Photonic crystal waveguides based active and passive devices for phased array antenna systems

Photonic crystals are a new class of artificial optical materials with periodic dielectric structures, which promise to miniaturize photonic devices. Optical true-time delay techniques are an emerging technology for the squint-free beam steering of phased array antennas with wide bandwidth, reduced system weight and size, and low electromagnetic interference. In this dissertation, highly dispersive photonic crystal fibers based optical true time delay modules were designed, integrated and characterized. An ultra-compact optical modulator based on silicon photonic crystal waveguides for phased array antenna systems was designed, fabricated and characterized. A true-time delay controlled X-band phased array antenna system was designed, integrated, and characterized. The continuously tunable optical true time delay module employ highly dispersive photonic crystal fibers connected with various lengths of nondispersive telecom fiber. A highly dispersive silica photonic crystal fiber using dual-core structure was developed to achieve high chromatic dispersion. By employing photonic crystal fibers to increase the dispersion, the true time delay module size can be proportionally reduced. A 4-element linear X-band phased array antenna system using photonic crystal fibers based true-time delay modules was developed and demonstrated. The beam steering angle of the phased array antenna system was scanned by tuning the optical wavelength. Squint-free operation is experimentally confirmed. An optical modulator based on silicon photonic crystal waveguides was developed, which could be implemented in phased array antenna systems to replace conventional optical modulators. Silicon photonic crystal waveguides were firstly developed and demonstrated. Photonic crystal line-defect waveguides showed high group velocity dispersion and slow photon effect near the transmission band edge. An ultra-compact silicon electro-optic modulator based on silicon photonic crystal waveguides was proposed, developed and demonstrated for the first time. Modulation operation was demonstrated by carrier injection into an 80 µm-long silicon photonic crystal waveguide of a Mach-Zehnder interferometer structure.