Nanostructured diode for infrared photodetection through nondegenerate two-photon absorption

We investigate infrared detection at room temperature using non-degenerate two-photon absorption in a nanostructured indium phosphide photodiode. We designed the detector structure to achieve a good nonlinear absorption by combining three major ideas: first, we use the non-degenerate two-photon absorption process, which is known to be more efficient than the previously used degenerate two-photon absorption. Second, we ensured a correct spatial overlap of our pump field with our signal field. Third, we optimized the nanostructuration to increase the signal field amplitude locally within the active medium of the device. The resulting device consists of a PIN junction embedded between a back-reflecting gold mirror and a top grating. We experimentally characterized our diode with regard to reflectivity and two-photon absorption generated photocurrent for a continuous-wave pump and a nanosecond pulsed signal of around 3.39 μm. Owing to the nanostructuration, the generated photocurrent shows a gain of 24 with r...