A light generating system that comprises a narrow evacuated slot defined between at least two high index contrast waveguide elements. The apparatus can be fabricated using a material such as a SOI wafer having an oxide layer thickness of the order of 1 micron and a top silicon layer thickness of the order of 100-150 nm. Electrode contacts are provided to at least two waveguide elements fabricated in the top silicon layer, each waveguide element having a thickness comparable to the top silicon layer thickness, a width of some hundreds of nm, and having a slot having dimensions in the range of 50-200 nm defined therebetween. The length of the slot is at least as long as the slot width. Charged particles, such as electrons, that are emitted and accelerated across the slot by an applied electrical signal provide a source of photons as a consequence of being accelerated and/or decelerated.