535 research outputs found
Acoustic confinement and Stimulated Brillouin Scattering in integrated optical waveguides
We examine the effect of acoustic mode confinement on Stimulated Brillouin
Scattering in optical waveguides that consist of a guiding core embedded in a
solid substrate. We find that SBS can arise due to coupling to acoustic modes
in three different regimes. First, the acoustic modes may be guided by total
internal reflection; in this case the SBS gain depends directly on the degree
of confinement of the acoustic mode in the core, which is in turn determined by
the acoustic V-parameter. Second, the acoustic modes may be leaky, but may
nevertheless have a sufficiently long lifetime to have a large effect on the
SBS gain; the lifetime of acoustic modes in this regime depends not only on the
contrast in acoustic properties between the core and the cladding, but is also
highly dependent on the waveguide dimensions. Finally SBS may occur due to
coupling to free modes, which exist even in the absence of acoustic
confinement; we find that the cumulative effect of coupling to these
non-confined modes results in significant SBS gain. We show how the different
acoustic properties of core and cladding lead to these different regimes, and
discuss the feasibility of SBS experiments using different material systems
Optimizing optical Bragg scattering for single-photon frequency conversion
We develop a systematic theory for optimising single-photon frequency
conversion using optical Bragg scattering. The efficiency and phase-matching
conditions for the desired Bragg scattering conversion as well as spurious
scattering and modulation instability are identified. We find that third-order
dispersion can suppress unwanted processes, while dispersion above the fourth
order limits the maximum conversion efficiency. We apply the optimisation
conditions to frequency conversion in highly nonlinear fiber, silicon nitride
waveguides and silicon nanowires. Efficient conversion is confirmed using full
numerical simulations. These design rules will assist the development of
efficient quantum frequency conversion between multicolour single photon
sources for integration in complex quantum networks.Comment: 9 pages, 14 figure
Nonlinear Integrated Microwave Photonics
Harnessing nonlinear optical effects in a photonic chip scale has been proven
useful for a number of key applications in optical communications. Microwave
photonics can also benefit from the adoption of such a technology, creating a
new concept of nonlinear integrated microwave photonics. Here, we discuss the
potential of on-chip nonlinear processing towards the creation of robust and
multifunctional microwave photonic (MWP) processors. We also highlight key
recent results in the field, including frequency agile MWP filters and
ultra-wideband signal generators.Comment: 5 pages, 3 figures, invited paper at 2013 IEEE Topical Meeting on
Microwave Photonic
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