Surface emitting laser devices and methods for manufacturing same

A photonic crystal surface emitting laser (PCSEL) device 20 comprises a semiconductor substrate located on a photonic crystal (PC) structure comprising a bulk medium having a first refractive index and an array of scattering centres located within the bulk medium, The scattering centres have a second refractive index different to the first refractive index and an active layer, optically coupled to the photonic crystal structure. The semiconductor substrate comprises a p-type semiconductor substrate. The device 20 in Figure 4 may have a 30% reduction in gain threshold value and a 50% L-I (slope efficiency) and higher out put power than that of the PCSEL presented in Figure 1.