Circularly polarized emission from colloidal nanocrystal quantum dots confined in microcavities formed by chiral mirrors

Abstract

Colloidal semiconductor nanocrystal quantum dots (NQDs) confined in a microcavity device emit resonance-enhanced, circularly polarized (CP) light, when the device consists of a pair of chiral sculptured-thin-film mirrors separated by layers of emissive nanocrystals and spacers that form a λ∕2-resonant cavity. The resonant emission from the NQDs within the microcavity is strongly directed normally to the mirror surfaces. It is speculated that the enhanced coupling between the NQD excitons and the confined electromagnetic field resulted in the observed CP emission from the embedded NQDs with significant improvements in the light output's directionality and color purity.

Prospects for nanowire sculptured-thin-film devices

“…Consequently, SBD methods to deposit chiral films have recently been studied for optical applications utilizing the CBP. 6,12,13 In this paper, we will discuss the specifics of our fabrication process that modifies the original technique 5 and enables nanoengineering of the STF structure while retaining the desired optical properties. In addition, we will briefly review recent results using STFs in solar cell applications, chiral mirror microcavities, geological environmental sensors, and bioabsorbable metallic films.…”

“…Many important proof-of-concept devices have been fabricated and improved upon. [3][4][5][6][7][8] These devices have utilized one or more of the valuable properties of STFs, such as a high surface area or the circular Bragg phenomenon ͑CBP͒. These properties are controlled by using a low pressure deposition process and obliquely directed vapor; when deposited on a rotating substrate self-shadowing forces, growth toward the source and chiral STFs are created, which have a helical microstructure.…”

Empirical Model of Optical Sensing via Spectral Shift of Circular Bragg Phenomenon

“…Secondly, CSTFs are porous, and their multiscale porosity can be tailored to allow only species of certain shapes and sizes to infiltrate their void regions [10]. This engineered porosity, combined with the circular Bragg phenomenon, makes CSTFs attractive as platforms for light-emitting devices with precise control over the circular polarization state and the emission wavelengths [11,12], and optical biosensors [13,14].…”

Circular polarization emission from an external cavity diode laser

“…13 We have recently demonstrated narrow-band CP emission from both organic molecules and inorganic quantum dots embedded in high-Q-factor microresonant cavities formed by two chiral STF mirrors. 14 Our results clearly suggest the possibility of developing chiral-STF reflector-based laser devices to obtain very pure and controllable circular polarization. Polarization-selective resonance in helical mirror-based Fabry-Pérot cavities was also predicted and observed by Stockley et al and Abdulhalim recently.…”