1,721,005 research outputs found
Introduction to the physics of waves
No full textBalancing concise mathematical analysis with the real-world examples and practical applications that inspire students, this textbook provides a clear and approachable introduction to the physics of waves. The author shows through a broad approach how wave phenomena can be observed in a variety of physical situations and explains how their characteristics are linked to specific physical rules, from Maxwell's equations to Newton's laws of motion. Building on the logic and simple physics behind each phenomenon, the book draws on everyday, practical applications of wave phenomena, ranging from electromagnetism to oceanography, helping to engage students and connect core theory with practice. Mathematical derivations are kept brief and textual commentary provides a non-mathematical perspective. Optional sections provide more examples along with higher-level analyses and discussion. This textbook introduces the physics of wave phenomena in a refreshingly approachable way, making it ideal for first- and second-year undergraduate students in the physical sciences
On the design of enhancement cavities for second harmonic generation
Full text linkEnhancement cavities using off-axis spherical mirrors allow the elliptical Gaussian beams from semiconductor diode lasers to be matched directly to the optimum beam profile for frequency conversion in a nonlinear crystal. We give a general recipe for the design of such cavities
Rubidium pump-probe spectroscopy: Comparison between ab initio theory and experiment
No full textWe present a simple, analytic model for pump-probe spectroscopy in dilute atomic gases. Our model treats multilevel atoms, takes several broadening mechanisms into account and, with no free parameters, shows excellent agreement with experimentally observed spectra
Cavity-mediated cooling with a single mirror
No full textJust as an atom can replace one mirror in the Casimir effect, so cavity-mediated cooling appears possible through the retarded interaction of an illuminated particle with - or optical binding to - its own reflection. External cavity/plasmon resonances within the mirror offer to enhance this process, which may then be extended across a broad array. We describe our ongoing theoretical treatment of single mirror cooling, as well as planned experiments that are currently being assembled
Optical cooling of atoms and molecules using nanostructured surfaces
No full textThe dipole force, which avoids the closed cycle of pumping and spontaneous emission that renders laser cooling unsuitable for molecules, is conservative: without dissipation, particles entering a trap retain the energy to escape. Fortunately, dissipation need not involve spontaneous emission if it instead results from the decoherence or decay of the optical trapping field that is coupled to the particle. To enhance the weak attraction of an atom to its reflection, cavity-mediated cooling recycles light through multiple reflections, amplifying the force and the retardation - a process related to the mechanical amplification in a near confocal cavity [5]. Resonant cavities and structures can increase the retardation, but not the intensity, even when the atoms or particles lie outside them - e.g. when the cavity is the narrow-band coating of a single mirror. Plasmon resonances of a structured metal can enhance both the delay and the optical intensity. Such processes, possible with arrays of micromirrors, resemble speckle field cooling [6], except that spontaneous emission is again replaced by decay of the optical field, and offer a new class of cooling mechanisms in which weak cooling is extended over a broad array, rather than concentrated at the centre of a single external cavity
Fractional adiabatic passage in two-level systems: mirrors and beam splitters for atomic interferometry
No full textAtom interferometers require atom mirrors and beam-splitters that can maintain high fidelity
even when experimental parameters vary from the ideal. We address the use of chirped laser pulses
to provide such elements via rapid adiabatic passage, and present a prescription for practical pulses
that offer controlled adiabaticity throughout. Full- and half-adiabatic pulses, providing mirrors and
beam-splitters respectively, are derived, and the latter examined for robustness and suitability for experimental implementations
Cavity-enhanced toroidal dipole force traps for dark-field seeking species
Full text linkDipole force traps for dark-field seeking states of atoms and molecules require regions of low intensity that are completely surrounded by a brighter optical field. Confocal cavities allow the resonant enhancement of these interesting transverse mode superpositions, and put deep far-off-resonance traps within reach of low-power diode lasers. In this paper, we show how an array of dark-field rings may be created simply using a single Gaussian beam. Such a geometry lends itself to the study of toroidal Bose–Einstein condensates
Coherent amplification in laser cooling and trapping
No full textThe optical scattering force, behind Doppler cooling and magneto-optical trapping, may be amplified without incurring additional spontaneous emission by the state-dependent coherent deflection produced by a pulsed or chirped laser field. At some cost in experimental complexity, amplified forces allow efficient cooling on narrow transitions and permit the compact deceleration of beams with reduced transverse heating, and will be of interest for molecules and atoms with open level schemes where losses following spontaneous emission would otherwise prevail. We present a general analysis of the amplification scheme, and propose an optimized, dynamic cooling scheme that allows the temperature of a sample to be reduced by around a factor of two per excited state lifetime
Semi-classical theory of coherent atom cooling with a single mirror
No full textWe investigate theoretically a novel optical technique to cool atomic or molecular species without a closed transition: a particle in front of a mirror illuminated by an off-resonant light beam. The interaction between the particle, the pump and the time-delayed reflected pump results in a net loss of energy from the particle to the field and therefore cooling. Cooling rates depending on particle position and coupling parameters are obtained by an analytical perturbative approach. Finally, we present a semiclassical computational model incorporating momentum diffusion, which will eventually allow us to predict steady-state temperatures
Atom cooling using the dipole force of a single retroflected laser beam
Full text linkWe present a mechanism for cooling atoms by a laser beam reflected from a single mirror. The cooling relies on the dipole force and thus in principle applies to arbitrary refractive particles including atoms, molecules, or dielectric spheres. Friction and equilibrium temperatures are derived by an analytic perturbative approach. Finally, semiclassical Monte Carlo simulations are performed to validate the analytic results
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