Abstract

We present subwavelength nanopatch cavities with colloidal quantum dots (QDs). These cavities, depicted in Fig. 1b and Fig. 1c, consist of luminescent material (QDs embedded in a SiNx matrix in our case) sandwiched between two metallic surfaces. They allow the confinement of optical resonant modes in subwavelength volumes of the order of 10⁻³-10⁻⁴ λ³. From FDTD simulations, high Purcell factors of 10-100 are expected, despite the metal losses and resulting low Q-factors. Previously, lasing at 1.3µm was reported in 500nm-sized nanopatch cavities of a similar design in which the gain material was a bulk InGaAsP layer [1] instead of a QD layer in a SiNx matrix. Our cavities are smaller (a diameter of 100 to 300 nm), designed for emitting at 620 nm, and more lossy. Low Q-factors are desirable since colloidal QDs typically show an emission linewidth of 30-40 nm. An advantage of nanopatch cavities is their inherent compatibility with electrical injection from the top and bottom metal layer. Their combination with cheap and engineered light sources such as colloidal QDs would allow for compact, low-cost and efficient lasers, LED and possibly also single-photon sources.

© 2015 IEEE