325 research outputs found
Wideband pulse propagation: single-field and multi-field approaches to Raman interactions
We model the process of ultra broadband light generation in which a pair of
laser pulses separated by the Raman frequency drive a Raman transition. In
contrast to the usual approach using separate field envelopes for the different
frequency components, we treat the field as a single entity. This requires the
inclusion of few-cycle corrections to the pulse propagation. Our single-field
model makes fewer approximations and is mathematically (and hence
computationally) simpler, although it does require greater computational
resources to implement. The single-field theory reduces to the traditional
multi-field one using appropriate approximations.Comment: 6 pages, two 3-part figure
Four Poynting Theorems
The Poynting vector is an invaluable tool for analysing electromagnetic
problems. However, even a rigorous stress-energy tensor approach can still
leave us with the question: is it best defined as \Vec{E} \cross \Vec{H} or
as \Vec{D} \cross \Vec{B}? Typical electromagnetic treatments provide yet
another perspective: they regard \Vec{E} \cross \Vec{B} as the appropriate
definition, because \Vec{E} and \Vec{B} are taken to be the fundamental
electromagnetic fields. The astute reader will even notice the fourth possible
combination of fields: i.e. \Vec{D} \cross \Vec{H}. Faced with this diverse
selection, we have decided to treat each possible flux vector on its merits,
deriving its associated energy continuity equation but applying minimal
restrictions to the allowed host media. We then discuss each form, and how it
represents the response of the medium. Finally, we derive a propagation
equation for each flux vector using a directional fields approach; a useful
result which enables further interpretation of each flux and its interaction
with the medium.Comment: 8 pages. Updated slightly from EJP versio
Composition and assembly of a spectral data base for corn and soybean multicrop segments
There are no author-identified significant results in this report
Composition and assembly of a spectral data base for transition year spring wheat blind sites
There are no author-identified significant results in this report
Seminar on Theological Education
Series 1: Occasional Papers, Notebook 6https://digitalcommons.fuller.edu/kinsler-tee/1005/thumbnail.jp
Optical carrier wave shocking: detection and dispersion
Carrier wave shocking is studied using the Pseudo-Spectral Spatial Domain
(PSSD) technique. We describe the shock detection diagnostics necessary for
this numerical study, and verify them against theoretical shocking predictions
for the dispersionless case. These predictions show Carrier Envelope Phase
(CEP) and pulse bandwidth sensitivity in the single-cycle regime. The flexible
dispersion management offered by PSSD enables us to independently control the
linear and nonlinear dispersion. Customized dispersion profiles allow us to
analyze the development of both carrier self-steepening and shocks. The results
exhibit a marked asymmetry between normal and anomalous dispersion, both in the
limits of the shocking regime and in the (near) shocked pulse waveforms.
Combining these insights, we offer some suggestions on how carrier shocking (or
at least extreme self-steepening) might be realised experimentally.Comment: 9 page
Few-cycle soliton propagation
Soliton propagation is usually described in the ``slowly varying envelope
approximation'' (SVEA) regime, which is not applicable for ultrashort pulses.
We present theoretical results and numerical simulations for both NLS and
parametric () ultrashort solitons in the ``generalised few-cycle
envelope approximation'' (GFEA) regime, demonstrating their altered
propagation.Comment: 4 pages, 4 figure
- …