344 research outputs found
Lattice topology and spontaneous parametric down-conversion in quadratic nonlinear waveguide arrays
We analyze spontaneous parametric down-conversion in various experimentally
feasible 1D quadratic nonlinear waveguide arrays, with emphasis on the
relationship between the lattice's topological invariants and the biphoton
correlations. Nontrivial topology results in a nontrivial "winding" of the
array's Bloch waves, which introduces additional selection rules for the
generation of biphotons. These selection rules are in addition to, and
independent of existing control using the pump beam's spatial profile and phase
matching conditions. In finite lattices, nontrivial topology produces single
photon edge modes, resulting in "hybrid" biphoton edge modes, with one photon
localized at the edge and the other propagating into the bulk. When the single
photon band gap is sufficiently large, these hybrid biphoton modes reside in a
band gap of the bulk biphoton Bloch wave spectrum. Numerical simulations
support our analytical results.Comment: 11 pages, 12 figure
Infrared spectra of some sulfides and their analogs of binary composition in the long-wave region
The far infrared spectra (500-60/cm) of some simple sulfides and their analogs were studied. In all, 22 minerals with different structure types were investigated, out of which 14 are sulfides (galena, alabandite, pyrrhotite, sphalerite, wurtzite, cinnabar, realgar, orpiment, getchelite antimonite, molybdenite, pyrite, marcasite and heazlewoodite) 6 arsenides (niccolite, domeykite, arsenopyrite, lollingite, rammelsbergite and skutterudite), one telluride (tetradymite) and native arsenic. The main bands of infrared absorption spectra of the minerals are compared with the relative strength of the interatomic bonds and their interpretation is given
Suppression of Spectral Diffusion by Anti-Stokes Excitation of Quantum Emitters in Hexagonal Boron Nitride
Solid-state quantum emitters are garnering a lot of attention due to their
role in scalable quantum photonics. A notable majority of these emitters,
however, exhibit spectral diffusion due to local, fluctuating electromagnetic
fields. In this work, we demonstrate efficient Anti-Stokes (AS) excitation of
quantum emitters in hexagonal boron nitride (hBN), and show that the process
results in the suppression of a specific mechanism responsible for spectral
diffusion of the emitters. We also demonstrate an all-optical gating scheme
that exploits Stokes and Anti-Stokes excitation to manipulate spectral
diffusion so as to switch and lock the emission energy of the photon source. In
this scheme, reversible spectral jumps are deliberately enabled by pumping the
emitter with high energy (Stokes) excitation; AS excitation is then used to
lock the system into a fixed state characterized by a fixed emission energy.
Our results provide important insights into the photophysical properties of
quantum emitters in hBN, and introduce a new strategy for controlling the
emission wavelength of quantum emitters
Temporal dynamics of all-optical switching in quadratic nonlinear directional couplers
We study the temporal dynamics of all-optical switching in nonlinear directional couplers in periodically poled lithium niobate. The characteristic features of such switching, including asymmetric pulse break-up and back-switching were measured in full agreement with the theoretical predictions. Based on the time-resolved measurement of intensity-dependent switching, finally the theoretically long-known continuous-wave switching curve has experimentally been confirmed.We acknowledge the support by the Australian Research
Council Centre of Excellence program (project CE110001018), the Australian Academy of Science, and the
International Bureau of the Federal Ministry of Education
and Research (BMBF), Germany (Australia-Germany
Researcher Mobility Call 2010-2011)
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