Near-field nanoimaging by nanoscale photodetector array

Abstract

We report a demonstration of near-field nanoimaging using nanoscale photodetector (NPD) array. The NPD array has detector pixels with subwavelength dimension and is capable of pixel addressing. An active-media finite-difference time-domain simulation of the NPD array shows an imaging resolution of 150 nm for 1.55 microm light. Additionally, we demonstrate the realization and characterization of the NPD array. The smallest NPD array obtained has 100-nm-wide pixels with 100 nm spacing. A responsivity of 0.28 A/W at 1.31 microm and 3.3 V bias is registered for a 2x2 NPD array pixel. The corresponding photocurrent is 735 nA with a dark current of 0.483 nA. Using near-field photocurrent microscopy, an imaging resolution of 390 nm has been demonstrated.