This paper reviews the operation of optical switch fabrics which have been the subject of much research in recent years, being regarded as potential key components for meeting future communications routing requirements for optical interconnects and access networks. The paper first notes the performance of high-capacity low speed large port count optical switches which have been realized using technologies such as MEMS, and contrasts these with high capacity, high speed optical packet switches which have proved to be challenging to develop with large port counts. This paper therefore reviews a number of high speed options before describing a modified hybrid switch. This switch uses dilated MZI devices to route signals with nanosecond switching times in tandem with short SOAs to enhance extinction and introduce low gain with reduced ASE. Using this approach, a monolithic 2×2 hybrid MZI-SOA switch module has been fabricated with an excellent crosstalk/extinction ratio of -40 dB and switching times of 3 ns. Low-penalty operation is achieved for 10 Gb/s data on both a single wavelength and simultaneously on 10 wavelengths. The feasibility of extending this concept to allow the construction of a large port count hybrid switch is finally reported.