Order-of-magnitude enhancement of intersubband photoresponse in a plasmonic quantum dot system.

The unprecedented ability of metallic subwavelength structures to confine and concentrate light into subwavelength spaces has led to new physics and exploration of novel devices. In this Letter, we demonstrate a 20 times enhancement of intersubband photoresponse in a InAs quantum dot (QD) system due to evanescently coupled plasmonic field. The resulting enhancement is accompanied by significant narrowing of photoresponse linewidth. The strong enhancement is attributed to efficient coupling of incident field to surface modes and to QDs, the presence of polarization-dependent absorption from QDs, and a fairly strong plasmon-QD interaction.

A surface plasmon enhanced infrared photodetector based on InAs quantum dots.

In this paper, we report a successful realization and integration of a gold two-dimensional hole array (2DHA) structure with semiconductor InAs quantum dot (QD). We show experimentally that a properly designed 2DHA-QD photodetector can facilitate a strong plasmonic-QD interaction, leading to a 130% absolute enhancement of infrared photoresponse at the plasmonic resonance. Our study indicates two key mechanisms for the performance improvement. One is an optimized 2DHA design that permits an efficient coupling of light from the far-field to a localized plasmonic mode. The other is the close spatial matching of the QD layers to the wave function extent of the plasmonic mode. Furthermore, the processing of our 2DHA is amenable to large scale fabrication and, more importantly, does not degrade the noise current characteristics of the photodetector. We believe that this demonstration would bring the performance of QD-based infrared detectors to a level suitable for emerging surveillance and medical diagnostic applications.

Design of plasmonic photonic crystal resonant cavities for polarization sensitive infrared photodetectors.

We design a polarization-sensitive resonator for use in mid-infrared photodetectors, utilizing a photonic crystal cavity and a single or double-metal plasmonic waveguide to achieve enhanced detector efficiency due to superior optical confinement within the active region. As the cavity is highly frequency and polarization-sensitive, this resonator structure could be used in chip-based infrared spectrometers and cameras that can distinguish among different materials and temperatures to a high degree of precision.