CAREER: Modules for Fiber Optic Communication Systems

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9502491 Bergman Optical fibers are essential to many emerging optical technologies, including communication systems, data processing, video transmission, and computing. The bandwidths and data rates achievable using guided photons are several orders of magnitude greater than comparable systems using electronic or microwave technologies. Fibers are inexpensive low-loss waveguides, and exhibit the type of nonlinearities which can be exploited in making ultrafast all-optical switching devices, pulsed fiber lasers, multiplexers and demultiplexers, as well as various timing control modules for fiber optic communication systems. Long-haul and local area fiber optic communication networks as multigigabit-rates will inevitably be done by a combination of time domain multiplexing (TDM) and wavelength (frequency) division multiplexing (WDM) techniques. TDM can be used to reduce the number of frequency channels allowing the WDM channels broader tolerances in carrier frequency placement and filter requisites. Our objective is to investigate novel fiber optic modules that incorporate ultrafast time domain techniques with WDM functions. We propose to build ultrahigh bit-rate femtosecond fiber lasers in both the soliton and zero dispersion regimes. The method is based on the nonlinear properties of pulse formation including frequency selection and shifting, as well as TDM applications such as ultra-high bit-rate demultiplexing and data retrieval. A new technique we propose to use has been shown to generate considerable pulse shortening in actively modelocked lasers beyond the predicted pulsewidths from active modelocking theory. The method is based on the nonlinear properties on pulse formation and propagation in the soliton or negative dispersion regime, and has the great advantage of simplicity over previous modelocked lasers and switching devices that were designed based on fast fiber nonlinearities concepts. The initial work will focus on developing novel fiber optic laser sources for hi gh bit-rate pulses at both 1.5p.m and 1.3p.m. The lasers will then be modified to produce carrier frequency tunable pulse trains for WDM applications. We will use the pulse streams to test a frequency shifting module operating on similar mechanisms. Next, a TDM demultliplexer and a ultrafast data retriever will be demonstated. Finally, a complete system prototype implementation that integrates the fiber laser source, WDM and TDM devices will be demonstrated. The successful completion of the proposed research will have significant impact on research and development efforts in fiber optic communication technology. This proposed research program addresses the issue of integrating WDM capabilities with high bit-rate soliton sources and switches, and will be unquestionable value to future high capacity optical communication networks. Two particularly important fields positioned to gain from our research efforts are long-haul communication systems and terrestrial fiber loop networks. In conjuction with our proposed development of soliton devices for long-haul communication, we will apply the same nonlinear modelocking principles to the construction of high bit-rate short pules with Pr-doped fiber amplifiers at the zero dispersion wavelength wavelength near 1.3p.m The teaching and educational plans proposed will enter about the following objectives: (1) develop a new optoelectronic engineering curriculum, incorporating into both, the undergraduate and graduate courses, new knowledge gained from the explosive recent advancements in fiber optics research, (2) increase involvement of undergraduate students in current research efforts to build a foundation for independent thinking and excitement for new discovery, (3) facilitate participation of women in engineering research activities, with particular encouragement for students at the secondary school and freshman year levels, and (4) train graduate students in broader experimental techniques that the normal confined experience dictated by a specific thesis research topic: Research opportunities for undergraduates will be provided in the n new fiber optic laboratory facilities through supervision of theses and independent projects. Increased participation of women in engineering research will be accomplished by a special summer program aimed at offering laboratory experience to senior high school and college freshman students. The students will be exposed to a scientific research environment and obtain a first hand view of what a career in engineering research entails. Mentor support will be included to follow progress of individual female students through their university curriculum. The increasing complexity of technology necessitates further specialization by graduate students who desire to contribute to the field's advancement . This loop deprives graduate students from gaining the important broad range of experiences that are required for successful careers in today's rapidly changing high tech economy. To enhance the graduate students experience and better prepare them to identify and solve future research problems, a research "rotation" system will be implemented. ***