Hybrid superprism with low insertion losses and suppressed cross-talk.

We demonstrate with the two-dimensional finite-difference time-domain method that an adiabatic transition in a superprism with an interface along the [1 2 ] direction enhances the transmission through the superprism to more than 90% (-0.5 dB) over the wavelength range 1.47-1.68 mum , including the telecommunication C and L bands. We also show that diffraction governed by a quasinegative index of refraction inside the superprism can be used to obtain nearly transform-limited beam widths at the output of the superprism. The reduction of the beam width at the output suppresses cross-talk and greatly enhances the achievable frequency resolution of the superprism.