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"Optical control"
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The eye of war : military perception from the telescope to the drone
\"This project explores how technologies of perception -- the ability to detect and to avoid detection -- have transformed modern warfare. The book spans from the Renaissance, where the rationalization of vision and space started to influence military strategy, to the present day, where combatants increasingly face off in the perceptual realm of drones and satellites as much as the physical battlefield. Each chapter explores a different perceptual theme: sensing, imaging, mapping and hiding\"-- Provided by publisher.
Book
Thermo-Optical Control of Raman Solitons in a Functionalized Silica Microsphere
The investigation of optical microcavity solitons is in demand both for applications and basic science. Despite the tremendous progress in the study of microresonator solitons, there is still no complete understanding of all features of their nonlinear dynamics in various regimes. Controlling soliton properties is also of great interest. We proposed and investigated experimentally and theoretically a simple and easily reproducible way to generate Raman solitons with controllable spectral width in an anomalous dispersion region in a functionalized silica microsphere with whispering gallery modes (WGMs) driven in a normal dispersion regime. To functionalize the microsphere, coating (TiO2 + graphite powder) was applied at the pole. The coating is used for effective thermalization of the radiation of an auxiliary laser diode launched through the fiber stem holding the microsphere to control detuning of the pump frequency from exact resonance due to the thermo-optical shift of the WGM frequencies. We demonstrated that the thermo-optical control by changing the power of an auxiliary diode makes it possible to switch on/off the generation of Raman solitons and control their spectral width, as well as to switch Raman generation to multimode or single-mode. We also performed a detailed theoretical analysis based on the Raman-modified Lugiato–Lefever equation and explained peculiarities of intracavity nonlinear dynamics of Raman solitons. All experimental and numerically simulated results are in excellent agreement.
Journal Article
Robotics, Vision and Control : Fundamental Algorithms In MATLAB® Second, Completely Revised, Extended And Updated Edition
Robotic vision, the combination of robotics and computer vision, involves the application of computer algorithms to data acquired from sensors. The research community has developed a large body of such algorithms but for a newcomer to the field this can be quite daunting. For over 20 years the author has maintained two open-source MATLAB® Toolboxes, one for robotics and one for vision. They provide implementations of many important algorithms and allow users to work with real problems, not just trivial examples. This book makes the fundamental algorithms of robotics, vision and control accessible to all. It weaves together theory, algorithms and examples in a narrative that covers robotics and computer vision separately and together. Using the latest versions of the Toolboxes the author shows how complex problems can be decomposed and solved using just a few simple lines of code. The topics covered are guided by real problems observed by the author over many years as a practitioner of both robotics and computer vision. It is written in an accessible but informative style, easy to read and absorb, and includes over 1000 MATLAB and Simulink® examples and over 400 figures. The book is a real walk through the fundamentals of mobile robots, arm robots. then camera models, image processing, feature extraction and multi-view geometry and finally bringing it all together with an extensive discussion of visual servo systems. This second edition is completely revised, updated and extended with coverage of Lie groups, matrix exponentials and twists; inertial navigation; differential drive robots; lattice planners; pose-graph SLAM and map making; restructured material on arm-robot kinematics and dynamics; series-elastic actuators and operational-space control; Lab color spaces; light field cameras; structured light, bundle adjustment and visual odometry; and photometric visual servoing. \"An authoritative book, reaching across fields, thoughtfully conceived and brilliantly accomplished!\" OUSSAMA KHATIB, Stanford.
Book
All-Optically Controllable Photonic Crystals Based on Chiral-Azobenzene-Doped Blue Phase Liquid Crystals
In this study, the all-optical control properties of photonic crystals based on self-assembled chiral-azobenzene-doped blue phase liquid crystals (CA-BPLCs) were investigated. The difference in the photothermal characteristics of CA-BPLCs with and without homogeneous surface alignment was discussed. Results revealed that surface alignment could induce more uniform and diverse blue phase (BP) structures, including BPII, BPI, and BPS-like phases during cooling. Consequently, the temperature range of BP was wider than that of the sample without surface alignment. All-optical control experiments with light illumination were then performed on the aligned or nonaligned CA-BPLC samples. During continuous irradiation with light beams at wavelengths of 405 and 450 nm, CA dopants underwent trans→cis and cis→trans back photoisomerizations, respectively. These processes promoted isothermal phase transition and wavelength shifting, which further enabled the all-optical control of the CA-BPLC samples. Various optical control modes of BPLC could be achieved through phase change and wavelength shifting by appropriately selecting the working temperature and surface treatment of BPLC. This study could be further used as a basis for developing photoswitchable and tunable BPLC photonic devices, such as light-controllable gratings, filters, mirrors, and lasers.
Journal Article
20 krad/s endless optical polarisation and phase control
Presented is endless optical control not only of the state-of-polarisation of an analysed signal and its orthogonal, but also of the phase difference between the two. The normalised Stokes vector space is thereby stabilised, at the polarisation scrambling speeds of up to 20 krad/s.
Journal Article
All-optical controllable electromagnetically induced transparency in coupled silica microbottle cavities
An all-optical control scheme of electromagnetically induced transparency (EIT) based on two coupled silica microbottle cavities coated with iron oxide nanoparticles is proposed and experimentally demonstrated. The specially designed and fabricated silica microbottle cavity with a short and spherical end, which is coated with iron oxide nanoparticles, possesses a quality (
) factor of 1.39×10
and large all-optical tunability in a range of 282.32 GHz (2.25 nm) arising from the strong photothermal effect of the nanoparticles. Based on two coupled silica microbottle cavities, we achieve the EIT spectrum with a transparency window bandwidth of 2.3 MHz. The transparency window can be flexibly controlled by tuning the resonant frequency of the higher-
microcavity. Besides, by tuning the resonant frequencies of the two microcavities separately, the whole EIT spectrum can be shifted with a range of 71.52 GHz, to the best of our knowledge, for the first time. Based on this scheme, we have realized all-optical and independent control of the transparency window and the whole EIT spectrum. We believe this work has great potential in applications such as light storage, optical sensing, and quantum optics.
Journal Article
Optical information transmission through complex scattering media with optical-channel-based intensity streaming
For the past decade, optical wavefront shaping has been the standard technique to control light through scattering media. Implicit in this dominance is the assumption that manipulating optical interference is a necessity for optical control through scattering media. In this paper, we challenge this assumption by reporting on an alternate approach for light control through a disordered scattering medium – optical-channel-based intensity streaming (OCIS). Instead of actively tuning the interference between the optical paths via wavefront shaping, OCIS controls light and transmits information through scattering media through linear intensity operations. We demonstrate a set of OCIS experiments that connect to some wavefront shaping implementations, i.e. iterative wavefront optimization, digital optical phase conjugation, image transmission through transmission matrix, and direct imaging through scattering media. We experimentally created focus patterns through scattering media on a sub-millisecond timescale. We also demonstrate that OCIS enables a scattering medium mediated secure optical communication application.
Controlling light through disordered scattering media is traditionally done by manipulating optical interference for wavefront shaping. Here, the authors present optical-channel-based intensity streaming, an approach which controls light and transmits information through linear intensity operations.
Journal Article
Temporal solitons in microresonators driven by optical pulses
Continuous-wave laser-driven, high-
Q
Kerr–nonlinear optical microresonators have enabled the generation of optical frequency combs, ultralow-noise microwaves and ultrashort optical pulses at tens of gigahertz repetition rate. Here, we break with the paradigm of the continuous-wave driving and instead use periodic, picosecond optical pulses. In a fibre-based Fabry–Pérot microresonator we observe the deterministic generation of stable femtosecond dissipative cavity solitons ‘on top’ of the resonantly enhanced driving pulses. The solitons lock to the driving pulse, which enables direct all-optical control of the soliton's repetition rate and tuning of its carrier-envelope offset frequency. When compared with continuous-wave-driven microresonators or non-resonant pulsed supercontinuum generation, this new approach is more efficient and can yield broadband frequency combs at an average driving power significantly below the continuous-wave parametric threshold. Bridging the fields of continuous-wave-driven resonant and pulse-driven non-resonant nonlinear optics, these results enable efficient microresonator frequency combs, resonant supercontinuum generation and microphotonic pulse compression.
By driving a high-
Q
fibre-based Fabry–Pérot microresonator with periodic, picosecond optical pulses, deterministic generation of stable femtosecond dissipative cavity solitons has been experimentally realized.
Journal Article
Ultra-narrow optical linewidths in rare-earth molecular crystals
Rare-earth ions (REIs) are promising solid-state systems for building light–matter interfaces at the quantum level
1
,
2
. This relies on their potential to show narrow optical and spin homogeneous linewidths, or, equivalently, long-lived quantum states. This enables the use of REIs for photonic quantum technologies such as memories for light, optical–microwave transduction and computing
3
–
5
. However, so far, few crystalline materials have shown an environment quiet enough to fully exploit REI properties. This hinders further progress, in particular towards REI-containing integrated nanophotonics devices
6
,
7
. Molecular systems can provide such capability but generally lack spin states. If, however, molecular systems do have spin states, they show broad optical lines that severely limit optical-to-spin coherent interfacing
8
–
10
. Here we report on europium molecular crystals that exhibit linewidths in the tens of kilohertz range, orders of magnitude narrower than those of other molecular systems. We harness this property to demonstrate efficient optical spin initialization, coherent storage of light using an atomic frequency comb, and optical control of ion–ion interactions towards implementation of quantum gates. These results illustrate the utility of rare-earth molecular crystals as a new platform for photonic quantum technologies that combines highly coherent emitters with the unmatched versatility in composition, structure and integration capability of molecular materials.
A study reports europium molecular crystals with optically addressable spin states that exhibit ultra-narrow linewidths, demonstrating the use of rare-earth molecular crystals as a platform for photonic quantum technologies.
Journal Article
Optical control of coherent magneto-optical resonances in potassium
The influence of Light Induced Atomic Desorption (LIAD) on the potassium D2 line magneto-optical resonances in uncoated buffer-gas optical cell is investigated. LIAD effect reduces the drawbacks of conventional heating for achieving high atomic density that is essential for many spectroscopy-based applications. Another feature of LIAD is the impact on the dwelling time of the atoms when colliding with the surface of the cell. In this work we investigate LIAD from point of view to distinguish the influence of LIAD on the atomic density from the dwelling time as well as to control and improve the parameters of magneto-optical resonances in potassium vapor. The results are interesting for development of new precise optical sensors and devices for various applications.
Journal Article