III-nitride-based waveguides for ultrafast all-optical signal processing at 1.55 μm

We present an overview of the recently developed III-nitride-based optical waveguides for application in ultrafast signal processing at telecom wavelengths. We focus on different active and passive optical devices for further implementation within all-optical integrated circuits. Optical waveguides based on GaN/AlN quantum dots have been demonstrated to act as saturable absorbers requiring ∼3 pJ of input pulse energy to reach +3 dB transmittance contrast for TM-polarized light. On the contrary, sputtered-InN-based devices show −3 dB transmittance contrast associated to two-photon absorption for input pulse energies of ∼1 pJ, making them suitable to act as highly-efficient reverse saturable absorbers. Finally, the passive optical nature of waveguides based on sputtered AlN at 1.55 μm makes them suitable for further connections between different III-nitride-based active devices.