Photonic generation, transmission, and detection of high-speed electrical signals.

摘要

Over the decades, a number of electronic methods and systems have been implemented to process high-speed electrical signals. Technological advances and the large operational bandwidth of electro-optic and fiber-optic components have motivated interest in the processing of electrical signals in the optical domain. In this dissertation, we present three significant advances in photonic methods of generation, transmission, and detection of high-speed electrical signals.; Photonic methods are able to generate electrical waveforms with spectral content (bandwidths in excess of 50 GHz) that can far exceed the state-of-the-art obtainable by electrical methods of waveform generation. We propose and experimentally demonstrate a spectral predistortion technique that overcomes substantial gain spectrum fluctuations found in the RF portion of an RF-Photonic AWG in order to generate high-power, ultrawideband, microwave waveforms. We produced an RF sawtooth waveform with a spectrum spanning more than a decade and voltage amplitudes of more than 13 V.; Once such electrical high-speed waveforms are generated, optical transmission of these signals over long distances via external modulation remains a significant challenge. We investigate an integrated electrooptic polymer ring-type modulator that operates in the millimeter-wave regime. We demonstrate modulation at the 84 GHz, 111 GHz, 139 GHz, and 165 GHz resonances of this device. The modulation response is characterized throughout the W-band (75--110 GHz), illustrating the resonant response at 84 GHz and 111 GHz. A traveling-wave analysis that includes the compound effect of microwave loss and optical/microwave velocity mismatch in a ring resonator-based modulator is presented and shows good agreement with experimental results. The ring modulator shows superior millimeter-wave performance compared to a Mach-Zehnder modulator in the presence of these limitations when both structures have the same equivalent low-frequency Vpi.; In addition, observation of such signals remains an important technological and scientific capability. In this dissertation, we propose and experimentally demonstrate a photonically assisted analog-to-digital system that employs a continuous wave (CW) multiwavelength source and single frequency phase modulation to perform discrete wavelength time stretching on sampled pulses. The use of a CW source and phase modulator allows for greater system flexibility while reducing complexity, cost, and easing the optical source performance requirements.