46 research outputs found
Efficient generation of >2 W of green light by single pass frequency doubling in PPMgLN
We report 32% efficient frequency doubling of single frequency 1029 nm light
to green light at 514.5 nm using a single pass configuration. A congruent
composition, periodically poled magnesium doped lithium niobate (PPMgLN)
crystal of 50 mm length was used to generate a second harmonic power of 2.3 W.
To our knowledge, this is the highest reported frequency doubling efficiency of
any wavelength light in a PPMgLN crystal and also the highest reported SHG
output power in the green for PPMgLN.Comment: 5 pages, 3 figures. Submitted to Optics Express, awaiting respons
Quasi two-dimensional carriers in dilute-magnetic-semiconductor quantum wells under in-plane magnetic field
Due to the competition between spatial and magnetic confinement, the density
of states of a quasi two-dimensional system deviates from the ideal step-like
form both quantitatively and qualitatively. We study how this affects the
spin-subband populations and the spin-polarization as functions of the
temperature, , and the in-plane magnetic field, , for narrow to wide
dilute-magnetic-semiconductor quantum wells. We focus on the quantum well
width, the magnitude of the spin-spin exchange interaction, and the sheet
carrier concentration dependence. We look for ranges where the system is
completely spin-polarized. Increasing , the carrier spin-splitting,
, decreases, while increasing , increases.
Moreover, due to the density of states modification, all energetically higher
subbands become gradually depopulated.Comment: 3 pages, 3 figure
Joint Temporal Density Measurements for Two-Photon State Characterization
We demonstrate a new technique for characterizing two-photon quantum states
based on joint temporal correlation measurements using time resolved single
photon detection by femtosecond upconversion. We measure for the first time the
joint temporal density of a two-photon entangled state, showing clearly the
time anti-correlation of the coincident-frequency entangled photon pair
generated by ultrafast spontaneous parametric down-conversion under extended
phase-matching conditions. The new technique enables us to manipulate the
frequency entanglement by varying the down-conversion pump bandwidth to produce
a nearly unentangled two-photon state that is expected to yield a heralded
single-photon state with a purity of 0.88. The time-domain correlation
technique complements existing frequency-domain measurement methods for a more
complete characterization of photonic entanglement in quantum information
processing.Comment: 4 pages, 5 figure
Lasers and optics: Looking towards third generation gravitational wave detectors
Third generation terrestrial interferometric gravitational wave detectors will likely require significant advances in laser and optical technologies to reduce two of the main limiting noise sources: thermal noise due to mirror coatings and quantum noise arising from a combination of shot noise and radiation pressure noise. Increases in laser power and possible changes of the operational wavelength require new high power laser sources and new electro-optic modulators and Faraday isolators. Squeezed light can be used to further reduce the quantum noise while nano-structured optical components can be used to reduce or eliminate mirror coating thermal noise as well as to implement all-reflective interferometer configurations to avoid thermal effects in mirror substrates. This paper is intended to give an overview on the current state-of-the-art and future trends in these areas of ongoing research and development.NSF/PHY0555453NSF/PHY0757968NSF/PHY0653582DFG/SFB/407DFG/SFB/TR7DFG/EXC/QUES
Elementary excitations in tunnel-coupled electron bilayers
A new class of single-particle excitations in tunnel-coupled electron
bilayers is investigated by inelastic light scattering. The dispersion
law and the dependence of the energies of these excitations on the
degree of unbalance between the layers have been measured. A new
spectroscopic method is proposed for determining the degree of
unbalance between bilayers. (C) 2003 MAIK "Nauka/Interperiodica"
Collective excitations in double quantum wells with strong tunnel coupling
Spectra of collective and magnetic excitations in symmetric double
quantum wells with strong tunnel coupling were studied by inelastic
scattering. Gaps in the spectrum of collective and single-particle
excitations associated with tunnel interwell splitting were measured.
New excitation modes, namely, tunnel Bernstein modes, were detected in
a magnetic field. Based on the dispersion and magnetic-field
dependences of the energies of inelastic light scattering lines, a
classification of excitations and magnetic excitations was given. (C)
2004 MAIK "Nauka / Interperiodica"