Leaky wave radiation of millimetre waves by photoinduced plasma grating in a semiconductor slab

The paper reports investigations on leaky wave radiation of millimetre waves from a periodically photoinduced semiconductor slab waveguide. The photoinduced plasma grating structure is modelled as a permittivity modulated layer by considering the average permittivity as of a uniform plasma occupied thin layer and is systematically analysed using a singular perturbation procedure based on multiple space scales up to second order. The radiation efficiency of a leaky wave is derived and the results are outlined as a function of optically induced plasma density. Experiments have been carried out at 40 GHz by illuminating the grounded silicon slab using the slide of a periodic slit pattern through a xenon arc lamp. The dependence of periodicity on the radiation pattern is also reported.