Spectroscopy of 1.55 υm PbS Quantum Dots on Si Photonic Crystal Cavities with a Fiber Taper Waveguide

Abstract

We use an optical fiber taper waveguide to probe PbS quantum dots (QDs) dried on Si photonic crystal cavities near 1.55 υm. We demonstrate that a low density ({less than or equal to} 100υm^-2) of QDs does not significantly degrade cavity quality factors as high as ≅3×10⁴. We also show that the tapered fiber can be used to excite the QDs and collect the subsequent cavity-filtered photoluminescence, and present measurements of reversible photodarkening and QD saturation. This method represents an important step towards spectroscopy of single colloidal QDs in the telecommunications band.