High speed coherent subsystems analysis using photoelectric real-time analog-to-digital acquisition and offline signal processing

Author(s)

Tiago Sutili

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Elétrica e de Computação
• Defense date: 2018-02-23

Examining board members

Evandro Conforti; Murilo Araujo Romero; Glauco Fontgalland; Helio Waldman; Darli Augusto de Arruda Mello

• Advisor: Evandro Conforti; Rafael Carvalho Figueiredo; Cristiano de Mello Gallep

Abstract

Techniques for characterization of photonic devices are presented. The experimental procedures employ ultrafast acquisition of the electromagnetic optical wave, after its photodetection through direct or coherent reception schemes. The acquired data is digitalized and stored in high-speed memories, resulting in packets suitable for the posterior offline analysis. The developed algorithms allow the extraction of information regarding the dynamic operation of the photonic devices responsible for the optical carrier generation, modulation, or amplification. By employing this new methodology and interferometric principles, the harmonic distortions on electro-optical modulators are characterized as a function of their electrical modulation frequency. Therefore, a characterization technique based on the overmodulation analysis was developed, allowing the verification of the signal quality in the time and frequency domains as a function of the properties of the electrical modulation signals. The achieved results show the device frequency limitations, resulting in the increase of its half-wave voltage, as well as some nonlinear effects. Following, the phase and frequency noise in semiconductor lasers under continuous wave operating mode are characterized. The employed technique is based on the optical carrier coherent reception, mixed with a reference local oscillator, allowing its temporal analysis with an offline algorithm. The achieved results allow a thoughtful insight on the loss of coherence events nature, in addition to the estimation of lasers' linewidth. Finally, the characterization of amplitude, frequency, and phase distortions due to the optical carrier switching by an electro-optical space switch based on semiconductor optical amplifier (SOA), as a function of its operating properties, are discussed. In this sense, the optimum operational region and the desired device characteristics are determined for the switching of an amplitude modulated optical carrier case. Additionally, the frequency chirp and phase noise, due to SOAs' intrinsic nonlinear behavior, are characterized (AU)

• FAPESP's process: 14/18791-7 - High Speed Space Switches for Coherent Optical Networks
• Grantee: Tiago Sutili
• Support Opportunities: Scholarships in Brazil - Doctorate