1,721,140 research outputs found
Frequency noise of laser gyros
Full text linkLaser gyros are powerful tools used to test the predictions of the general theory of relativity. The precision of a measurement of the rotation rate with a laser gyro is limited by the frequency noise of the beat between two counterpropagating modes of a ring laser. The frequency noise of a single mode of a laser is limited by quantum mechanical constraints because it is related to the maximum precision with which the phase of a coherent state can be measured. If two modes are not correlated, the variance of the fluctuations of the difference of their frequencies is the sum of the variance of the frequency noise of the two modes. If the two modes are correlated, this result does not hold any longer. In this paper, we show that a laser gyro has mechanisms capable of dynamically locking the two modes together without forcing them to the same frequency. The lock of modes decouples the noise of the beat note from the frequency noise of the individual modes, thus allowing the realization of sub-shot noise laser gyros
Near-Zero Modal-Dispersion (NEMO) Coupled-Core Multi-Core Fibers
Full text linkWepropose a design for coupled-core multi-core fibers that allows to achieve extremely low levels of modal dispersion. These fibers, which we dub NEar-zero MOdal-dispersion (NEMO) fibers, have an even number of cores regularly distributed on a circle, and the optimal design parameters follow from a simple condition independent of the number of cores. The modal-dispersion reduction trades off some of the fiber mode-mixing effectiveness, yet without compromising its beneficial property of mitigating nonlinear signal distortions. The semi-analytical tool developed for this study allows to effectively characterize the effect of various types of perturbations to the ideal fiber structure
Kramers-Kronig receivers
No full textThis paper reviews the foundations of the Kramers-Kronig (KK) receiver, a recently proposed scheme designed to reconstruct a complex-valued signal from the measurement of its intensity in the context of fiber-optic communications. We provide a comprehensive characterization of the signal properties that are required for the proper operation of the KK receiver and discuss the most relevant implementation requirements, such as the need for digital up-sampling, the implications of receiver imperfections, line chromatic dispersion, optical filtering, and polarization multiplexing. (C) 2019 Optical Society of Americ
Random Polarization-Mode Coupling Explains Inter-Core Crosstalk in Uncoupled Multi-Core Fibers
No full textExisting models for inter-core crosstalk in uncoupled multi-core fibers neglect intra-core random polarization-mode coupling, and conjecture other mechanisms to justify experimental findings. In this work we show that random polarization-mode coupling can explain observed crosstalk values. Good agreement between theory and experiments is obtained
Fundamental limits to the measurement of the polarization of classical light
No full textWe study the limits that quantum mechanics imposes on the accuracy of the measurement of the Stokes polarization-vector in the case of classical states. Using the apparatus of the conventional Stokes receiver, we propose an estimation method that allows not only to exceed the signal-to-noise limit that is achieved by a heterodyne measurement or after ideal phase-insensitive amplification, but also to achieve the quantum SNR limit for the measurement of classical light. We refer to this receiver scheme as the enhanced Stokes receiver
PDB51. Direct and indirect cost of diabetes in italy: A prevalence probabilistic approach
Full text linkDistributed measurement of birefringence in uncoupled multicore fibers
No full textWe report the results of the first distributed measurement of local birefringence performed on a nominally-uncoupled four-core fiber. The data show correlation between the intrinsic birefringence of the individual cores. (c) 2021 The Author(s
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Trattamento multidisciplinare del Ca della mammella. Trattamento chirurgico oggi.
No full textSETTIMANA MEDICO-CHIRURGICA DELL’OSPEDALE SAN CAMILLO DE LELLIS
INCONTRI DI ONCOLOGIA. ROMA 6 - 10 MAGGIO 199
- …
