High-speed optical signal processing and detection: Toward efficient dispersion-engineered parametric devices controlled by few photons
Ana Pejkic
In this Internet era, rapid transitioning of many aspects of medical, defense and commercial applications to digital platforms dictates their heavy reliance on optical communication systems. This trend places severe challenges on contemporary communication systems, expected to provide wide-bandwidth services and high degree of information security, with minimum energy dissipation. To meet the rising bandwidth demand, current bandwidth limited technology requires implementation of parallel processing; however, energy dissipation of such a system is globally and environmentally significant. A solution to this problem is envisioned in a form of an optical processor, a device recognized for its high speed, low loss and signal quality preservation. In this dissertation we investigate two optical processor roles: direct signal processing role (all-optical switching) and preprocessing role in preamplified few photon detection. \tIn the direct signal processing role, an optical switch controls the state of one wave by a low-energy control signal. It is realized in a highly nonlinear fiber, a medium acclaimed for its inherent femtosecond response time, a low loss and a high figure of merit. The switching functionality is implemented by employing the four wave mixing process in the depleted pump regime. To maximize the energy exchange, we revisit the saturated parametric mixer phase matching condition and propose a novel dispersion engineering method enhancing the performance. This study advances the understanding of the phase-matched interaction in the saturated parametric mixer and enables the first realization of a few-photon controlled silica-fiber-based device. \tIn the preprocessing role, the all-fiber photonic sampler is implemented prior to detection of a preamplified few photon signal with a low duty cycle; the sampler function is limited to amplified spontaneous emission noise alleviation. The proposed few photon detection method shows an order of magnitude improvement in the Bit Error Ratio and detection efficiency with respect to conventional preamplified receiver, and operates at speed beyond the reach of current single photon detector technology.
•Jan 1, 2015•0 citations