High index contrast photonic platforms for on-chip Raman spectroscopy

Nanophotonic waveguide enhanced Raman spectroscopy (NWERS) is a sensing technique that uses a highly confined waveguide mode to excite and collect the Raman scattered signal from molecules in close vicinity of the waveguide. The most important parameters defining the figure of merit of an NWERS sensor include its ability to collect the Raman signal from an analyte, i.e. "the Raman conversion efficiency" and the amount of "Raman background" generated from the guiding material. Here, we compare different photonic integrated circuit (PIC) platforms capable of on-chip Raman sensing in terms of the aforementioned parameters. Among the four photonic platforms under study, tantalum oxide and silicon nitride waveguides exhibit high signal collection efficiency and low Raman background. In contrast, the performance of titania and alumina waveguides suffers from a strong Raman background and a weak signal collection efficiency, respectively

Tantalum pentoxide waveguides for spectral broadening of vertical external cavity surface emitting lasers

We show the characterisation of spectral broadening in the Tantalum Pentoxide waveguide system as a function of pump wavelength, showing spectra for central pump wavelengths of 0.9 to 1.5 µm (150 fs, 80 MHz). We have achieved octave spanning spectra with approximately 5 mW of laser power coupled in the waveguide at 1 µm pumping wavelength for a linear buried waveguide using a commercial source

Dataset for "Supercontinuum generation in tantalum pentoxide waveguides for pump wavelengths in the 900 nm to 1500 nm spectral region"

Data supports article &quot;Supercontinuum generation in tantalum pentoxide waveguides for pump wavelengths in the 900&thinsp;nm to 1500&thinsp;nm spectral region&quot; by Jonathan R. C. Woods, Jake Daykin, Amy S. K. Tong, Cosimo Lacava, Periklis Petropoulos, Anne C. Tropper, Peter Horak, James S. Wilkinson, and Vasilis Apostolopoulos in Optics Express, OSA, 10.1364/OE.403089. Includes data and instructions for the recreation of figures included in the above publication.</span

Visual mismatch negativity to vanishing parts of objects in younger and older adults.

We investigated visual mismatch negativity (vMMN) to vanishing parts of continuously present objects by comparing the event-related potentials (ERPs) to infrequently (deviant) and frequently (standard) disappearing parts of the objects. This paradigm both excludes low-level stimulus-specific adaptation differences between the responses to deviants and standards, and increases the ecological validity of the stimuli. In comparison to frequently disappearing parts of the stimulus objects, infrequently vanishing parts elicited posterior negative event-related brain activity (vMMN). However, no vMMN emerged to the reappearance of the same parts of the objects. We compared the ERPs of an older and a younger sample of participants. In the 120-180 ms time period vMMN was similar in the two age groups, but in the 180-220 ms time period vMMN emerged only in the younger participants. We consider this difference as an index of more elaborate automatic processing of infrequent stimulus changes in younger adults

Association analysis identifies 65 new breast cancer risk loci

NATURE551767892-