Advanced nonlinear optical signal processing techniques for high speed, reconfigurable optical fiber networks

Optical fiber telecommunications is facing the bottleneck of electronics due to the increasing demand for higher bandwidth by the consumers. The increase in the single channel data speeds are accompanied by the multiple access methods such as wavelength division multiplexing, electrical time division multiplexing, and optical time division multiplexing. Moreover, recently there is extensive research on spatial division multiplexing schemes using multi-mode and multi-core fibers. All these increase the aggregate data rate that needs to be process in the routers and distribution centers. ❧ The limited speed of state-of-the-art electronics and inefficient optical-electrical-optical conversions has encouraged the researchers in the photonics society to look for alternatives to electronics and electronic signal processing. Optics offer very high bandwidths (>Terahertz) for data transmission and ultra-fast responses (a few tens of femto-seconds) for signal processing applications. The inherent transparency to the data rates and data modulation formats of photonic nonlinear interactions enables various types of signal processing applications. Many of these tend to use a single nonlinear medium and a unique process that enables the desired signal processing function. However, these tend to be simple functions and have been far from realistic signal processing functions that have been used in the electronics. ❧ In this Ph.D. dissertation, a systematical development to the nonlinear optical signal processing methods for enabling complex signal processing functionalities for advanced modulation format signals, including coherent detection, is proposed and experimentally demonstrated. It is shows that optical signal processing can be used for achieving complex system level applications such as buffering, and time-slot interchange of packets, correlation, equalization, matched filtering, and even for applications of analog radio frequency (RF) signals with excellent performance metrics. For these and for many other applications, one needs to generate signal copies, i.e. wavelength multicast the input data. These copies then need to be correlated in some fashion. This can be achieved by using optical delays using chromatic dispersion. The delayed signal copies are then interacted to each other in a multiplexing stage. Each of these consists of sub-systems that need improvements to form a complete, utilizable functional block for optical communication signals. In the work presented in this Ph.D. dissertation, novel solutions to these problems are proposed and versatile methods that can enable many other ultra-fast signal processing functionalities are developed.