Transparent Li2O–Ga2O3–SiO2 (LGS) glass-ceramics embedding Ni:LiGa5O8 nanocrystals were fabricated. An intense emission centered around 1300nm with the width of more than 300nm was observed by 976nm photoexcitation of the glass-ceramics. The lifetime was more than 900μs at 5K and 500μs at 300K. The emission could be attributed to the T2g3(F3)→A2g3(F3) transition of Ni2+ in distorted octahedral sites in LiGa5O8. The product of stimulated emission cross section and lifetime for the emission was about 3.7×10−24cm2s and was a sufficiently practical value.

The propulsion of 3 microm polystyrene spheres along a subwavelength optical wire is demonstrated. Velocities in the range of 7-15 microm/s are observed. Simulations are carried out to evaluate the evanescent field at the waveguide-water suspension interface.

Micro-resonators have attracted considerable attention as a potential geometry for photonic devices used in multiplexing, memory and switching. These all-optical-resonators allow light at certain wavelengths to build up in intensity allowing nonlinear effects to be seen for much lower input power than in a bulk material. We report here on microspheres made from gallium-lanthanum-sulphide glass. Spheres have been produced with diameters from less than 1 mum up to 450 microm, and we demonstrate a first measured quality factor of 8x10(4) at 1.55 microm, for a chalcogenide sphere diameter of 100 microm. We also predict an ultimate Q of up to 4x10(10) at 3 microm.

We report transmission measurements of germanium on silicon waveguides in the 7.5-8.5 μm wavelength range, with a minimum propagation loss of 2.5 dB/cm at 7.575 μm. However, we find an unexpected strongly increasing loss at higher wavelengths, potential causes of which we discuss in detail. We also demonstrate the first germanium on silicon multimode interferometers operating in this range, as well as grating couplers optimized for measurement using a long wavelength infrared camera. Finally, we use an implementation of the "cut-back" method for loss measurements that allows simultaneous transmission measurement through multiple waveguides of different lengths, and we use dicing in the ductile regime for fast and reproducible high quality optical waveguide end-facet preparation.

Nanophotonic waveguides are at the core of a great variety of optical sensors. These structures confine light along defined paths on photonic chips and provide light–matter interaction via an evanescent field. However, waveguides still lag behind free-space optics for sensitivity-critical applications such as trace gas detection. Short optical pathlengths, low interaction strengths, and spurious etalon fringes in spectral transmission are among the main reasons why on-chip gas sensing is still in its infancy. In this work, we report on a mid-infrared integrated waveguide sensor that successfully addresses these drawbacks. This sensor operates with a 107% evanescent field confinement factor in air, which not only matches but also outperforms free-space beams in terms of the per-length optical interaction. Furthermore, negligible facet reflections result in a flat spectral background and record-low absorbance noise that can finally compete with free-space spectroscopy. The sensor performance was validated at 2.566 μm, which showed a 7 ppm detection limit for acetylene with only a 2 cm long waveguide.