Switched Three dimensional photonic delay line using directly modulated semiconductor lasers for microwave radar processing

A 3-bit binary photonic delay line is demonstrated at 1 Ghz using a directly modulated semiconductor laser and remote interconnection fiber-optics. Three types of freespace delay bit geometries are tested for 5.686 ns, 1.667 ns, and 8.83 ps delay bits. This photonic delay line uses ferroelectric liquid crystal optical on/off devices for optical path switching and active polarization noise filtering. Three dimensional imaging optics and antireflection coated optics (for all but 5 components) are successfully used to minimize photonic delay line insertion losses and interchannel crosstalk. The 3-bit system is fully characterized for measured and designed performance.