Ultralong continuous wave and ultrafast bre lasers at telecommunication wavelengths
The birth of lasers in 1960 had a strong impact on the development of bre optics, and consequently on nonlinear optics. Despite the enormous amount of literature concerning bre lasers, the topic is still actual and thriving and always looking for new solutions addressing the necessities of scienti c...
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| Tipo de recurso: | tesis doctoral |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Universidad de Alcalá (UAH) |
| Repositorio: | e_Buah Biblioteca Digital Universidad de Alcalá |
| Idioma: | inglés |
| OAI Identifier: | oai:ebuah.uah.es:10017/50850 |
| Acceso en línea: | http://hdl.handle.net/10017/50850 |
| Access Level: | acceso abierto |
| Palabra clave: | Fibra óptica Laseres Óptica no lineal Dispositivos láser Electrónica Electronics |
| Sumario: | The birth of lasers in 1960 had a strong impact on the development of bre optics, and consequently on nonlinear optics. Despite the enormous amount of literature concerning bre lasers, the topic is still actual and thriving and always looking for new solutions addressing the necessities of scienti c research and industry for what regards either continuous wave or ultrafast radiation sources. This thesis develops around two research lines, Raman distributed ampli ers, in the form of ultralong Raman bre lasers, and passive ultrafast bre lasers, which we will try to combine for the rst time. The second order Raman distributed ampli er called ultralong Raman bre laser has proven its suitability and e ciency in both unrepeatered and long-haul optical communication links. Nevertheless relative intensity noise transfer from pump to signal, especially in the case of high power co-propagating pump necessary to achieve the lowest signal power variation in the ampli er cell, may severely hinder the transmission performances. In the rst part of the thesis, a characterization of the relative intensity noise transfer in the cavity and an optimization of the architecture of the ampli er (changing the front-end re ectivity and the pump power split) is performed in order to improve the performance in a transmission system, which nds its optimal balance with a 20% forward pump power ratio and 10% front-end re ectivity with a transmission reach of 6479 km. Ultrafast radiation sources have a widespread use and are highly demanded. Modelocked bre lasers attract much attention due to their many advantageous features, such as compactness, low-cost, stability and easy handling. In the second part of the thesis, we focus on ultrafast passively mode-locked bre lasers trying to overcome one of their usual limits, that is the achievement of high peak power and pulse energies in the femtosecond range. Solutions for a simple, inexpensive, polarisation independent, high peak-power passively mode-locked femtosecond ring bre laser are developed, relying on standard and commercial components and a novel InN-based semiconductor saturable absorber mirror, that ensures self-starting mode-locking. Using a cavity 2.4 km long it is possible to obtain Gaussian pulses below 250 fs with a peak power over 1 MW and pulse energy over 250 nJ, properties that open up to new power demanding application elds. The developed laser system is then applied to the generation of supercontinuum and pulse compression, achieved through the addition of an external reel of single mode bre to the resonator. Fibres with di erent lengths and dispersion are employed to test the applicability and tunability of this low-cost, simple system. In particular with standard 3 single mode bre supercontinuum is generated over 200 nm with pulse compression down to 50 fs. Such radiation source is tested to prove its feasibility for gas sensing. In the last part, the developed ultrafast laser is used to implement for the rst time an ultralong Raman bre laser into a pulsed laser, with the objective of generating high power ultrashort pulses taking advantage of the virtually lossless and transparent span produced by the Raman cell. Mode-locking with sub-picosecond pulses is maintained in cavity up to 25 km in length, demonstrating this new application area for distributed Raman ampli ers. |
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