Search query: optical fiber based Nano technology

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abstract: Abstract In this paper, a distributed optical fiber senor system for multi intrusion monitoring has been proposed along a 25 km distance based on phase sensitive optical time domain reflectometer D t 100 n s and a remote optically pump amplifier (ROPA) The ROPA is based on Raman pump relay free amplification and remote connected in erbium doped fiber (EDF) It makes the detection distance increase 108% from 12km to 25km. The best amplification effect is achieved when the EDF is connected in the middle area. In the experiments, several vibrations of the fiber at different locations given by piezoelectric transducers (PZTs) simulate the vibrations caused by intrusions. Three remote intrusions have been detected and located simultaneously along a 25km optical fiber with a spatial resolution of 10m. In order to improve the signal to noise ratio (SNR) and detection distance, the semiconductor optical amplifier (SOA) with high extinction ratio and narrow pulse width has been used to modulate light into pulses. The SNR of 9.5dB has realized for intrusion detection at remote tail end of 25km distance. The experimental results can be the references for improving the remote intrusion detection and location technology of Ph O T D R sensor system.
author_names: Yage Zhan

Zhong-kang Song

Zeyu Sun

Muhuo Yu

Aijin Guo

Changheng Feng

Jiaxin Zhong
title: A distributed optical fiber sensor system for intrusion detection and location based on the phase sensitive OTDR with remote pump EDFA
year: 2021

abstract: The use of hydrogen as a clean and renewable alternative to fossil fuels requires a suite of flammability mitigating technologies, particularly robust sensors for hydrogen leak detection and concentration monitoring. To this end, we have developed a class of lightweight optical hydrogen sensors based on a metasurface of Pd nano patchy particle arrays, which fulfills the increasing requirements of a safe hydrogen fuel sensing system with no risk of sparking. The structure of the optical sensor is readily nano engineered to yield extraordinarily rapid response to hydrogen gas <3 s at 1 mbar H2) with a high degree of accuracy <5% By incorporating 20% Ag, Au or Co, the sensing performances of the Pd alloy sensor are significantly enhanced, especially for the Pd80Co20 sensor whose optical response time at 1 mbar of H2 is just ~0.85 s, while preserving the excellent accuracy <2.5% limit of detection (2.5 ppm) and robustness against aging, temperature, and interfering gases. The superior performance of our sensor places it among the fastest and most sensitive optical hydrogen sensors.
author_names: Hoang Mai Luong

Minh Thien Pham

Tyler C Guin

Richa Pokharel Madhogaria

M H Phan

George Keefe Larsen

Tho Duc Nguyen
title: Sub second and ppm level optical sensing of hydrogen using templated control of nano hydride geometry and composition
venue: Nature communications
year: 2021

abstract: Abstract Due to the transmission mode and multiple loss peak of a long period fiber grating pair (LPGP) there are some difficulties in multiplexing and demodulating it. To realize the multi point detection of LPGP, a new distributed demodulation system based on space division multiplexing is proposed. The relationship between the spectra of the LPGP and the grating parameters (grating length, grating period, separation of the long period fiber grating) were investigated, and a series of rules for optimizing the spectrum characteristics of the LPGP were obtained. By using optical switches, the traditional spectrometer demodulation is combined with computer technology to design a multiplex demodulation system of distributed LPGPs. Spectrum reduction, resonant wavelength, and temperature demodulation of the LPGP were realized. The experimental results show that the demodulation speed of the system is 1.1 seconds and the wavelength accuracy is 0.01 nm. The designed system has the advantages of high precision, strong compatibility and friendly operation interface. This multiplexing method is appealing to construct distributed LPGP sensors since it is easy to extend multiplexing channels.
author_names: Xingliu Hu

Haifei Si

Hao Shen
title: Spectral characteristics and space division multiplexing scheme of long period fiber grating pair
year: 2021

abstract: Abstract Reducing the complexity and the cost is the key to introducing high performance coherent technologies into practical radio over fiber (RoF) links. In this paper, we propose a coherent detected RoF link with low complexity optical configuration and a light digital signal processing (DSP) unit. Based on a dual parallel Mach Zehnder modulator (DP MZM) at the transmitter, the amplitude and phase of a light wave are modulated to achieve spectral efficient use of the optical source. After transmission over a single optical fiber, the modulated signals are coherent detected at the receiver by being interfered with an independent local oscillator laser and then are demodulated digitally. Compared with other two optical source coherent detected RoF links, our proposed scheme can accomplish dual channel RF signal transmission albeit with halved optical configuration. Additionally, the DSP algorithm to get rid of the laser phase fluctuation between two lasers is simple and efficient. An experimental demonstration is done. Two 16 QAM microwave vector signals at the same symbol rate of 50 Msymbol/s are transmitted over 25 km single mode fiber (SMF) and the error vector magnitudes (EVMs) of 3.15% and 3.53% are obtained respectively. To explore its potential, two 64 QAM microwave vector signals are transported with similar conditions and the measured EVMs are 4.05% and 5.88% respectively.
author_names: Huixing Zhang

Aijun Wen

Wu Zhang

Weipeng Zhang
title: A simplified coherent detected radio over fiber link with intensity and phase modulation and simple digital phase noise cancellation
year: 2021

abstract: Complex optical systems such as high quality microcavities enabled by advanced lithography and processing techniques paved the way to various light matter interactions (LMI) studies. Without lattice matching constraints in epitaxy, coating techniques or shaky open cavity constructions, sub micrometer precise lithographic development of a polymer photoresist paves the way to polymer microcavity structures for various spectral regions based on the material's transparency and the geometrical sizes. We introduce a new approach based on 3D nanowriting in photoresist, which can be employed to achieve microscopic photonic Fabry P\'erot cavity structures with mechanically tunable resonator modes and polymer/air Bragg mirrors, directly on a chip or device substrate. We demonstrate by transfer matrix calculations and computer assisted modelling that open microcavities with up to two "air Bragg" reflectors comprising alternating polymer/air mirror pair layers enable compression induced mode tuning that can benefit many LMI experiments, such as with 2D materials, nanoparticles and molecules.
author_names: Chirag Chandrakant Palekar

Arash Rahimi-Iman
title: Tunable Polymer/Air Bragg Optical Microcavity Configurations for Controllable Light Matter Interaction Scenarios
year: 2021

abstract: We demonstrate DML based net 325 Gb/s at back to back and 321.24 Gb/s after 2 km standard single mode fiber transmissions for >300 Gbps/l short reach optical interconnects. Our net rate performance denotes an increase of ~34% compared to our previous works, while the pre FEC rates are >400 Gbps. The DML transmitter is based on a PPR enhanced, >100 GHz bandwidth DML, fabricated by our novel membrane III V on SiC technology. Also wide band, entropy loaded DMT modulation is utilized based on a novel adaptive algorithm and via a digitally preprocessed analog multiplexer. These results pave the way towards low cost and energy efficient Terabit Ethernet and a significant step towards achieving DML based 400 Gbps/l IM/DD systems in the future.
author_names: Nikolaos P Diamantopoulos

Hiroshi Yamazaki

Suguru Yamaoka

Munehiko Nagatani

Hidetaka Nishi

Hiromasa Tanobe

Ryo Nakao

Takuro Fujii

Koji Takeda

Takaaki Kakitsuka

Hitoshi Wakita

Minoru Ida

Hideyuki Nosaka

Fumio Koyama

Yutaka Miyamoto

Shinji Matsuo
title: >100 GHz Bandwidth Directly Modulated Lasers and Adaptive Entropy Loading for Energy Efficient >300 Gbps/l IM/DD Systems
venue: Journal of Lightwave Technology
year: 2021

abstract: Quadriwave lateral shearing interferometry (QLSI) is a quantitative phase imaging technique based on the use of a diffraction grating placed in front of a camera. This grating creates a wire mesh like image, called an interferogram, that is postprocessed to retrieve both the intensity and phase profiles of an incoming light beam. Invented in the 90s, QLSI has been used in numerous applications, e.g. laser beam characterization, lens metrology, topography measurements, adaptive optics, and gas jet metrology. More recently, the technique has been implemented in optical microscopes to characterize micro and nano objects for bioimaging and nanophotonics applications. However, not much effort has been placed on disseminating this powerful technology so far, while it is yet a particularly simple technique. In this article, we intend to popularize this technique by describing all its facets in the framework of optical microscopy, namely the working principle, its implementation on a microscope and the theory of image formation, using simple pictures. We also provide and comment on an algorithm for interferogram processing, written in Matlab. Then, following the new extension of the technique for microscopy and nanophotonics applications, and the deviation from what the technique was initially invented for, we propose to revisit the description of the technique, in particular, by discussing the terminology, insisting more on a grating shadow description rather than a quadriwave process, and proposing an alternative appellation, namely 'grating shadow phase microscopy' or 'grating assisted phase microscopy'
author_names: Guillaume Baffou
title: Quantitative phase microscopy using quadriwave lateral shearing interferometry (QLSI) principle, terminology, algorithm and grating shadow description
year: 2021

abstract: Manipulating and cooling small particles with light are long standing challenges in many areas of science, from the foundations of physics to applications in biology and nano technology. Light fields can, in particular, be used to isolate mesoscopic particles from their environment by levitating them optically. These levitated particles of micron size and smaller exhibit pristine mechanical resonances and can be cooled down to their motional quantum ground state. Significant roadblocks on the way to scale up levitation from a single to multiple particles in close proximity are the requirements to constantly monitor the particles' positions as well as to engineer light fields that react fast and appropriately to their displacements. Given the complexity of light scattering between particles, each of these two challenges currently seems insurmountable already in itself. Here, we present an approach that solves both problems at once by forgoing any local information on the particles. Instead, our procedure is based on the far field information stored in the scattering matrix and its changes with time. We demonstrate how to compose from these ingredients a linear energy shift operator,
author_names: Markus Fabian Kaczvinszki

Nicolas Bachelard

Jakob Hupfl

Michael Horodynski

Matthias Kuhmayer

Stefan Rotter
title: Optimal Cooling of Multiple Levitated Particles through Far Field Wavefront Shaping
year: 2021

abstract: Quantum key distribution (QKD) is a technology that allows secure key exchange between two distant users. A widespread adoption of QKD requires the development of simple, low cost, and stable systems. However, implementation of the current QKD requires a complex self alignment process during the initial stage and an additional hardware to compensate the environmental disturbances. In this study, we present the implementation of a simple QKD with the help of a stable transmitter receiver scheme, which simplifies the self alignment and is robust enough to withstand environmental disturbances. In case of the stability test, the implementation system is able to remain stable for 48 h and exhibits an average quantum bit error rate of less than 1% without any feedback control. The scheme is also tested over a fiber spool, obtaining a stable and secure finite key rate of 7.32k bits per second over a fiber spool extending up to 75 km. The demonstrated long term stability and obtained secure key rate prove that our method of implementation is a promising alternative for practical QKD systems, in particular, for CubeSat platform and satellite applications.
author_names: Di Ma

Xin Liu

Chunfeng Huang

Huanbin Lin

Kejin Wei
title: Simple quantum key distribution using a stable transmitter receiver scheme.
venue: Optics letters
year: 2021

abstract: We report a self guided and "stimulated" single crystal growth acceleration effect in static super saturated aqueous solutions, producing inorganic (KH2PO4) and organic (tetraphenyl phosphonium family) nonlinear optical single crystals with novel morphologies. The extraordinarily fast unidirectional growth in the presence of complete lateral growth suppression defies all current impurity, defect and dislocation based crystal growth inhibition mechanisms. We propose a self channeling stimulated accelerated growth theory that can satisfactorily explain all experimental results. Using molecular dynamics analysis and a modified two component crystal growth model that includes microscopic surface molecular selectivity we show the lateral growth arrest is the combined result of the self channeling and a self shielding effect. These single crystals exhibit remarkable mechanical flexibility in winding and twisting, demonstrating their unique advantages for chip size quantum and biomedical applications, as well as for production of high yield/high potency pharmaceutical materials. One Sentence Summary: Discovery of a robust, self guided and self stimulated material growth acceleration effect in aqueous inorganic and organic single crystals. Single crystal (1,2) is a catalyst for diverse scientific advances in optical science (3,4) chemical and biomedical science (5 7) mineralogy (8) interstellar astro chemistry (9,10) and even pharmaceutical (11 14) development. It has significantly impacted many scientific fields ranging from quantum entanglement and communication technologies (3,4) to chemical engineering, protein crystallization (13) and pharmaceutical manufacturing of high potency single crystal/co crystal drugs (12,14) For decades, self restricted growth of certain crystal faces, even in a supersaturated solution that favors growth, has been a subject of active investigations. The well established Cabrera Vermilyea theory (15) on surface chemistry by impurities has stimulated extensive research and it is now widely accepted (16) that crystal growth eventually arrests by one of two means: (i) the depletion of growth molecules from the surrounding solution when the super saturation reaches zero, or (ii) the presence of metal impurities that "poison" surface chemistry, thereby inhibiting the crystalline growth of native molecules (15 24) Here, we report a single crystal growth phenomenon that defies this well established theoretical understanding. Indeed, the observed growth bi morphology cannot be explained by any currently known theories of crystalline surface growth inhibition mechanisms, including all impurity, restricted nucleation, dislocation or defect based theories, as well as solid state chemistry and material science in general, a strong indication of unknown surface physics effects and processes. We propose a self channeling stimulated matter growth acceleration theory, in analogy to the coherent stimulated Raman light scattering process in optical science, and show that it can satisfactorily explain all experimental results. Fig. 1 Bi morphologies of single crystalline pendants grown by self channeling stimulated growth acceleration technique. Self channeling stimulated growth of a bulk crystal fused to two single crystal fibers that are under lateral growth arrest. Inset: Single crystal KDP fiber with its pyramidal face fused to the pyramidal face of a bulk crystal of the similar size (see Fig. 4E for the corresponding simulation) The growth of the fiber is completely suppressed whereas the bulk crystal grows un impeded to nearly ninety times larger in a few minutes. Figure 1 shows bi morphologies of inorganic KH2PO4 (KDP) single crystals grown by the novel stimulated single crystal growth acceleration technique. Similar bi morphologies using organic TTP X family single crystals (X: Cl, Br, I, etc. have also been produced. To achieve this, we bring the ends (also referred to as pyramidal faces) of two single crystal fibers (aspect ratio R 60, radius 3 mm, length 180 mm) and a small bulk single crystal (initial size 3 mm, R 2) in contact in situ in an aqueous solution. In the subsequent growth period we observed no growth on the fibers' lateral faces (also referred to as prismatic faces) However, the small bulk crystal grows with an astonishingly fast rate of v 350 nm/s [see (26) for more] in each direction (from 3 mm initial size to nearly 190 mm in just a few minutes! That is, in the same growth environment and proximity the fiber sections experience complete prismatic face growth arrest and yet the bulk crystal grows steadily unimpeded to more than sixty times of its original size in just a few minutes. When the pyramidal face of a single crystal fiber is fused to the pyramidal face of a small bulk single crystal (Fig. 1 inset) the latter can grow to nearly ninety times larger in a few minutes during which the fiber section does not grow at all. This bi morphology clearly demonstrates that impurity based growth inhibition mechanisms do not play any important role. Indeed, there is no reasonable explanation as to why impurities in the same solution and proximity only severely impact and suppress the lateral growth characteristics of the fiber section, while leaving the growth dynamics of the bulk crystal completely intact. Furthermore, extensive X ray diffraction studies show extremely sharp single peaked spectra that rule out any defect/dislocation based arguments [see Supplementary Material (SM) I] This bi morphology rapid growth of single crystals is a testimony to the robust self channeling stimulated matter growth acceleration mechanism we explain below. Seed crystals with large aspect ratios can produce a solute self channeling effect similar to the "point effect" in electrostatics. This effect makes the pyramidal face a strong "solute collector" creating a steep concentration gradient at the pyramidal face. This solute gradient results in a pyramidal face guided solute flow that enables an accelerated matter growth phenomenon never before observed in the field of crystallography and material science. Figures 2A and 2B show the pyramidal face growth rates as functions of R for KDP and TPPCl crystals subjecting to strong prismatic face growth arrest. Remarkably, the measured growth rate can be well approximated by vv (ln[CC|(RR) where we introduce an "R dispersive" local concentration CC|(RR) in analogous to the resonant/near resonant frequency dispersion of molecular optical polarizability (25) The crystal growth driving force (GDF) for such a highly dynamic "R dispersive" process can be expressed as [see SM II, III] GGGGGG ln dd| (1) CC|(RR) (1) in analogous to the coherent stimulated Raman light scattering enhancement by lattice normal mode vibrations (25) The physical meaning of the tensor dd| (1) is the strength of "R sloped" contribution, i.e. the R dependent growth acceleration, arising from the microscopic concentration gradient. Therefore, the postulation of "R dispersive" local concentration and Eq. (1) collectively represent the concept of "Raman like" stimulated material growth mechanism. Indeed, the excellent fits in Figs. 2A and 2B to Eq. (1) clearly demonstrate that it is the local concentration gradient near the pyramidal face, i.e, CC| rather than the quasi steady macroscopic solution concentration as conventional theories have always assumed, that drives the accelerated surface growth. For sufficiently large R Figs. 2A and 2B indicate the presence of a characteristic aspect ratio that acts as an effective "healing length" beyond which the self channeling effect saturates. Fig. 2 Self channeling stimulated growth acceleration effect. Pyramidal face growth rate as a function of fiber aspect ratio R for KDP (A) and TPPCl (B) single crystalline fibers subjecting to prismatic face growth suppression. Green curves are fits using Eq. (1) The idea of stimulated matter growth mechanism that defies all currently accepted theories arises from a series of single crystalline fiber studies. We prepare and submerge single crystalline KDP/TPPCl/TPPBr fibers (typically diameter 3 mm, length 50 100 mm) in ultra high purity supersaturated (s 0.237) aqueous solution at room temperatures [see SM I] The growth process is static and we routinely obtain single crystalline KDP/TPPCl/TPPBr fibers with large aspect ratio R 1000 [Figs. 3A, 3B] excellent optical properties and remarkable mechanical flexibility in twisting [Fig. 3C] and winding [Fig. 3D] Fig. 3 Images of single crystalline organic and inorganic nonlinear crystal fibers. Both KDP (A) and TPPCl (B) show prismatic face growth suppression (diameter remain unchanged) whereas the growth of pyramidal faces is unimpeded. They exhibit remarkable mechanical flexibility for twisting (C) and winding (D) (winding posts are optical fibers) (E) Prismatic face growth suppression (red dots) and quadratic growth characteristics of fibers with imperfections (blue triangles) From a single crystal growth perspective, the most striking feature shown in Figs. 3A and 3B is the rapid pyramidal face growth coupled with complete prismatic face growth suppression. We observed no change in prismatic faces in a 15 hour growth period during which the crystal pyramidal face grows at a fast rate 400 nm/s in a static super saturated solution for KDP and even much faster for TPP X family single crystals) yielding crystal fibers with aspect ratios R 1000. This is in stark contrast to the growth of a low R KDP/TPPCl/TPPBr crystal under the same growth conditions where all surfaces grow with a similar slower rate 30 nm/s (26) resulting in a bulk crystal typically having R 3. Figure 3E shows the diameter of a growing fiber as a function of its initial diameter in a fixed 60 seconds period. Fibers with excellent uniformity (verified by microscope inspection) follow a perfect y x relation, indicating compl
author_names: Yan Ren

Changfeng Fang

Chengjie Zhu

Yvonne Y Li

Bo Durbeej

Xian Zhao

Lu Deng
title: Accelerating single crystal growth by stimulated and self guided channeling
year: 2021