado en Ingeniería Eléctrica, Electrónica y Automática
- Calificación: Sobresaliente Cum Laude
- Materias:
- Enlaces
- Tesis en acceso abierto en: e-Archivo
- Resumen
In the last years, mid-infrared photonics has received renewed interest for a variety of applications. This spectral region provides a series of challenges from the technological point of view as light sources working in this span present limited wavelength tunability without the use of complex systems. Consequently, miniaturization efforts allowing for the development of widely tunable mid-infrared sources are extensively discussed, as product development consists of separated mechanisms, such as light sources and passive components that are put together and therefore present individual limitations and bottlenecks that hinder the further development of these technologies. Quantum Cascade Laser diodes are, from the optics point of view, one of the most common ways to generate mid-infrared light. Their properties, such as high integrability, operation at room temperature and reduced cost make them good technologies to implement in new systems. However, the limited tunability characteristics of these devices require the introduction of additional multiplexing stages in order to generate a single output device from the combination of several light sources. The present thesis investigates the design and characterization of InP/InGaAs passive optical functions for the development of multiplexer structures for the 7 – 10 ?m wavelength range. This work is described in a series of logical steps, starting with the description of basic passive optical functions and a waveguiding analysis that allows for the identification of the most important design parameters in straight and bent waveguides, such as waveguide width, etching depth and minimum bending radius. By simulating different combination of those parameters, we have studied the modal behavior and loss characteristics as a function of the injected wavelength. Based on those results, Y-junction based structures are designed and simulated as a first approach. However, they present large footprint areas, limiting their scalability and increasing propagation losses, as the size and number of ramifications increase as a function of the number of lasers to combine. A second approach, based on Echelle grating structures, is proposed as an alternative, presenting smaller footprints and better scalability. A dual Echelle grating multiplexer was designed in order to further improve the channel crosstalk and crossing levels, with the added objective of reducing the footprint in these multiplexer schemes by dividing the number of multiplexed inputs into multiple subdesigns which are later coupled into a single waveguide output. Results for the fabricated optical functions and basic Building Blocks are in agreement with the design and simulation results, confirming the feasibility of an InP/InGaAs epilayer structure to fabricate photonic building blocks to operate in the mid-infrared range. The characterization of the Echelle grating based multiplexers demonstrates the potential to monolithically integrate light generation and passive optical functions with an individual device. Despite having high insertion losses, a comprehensive review allows for better understanding of the device and suggests solutions for further improvements in the development of grating based mid-infrared multiplexers.
