Feasibility Assessment and Analysis of a Forward Injected Photonic Crystal Device

A forward injected photonic crystal device design has been proposed for the purpose of injecting a high carrier concentration across the intrinsic region of a p-i-n diode formed across the waveguide of a photonic crystal in order to modulate the refractive index of the waveguide and generate a highly compact optical device. A numerical model was developed and evaluated both to assess the feasibility of this particular approach and to optimize the design. Carrier concentrations as high as 5.5 times10¹⁷ cm^-3 were injected across the intrinsic region of a p-i-n diode formed across the waveguide of an InP photonic crystal slab by highly forward biasing the device. This level of injection was capable of causing a negative shift in the refractive index of approximately -0.004 with response times of around 1 ns. The refractive indexes and absorption coefficients generated during this analysis were then applied to a photonic crystal waveguide in order to assess the feasibility of developing a compact optical device using a strongly forward injected p-i-n diode.