Signal Stability in Periodically Amplified Fiber Transmission Systems Using Multiple Quantum Well Saturable Absorbers for Regeneration

The use of multiple quantum well (MQW) saturable absorbers (SAs) for signal regeneration in periodically amplified fiber transmission systems is explored. A systematic study of signal destabilization resulting from incomplete saturation of MQW SAs used for regeneration, and of means of overcoming such destabilization, is presented. A computer model for MQW SAs, which considers the asymmetric Fabry-Perot (AFP) cavity structure commonly employed to increase the contrast of such devices, is presented. The model is used to simulate nitrogen-implanted MQW SAs with 7000 km when the two components are combined.</p

Chirp-based direct phase modulation of VCSELs managed by Neural Networks

VCSEL's capacity of direct modulation and its low cost makes this device a feasible cost-effective transmitter for ultra-dense wavelength division multiplexing (uDWDM) metro-access networks using coherent detection. However, performing direct-phase modulation in semiconductors can be complex due to its nonlinear characteristics. This research presents Neural Network (NN) training techniques for Time-Series analysis in order to describe the correlation between the input current given to the device and its output optical phase, using a 1550nm RayCan SM-VCSEL. Main goal is training a NN capable of predicting an ideal optical power signal for a specific phase result achievable by inverse training, that is: optical phase is the neural network input while the optical power is the desired target. The experiment is done in three stages: (i) VCSEL's characterization, (ii) NN training to predict input current knowing optical power, and (iii) NN training to predict optical power from a known optical phase

Investigation on Material Dispersion as a Function of Pressure and Temperature for Sensor Design

The concept of material dispersion is an important factor in analyzing the performance of an optical fiber system. The thesis presents an analysis of the material dispersion as a function of any pressure (in Mega Newton\u27s per square meter) and temperature (in degrees Celsius). The pressure dependent and temperature dependent Sellmeier coefficients are considered for the analysis. The results obtained can be used in building a sensor that can be used for measuring dispersion as a function of pressure or temperature

Investigation on Material Dispersion as a Function of Pressure and Temperature for Sensor Design

The concept of material dispersion is an important factor in analyzing the performance of an optical fiber system. The thesis presents an analysis of the material dispersion as a function of any pressure (in Mega Newton\u27s per square meter) and temperature (in degrees Celsius). The pressure dependent and temperature dependent Sellmeier coefficients are considered for the analysis. The results obtained can be used in building a sensor that can be used for measuring dispersion as a function of pressure or temperature

Characterization and Dynamic Analysis of Long-Cavity Multi-Section Gain-Levered Quantum-Dot Lasers

This research investigates the impact of different device architectures on the frequency response of long-cavity multi-section quantum-dot lasers. This work focused on a novel 8.3-mm multi-section quantum-dot device which possessed the flexibility to be configured either as a single- or multi-section device having gain-to-modulation section ratios of 14:2 and 15:1. The long-cavity device design facilitated the testing of increased gain-to-modulation section length ratios previously unexplored in the context of the gain-lever effect. The investigation of the gain-lever effect showed improvements to both the modulation efficiency and modulation bandwidth of the device under test. The modulation efficiency and modulation bandwidth were found to vary as the modulation section length was increased, leading to the conclusion of an ideal gain-to-modulation section ratio. In addition to providing a means to investigate the gain-lever effect, the long-cavity quantum-dot device exhibited passive mode locking both with and without a saturable absorber present. While the predictable gain-lever effects were observed, long-cavity and mode-locking effects were also present in the response; these effects presented unexpected characteristics that are not captured by current published models