Large mode area silicon microstructured fiber with robust dual mode guidance

A silicon microstructured fiber has been designed and fabricated using a pure silica photonic bandgap guiding fiber as a 3D template for materials deposition. The resulting silicon fiber has a micron sized core but with a small core-cladding index contrast so that it only supports two guided modes. It will be shown that by using the microstructured template this fiber exhibits a number of similar guiding properties to the more traditional index guiding air-silica structures. The large mode areas and low optical losses measured for the silicon microstructured fiber demonstrate its potential to be integrated with existing fiber infrastructures

Nonlinear transmission properties of hydrogenated amorphous silicon core optical fibers

The nonlinear properties of a low loss hydrogenated amorphous silicon core fiber have been characterized for transmission of high power pulses at 1540nm. Numerical modelling of the pulse propagation in the amorphous core material was used to establish the two-photon absorption, free-carrier absorption and the nonlinear refractive index, which were found to be larger than the values typical for crystalline silicon. Calculation of a nonlinear figure of merit demonstrates the potential for these hydrogenated amorphous silicon core fibers to be used in nonlinear silicon photonics applications

Chemical fluid deposition of semiconductors inside a Microstructured optical fiber for optoelectronic applications

A technique to fill semiconductors inside a microstructured optical fiber is developed. The structural, electrical and optical properties are investigated. All-optical modulation of light and an in-fiber field effect transistor are demonstrated using this device

Whispering gallery mode emission at telecommunications-window wavelengths using PbSe nanocrystals attached to photonic beads

We report the selective chemical attachment of infrared emitting PbSe nanocrystal quantum dots onto micron-scale glass photonic beads. Upon optical excitation, photoluminescence from the shell of nanocrystals is seen to couple into the high-Q 'whispering gallery' modes of the bead via the evanescent optical field, resulting in a series of sharp peaks being observed at wavelengths of around 1550 nm. Theoretical modelling gives a close agreement with the data for angular modes corresponding to l ~ 120. This work demonstrates the potential of narrow-bandgap II–VI semiconductor nanocrystals for use in a wide range of telecommunications-window photonics applications

Infrared emitting PbSe nanocrystals for telecommunications window applications

We demonstrate the colloidal synthesis of PbSe nanocrystal quantum dots, via an organometallic-precursor route, developed from recently reported techniques. This synthesis typically yields a particle size distribution of approximately 5-10%, as may be inferred from the sharp spectral features seen in absorption and from our effective-mass model correlating spectral features to nanocrystal size. An accurate quantitative analysis, using an infrared reference dye, shows these nanocrystals to exhibit infrared photoluminescence from intrinsic quantum-confined states, with high quantum efficiencies of up to 60% in solution. The wavelength of the photoluminescence may also be conveniently size tuned in order to access the 1.3-1.5 µm 'telecommunications window'. We discuss the significance of this work in the context of future optoelectronic applications