Modification of erbium photoluminescence decay rate due to ITO layers on thin films of SiO2:Er doped with Si-nanoclusters

International audienceDuring the fabrication of MOS light emitting devices, the thin film of active material is usually characterized by photoluminescence measurements before electrical contacts are deposited. However, the presence of a conductive contact layer can alter the luminescent properties of the active material. The local optical density of states changes due to the proximity of luminescent species to the interface with the conductive medium (the top electrode), and this modifies the radiative rate of luminescent centers within the active layer. In this paper we report enhancement of the observed erbium photoluminescence rate after deposition of indium tin oxide contacts on thin films of SiO 2 :Er containing silicon nanoclusters, and relate this to Purcell enhancement of the erbium radiative rate

Electrically pumped silicon waveguide light sources

We report simulations of electrically pumped waveguide emitters in which the emissive layer contains silicon nanoclusters and erbium ions. Plasmonic coupling to metallic or semi-metallic overlayers provides enhancement of the radiative rate of erbium ions, enabling high quantum efficiency emission. Using 2D and 3D finite difference time domain (FDTD) simulations we show that up to 75% of the light emitted from the active layer can be coupled into a nanowire silicon rib waveguide. Our results suggest that such devices, which can readily be fabricated using CMOS processing techniques, pave the way for viable waveguide optical sources to be realized in silicon photonics

Probing energy transfer in an ensemble of silicon nanocrystals

Time-resolved photoluminescence measurements of silicon nanocrystals formed by ion implantation of silicon into silicon dioxide reveal multi-exponential luminescence decays. Three discrete time components are apparent in the rise and decay data, which we associate with different classes of nanocrystals. The values of decay time are remarkably constant with emission energy, but the relative contributions of the three components vary strongly across the luminescence band. In keeping with the quantum confinement model for luminescence, we assign emission at high energies to small nanocrystals and that at low energies to large nanocrystals. By deconvolving the decay data over the full emission band, it is possible to study the migration of excitation from smaller (luminescence donor) to larger (luminescence acceptor) nanocrystals. We propose a model of diffusion of excitation between neighboring nanocrystals, with long lifetime emission being from the largest nanocrystal in the local neighborhood. Our data also allow us to study the saturation of acceptor nanocrystals, effectively switching off excitation transfer, and Auger recombination in non-interacting nanocrystals. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3622151

Programmable dispersion on a photonic integrated circuit for classical and quantum applications

We demonstrate a large-scale tunable-coupling ring resonator array, suitable for high-dimensional classical and quantum transforms, in a CMOS-compatible silicon photonics platform. The device consists of a waveguide coupled to 15 ring-based dispersive elements with programmable linewidths and resonance frequencies. The ability to control both quality factor and frequency of each ring provides an unprecedented 30 degrees of freedom in dispersion control on a single spatial channel. This programmable dispersion control system has a range of applications, including mode-locked lasers, quantum key distribution, and photon-pair generation. We also propose a novel application enabled by this circuit – high-speed quantum communications using temporal-mode-based quantum data locking – and discuss the utility of the system for performing the high-dimensional unitary optical transformations necessary for a quantum data locking demonstration