Photonic time stretch analog-to-digital conversion for high resolution and real-time burst sampling of ultra-wideband signals.

摘要

With rapidly growing speeds and capabilities of electronics, vast amount of information can now be stored, processed and transmitted in digital format. However, most signals that represent this information are generated and transmitted by physical systems in analog format. For instance, next generation optical communication links will transmit >100-Gbit/s digital data per wavelength channel using advanced bandwidth efficient modulation formats. At the receiver, fast, high resolution analog-to-digital converters (ADCs) will be required to digitize these signals before they can be demodulated using digital signal processing. Fast and high resolution ADCs, therefore, become crucial for future communications systems, emerging biomedical and sensing applications, and fast yet accurate test and measurement equipment.;Ironically, even with improving speeds, electronics lack the capability of meeting this growing demand. Photonics, in particular the photonic time stretch preprocessing technique, can be very helpful in overcoming these limitations to meet this demand. In this dissertation, the underlying concepts in a photonic time stretch analog-to-digital converter (TS-ADC) have been discussed. The goal of this work was to study different sources of noise and distortion in the TS-ADC and to develop techniques for reducing or removing them. Such techniques, developed to obtain high resolution wide bandwidth TS-ADC and achieve this goal, have been described. Some of these techniques have led to the demonstration signal capture with a record >7 ENOB resolution over 10-GHz bandwidth. Power scaling with frequency in high-speed ADCs has been discussed and it is shown that the TS-ADC can actually be useful in reducing the overall power dissipation in ultra-high-speed ADCs.;Real-time burst sampling (RBS), a new mode of capturing ultrafast signals achieved using only a single channel TS-ADC, is introduced. This technique combines real-time capability with ultrawide bandwidth operation, and holds great potential for revolutionizing future high speed test and measurement equipment.