17,982 research outputs found
Spatial and temporal filtering of a 10-W Nd:YAG laser with a Fabry-Perot ring-cavity premode cleaner
We report on the use of a fixed-spacer Fabry–Perot ring cavity to filter spatially and temporally a 10-W laser-diode-pumped Nd:YAG master-oscillator power amplifier. The spatial filtering leads to a 7.6-W TEMinfinity beam with 0.1% higher-order transverse mode content. The temporal filtering reduces the relative power fluctuations at 10 MHz to 2.8 x 10^-/sqrtHz, which is 1 dB above the shot-noise limit for 50 mA of detected photocurrent
Structured Optical Receivers for Efficient Deep-Space Communication
We discuss conceptual designs for structured optical receivers that can
alleviate the requirement for high peak-to-average power ratio in
photon-starved optical communication. The basic idea is to transmit sequences
of suitably modulated coherent light pulses whose energy can be concentrated in
a single temporal bin on the receiver side through optical interference. Two
examples of scalable architectures for structured receivers are presented. The
first one, based on active polarization switching, maps Hadamard codewords
composed from the binary phase shift keying (BPSK) constellation onto the
standard pulse position modulation (PPM) format. The second receiver, using
solely passive optical elements, converts phase-polarization patterns of
coherent light pulses into a single pulse preserving a synchronized time of
arrival. Such a conversion enables implementation of a communication protocol
equivalent to the PPM scheme but with distributed optical power provided that
the intersymbol guard-time exceeds the pattern length.Comment: 4 pages, 2 figures. To be presented at the IEEE International
Conference on Space Optical Systems and Applications, 14-16 November 2017,
Naha, Okinawa, Japa
Coherent switching of semiconductor resonator solitons
We demonstrate switching on and off of spatial solitons in a semiconductor
microresonator by injection of light coherent with the background illumination.
Evidence results that the formation of the solitons and their switching does
not involve thermal processes.Comment: 3 pages, 5 figure
Observation of Defect States in PT-Symmetric Optical Lattices
We provide the first experimental demonstration of defect states in
parity-time (PT) symmetric mesh-periodic potentials. Our results indicate that
these localized modes can undergo an abrupt phase transition in spite of the
fact that they remain localized in a PT-symmetric periodic environment. Even
more intriguing is the possibility of observing a linearly growing radiation
emission from such defects provided their eigenvalue is associated with an
exceptional point that resides within the continuum part of the spectrum.
Localized complex modes existing outside the band-gap regions are also reported
along with their evolution dynamics
Preparation of an Exponentially Rising Optical Pulse for Efficient Excitation of Single Atoms in Free Space
We report on a simple method to prepare optical pulses with exponentially
rising envelope on the time scale of a few ns. The scheme is based on the
exponential transfer function of a fast transistor, which generates an
exponentially rising envelope that is transferred first on a radio frequency
carrier, and then on a coherent cw laser beam with an electro-optical phase
modulator (EOM). The temporally shaped sideband is then extracted with an
optical resonator and can be used to efficiently excite a single Rb-87 atom.Comment: 3 pages, 4 figures, small technical not
Demonstration of a programmable source of two-photon multiqubit entangled states
We suggest and demonstrate a novel source of two-photon multipartite
entangled states which exploits the transverse spatial structure of spontaneous
parametric downconversion together with a programmable spatial light modulator
(SLM). The 1D SLM is used to perform polarization entanglement purification and
to realize arbitrary phase-gates between polarization and momentum degrees of
freedom of photons. We experimentally demonstrate our scheme by generating
two-photon three qubit linear cluster states with high fidelity using a diode
laser pump with a limited coherence time and power on the crystal as low as
2.5$mW.Comment: 5 pages, 4 figures, to appear on PR
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