108 research outputs found
Holographic recording of laser-induced plasma
We report on a holographic probing technique that allows for measurement of free-electron distribution with fine spatial detail. Plasma is generated by focusing a femtosecond pulse in air. We also demonstrate the capability of the holographic technique of capturing the time evolution of the plasma-generation process. © 2004 Optical Society of America
III-V-on-silicon mode-locked lasers with 1-GHz line spacing for dual-comb spectroscopy
We demonstrate dual-comb interferometry and spectroscopy with a III-V-on-silicon passively mode- locked laser of 1-GHz repetition rate and 1-THz span. We heterodyne the on-chip device with an electro-optic modulator comb for initial assessment. (C) 2020 The Author(s
Study of hyperfine structure in simple atoms and precision tests of the bound state QED
We consider the most accurate tests of bound state QED, precision theory of
simple atoms, related to the hyperfine splitting in light hydrogen-like atoms.
We discuss the HFS interval of the 1s state in muonium and positronium and of
the 2s state in hydrogen, deuterium and helium-3 ion. We summarize their QED
theory and pay attention to involved effects of strong interactions. We also
consider recent optical measurements of the 2s HFS interval in hydrogen and
deuterium.Comment: presented at The International Workshop "e+e- collisions from phi to
psi
Coherence as ultrashort pulse train generator
Intense, well-controlled regular light pulse trains start to play a crucial
role in many fields of physics. We theoretically demonstrate a very simple and
robust technique for generating such periodic ultrashort pulses from a
continuous probe wave which propagates in a dispersive thermal gas media
Ultra-cold atoms in an optical cavity: two-mode laser locking to the cavity avoiding radiation pressure
The combination of ultra-cold atomic clouds with the light fields of optical
cavities provides a powerful model system for the development of new types of
laser cooling and for studying cooperative phenomena. These experiments
critically depend on the precise tuning of an incident pump laser with respect
to a cavity resonance. Here, we present a simple and reliable experimental
tuning scheme based on a two-mode laser spectrometer. The scheme uses a first
laser for probing higher-order transversal modes of the cavity having an
intensity minimum near the cavity's optical axis, where the atoms are confined
by a magnetic trap. In this way the cavity resonance is observed without
exposing the atoms to unwanted radiation pressure. A second laser, which is
phase-locked to the first one and tuned close to a fundamental cavity mode
drives the coherent atom-field dynamics.Comment: 7 pages, 7 figure
Destabilization of dark states and optical spectroscopy in Zeeman-degenerate atomic systems
We present a general discussion of the techniques of destabilizing dark
states in laser-driven atoms with either a magnetic field or modulated laser
polarization. We show that the photon scattering rate is maximized at a
particular evolution rate of the dark state. We also find that the atomic
resonance curve is significantly broadened when the evolution rate is far from
this optimum value. These results are illustrated with detailed examples of
destabilizing dark states in some commonly-trapped ions and supported by
insights derived from numerical calculations and simple theoretical models.Comment: 14 pages, 10 figure
Influence of the 6^1S_0-6^3P_1 Resonance on Continuous Lyman-alpha Generation in Mercury
Continuous coherent radiation in the vacuum-ultraviolet at 122 nm
(Lyman-alpha) can be generated using sum-frequency mixing of three fundamental
laser beams in mercury vapour. One of the fundamental beams is at 254 nm
wavelength, which is close to the 6^1S_0-6^3P_1 resonance in mercury.
Experiments have been performed to investigate the effect of this one-photon
resonance on phasematching, absorption and the nonlinear yield. The efficiency
of continuous Lyman-alpha generation has been improved by a factor of 4.5.Comment: 8 pages, 7 figure
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