Mid-infrared spectroscopic imaging enabled by an array of Ge-filled waveguides in a microstructured optical fiber probe.

We demonstrate mid-infrared spectroscopic imaging using a unique optical fiber probe consisting of an array of Ge waveguide cores embedded in a silica fiber matrix. Biological tissue slices are characterized to illustrate its potential endoscopic uses. The fiber probe based transmission measurements show excellent agreement with the result obtained from standard Fourier Transform Infrared spectroscopy transmission measurements in the wavelength range of 3289.8 nm to 3383.3 nm, where fat and muscle tissues could be spectroscopically distinguished.

Silicon p-i-n junction fibers.

Flexible Si p-i-n junction fibers made by high pressure chemical vapor deposition offer new opportunities in textile photovoltaics and optoelectronics, as exemplified by their photovoltaic properties, gigahertz bandwidth for photodetection, and ability to waveguide light.

Confined high-pressure chemical deposition of hydrogenated amorphous silicon.

Hydrogenated amorphous silicon (a-Si:H) is one of the most technologically important semiconductors. The challenge in producing it from SiH(4) precursor is to overcome a significant kinetic barrier to decomposition at a low enough temperature to allow for hydrogen incorporation into a deposited film. The use of high precursor concentrations is one possible means to increase reaction rates at low enough temperatures, but in conventional reactors such an approach produces large numbers of homogeneously nucleated particles in the gas phase, rather than the desired heterogeneous deposition on a surface. We report that deposition in confined micro-/nanoreactors overcomes this difficulty, allowing for the use of silane concentrations many orders of magnitude higher than conventionally employed while still realizing well-developed films. a-Si:H micro-/nanowires can be deposited in this way in extreme aspect ratio, small-diameter optical fiber capillary templates. The semiconductor materials deposited have ~0.5 atom% hydrogen with passivated dangling bonds and good electronic properties. They should be suitable for a wide range of photonic and electronic applications such as nonlinear optical fibers and solar cells.