1,364 research outputs found
Antiresonant ring interferometer for laser cavity dumping, mode locking, and other applications
Applications in lasers for antiresonant ring interferometer include coupled laser cavities, variable laser-output coupling, intercavity harmonic-output coupling, mode locking, cavity dumping, and pulse code modulation
Laser system with an antiresonant optical ring
Various applications of an antiresonant ring, consisting of a beam splitter and a number of optical reflectors, are described. With a beam splitter having a transmission coefficient and a reflection coefficient, an optical beam incident on the beam splitter along a first axis is split into two components which circulate around the ring in opposite directions. They are recombined to reflect back the beam along the first axis, with none of the beam power being directed along a second axis. The ring can be part of the cavity of two otherwise independent lasers, with two separate laser mediums external to the ring, or with a multi-wavelength laser medium in the ring. The ring together with a second-harmonic generation crystal and a dispersive phase shifter in the ring can generate the second harmonic of an optical beam
Estimate of Tilt Instability of Mesa-Beam and Gaussian-Beam Modes for Advanced LIGO
Sidles and Sigg have shown that advanced LIGO interferometers will encounter
a serious tilt instability, in which symmetric tilts of the mirrors of an arm
cavity cause the cavity's light beam to slide sideways, so its radiation
pressure exerts a torque that increases the tilt. Sidles and Sigg showed that
the strength T of this torque is 26.2 times greater for advanced LIGO's
baseline cavities -- nearly flat spherical mirrors which support Gaussian beams
(``FG'' cavities), than for nearly concentric spherical mirrors which support
Gaussian beams with the same diffraction losses as the baseline case -- ``CG''
cavities: T^{FG}/T^{CG} = 26.2. This has motivated a proposal to change the
baseline design to nearly concentric, spherical mirrors. In order to reduce
thermoelastic noise in advanced LIGO, O'Shaughnessy and Thorne have proposed
replacing the spherical mirrors and their Gaussian beams by ``Mexican-Hat''
(MH) shaped mirrors which support flat-topped, ``mesa'' shaped beams. In this
paper we compute the tilt-instability torque for advanced-LIGO cavities with
nearly flat MH mirrors and mesa beams (``FM'' cavities) and nearly concentric
MH mirrors and mesa beams (``CM'' cavities), with the same diffraction losses
as in the baseline FG case. We find that the relative sizes of the restoring
torques are T^{CM}/T^{CG} = 0.91, T^{FM}/T^{CG} = 96, T^{FM}/T^{FG} = 3.67.
Thus, the nearly concentric MH mirrors have a weaker tilt instability than any
other configuration. Their thermoelastic noise is the same as for nearly flat
MH mirrors, and is much lower than for spherical mirrors.Comment: 10 pages, 3 figures, 4 table
Study of Laser Frequency Stability and Spectral Purity Semiannual Status Report, 1 Mar. - 31 Aug. 1968
Quantum phase noise and plasma-induced phase noise in He-Ne laser
Further Measurement of Quantum Phase Noise in a He-ne Laser
Measurement of spontaneous emission phase fluctation in helium, neon laser
Comment on " Gain coefficient method for amplified spontaneous emission in thin waveguided film of a conjugated polymer " [APL 93, 163307 (2008)]
Comment on " Gain coefficient method for amplified spontaneous emission in
thin waveguided film of a conjugated polymer " [APL 93, 163307 (2008)
PT-symmetric laser-absorber
In a recent work, Y.D. Chong et al. [Phys. Rev. Lett. {\bf 105}, 053901
(2010)] proposed the idea of a coherent perfect absorber (CPA) as the
time-reversed counterpart of a laser, in which a purely incoming radiation
pattern is completely absorbed by a lossy medium. The optical medium that
realizes CPA is obtained by reversing the gain with absorption, and thus it
generally differs from the lasing medium. Here it is shown that a laser with an
optical medium that satisfies the parity-time symmetry
condition for the dielectric
constant behaves simultaneously as a laser oscillator (i.e. it can emit
outgoing coherent waves) and as a CPA (i.e. it can fully absorb incoming
coherent waves with appropriate amplitudes and phases). Such a device can be
thus referred to as a -symmetric CPA-laser. The general
amplification/absorption features of the CPA-laser below lasing
threshold driven by two fields are determined.Comment: 5 pages; to be published in Phys. Rev. A (Rapid Communications
Impedance-matched cavity quantum memory
We consider an atomic frequency comb based quantum memory inside an
asymmetric optical cavity. In this configuration it is possible to absorb the
input light completely in a system with an effective optical depth of one,
provided that the absorption per cavity round trip exactly matches the
transmission of the coupling mirror ("impedance matching"). We show that the
impedance matching results in a readout efficiency only limited by irreversible
atomic dephasing, whose effect can be made very small in systems with large
inhomogeneous broadening. Our proposal opens up an attractive route towards
quantum memories with close to unit efficiency.Comment: 4 pages, 2 figure
Complexity of 2D random laser modes at the transition from weak scattering to Anderson localization
The spatial extension and complexity of the eigenfunctions of an open
finite-size two-dimensional (2D) random system are systematically studied for a
random collection of systems ranging from weakly scattering to localized. The
eigenfunctions are obtained by introducing gain in the medium and pumping just
above threshold. All lasing modes are found to correspond to quasimodes of the
passive system, for all regimes of propagation. We demonstrate the existence of
multipeaked quasimodes or necklace states in 2D at the transition from
localized to diffusive, resulting from the coupling of localized states.Comment: Submitted to PR
Prospects of higher-order Laguerre Gauss modes in future gravitational wave detectors
The application of higher-order Laguerre Gauss (LG) modes in large-scale
gravitational wave detectors has recently been proposed. In comparison to the
fundamental mode, some higher-order Laguerre Gauss modes can significantly
reduce the contribution of coating Brownian noise. Using frequency domain
simulations we give a detailed analysis of the longitudinal and angular control
signals derived with a LG33 mode in comparison to the fundamental TEM00 mode.
The performance regarding interferometric sensing and control of the LG33 mode
is found to be similar, if not even better in all aspects of interest. In
addition, we evaluate the sensitivity gain of the implementation of LG33 modes
into the Advanced Virgo instrument. Our analysis shows that the application of
the LG33 mode results in a broadband improvement of the Advanced Virgo
sensitivity, increasing the potential detection rate of binary neutron star
inspirals by a factor 2.1.Comment: 12 pages, 8 figure
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