18,622 research outputs found
Injection locking of optomechanical oscillators via acoustic waves
Injection locking is a powerful technique for synchronization of oscillator
networks and controlling the phase and frequency of individual oscillators
using similar or other types of oscillators. Here, we present the first
demonstration of injection locking of a radiation-pressure driven
optomechanical oscillator (OMO) via acoustic waves. As opposed to previously
reported techniques (based on pump modulation or direct application of a
modulated electrostatic force), injection locking of OMO via acoustic waves
does not require optical power modulation or physical contact with the OMO and
it can easily be implemented on various platforms. Using this approach we have
locked the phase and frequency of two distinct modes of a microtoroidal silica
OMO to a piezoelectric transducer (PZT). We have characterized the behavior of
the injection locked OMO with three acoustic excitation configurations and
showed that even without proper acoustic impedance matching the OMO can be
locked to the PZT and tuned over 17 kHz with only -30 dBm of RF power fed to
the PZT. The high efficiency, simplicity and scalability of the proposed
approach paves the road toward a new class of photonic systems that rely on
synchronization of several OMOs to a single or multiple RF oscillators with
applications in optical communication, metrology and sensing. Beyond its
practical applications, injection locking via acoustic waves can be used in
fundamental studies in quantum optomechanics where thermal and optical
isolation of the OMO are critical
Automated routing and control of silicon photonic switch fabrics
Automatic reconfiguration and feedback controlled routing is demonstrated in an 8Ă—8 silicon photonic switch fabric based on Mach-Zehnder interferometers. The use of non-invasive Contactless Integrated Photonic Probes (CLIPPs) enables real-time monitoring of the state of each switching element individually. Local monitoring provides direct information on the routing path, allowing an easy sequential tuning and feedback controlled stabilization of the individual switching elements, thus making the switch fabric robust against thermal crosstalk, even in the absence of a cooling system for the silicon chip. Up to 24 CLIPPs are interrogated by a multichannel integrated ASIC wire-bonded to the photonic chip. Optical routing is demonstrated on simultaneous WDM input signals that are labelled directly on-chip by suitable pilot tones without affecting the quality of the signals. Neither preliminary circuit calibration nor lookup tables are required, being the proposed control scheme inherently insensible to channels power fluctuations
Principles of Neuromorphic Photonics
In an age overrun with information, the ability to process reams of data has
become crucial. The demand for data will continue to grow as smart gadgets
multiply and become increasingly integrated into our daily lives.
Next-generation industries in artificial intelligence services and
high-performance computing are so far supported by microelectronic platforms.
These data-intensive enterprises rely on continual improvements in hardware.
Their prospects are running up against a stark reality: conventional
one-size-fits-all solutions offered by digital electronics can no longer
satisfy this need, as Moore's law (exponential hardware scaling),
interconnection density, and the von Neumann architecture reach their limits.
With its superior speed and reconfigurability, analog photonics can provide
some relief to these problems; however, complex applications of analog
photonics have remained largely unexplored due to the absence of a robust
photonic integration industry. Recently, the landscape for
commercially-manufacturable photonic chips has been changing rapidly and now
promises to achieve economies of scale previously enjoyed solely by
microelectronics.
The scientific community has set out to build bridges between the domains of
photonic device physics and neural networks, giving rise to the field of
\emph{neuromorphic photonics}. This article reviews the recent progress in
integrated neuromorphic photonics. We provide an overview of neuromorphic
computing, discuss the associated technology (microelectronic and photonic)
platforms and compare their metric performance. We discuss photonic neural
network approaches and challenges for integrated neuromorphic photonic
processors while providing an in-depth description of photonic neurons and a
candidate interconnection architecture. We conclude with a future outlook of
neuro-inspired photonic processing.Comment: 28 pages, 19 figure
Cellular Underwater Wireless Optical CDMA Network: Potentials and Challenges
Underwater wireless optical communications is an emerging solution to the
expanding demand for broadband links in oceans and seas. In this paper, a
cellular underwater wireless optical code division multiple-access (UW-OCDMA)
network is proposed to provide broadband links for commercial and military
applications. The optical orthogonal codes (OOC) are employed as signature
codes of underwater mobile users. Fundamental key aspects of the network such
as its backhaul architecture, its potential applications and its design
challenges are presented. In particular, the proposed network is used as
infrastructure of centralized, decentralized and relay-assisted underwater
sensor networks for high-speed real-time monitoring. Furthermore, a promising
underwater localization and positioning scheme based on this cellular network
is presented. Finally, probable design challenges such as cell edge coverage,
blockage avoidance, power control and increasing the network capacity are
addressed.Comment: 11 pages, 10 figure
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