2,553 research outputs found
Controlled fabrication of tunable delay using compound phase shifted resonators
Fine tuned, narrowband group delay (“slow light”) is obtained using a compound phase shifted grating and superposing resonances. Both simulation and experiments are reported
Design of arbitrary optical filters in silicon-on-insulator using evanescently-coupled Bragg gratings
Spectral filters are experiencing an increasing demand in several applications of the silicon-
on-insulator (SOI) platform. Many works have demonstrated that arbitrary frequency
responses can be synthesized by apodizing the coupling coefficient profile of an integrated
Bragg grating. However, the high index contrast of the SOI platform hinders their
practical implementation, due to the difficulty of achieving the precise control required in
the Bragg strength. In this paper, we propose the implementation of spectral filters using
an architecture based on placing loading segments within the evanescent field region of a
photonic wire waveguide. The Bragg coupling coefficient can be accurately controlled by
simply moving the segments away from, or closer to, the waveguide core. The layerpeeling
algorithm, in conjunction with a Floquet-Bloch modal analysis, allows to determine
the spatial distribution of the segments that synthesizes the desired spectrum. The
proposed topology is verified by designing a filter with five arbitrary passbands.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
High performance silicon photonic devices based on practical metamaterials
Robert Halir, et al., "High performance silicon photonic devices based on practical metamaterials," OECC/PSC, 7-12 July 2019, Fukuoka (Japan)Subwavelength grating metamaterials are enabling a new generation of high-performance silicon photonic devices. Here we discuss the fundamental physics along with some of the latest advances in this rapidly expanding field.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.
Ministerio de Economía y Competitividad, Programa Estatal de Investigación Orientada a los Retos de la Sociedad (cofinanciado FEDER) – TEC2016-80718-R, TEC2015-71127-C2-1-R (FPI BES-2016-077798) and IJCI-2016-30484; Community of Madrid – S2018/NMT-4326, Marie Sklodowska-Curie –734331, Czech Science Foundation – 1900062
Enhanced Autocompensating Quantum Cryptography System
We have improved the hardware and software of our autocompensating system for
quantum key distribution by replacing bulk optical components at the end
stations with fiber-optic equivalents and implementing software that
synchronizes end-station activities, communicates basis choices, corrects
errors and performs privacy amplification over a local area network. The all
fiber-optic arrangement provides stable, efficient and high-contrast routing of
the photons. The low bit error rate leads to high error correction efficiency
and minimizes data sacrifice during privacy amplification. Characterization
measurements made on a number of commercial avalanche photodiodes are presented
that highlight the need for improved devices tailored specifically for quantum
information applications. A scheme for frequency shifting the photons returning
from Alice's station to allow them to be distinguished from backscattered noise
photons is also described.
OCIS codes: 030.5260, 060.0060, 060.2360, 230.2240, 270.5570.Comment: 13 pages, 1 table, 9 figures; Applied Optics LP (in press, to appear
3/02
Efficient generation of tunable photon pairs at 0.8 and 1.6 micrometer
We demonstrate efficient generation of collinearly propagating, highly
nondegenerate photon pairs in a periodically-poled lithium niobate cw
parametric downconverter with an inferred pair generation rate of 1.4*10^7/s/mW
of pump power. Detection of an 800-nm signal photon triggers a
thermoelectrically-cooled 20%-efficient InGaAs avalanche photodiode for the
detection of the 1600-nm conjugate idler photon. Using single-mode fibers as
spatial mode filters, we obtain a signal-conditioned idler-detection
probability of about 3.1%.Comment: 8 pages, 3 figure
Inverse design and implementation of a wavelength demultiplexing grating coupler
Nanophotonics has emerged as a powerful tool for manipulating light on chips.
Almost all of today's devices, however, have been designed using slow and
ineffective brute-force search methods, leading in many cases to limited device
performance. In this article, we provide a complete demonstration of our
recently proposed inverse design technique, wherein the user specifies design
constraints in the form of target fields rather than a dielectric constant
profile, and in particular we use this method to demonstrate a new
demultiplexing grating. The novel grating, which has not been developed using
conventional techniques, accepts a vertical-incident Gaussian beam from a
free-space and separates O-band and C-band
light into separate waveguides. This inverse design concept
is simple and extendable to a broad class of highly compact devices including
frequency splitters, mode converters, and spatial mode multiplexers.Comment: 17 pages, 4 figures, 1 table. A supplementary section describing the
inverse-design algorithm in detail has been added, in addition to minor
corrections and updated reference
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