Controlling Spontaneous Emission with Photonic Crystals – University of Copenhagen

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02 November 2011

Controlling Spontaneous Emission with Photonic Crystals

Spontaneous emission of a quantum emitter depends not only on the intrinsic properties of the emitter, but also on the density of vacuum fluctuations surrounding the emitter. Photonic crystals can significantly modify the local density of optical states (LDOS) and are therefore useful for controlling the spontaneous emission of photons [1, 2]. The LDOS is highly complex in nanophotonic structures such as photonic crystals and reliable ways of extracting it are therefore essential.

We use single self-assembled InGaAs quantum dots as internal probes to map the LDOS of photonic crystal membranes [3]. By properly accounting for the role of the exciton fine structure, we can separate contributions from nonradiative recombination and spin-flip processes. We have done a systematic frequency map of the LDOS and a detailed comparison to existing theory. We observe inhibition factors as high as 70, which clearly demonstrates the potential of photonic crystal membranes for efficient spontaneous emission control.

Left: Schematic of a photonic crystal membrane with an internal quantum dot emitting photon wavepackets. Right: Measured projected LDOS of PC membranes versus scaled emission frequencies for X and Y dipole orientations with comparison to theory.

[1] E. Yablonovitch, Phys. Rev. Lett. 58, 2059 (1987). Inhibited Spontaneous Emission in Solid-State Physics and Electronics”.

[2] P. Lodahl, A.F. van Driel, I.S. Nikolaev, A. Irman, K. Overgaag, D. Vanmaekelbergh, and W.L. Vos, Nature 430, 654 (2004).“Controlling the dynamics of spontaneous emission from quantum dots by photonic crystals”.

[3] Q. Wang, S. Stobbe, and P. Lodahl, Phys. Rev. Lett. 107, 167404 (2011). “Mapping the Local Density of Optical States of a Photonic Crystal with Single Quantum Dots”