381 research outputs found
Taxonomy of hybridly polarized Stokes vortex beams
Structured beams carrying topological defects, namely phase and Stokes
singularities, have gained extensive interest in numerous areas of optics. The
non-separable spin and orbital angular momentum states of hybridly polarized
Stokes singular beams provide additional freedom for manipulating optical
fields. However, the characterization of hybridly polarized Stokes vortex beams
remains challenging owing to the degeneracy associated with the complex
polarization structures of these beams. In addition, experimental noise factors
such as relative phase, amplitude, and polarization difference together with
beam fluctuations add to the perplexity in the identification process. Here, we
present a generalized diffraction-based Stokes polarimetry approach assisted
with deep learning for efficient identification of Stokes singular beams. A
total of 15 classes of beams are considered based on the type of Stokes
singularity and their associated mode indices. The resultant total and
polarization component intensities of Stokes singular beams after diffraction
through a triangular aperture are exploited by the deep neural network to
recognize these beams. Our approach presents a classification accuracy of
98.67% for 15 types of Stokes singular beams that comprise several degenerate
cases. The present study illustrates the potential of diffraction of the Stokes
singular beam with polarization transformation, modeling of experimental noise
factors, and a deep learning framework for characterizing hybridly polarized
beam
How Can Optical Communications Shape the Future of Deep Space Communications? A Survey
With a large number of deep space (DS) missions anticipated by the end of
this decade, reliable and high capacity DS communications systems are needed
more than ever. Nevertheless, existing DS communications technologies are far
from meeting such a goal. Improving current DS communications systems does not
only require system engineering leadership but also, very crucially, an
investigation of potential emerging technologies that overcome the unique
challenges of ultra-long DS communications links. To the best of our knowledge,
there has not been any comprehensive surveys of DS communications technologies
over the last decade. Free space optical (FSO) technology is an emerging DS
technology, proven to acquire lower communications systems size, weight, and
power (SWaP) and achieve a very high capacity compared to its counterpart radio
frequency (RF) technology, the current used DS technology. In this survey, we
discuss the pros and cons of deep space optical communications (DSOC).
Furthermore, we review the modulation, coding, and detection, receiver, and
protocols schemes and technologies for DSOC. We provide, for the very first
time, thoughtful discussions about implementing orbital angular momentum (OAM)
and quantum communications (QC) for DS. We elaborate on how these technologies
among other field advances, including interplanetary network, and RF/FSO
systems improve reliability, capacity, and security and address related
implementation challenges and potential solutions. This paper provides a
holistic survey in DSOC technologies gathering 200+ fragmented literature and
including novel perspectives aiming to setting the stage for more developments
in the field.Comment: 17 pages, 8 Figure
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