Biomedical subjects

W J Wadsworth

Publications and source records attributed to W J Wadsworth.

6 recordsLinked to original sources

PubMed2006

All-fiber anamorphic core-shape transitions.

We demonstrate low-loss anamorphic transitions between circular and rectangular fiber cores with aspect ratios up to 5:1, and hence improved coupling from a diode laser by using only a spherical lens. Differential hole pressurization and localized heating of a stock photonic crystal fiber inflates the holes at different rates. Some holes are plugged in the fiber end face where pressure is applied, so they remain at ambient pressure. Alternatively, holes of different sizes expand at different rates because the effective pressure due to surface tension differs.

Journal Article↗

PubMed2005

Engineering the dispersion of tapered fibers for supercontinuum generation with a 1064 nm pump laser.

We experimentally demonstrate dispersion tailoring of tapered fibers by immersing them in fluids. We obtain a 1200 nm wide supercontinuum in a train of two tapered fibers pumped by a low-cost diode-pumped Nd:YAG laser with a pulse width of 0.6 ns and an output power of 40 mW, where one tapered fiber is immersed in heavy water. To our knowledge, this is the widest spectrum ever generated with a system of such simplicity.

Journal Article↗

PubMed2005

Splice-free interfacing of photonic crystal fibers.

We report a new method for making low-loss interfaces between conventional single-mode fibers and photonic crystal fibers (PCFs). Adapted from the fabrication of PCF preforms from stacked tubes and rods, this method avoids the need for splicing and is versatile enough to interface to virtually any type of index-guiding silica PCF. We illustrate the method by forming interfaces to two problematic types of PCF, highly nonlinear and multicore. In particular, we believe this to be the first method capable of individually coupling light into and out of all the cores of a fiber with multiple closely spaced cores, without input or output cross talk.

Journal Article↗

PubMed2005

Widely tunable optical parametric generation in a photonic crystal fiber.

We report on the observation of widely tunable optical parametric generation in a photonic crystal fiber. The frequency shift of the generated sidebands that arise from modulational instability is strongly dependent on the detuning of the pump from the fiber's zero-dispersion wavelength. We are able to demonstrate experimentally more than 450 nm of sideband tunability as we tune the pump wavelength over 10 nm. Excellent agreement has been found between the experimentally measured and theoretically predicted shifts.

Journal Article↗

PubMed2003

Enhanced two-photon biosensing with double-clad photonic crystal fibers.

A double-clad photonic crystal fiber was used to improve detection efficiency over a standard single-mode fiber in a two-photon fluorescence detection scheme in which the dye was excited and the fluorescence was detected back through the same fiber.

Biosensing Techniques↗

PubMed2002

Experimental evidence for supercontinuum generation by fission of higher-order solitons in photonic fibers.

We report on an experimental study of supercontinuum generation in photonic crystal fibers with low-intensity femtosecond pulses, which provides evidence for a novel spectral broadening mechanism. The observed results agree with our theoretical calculations carried out without making the slowly varying envelope approximation. Peculiarities of the measured spectra and their theoretical explanation demonstrate that the reason for the white-light generation in photonic crystal fibers is fission of higher-order solitons into redshifted fundamental solitons and blueshifted nonsolitonic radiation.

Journal Article↗