Active planar optical waveguide made from luminescent silicon nanocrystals

We show experimentally that a layer of silicon nanocrystals, prepared by the Si-ion implantation (with the energy of 400 keV) into a synthetic silica slab and exhibiting room-temperature red photoluminescence, can serve simultaneously as a single-mode planar optical waveguide. The waveguide is shown to self-select guided transverse electric and transverse magnetic modes from the broad photoluminescence emission of the nanocrystals resulting in a substantially narrower emission spectrum for these modes. We further report on an investigation of optical gain in a sample implanted to a dose of 4×1017 cm−2. Despite the occurrence of strong waveguiding, results of the variable stripe length method turned out not to be able to give unambiguous evidence for optical gai

Waveguide Cores Containing Silicon Nanocrystals as Active Spectral Filters for Silicon-based Photonics

Layers of densely packed luminescent Si nanocrystals embedded in fused silica act as wavelength-specific planar waveguides that filter the wide-band spontaneous emission. The waveguides' light output consists of two spectrally narrow (∼ 10 nm), orthogo

Photoluminescence from an Active Planar Optical Waveguide made of Silicon Nanocrystals: Dominance of Leaky Substrate Modes in Dissipative Structures

Samples with the structure of asymmetric planar waveguides are fabricated by implanting Si+ ions with energy of 400 keV and doses from 3 to 6 × 1017 cm-2 into synthetic silica slabs. Broad photoluminescence spectrum is observed when collecting photolumi

Optical gain in nanocrystalline silicon: comparison of planar waveguide geometry with a non-waveguiding ensemble of nanocrystals

Stimulated emission from nanocrystalline silicon in the visible has become a hot topic during the past years. Various forms of silicon nanostructures are being exploited, among them planar optical waveguides made of silicon nanocrystals, silicon superlattices and tiny silicon nanoparticles. We report on optical gain measurements using the variable-stripe-length and the shifting-excitation-spot methods in two different types of nanocrystalline samples: a planar nanocrystalline waveguide prepared by silicon-ion implantation (400 keV, 4 × 1017 cm-2) into a silica substrate and a layer of porous silicon grains embedded in a sol-gel derived SiO 2 matrix. The latter does not exhibit any waveguiding. At a first sight one would expect much more favorable conditions for the stimulated emission occurrence in the former type of samples. We observed in fact small optical gain in both types (modal gain of 12 cm-1 at ∼760 nm in ion implanted sample and of 25 cm-1 at ∼650 nm in sol-gel embedded sample, respectively), however, under different pumping conditions. We discuss advantages and disadvantages of both nanostructures, referring in particular to leaky-mode emission that may occur in planar waveguides on transparent substrates

Silicon nanostructures for photonics and photovoltaics

Silicon has long been established as the material of choice for the microelectronics industry. This is not yet true in photonics, where the limited degrees of freedom in material design combined with the indirect bandgap are a major constraint. Recent developments, especially those enabled by nanoscale engineering of the electronic and photonic properties, are starting to change the picture, and some silicon nanostructures now approach or even exceed the performance of equivalent direct-bandgap materials. Focusing on two application areas, namely communications and photovoltaics, we review recent progress in silicon nanocrystals, nanowires and photonic crystals as key examples of functional nanostructures. We assess the state of the art in each field and highlight the challenges that need to be overcome to make silicon a truly high-performing photonic material

Structure and Properties of Nanoparticles Formed by Ion Implantation

This chapter broadly describes the formation, basic microstructure, and fundamental optoelectronic properties of nanocomposites synthesized by ion implantation. It is not meant as a complete literature survey and by no means includes all references on a subject that has seen a considerable amount of research effort in the past 15 years. However, it should be a good starting point for those new to the field and in a concise way summarize the main lines of research by discussing the optical, magnetic, and smart properties of these nanoparticles and the dependence of these properties on the overall microstructure. The chapter concludes with an outlook for the future