Quantum Optoelectronics

Abstract:

Abstract:

Abstract:

Abstract:

Spectral diffusion can lead to considerable broadening of the line width of nitride quantum dots. Here, InGaN quantum dots grown on a nonpolar plane were shown to exhibit a decreased spectral diffusion rate compared to polar nitride dots. A robust intensity correlation method was used to measure the spectral diffusion rate of six quantum dots. A maximum spectral diffusion time of 1170 ± 50 ns was found. An increase of the rate with increasing power was observed. The decreased internal field leads to a lifetime for the nonpolar dots that is shorter than that for polar dots; the important ratio of spectral diffusion time to lifetime is more favorable for nonpolar quantum dots, thereby increasing the chances of generating indistinguishable photons.

Abstract:

A method for controlling the optical properties of a solid-state film over a broad wavelength range is highly desirable and could have significant commercial impact. One such application is smart glazing technology where near-infrared solar radiation is harvested in the winter and reflected it in the summer─an impossibility for materials with fixed thermal and optical properties. Here, we experimentally demonstrate the first spectrally tunable, low-emissivity coating using a chalcogenide-based phase-change material (Ge20Te80), which can modulate the solar heat gain of a window while maintaining neutral-coloration and constant transmission of light at visible wavelengths. We additionally demonstrate the controlled transfer of absorbed near-infrared energy to far-infrared radiation, which can be used to heat a building’s interior and show fast, sub-millisecond switching using transparent electrical heaters integrated on glass substrates. These combined properties result in a smart window that is efficient and aesthetically pleasing─crucial for successful adoption of green technology.