This paper demonstrates an optically controlled Co-Planar Waveguide (CPW) switch operating in the millimetre wave region. Full wave electromagnetic analysis used a multi-layer model to simulate the photoinduced plasmas and good agreement between measured and simulated results has been achieved. The insertion loss is less than 4dB and isolation is greater than 15dB from 32GHz-50GHz. This approach requires the use of 175mW of optical power at a wavelength 980nm, but it removes the need for bandwidth limiting electrical bias networks. Index Terms-Optically induced plasmas (OIP), Co-Planar Waveguide (CPW), millimeter wave (mmW), optical switch