High Efficiency Perfluorocyclobutyl

School of Graduate Studies The University of Alabama in Huntsville Degree Doctor of Philosophy Program Optical Science and Engineering Name of Candidate Nazli Rahmanian Title High Efficiency Perfluorocyclobutyl Air-trench Splitters for Use in Compact Ring Resonators Planar lightwave circuits with higher integration, lower cost, and added functionality can reduce costs in optical network components. To facilitate large scale integration of planar lightwave circuits the size of their fundamental building blocks such as splitters and bends needs to be reduced. In this dissertation compact air trench splitters are demonstrated in perfluorocyclobutyl (PFCB) polymers. To realize these high efficiency splitters we have developed a very high aspect ratio (18:1) anisotropic PFCB etch for submicron features using a CO/O2 etch chemistry in an inductively coupled plasma reactive ion etcher (ICP-RIE). A low loss of 0.45 dB/splitter (90.1% efficiency) has been measured on splitters fabricated on silicon substrates. The etch process was successfully transferred to Ultem substrates to reduce the effects of the coefficient of thermal expansion (CTE) mismatch between PFCB and silicon. An ultra-compact ring resonator was demonstrated in PFCB with a splitting ratio of 85% to 15% (85-15) air-trench splitters and air-trench bends. The ring resonator size is only 70 !m x 100 !m. Measurements show a 7.2 nm free spectral range (FSR) in agreement with 2 dimensional finite difference time domain (2-D FDTD) simulation results. A 1.8 nm full width at half maximum