Angular redistribution of near-infrared emission from quantum dots in 3D photonic crystals

TL;DR

This study investigates how near-infrared emission from quantum dots in 3D photonic crystals redistributes angularly, revealing deviations from Lambertian profiles and demonstrating the effectiveness of an adapted escape-function model.

Contribution

It provides the first measurements of angular redistribution of near-infrared emission in photonic crystals and applies a diffusion-based model to optically thick samples at telecom wavelengths.

Findings

60% attenuation in emitted flux due to stop bands

Up to 34% increase in flux at stop band edges

First application of the model to near-infrared emission in photonic crystals

Abstract

We study the angle-resolved spontaneous emission of near-infrared light sources in 3D photonic crystals over a wavelength range from 1200 to 1550 nm. To this end PbSe quantum dots are used as light sources inside titania inverse opal photonic crystals. Strong deviations from the Lambertian emission profile are observed. An attenuation of 60 % is observed in the angle dependent radiant flux emitted from the samples due to photonic stop bands. At angles that correspond to the edges of the stop band the emitted flux is increased by up to 34 %. This increase is explained by the redistribution of Bragg-diffracted light over the available escape angles. The results are quantitatively explained by an expanded escape-function model. This model is based on diffusion theory and adapted to photonic crystals using band structure calculations. Our results are the first angular redistributions and escape functions measured at near-infrared, including telecom, wavelengths. In addition, this is the first time for this model to be applied to describe emission from samples that are optically thick for the excitation light and relatively thin for the photoluminesence light.