Neste trabalho apresentamos uma instrumentação que é capaz de estabilizar e medir o comprimento de onda emitido por um laser de semicondutor em 1 parte de 106. Para obtermos essa precisão foi necessário desenvolver um controlador de temperatura, uma fonte de corrente e um medidor de onda. / In this work we present an instrumentation that is able to stabilize and measure the semiconductor laser wavelength with a precision of 1 part in 106. To obtain this precision was necessary to develop a temperature controller, current source and wave meter.

Neste trabalho apresentamos uma instrumentação que é capaz de estabilizar e medir o comprimento de onda emitido por um laser de semicondutor em 1 parte de 106. Para obtermos essa precisão foi necessário desenvolver um controlador de temperatura, uma fonte de corrente e um medidor de onda. / In this work we present an instrumentation that is able to stabilize and measure the semiconductor laser wavelength with a precision of 1 part in 106. To obtain this precision was necessary to develop a temperature controller, current source and wave meter.

2025 / The development of fiber amplifiers plays a critical role in a wide range of applications, including high-energy systems, weak signal sensing and imaging, and optical communications, where Erbium-doped fiber amplifiers (EDFAs) are commonly utilized. In particular, the increasing demand for amplifiers capable of supporting a high number of data channels is essential to avoid the looming “capacity crunch” in information networks. However, any significant expansion in capacity will inevitably drive a substantial rise in energy consumption. Consequently, the integration of additional data channels in telecommunications must be approached with energy efficiency in mind. Spatial division multiplexing (SDM) has emerged as a promising solution, leveraging spatial dimensions such as modes or fiber cores to enable data parallelism, and is becoming the preferred technology for reducing energy usage in optical networks. This thesis examines the amplification dynamics and properties of multimode (MMF) ring-core fibers (RCFs) that can stably support spatial modes carrying orbital angular momentum (OAM), which can serve as independent, uncoupled signal channels. Notably, RCFs featuring topologically confined modes (TCMs) have demonstrated the highest uncoupled mode capacity among MMFs to date. We explore how these fibers can be turned into amplifiers by utilizing χ^(3) material nonlinearities and by developing doped MMF-EDFAs.In this work, we investigate the nonlinear effects of OAM modes in multimode fibers, with a particular focus on acousto-optic interactions between these modes and phonons, leading to the generation of Stimulated Brillouin Scattering (SBS). Traditionally, SBS in single-mode fiber amplifies a narrowband Stokes signal using a powerful pump, operating through a self-phase matching process. However, by utilizing OAM modes, we exploit their distinctive phase characteristics to exert greater control over this interaction. This leads to the introduction of a novel OAM conservation law, which governs the modulation of inter-modal interactions between the pump, phonons, and Stokes, allowing for adjustable nonlinear gain. Furthermore, the chiral properties of OAM modes enable the launch of superposition-state pumps in RCFs, resulting in polarization rotation, a phenomenon known as optical activity. This optical activity, characterized as a stable birefringent interference effect due to its geometrodynamic nature, creates a special phase-matching and polarization-selective condition. This condition allows for complete spatial phase conjugation of the pump state, as the Stokes signal must retrace the pump’s polarization rotation to achieve significant gain. This mechanism also provides control over Stokes growth and the gain threshold condition. Overall, our analysis demonstrates that OAM modes offer up a versatile degree of freedom for controlling amplification through fiber nonlinearities. RCFs and OAM modes present significant potential for developing high-data-capacity SDM-EDFAs, offering key advantages for stimulated emission-based amplification. The strong confinement of these modes within a doped fiber core enhances their interaction with erbium ions, facilitating the creation of highly absorbing and emitting amplifiers that outperform their single-mode and multi-core EDFA counterparts. Another benefit of using OAM modes lies in their similar intensity profiles, with their orthogonality primarily derived from distinct phase characteristics. Since EDFA amplification depends on intensity rather than phase, this architecture enables high, equalized gain and low-noise amplification across numerous spatial channels. We experimentally characterize an RCF-EDFA that leverages these advantages and topological confinement to achieve high-gain amplification across a record number of uncoupled OAM modal channels. Furthermore, simulations of an optimized, deployment-ready version of the EDFA further demonstrate its ability to amplify numerous spectral and spatial data channels simultaneously while maintaining high energy efficiency. This performance is made possible through a proposed pumping scheme in which the pump consists of a superposition of OAM fiber modes, like the signal, benefiting from the large and stable mode ensemble. By sculpting the modal distribution of the pump, the amplifier architecture is optimized to increase pump-signal overlap, achieving both high, equalized gain and low noise figures while reducing pump power requirements. This thesis explores this parameter space, through both simulations and experimental investigations, with the aim of developing optimal SDM fiber amplifiers that address the capacity, energy efficiency, and cost demands of future optical fiber networks.