Active planar optical waveguide made from luminescent silicon nanocrystals

Abstract

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 gain.

Microcavity-like leaky mode emission from a planar optical waveguide made of luminescent silicon nanocrystals

“…The broad emission bands appearing in the samples 3 ϫ 10 17 Si cm −2 and 4 ϫ 10 17 Si cm −2 represent guided modes scattered into the detector collection angle.solved with a linear polarization filter parallel (TE) or perpendicular (TM) to the layer edge. Such surprising PL spectra from a simple layer of Si-NCs have been reported for the first time only recently 13,14. Typical PL spectra from Si-NCs consist of a broad band centered at 700-800 nm with FWHM of 150-200 nm, consistent with the dotted curves inFig.…”

Silicon nanocrystals in silica—Novel active waveguides for nanophotonics

“…2-4 present results from one set of samples and another set with lower refraction index is shown in Figs. [5][6][7]. In order to numerically model the optical properties of particular samples the refraction index profiles were measured separately for each implanted sample.…”

“…Ensembles of Si-NCs can also be employed to fabricate active optical waveguides [4][5][6][7][8] that exhibit spectral filtering of the Si-NC PL emission, if the refractive index profile is properly designed. The occurrence of narrow ($10 nm), polarization-dependent emission lines was reported by Khriachtchev et al [4] for Si/SiO 2 waveguides and by our group [5,9] for samples containing Si-NC prepared by Si + -implantation into silica slabs. In our previous papers we explained the unexpected waveguiding properties using a model based on substrate leaking modes of a lossy waveguide [10,11].…”

“…Silicon quantum dots or nanocrystals (Si-NCs) have attracted much attention due to their strong photoluminescence (PL) [1] and have been used to demonstrate silicon-based light-emitting diodes [2,3]. Ensembles of Si-NCs can also be employed to fabricate active optical waveguides [4][5][6][7][8] that exhibit spectral filtering of the Si-NC PL emission, if the refractive index profile is properly designed. The occurrence of narrow ($10 nm), polarization-dependent emission lines was reported by Khriachtchev et al [4] for Si/SiO 2 waveguides and by our group [5,9] for samples containing Si-NC prepared by Si + -implantation into silica slabs.…”

Stimulated emission in the active planar optical waveguide made of silicon nanocrystals

“…Crucial to gain observation is the formation of active planar waveguides where the active core layer is formed by Si-nc embedded in a SiO 2 matrix. However, this system shows under certain conditions unusual photoluminescence (PL) properties [8,9], namely, polarization resolved narrow modes. Similar observations have been reported for luminescent thin films on transparent substrates which form asymmetric planar waveguides [10][11][12].…”