856 research outputs found
Frequency conversion in nonlinear optical waveguides : from classical to quantum applications
This thesis encompasses a broad area of physics including linear and nonlinear optics, photonics and quantum physics. It combines the phenomena of nonlinearoptical frequency conversion with waveguiding and coupling, taking advantage of new opportunities presented by advances in fabrication technologies of micro- and nano-waveguides. In this dissertation an in-depth analysis of quantum and classical properties of light traveling in nonlinear optical waveguides, directional couplers and waveguide arrays is performed. The concepts of spatial and temporal dispersion, waveguiding in structures with subwavelength dimensions and nonlinear interactions between different frequencies of light are studied both theoretically and experimentally. Some sections of this thesis include development and implementation of novel physical ideas, while other sections are focused on comprehensive experimental and numerical analysis of advanced theoretical concepts. The results presented in this dissertation demonstrate new physical phenomena with potential applications in the areas of telecommunications and quantum information. The research performed in this thesis opens opportunities for frequency conversion with world-leading power efficiency, including operation with ultrashort pulses for a variety of wavelengths to suit a wide range of perspective application requirements. It also shows an approach for simple and energy efficient spatio-temporal optical signal control, which can find applications in next generation telecommunications networks. Furthermore, the results obtained in this dissertation demonstrate the possibility for flexible shaping of quantum statistics of photons generated in photonic waveguiding structures through spontaneous frequency conversion, contributing to the development of integrated quantum circuits. The new methods of frequency conversion in micro- and nano-scale waveguides and optical circuits have potential to advance the performance, energy efficiency, and security of future optical communication networks and computing systems
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
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
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
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