UC San Diego

The motivation of this thesis originated from the challenge of building high-speed underwater optical communication links. Since current optical communication technologies cannot be directly applied to the sea water transmission window (480-560nm) due to the significant loss, a solution was pursued by building an optical mixer that can translate the modulation from conventional optical communication window (1550nm) to the visible spectral window, using parametric conversion based on photonic crystal fiber (PCF) platform. The thesis therefore mainly focuses on the investigation of the near- infrared band to visible band parametric translation process, both experimentally and theoretically. We, for the first time, to the best of our knowledge, successfully demonstrated Gb/s both amplitude and phase modulation translation across the record 400THz optical spectrum with error-free performance. At the same time, we achieved the record conversion efficiency for such distant band translation in the PCF. We also, for the first time, identified and characterized the impairment mechanisms of the parametric conversion process in the PCF. The mathematical methods and fiber design process are developed for PCF calculation and PCF fiber design. Proper fiber structure was designed for optimizing parametric phase matching and addressing the impairment mechanisms. The idea of optical mixer is not confined to the NIR-to- visible translation application and can be extended to other applications such that the complex transmission, processing, amplification and reception technologies are accessible to arbitrary spectral bands as well, by translating the telecom-band signal to arbitrary optical bands, which is particularly useful and has found important applications in the fields of sensing, spectroscopy, atmospheric communication and so on, detailed in the thesis. The thesis is divided into seven chapters. Chapter 1 serves as the introduction of the thesis, discussing in detail the motivation and the background knowledge including the current relevant technologies and the rationality of our technologies. The content and structure of the thesis are also briefed in Chapter 1. In Chapter 2, we study the parametric conversion within the telecom band using step-index highly nonlinear fibers (HNLF). One-pump and two-pump structures are compared and the differences between the two structures are quantified. In Chapter 3, we discuss the PCF, focusing on its guiding property and dispersion engineering feature. We also develop mathematical tools for PCF transverse structure calculation in this chapter. In Chapter 4, we characterize the parametric translation process from the telecom band to the visible band in PCF. For the first time, to the best of our knowledge, we have demonstrated Gb/s amplitude and phase translation from the telecom band to the visible band with error-free performance. The impairment mechanisms are identified, quantified and simulated. In Chapter 5, we perform the PCF structure design that aims for optimized phase matching condition and at the same time, address or mitigate the impairment mechanisms discussed in chapter 4. In Chapter 6, parametric translation from the telecom band to the middle -wavelength infrared band was studied, using Chalcogeinde glass fibers. We summarize the work in Chapter 7 and discuss the potential future directions