[3] Kao K CHockham G A. Dielectric-fibre surface waveguides for optical frequencies [J]. They can also be used as transduction elements, converting the output of another sensor, which generates a strain or temperature change from the measurand, for example fiber Bragg grating gas sensors use an absorbent coating, which in the presence of a gas expands generating a strain, which is measurable by the grating. The content of this test is confidential. The pump and Stokes beams are temporally synchronised by a SynchroLock system, which electronically adjusts the time delay between the two pulse trains. The sensitivity of Raman spectroscopy can be enhanced through various techniques such as resonance Raman spectroscopy [81], TERS [82, 83] or SERS [84]. This means that fiber Bragg gratings can be used as sensing elements in optical fiber sensors. J Phys Chem B 114:1020010208 https://doi.org/10.1021/jp103216j, Fu Y, Huff TB, Wang H-W et al (2008) Ex vivo and in vivo imaging of myelin fibers in mouse brain by coherent anti-Stokes Raman scattering microscopy. A narrow linewidth is preferable for Raman spectroscopy because the measured shift in the Raman scattering process is limited by the lasers linewidth. Mol. We present a review of quantum computation with neutral atom qubits. Opt. It can be observed that the laser-irradiated area is modified, instead of material removal. They are also used in optical multiplexers and demultiplexers with an optical circulator, or optical add-drop multiplexer (OADM). Detailed Syllabus: graphene [8,9,10] and transition metal dichalcogenides [11,12,13]) and phonon modes in crystals [14,15,16]. Keldysh ionization theory is one of the main pillars of strong field physics and attosecond science. Device temperature rise determined using either E2 or A1 (LO) phonon mode alone (neglecting thermal stress) is shown in the top left insert. g Data were acquired in 6s using a bead mixture with a concentration of 2% solids. The resonance states yield dissociative potential curves which, when considered together with their widths, provide input for models of different electron-cation collision processes including dissociative recombination, and rotational and vibrational excitation. Liu et al. (a) Optical microscope image of field emission transistor structures created on Ge. An inverted microscope illuminates the sample from underneath and the tip is placed at the top surface of the sample. The LIPSS with different feature sizes exhibits various physical properties. {\displaystyle \scriptstyle n_{3}\,-\,n_{2}} Also, Each Hermite-Gaussian beam in the simulation is described by TEMm,n, where m and n represent the Hermite-Gaussian mode index. B. Wang, Near-field enhanced femtosecond laser nano-drilling of glass substrate,, M. Wu, R. Chen, J. Soh et al., Super-focusing of center-covered engineered microsphere,, M. X. Wu, B. J. Huang, R. Chen et al., Modulation of photonic nanojets generated by microspheres decorated with concentric rings,, Y. Zhou and M. Hong, Formation of a three-dimensional bottle beam via an engineered microsphere,, Y. Zhou, R. Ji, J. Teng, and M. Hong, Wavelength-tunable focusing via a Fresnel zone microsphere,, Y. Liao, Y. Ju, L. Zhang et al., Three-dimensional microfluidic channel with arbitrary length and configuration fabricated inside glass by femtosecond laser direct writing,, Y. Liao, J. While spontaneous Raman scattering is an incoherent process, SRS is a coherent four-wave nonlinear optical mixing process. Diode-pumped SLM lasers are readily available in compact form from the UV to the near-IR. Web Nanostructured optical microcavities and photonic "dots"; Inverse design and machine-learning-driven design of nanophotonic structures; Novel approaches to micro- and nanophotonics; Critical assessment of new application fields (light sources, lasers, biophotonics, detectors, optical components, atom and molecule confinement). Phys Rev A 89(13836) https://doi.org/10.1103/PhysRevA.89.013836, Cheng J-X, Pautot S, Weitz DA, Xie XS (2003) Ordering of water molecules between phospholipid bilayers visualized by coherent anti-Stokes Raman scattering microscopy. The interaction between laser and materials under different pulse durations is then discussed, including the strategies of two-/multiphoton absorption, near-field effect, and incubation effect. In this setup, the incident light is focused through an optically transmissive sample substrate. To scale up the femtosecond laser micron processing, high-power laser sources with stable and good beam quality are significant. These cross sections and rates may be used as entrance parameters in collisional-radiative models for fully ionized plasma simulations in the framework of studies concerning for example, switches in Marx generator and laser-induced plasmas in air. 4b) [198]. Figure 4e shows a typical nanofocused SPP-based TERS setup (i), the process of SPP nanofocusing by coupling the incident light to a focused ion beam-fabricated grating (ii), and an example SEM image of a SPP-nanofocusing tip (iii). The first is via EM enhancements where local surface plasmons concentrate the local electric field near the surface of the metal in hot spots located on the sharp edges of nanostructures or in regions of concentrated free-charge carriers due to the lighting rod effect [140]. A parabolic mirror can be used to mitigate mechanical interference and tightly focus the incident light to the tip apex as well as to collect the Raman signal [196, 197]. Certain SPM techniques ordain probe modifications for the plasmonically induced nanoscale evanescent light to activate/enhance the Raman signal. Electronic tuning of the pulse delay was used to achieve temporal overlap between the pump and Stokes laser pulse trains, which is a convenient substitution for mechanical optical delay paths. In the case of 35J/cm2 laser irradiation, the morphology of the nanohole structures characterized by AFM exhibits that the full-width at half-maximum of nanohole structures is 250nm and the depth is about 150nm, as shown in Figure 10(b). Essentially, the MFD is modeled and the resulting target NA and core diameter are developed. Nat Photonics 6:488496 https://doi.org/10.1038/nphoton.2012.138, Bozinovic N, Yue Y, Ren Y et al (2013) Terabit-scale orbital angular momentum mode division multiplexing in fibers. Cancer Res 62:53755380, CAS Multiple instances of prohibited behavior will result in automatic shut-down of the test and rejection of your application. In a tunable demultiplexer or OADM, the Bragg wavelength of the FBG can be tuned by strain applied by a piezoelectric transducer. The interaction between a proton and a ground state hydrogen atom is studied using a standard three-body classical trajectory Monte Carlo (CTMC) and a quasi-classical trajectory Monte Carlo (QCTMC) model where the quantum feature of the collision system is mimicking using the model potential in the Hamiltonian as was proposed by Kirschbaum and Wilets (C. L. Kirschbaun, and L. Wilet, Phys. We use the improved strong-field approximation (ISFA) theory to investigate the evolution of the energy spectra with the carrier-envelope phase (CEP) of a few-cycle laser pulse. Detailed Syllabus: Performing TERS in liquid with STM systems is much more difficult [86, 106]. The laser-induced plasma-assisted ablation (LIPAA), two-photon absorption (TPA), and direct irradiation are feasible to create 2D/3D microstructures on different transparent materials. The length of the tip (~ tens of micrometres) makes them plasmonically unfavourable for visible light enhancement. Metals are most often used as the conducting medium for surface plasmons; however, semiconductors also possess plasmonic characteristics [125]. RGF\EA\180228; STFC Grant No. In the case of spontaneous Raman scattering, the Raman effect is very weak; typically, 1 in 108 of the incident radiation undergoes spontaneous Raman scattering [6]. Nat Commun 4(2592) https://doi.org/10.1038/ncomms3592, Raman CV, Krishnan KS (1929) The production of new radiations by light scattering. The SRS-FC technique was based on broadband laser excitation and a multiplex spectral detection system. Phys. As shown in Figure 12, for the femtosecond laser precision engineering, three main challenges, including smaller HAZ, larger area/higher-speed processing, and feature size smaller than optical diffraction limit are demonstrated. Firstly, the incident laser light must be spectrally pure, which is accomplished with a narrow-linewidth laser source as discussed previously. The term apodization refers to the grading of the refractive index to approach zero at the end of the grating. Incremental improvements to this resolution have been reported [104, 158]. Phys Rev A 14:1748, Capitaine E, Ould Moussa N, Louot C et al (2016) Coherent anti-Stokes Raman scattering under electric field stimulation. The module tests the candidates ability to gather, comprehend and evaluate information from single or multiple source(s). The LIL is mostly used for the exposure and record of the patterns on the photoresist. In Figure 1(d), the hole drilled in a 100m thick steel foil using a laser fluence of 0.5J/cm2 for the laser pulse duration of 200fs irradiation is shown. Detailed Syllabus: 7c were attributed to a local membrane disruption, followed by its spontaneous reformation. Such multiple focus points at the partial Talbot plane are available to create high-density patterning using only single-pulse irradiation. Third-order nonlinear optical interactions (i.e. Using attosecond transient absorption spectroscopy for time delays where the near-infrared (NIR) pump and the extreme ultraviolet (XUV) probe pulses overlap, sub-cycle structures in the build-up of absorption lines in xenon ions are investigated as a function of the pump intensity during strong-field ionization. This technique achieves the desired resolution (beyond the diffraction limit) by forcing the evanescent light into the far field image formation. Organization of the House Keeping Department Organization Chart of the Housekeeping Department Routine systems and records Planning and organizing Cleaning and Procedures Guest room cleaning procedures Cleaning knowledge and practice Other Housekeeping Activities Linen and Laundry Safety and security Horticulture. The size, shape, composition of the nanostructures and inter-nanostructure spacing all affect the wavelength of the surface plasmon resonance [85, 86]. Process Engineer, Project Design Engineer, Quality Control Engineer, Service Engineer, Maintenance Engineer, etc. Properties such as number of monolayers [9, 12, 17, 18], inter-layer breathing and shear modes [19], in-plane anisotropy [20], doping [21,22,23], disorder [10, 24,25,26], thermal conductivity [11], strain [27] and phonon modes [14, 16, 28] can be extracted using Raman spectroscopy. The two pulse trains are spatially filtered, collinearly combined and expanded through beam expanders. 5c i. Surface plasmons can be excited by EM radiation and plasmonics is the study of these light-matter interactions [126]. These Yb-doped fiber lasers first operated at the 1kW CW power level in 2004[29] based on free space cavities but were not shown to operate with fiber Bragg grating cavities until much later. P Befitting Job Functions/Profiles:Telecommunications Field Engineer, Telecommunications Manager, Systems Developer, Radio communications Technician, Telecommunications Network Planner, Telecommunications Technical Officer-Technologist, RF Engineer, Switch Engineer. (e) Nanodrop and (f) nanohole structures created by the six-femtosecond laser beam interference; top right inset displays a nanodrop created by the interference of four beams. Thus, we suggest using dual flat-top beams to achieve ~10nm nanostructures. In many circumstances, the time scale for the electrons with high excitation energy to transform into heat is about one picosecond [36]. The diffraction limit of light restricts the focus spot size in standard optical techniques (such as Raman spectroscopy) to be at least half of the wavelength of the light according to Abbes criterion [152,153,154]. The challenges and perspectives in the femtosecond laser precision engineering are also discussed. Microsphere array assisting laser processing is one of the wonderful techniques which can overcome the diffraction limit as well [136, 137]. Besides, the engineering microsphere also provides a feasible way to increase the working distance and modulate the optical focus property of microspheres. The sensitivity of SERS makes it well-suited to study electron transfer reactions, which lie at the heart of numerous fundamental processes: electro-catalysis, solar energy conversion, energy storage in batteries, and biological events such as photosynthesis [93]. Opt Lett 30:99 https://doi.org/10.1364/OL.30.000099, van Howe J, Xu C (2005) Ultrafast optical delay line using soliton propagation between a time-prism pair. Basic Anatomy Brain and Skeleton Muscular System and Alimentary Canal Respiratory and Cardiac System Physiology-1 (Head and Thorax) Brain and Pituitary, Thyroid, Parathyroid Glands Neuro-transmission Respiration Lymphatic System and Complete Blood System Physilogy-2 (Below Thorax) Endocrine Glands and Gastrointestinal Tract Adrenals, Pancreas, Testes and Ovary Urinary System Reproductive System. Unlike SRS, CARS carries with it a nonresonant background contribution to the spectrum. Thus, it should use some hybrid methods to achieve nanostructures for smaller feature sizes, as shown in Figure 12(c). demonstrated that homogeneous triangular 2D-LIPSS were obtained using both two linearly crossed polarized beams and double counter-rotating circularly polarized beams [114]. ), called the Bragg wavelength, is defined by the relationship. This interaction ensures that the frequency, wavenumber and OAM matching conditions are conserved. Besides, the laser fluence, working distance, and irradiation time also decide the fabricated feature sizes. In this case, the laser microparticle deposition from the metal target creates defects on the back-side of the transparent substrate and leads to the absorption enhancement, which allows the subsequent laser pulses to ablate the transparent substrate easily. A relatively numerous designed microstructures can be obtained in a time much shorter compared to other lithography methods [96]. Figure 3d shows such a TERS setup with a modified AFM. Opt Express 17:11259 https://doi.org/10.1364/OE.17.011259, Brckner L, Buckup T, Motzkus M (2015) Enhancement of coherent anti-Stokes Raman signal via tailored probing in spectral focusing. In addition, non-specific binding of fluorescent labels as well as cellular autofluorescence can also reduce the clarity of the result. Specifically, fiber Bragg gratings are finding uses in instrumentation applications such as seismology,[26] pressure sensors for extremely harsh environments, and as downhole sensors in oil and gas wells for measurement of the effects of external pressure, temperature, seismic vibrations and inline flow measurement. This technique has yielded enhanced the signal-to-noise ratio by removing the far-field light from the apex region. The polarisation described by Eq. is the coefficient of strain, which is related to the strain optic coefficient https://doi.org/10.1021/jacs.5b01426, Fu Y, Kuppe C, Valev VK et al (2017) Surface-enhanced Raman spectroscopy: A facile and rapid method for the chemical component study of individual atmospheric aerosol. ST/R005842/1; EPSRC Grant No. Raman spectra are (by standard) presented with the wavenumber shift linearly increasing from right to left on the horizontal axis. Jones, R.R., Hooper, D.C., Zhang, L. et al. There are numerous treatments and approaches to formulating expressions for (3). The module assesses the candidates on the various laws, theories and principles governing the various physical phenomena in chemistry. Thus, the femtosecond laser pulses of a 1014~1015W/m2 peak intensity can localize numerous photons in a tiny focus zone. Ex vivo transdermal delivery studies are unfavourable because skin regeneration stops, the immune response ceases, and metabolic activity is usually lost. The wavelength of surface plasmons is much shorter than that of the associated propagating light for a given frequency [129]. These maps demonstrate that the frequency of the two modes only slightly vary in regions of the sample with a given layer thickness. The gratings were inscribed using a single 40mJ pulse from an excimer laser at 248nm. CrystEngComm 14:4834 https://doi.org/10.1039/c2ce25198a, Liu GL, Lee LP (2005) Nanowell surface enhanced Raman scattering arrays fabricated by soft-lithography for label-free biomolecular detections in integrated microfluidics. Appl Phys Lett 76:31303132 https://doi.org/10.1063/1.126546, Kelly KL, Coronado E, Zhao LL, Schatz GC (2003) The optical properties of metal nanoparticles: the influence of size, shape, and dielectric environment. These stabilising agents can either impede or augment the measured Raman signal [189]. Spiral phase plates or computer-generated holograms are usually used to generate visible light with OAM [273,274,275,276]. J Invest Dermatol 116:434442 https://doi.org/10.1046/j.1523-1747.2001.01258.x, Schuster KC, Reese I, Urlaub E et al (2000) Multidimensional information on the chemical composition of single bacterial cells by confocal Raman microspectroscopy. However, for small molecules, the fluorescent tags can perturb the biological function of the species. 3 is in agreement with first-order (i.e. OBJ, objective. Appl Opt 45:7005 https://doi.org/10.1364/AO.45.007005, Kneipp K, Kneipp H, Moskovits M (2006) Surface-enhanced Raman scattering. N Boroumand et al 2022 J. Phys. 4d) by focused ion beam lithography [115]. The reflected Raman light is filtered by an apertured mask (to remove any residual large NA pump light) and a notch filter. Figure 1b shows the energy level diagram for the process. Hence, the performance of transdermal drug delivery ex vivo is not an accurate reflection of the in vivo situation [32]. In neurological disorders, this compact structure is highly perturbed leading to dysfunctions of the central nervous system [257, 258]. They have been interpreted in different ways including dopant diffusion (oxygen being the most popular current interpretation) and glass structural change. This is because the process is based on chemical bond breaking during the laser irradiation of photoresist polymer materials. In contrast to the conventional STIRAP in -systems, the Gaussian approximations of the optimal laser pulse sequences allow reaching the infidelity of 107 for the adiabaticity parameter of 300 without noticeable oscillatory or other detrimental effects on population transfer accuracy. However, the charge transfer mechanism only applies to specific molecules, whereas the EM mechanism is applicable for all analytes [4, 92, 102, 148]. 2021, Article ID 9783514, 22 pages, 2021. https://doi.org/10.34133/2021/9783514, 1Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore. Phys Rev Lett 93:137404 https://doi.org/10.1103/PhysRevLett.93.137404, Ropers C, Neacsu CC, Elsaesser T et al (2007) Grating-coupling of surface plasmons onto metallic tips: A nanoconfined light source. A demultiplexer can be achieved by cascading multiple drop sections of the OADM, where each drop element uses an FBG set to the wavelength to be demultiplexed. In combining with special strategies, such as microlens array (MLA) and laser interference lithography (LIL), the feature size of the femtosecond laser precision engineering can be pushed down to submicron scale. The review also highlights the key experimental considerations for implementing the main experimental Raman spectroscopic techniques. created negative metal oxide semiconductor patterns employing 400nm femtosecond laser assisting NSOM nanofabrication strategy [53]. Microscopic examination of these gratings showed a periodic damage track at the grating's site within the fiber [10]; hence type II gratings are also known as damage gratings. J Invest Dermatol 122:443449 https://doi.org/10.1046/j.0022-202X.2004.22208.x, Meyer T, Bergner N, Bielecki C et al (2011) Nonlinear microscopy, infrared, and Raman microspectroscopy for brain tumor analysis. b v Atomic displacements of the four Raman-active modes and one infrared-active mode (E1u) in the unit cell of the bulk MoS2 crystal as viewed along the [1000] direction. For biological samples, approximately 90% of the peaks are found in the fingerprint spectral region, covering (\( \Delta \overset{\sim }{\nu } \) ~500cm1 to ~1800cm1; \( \Delta \overset{\sim }{\nu } \) is the wavenumber shift defined in the Analysis methods section), with the remaining found in the higher energy CH/OH stretching vibrational modes covering (\( \Delta \overset{\sim }{\nu } \) ~2700cm1 to ~3300cm1) [36]. In confocal Raman imaging applications, it is necessary to use diffraction-limited TEM00 beams for optimum spatial resolution. The ability to monitor lipid order without the need for fluorescent labels can provide information on lipid packing properties. Trans.Commun. Proc Natl Acad Sci 102:1680716812 https://doi.org/10.1073/pnas.0508282102, Potma EO, Xie XS (2005) Direct visualization of lipid phase segregation in single lipid bilayers with coherent anti-Stokes Raman scattering microscopy. 5b iv. This type of scattering is often referred to as Rayleigh scattering. In ref. Detailed Syllabus: By varying the sizes of the gold nanoparticles, the absorption features can be tuned, which is flexible to meet the requirements of different photonic sensors.
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