6^th International Conference on Photonics July 30-31, 2017 Milan, Italy

Biography:

Alexey Akimov received his PhD degree from Moscow Institute for Physics and Technology in 2003. In 1997, he started working in the Laboratory for Active Media at the Lebedev Physical Institute of the Russian Academy of Sciences. His research was focused on the narrow optical resonances in hot and laser-cooled atoms. During 2006-2012, he was a Visiting Scholar in Misha Lukin’s group in Physics Department of Harvard University, where he worked on a number of research projects related to surface plasmons, quantum dots and NV centers in diamond. The main focus of this activity was light-spin interfaces. During 2010-2012, he was the Acting Director of the Russian Quantum Center (RQC). He then assumed a Principal Investigator position at the RQC and conducted research in the fields of cold atoms and solid state spin systems. In October 2015, he joined the Physics Department of Texas A&M University as an Assistant Professor

Abstract:

Nitrogen Vacancy (NV) color centers in diamond attract a lot of attention of quantum optics and quantum information community. Due to its long coherence time, possibility of optical readout of electronic spin state and possibility to store information in nearby nuclear spins using this center long quantum memory even at room temperature, long distance quantum entanglement and quantum registers has been demonstrated. Besides, quantum information application, this color center is proven to be good high-resolution sensor of magnetic field. Such a sensor is able to combine nanometer resolution with single spin sensitivity. Furthermore, due to its low chemical activity, diamond could be used as in vivo sensor. Recently, successful implementation of NV nanodiamonds as temperature sensors for measurement of thermal activation of transient receptor potential was demonstrated. NV color center in diamond could also be used for measurement of electric fields, tension, rotation or force. This sensor could offer high resolution or cutting edge sensitivity, if bulk sample is used. Also, due to its unique photo stability, this color centers find application in imaging, in particular bio- imaging as well as high resolution imaging such as STED or RESOLFT. In many of these applications, one of the important issues is efficiency, with which light emission of the color center is collected. In this contribution, we present our results on broadband collection of NV color centers emission using optical fiber and nanostructures.

Figure 1: Procedure of single nanocrystal pickup onto optical fiber

Figure 2: Positioning on nanocrystals on nanostructures

Recent Publications

1. Alexander Sushkov, Nicholas Chisholm, Igor Lovchinsky, Minako Kubo, Pik Kwan Lo, Steven Bennett, David Hunger, Alexey Akimov, Ronald L Walsworth, Hongkun Park, Mikhail D Lukin (2014) All-optical sensing of a single-molecule electron spin. Nano Lett., 14 (11): 6443–6448.

2. Dmitry Sovyk, Victor Ralchenko, Maxim Komlenok, Andrew Khomich, Vladimir Shershulin, Vadim Vorobyev, Igor Vlasov, Vitaly Konov, and Alexey Akimov (2015) Fabrication of diamond microstub photoemitters with strong photoluminescence of SiV color centers:bottom-up approach. Applied Physics A, 118(1).

3. M Y Shalaginov, V V Vorobyov,            J Liu,   M Ferrera, A V Akimov,        A Lagutchev, A N Smolyaninov,            V V Klimov, J Irudayaraj,      A V Kildishev, A Boltasseva and V M Shalaev (2014) Enhancing the nanodiamond nitrogen-vacancy single‑photon source with TiN/AlScN hyperbolic metamaterial superlattice Laser Photonics Rev., 1–8.

4. Vorobyov V V, Soshenko V V, Bolshedvorskii S V, Javadzade J, Lebedev N, Smolyaninov A N, Sorokin V N, Akimov A V (2016) Coupling of single NV center to adiabatically tapered optical single mode fiber. Eur. Phys. J. D 70(12): 269.

5. Vorobyov V V, Kazakov A Y, Soshenko V V, Korneev A A, Shalaginov M Y, Bolshedvorskii S V, Sorokin V N, Divochiy A V, Vakhtomin Y B, et al (2017) Superconducting detector for visible and near-infrared quantum emitters. Opt. Mater. Express 7(2), 513.

Biography:

Branislav Vlahovic is Director of the National Science Foundation Computational Center of Research Excellence, NASA University Research Center for Aerospace Device, and NSF Center Partnership for Research and Education in Materials at North Carolina Central University. In 2004, he was awarded by the Board of Governors of The University System of North Carolina Oliver Max Gardner statewide award for his research and contribution to science. He has published more than 300 papers in peer-reviewed journals. His research interest includes pulsed laser deposition of nanostructures, nonlinear optics, computer simulations of nanostructures, tunneling and charge transfer between nanostructures, detectors and devices based on quantum confinement, nanophotonics, semiconductor structures and photovoltaics.

Abstract:

Weakly coupled binary nano-sized systems demonstrate perspectives for nano-sensor applications. We study electron/hole localization and spectral distributions of localized/delocalized states in binary InAs/GaAs quantum complexes, including quantum wells (QWs) and quantum dots (QDs). The InAs/GaAs heterostructures are described using the effective potential model. It was shown, that the electron tunneling and spectral distributions of localized/delocalized states in binary system is extremely sensitive on shape symmetry violations. The parameter, which defines delocalized () or localized (0) states of an electron, depends on the energy difference  of the spectra in left and right QDs. The difference can be caused by a shape symmetry violation. The sensitivity of the parameter  to the small variations of  is estimated as          . This work focuses on the optical registration of the localized/delocalized states dynamics. Modeling of carrier transfer from a barrier in InAs/GaAs dot-well, tunnel-injection structure is performed. In Fig 1, shown is the electron wave functions of the localized and delocalized states calculated for two spectral levels: E=0.345 eV and E=0.444 eV, respectively. The energy of the delocalized state corresponds to that one for which the tunneling between dot and well occurs. The relation to the PL experiments for such complexes is provided. We model the second pick of the PL spectrum, which corresponds to the carriers tunneling in the dot-well complex, in the terms of the localized/delocalized states. Influence of the variations of geometrical parameters of QD and QW on the tunneling will be presented.

Recent Publications

1. Filikhin I, Karoui A and Vlahovic B (2016) Nanosensing Backed by the Uncertainty Principle. Journal of Nanotechnology. doi:10.1155/2016/3794109.

2. Filikhin I, Suslov V M and Vlahovic B (2006) Modeling of InAs/GaAs quantum ring capacitance spectroscopy in the nonparabolic approximation. Phys. Rev. B 73: 205332-4.

3. Filikhin I, Matinyan S G and Vlahovic B (2015) Electronic structure of quantum dots and rings. Reviews in Theoretical Science 3: 1-22.

4. Filikhin I, Karoui A and B. Vlahovic B (2016) Single electron tunneling in double and triple quantum wells. International Journal of Modern Physics B 30: 1642011-9.

5. Filikhin I, Matinyan S G and Vlahovic B (2015) Localized-delocalized states and tunneling in double quantum dots: effect of symmetry violation. Quantum Matter 4: 1-7.

Biography:

H C Ong received his BA and PhD in Materials Science and Engineering from Northwestern University, USA. He currently is an Associate Professor in Physics Department, at the Chinese University of Hong Kong. He has been working on amorphous carbon, diamond, and ZnO for years and his current interest is light-matter interaction focusing on plasmonics. He has published more than 100 technical papers on fluorescence and sensing. He has been serving as an Organizer of international conferences.

Abstract:

In analogy to electron waves, electromagnetic waves also carry spin and orbital angular momentum (AM) and this property has been fascinating the world of optical science and engineering for many years. With the rise of nanotechnology, photonic systems can now be fabricated at the length scale of nanometers, manifesting many intriguing phenomena including the spin-orbit interaction in an observable extent. The polarization, the spatial field distribution, and the propagation direction are no longer treated separately and controlling one with another has become feasible. Plasmonic arrays are one of the most popular nanophotonic systems owing to their simplicity and well-defined structures for yielding controllable optical properties. They have been used in extraordinary transmission, fluorescence, photovoltaics, nonlinear optics, sensing, etc. In addition, since surface plasmon polaritons (SPPs) carry transverse spin AM, they should modify the AM of the outgoing radiation under the conservation of angular momentum. Unfortunately, this transverse spin is not properly taken into consideration even though plasmonic research has been carried out for years. Here, I will talk about the AM of light from plasmonic crystals. We have observed substantial polarization conversion and spin-orbital coupling from square lattice circular nanohole arrays, which do not possess intrinsic chirality. We find the transverse spin AM possessed by SPPs play a deterministic role in governing the far-field radiation. The experimental results are supported by finite-difference time-domain simulations and temporal coupled mode theory. Based on the AM study, we propose the AM can be used as a new parameter in surface plasmon resonance (SPR) sensing. As the transverse spin AM of SPPs is strongly dependent on the complex propagation wave vector, which is sensitive to the change of the local refractive index, the change in the AM of light thus reflects the sensing environment. The performance of the spin-SPR will be discussed.

Recent Publications

1. Cao ZL, Yiu LY, Zhang ZQ, Chan CT, Ong HC (2017) Understanding the role of surface plasmon polaritons in two-dimensional achiral nanohole arrays for polarization conversion. Phys. Rev. B (in press).

2. Lin M, Cao ZL, Ong HC (2017) Determination of the excitation rate of quantum dots mediated by momentum resolved Bloch-like surface plasmon polaritons. Opt. Exp. 25: 6092-6103.

3. Cao ZL, Ong HC (2016) Momentum-dependent group velocity of surface plasmon polaritons in two-dimensional metallic nanohole array. Opt. Exp. 24: 12489-12500.

4. Liu C, Chan CF, Ong HC (2016) Direct deconvolution of electric and magnetic responses of single nanoparticles by Fourier space surface plasmon resonance microscopy. Opt. Comm. 378: 28-34.

5. Liu SD, Leong ESP, Li GC, Hou YD, Deng J, Teng JH, Ong HC, Lei DY (2016) Polarization-independent multiple fano resonances in plasmonic nonamers for multimode-matching enhanced multiband second-harmonic generation. ACS Nano 10: 1442-1452.

Biography:

Jian Fu has completed his PhD at Zhejiang University. He is working as Associate Professor at Zhejiang University. He has published more than 45 papers in reputed journals.

Abstract:

The history to simulate quantum states using classical optical fields is long. Many researchers utilized classical optical fields to simulate quantum states and quantum computations. However, it is quickly found that the simulation is not efficient and scalable. This is because the classical optical field only supports the product structure but does not support tensor product structure. We proposed a possible scheme to solve the problem that optical fields modulated with pseudorandom phase sequences simulate any state of multiple quantum particles. By using the scheme, we demonstrated optical analogies to many quantum states such as Bell states, GHZ states and W states, and some quantum algorithms such as Shor’s algorithm, Grove’s algorithm and quantum Fourier Transformation. Firstly, we introduced a theoretical framework, a phase ensemble based on pseudorandom phase sequence referring from the concept of quantum ensemble. Then, we represented various quantum states of n particles by using classical fields modulated with n pseudorandom phase sequences and we also demonstrated nonlocal properties of quantum entanglement in the phase ensemble theoretical framework. Finally, we demonstrated some optical implementations to realize some quantum algorithms. We believe these optical implementations are not difficult to implement. After careful analysis and numerical simulation, we can conclude that our scheme provides an efficient approach to quantum computation without exponential classical resources.

Biography:

Jae Eun Jang received his PhD degree in Electrical Engineering from the University of Cambridge, UK in 2006. From 2007 to 2011, he was Principal Senior Researcher at Samsung Advanced Institute of Technology, Yongin, Korea. Since 2011, he has been a Professor in Information and Communication Engineering at Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Korea. He first demonstrated the mechanical nanoswitch and mechanical DRAM concept using vertically aligned carbon nanotubes in 2004 and 2008, respectively. More recently he was involved in nanodevices for ultra-fast driving, biomimic concepts and brain-machine interface. He has authored or co-authored over 200 journal and conference papers, and is an inventor of 100 granted patents.

Abstract:

The different working principles of nano hole array structure from general color can make promising features as a bio-detector because the structural color filter (SCF) changes easily, the filtering colors by covering of different biomaterials. Because the nano-hole arrays were designed to present a filtered peak wavelength in the visible light region, filtered color changes caused by different biomolecules were easily observed with a microscope or even by the naked eye. Generally, many biomolecules are transparent or colorless in the visible range, so that it is hard to distinguish among them using visible observation. However, their molecular structure and composition induce some differences in the dielectric constant or refractive index, causing a filtered color shift in the nano-hole array structure. Here, the contribution of geometric parameters such as the hole diameter and the spacing between nano-holes for bio-detection was evaluated to maximize the change in color among different biomolecules. A larger hole size and space between the holes enabled the biomolecules to be easily distinguished. Even if the change in color was not distinctive enough by eye in some cases, it was possible to distinguish the change by simple analysis of the ‘Hue’ values or by the ‘Lab’ color coordinates obtained from the photo images. Therefore, this skill can have high probability of realization for real-time detection of cells without the use of bio-markers

Figure 1: Concept images of bio-detection based on a SCF. (a) Image of a general red CF based on red pigments. Except for the red color component, the other components in white light are absorbed by the red pigments (b) Schematic image of a SCF. Nano-hole arrays induce a color filtering effect (c) Even though three different proteins are dropped on a general CF; there are no color changes due to its transparent optical property. (d) Different transparent biomolecules change the dielectric property of the surface of filters when they are dropped on the SCF. This causes spectral shifts in the SCF

Recent Publications

1. M Ryu, et. al. (2017) Enhancement of interface characteristics of neural probe based on graphene, ZnO nanowires, and conducting polymer PEDOT. ACS Applied Materials & Interfaces. 9 (12): 10577–10586.

2. M Sim et. al. (2016) Structural solution to enhance the sensitivity of a self-powered pressure sensor for an artificial tactile system. IEEE Transactions on Nanobioscience. 15: 804-811.
3. J H Shin et. al. (2016) Ultrafast metal-insulator-multi-wall carbon nanotube tunneling diode employing asymmetrical structure effect. Carbon 102: 172-180.
4. S Kim et. al. (2016) Geometric effects of nano-hole arrays for label free bio-detection. RSC Advances 6: 8935-8940.
5.  B O Jun et. al. (2015) Wireless thin film transistor based on micro magnetic induction coupling antenna. Scientific Reports 5:18621.

Biography:

Johan Bauwelinck received his PhD degree in Applied Sciences, Electronics from Ghent University, Belgium in 2005. Since Oct 2009, he is a Professor in the IDLab research group of the Department of Information Technology (INTEC) at the same university where he is leading the Design lab since 2014. He became a Guest Professor at iMinds in the same year, now IMEC since 2016. His research focuses on high-speed, high-frequency (opto) electronic circuits and systems, and their applications on chip and board level, including transmitter and receiver analog front-ends for wireless, wired and fiber-optic communication or instrumentation systems. He is an active person involved in the EU-funded projects GIANT, POWERNET, PIEMAN, EuroFOS, C3-PO, Mirage, Phoxtrot, Spirit, Flex5Gware, Teraboard, Streams, WIPE and Optima conducting research on advanced electronic integrated circuits for next generation transport, metro, access, datacenter and radio-over-fiber networks. He has promoted 18 PhDs and co-authored more than 200 publications and 10 patents in the field of High-Speed Electronics and Fiber-Optic Communications.

Abstract:

High-speed electronic integrated circuits are essential to the development of new fiber-optic communication systems. Exponentially increasing data consumption is expanding the applications of optical communication and driving the development of faster and more efficient transceivers. Fiber-optic communication networks operate on very different scales from very short interconnects in datacenters to very long links between cities, countries or continents. Optical fibers are also increasingly used for access networks (e.g. fiber-to-the-home) and for mobile fronthauling and backhauling. Advances in opto-electronic devices, high-volume manufacturing and packaging technologies are driving numerous developments in these diverse applications.  Because of the increasing speeds, close integration and co- design of photonic and electronic devices have become a necessity to realize high-performance sub-systems, while such co-design brings new opportunities as well on the sub-system architecture level to break traditional performance-cost trade-offs. There is no single best solution among electrical and optical technologies due to the different technological constraints in terms of distance, footprint, power consumption, cost, etc. Research is approaching this challenge from different angles, with technological improvements on photonic and electronic devices and/or by applying more complex modulation and signal processing. While each application operates on a very different scale (fiber length, number of users) with very different requirements (capacity, signal format, cost, power, etc.), they share one thing, their need for application-specific high-speed electronic transceiver circuits such as driver amplifiers, transimpedance amplifiers, equalizers and clock-and- data recovery circuits. This presentation will illustrate a few recent and ongoing developments from various H2020 projects.

Figure 1: 56Gb/s PAM-4 single-mode VCSEL driver array

Figure 2: 64Gb/s PAM-4 transimpedance amplifier array

Recent Publications

1.  M Vanhoecke et. al. (2017) Segmented optical transmitter comprising a CMOS driver array and an InP IQMZM for advanced modulation formats. J. Lightw. Technol. 35(4):862- 867.
2.   J Verbist et. al. (2016) A 40-GBd QPSK/16-QAM integrated silicon coherent receiver. IEEE Photon. Technol. Lett. 28(19):2070-2073.
3.  B. Moeneclaey et. al. (2017) 40-Gb/s TDM-PON downstream link with Low-Cost EML transmitter and APD-Based electrical duobinary receiver. J. Lightw. Technol. 35(4):1083-1089.

Biography:

Nikola Z Petrović received his BSc in Mathematics and in Physics at MIT (Massachusetts Institute of Technology) in 2003 and his PhD in Physics at University of Belgrade in 2013. He was employed as a Teaching Associate and Lab Coordinator at Texas A&M University at Qatar from 2005 to 2012. He is currently an Assistant Research Professor at Institute of Physics, Belgrade. His primary field of expertise is Mathematical Physics applied to nonlinear optics, in particular finding novel exact solutions to the nonlinear Schrodinger equation, the Gross-Pitaevskii equation and other related equations.

Abstract:

The advent of meta-materials has made materials with a negative refractive index possible. This has opened up a possibility of finding stable solutions to various nonlinear equations that naturally occur in the field of nonlinear optics through the use of dispersion management. Finding such stable solutions is invaluable for the field of photonics and has many potential practical applications. In our work we use the F-expansion method applied to the Jacobi elliptic function, along with the principle of harmonic balance to find novel solutions to various forms of the Nonlinear Schrödinger equation (NLSE). This approach allowed us to assume a quadratic form for the phase with respect to the longitudinal variable and thus find solutions both with and without chirp. Earlier work done on the NLSE with Kerr nonlinearity, with both normal and anomalous dispersion, was generalized to nonlinearities of arbitrary polynomial nonlinearity. Stable solutions were also obtained for the Gross-Pitaevskii equation. These solutions were determined to be modulationally stable, either unconditionally or with dispersion management, depending on the signs of various parameters in the original equation. The method was subsequently generalized for functions satisfying an arbitrary elliptic differential equation, including Weierstrass elliptic functions. A relatively new line of research has been finding solutions to the NLSE in a parity-time (PT) conserving potential, i.e. one for which the real part is an even function and the complex part is an odd function. We found a rich new class of exact solutions where the potential resembles the Scarf II potential.

Figure 1: Solution to the NLSE with Kerr nonlinearity using the Weierstrass elliptic function described in: (a) without chirp (b) with chirp

1. S L Xu, Y Zhao, N Z Petrović and M R Belić (2016) Spatiotemporal soliton supported by parity-time symmetric potential with competing nonlinearities. Europhysics Letters. 115: 14006.

2. N Z Petrović and M Bohra (2016) General Jacobi elliptic function expansion method applied to the generalized (3+1)-dimensional nonlinear Schrödinger equation. Optical and Quantum Electronics. 48: 1-8.
3. S L Xu, N Petrović, M R Belić and W Deng (2016) Exact solutions for the quintic nonlinear Schrödinger equation with time and space. Nonlinear Dynamics 84: 251.
4. N Z Petrović, N B Aleksić and M R Belić (2015) Modulational stability analysis of exact multidimensional solutions to the generalized nonlinear Schrödinger equation and the Gross-Pitaevskii equation using a variational approach. Optics Express 23: 10616.
4. W P Zhong, L Chen, M R Belić and N Petrović (2014) Controllable parabolic-cylinder optical rogue wave. Physical Review E. 90: 043201.

Biography:

V A Belyakov graduated from Moscow Engineering Institute in 1961 and was a Postgraduate student of I V Kurchatov Atomic Energy Institute during 1961–64. He received Doctor of Science degree in 1974. He was the Head of Laboratory in All-Union Physics-Technical and Radio–Technical Institute from 1964 to 1982 and Surface and Vacuum Research Centre, Moscow during 1982–1995. Since 1995, he is a Senior Researcher in L D Landau Institute for Theoretical Physics. Since 1982, he is a Part-time Professor in Moscow Institute for Physics and Technology; and short term Visiting Professor of some universities: Leuven (Belgium), Tokyo (Japan), Paris Sud (France), Glasgow Thrathclyde (Scotland), etc. He is the Author of the following monographs: Optics of Cholesteric Liquid Crystals, 1982, Optics of Chiral Liquid Crystals, 1989; Diffraction Optics of Complex Structured Periodic Media , 1988, 1992; Optics of Photonic Crystals, Publishing House of Moscow Institute of Physics and Technology, 2013 (Textbook, in Russian). He is honored with the Grants of Russian Foundation for Basic Research (RFBR), Soros Grants, and INTAS Grants. He is a Member of Russian Academy of Natural Sciences, Member of Russian Academy of Metrology, Member of International Liquid Crystal Society and Liquid Crystal Society of CIS (member Governing body 1982).

Abstract:

Recently great attention was paid to the localized optical modes in photonic crystals, in particular, in photonic liquid crystals due to their efficient application in the linear and nonlinear optics. Here a brief survey of the publications and original theoretical results on the localized optical modes in photonic liquid crystals in connection with explanation of the corresponding experimental observations are presented. Theoretical studies were performed for the certainty, as the example of chiral liquid crystals (CLCs). The chosen model (absence of dielectric interfaces in the studied structures) allows one to get rid off the polarization by mixing at the surface of the CLC layer and the defect structure (DMS) to reduce the corresponding equations to equations for the light of diffraction in the CLC polarization, to obtain an analytic description of localized edge (EM) and defect (DM) modes. The dispersion equations determining connection of the EM and DM frequencies with the CLC layer parameters and other parameters of the DMS are obtained. Analytic expressions for the transmission and reflection coefficients of the DMS are presented and analyzed. Specific cases were considered, as DMS with an active (i.e. transforming the light intensity or polarization) defect layer, CLC layer of local anisotropic absorption and conic-helical director structures. It is shown that the active layer (excluding an amplifying one) reduces the DM life-time (and increase the lasing threshold) in comparison with the case of DM at an isotropic defect layer. The case of CLC layers with an anisotropic local absorption is also analyzed and, in particular, shown that due to the Borrmann effect the EM life-times for the EM frequncies at the opposite stop-bands edges may be signifinately different and so in the experiment optimization of it should be taken into account. The experimentally observed enhancement of some optical effects in photonic liquid crystals at the EM and DM frequencies (lowering of the lasing threshold, abnormally strong absorption, etc.) are in good agreement with the presented theory. Options of experimental observations of the new theoretically revealed phenomena are discussed. It is emphasized that the presented localized modes in CLC results are of a general nature and are qualitatively applicable for the localized modes in other structures.
 

REFERENCES

1. Liquid Crystals Microlasers, Eds. L.M.Blinov, R.Bartolino, Transword Research Network, 2010.
2. V. I. Kopp, Z.-Q. Zhang, and A. Z. Genack, Prog. Quantum Electron. 27, 369 (2003).
3. V.A.Belyakov, S.V,Semenov, JETP , 118, 798 (2014).
4. V. A. Belyakov, Mol. Cryst. Liquid Cryst. 612, 81 (2015).

Biography:

Abstract:

Statement of the Problem: Infrared Nerve Stimulation (INS) is becoming popular because of its potential to provide targeted stimulation. Recently it was claimed that myelin sheath can guide light (200 nm – 1300 nm), however propagation characteristics were not reported for wavelengths l > 1500 nm, common in INS. We present them here for l up to 2000 nm for both myelinated and unmyelinated nerve fibers.

Methodology & Theoretical Orientation: Modal analysis was performed on the cross-section of the nerve fiber by solving Maxwell’s equations. The effective index (n_eff) of the first three modes was determined and the single mode operating wavelength range was determined for both myelinated and unmyelinated nerve fibers, using a 4-um diameter axon. The overall diameter of the myelinated fiber was 6.66 um. The refractive indices of the fiber cytoplasm, the myelin sheath, and the outside medium were set as 1.34, 1.44 and 1.38 respectively.

Findings: The optical power propagating through unmyelinated fiber is confined by the index of the fiber’s cytoplasm (1.38) being higher than its surrounding (1.34). The effective indices of the first three propagating modes were determined and plotted in for 200nm ≤ l ≤ 2000nm. It was found that the unmyelinated fiber is single-mode for l > 1700 nm. In the myelinated fiber, optical power is confined within the myelin sheath (1.44). The effective indices of the myelinated fiber indicate that it supports more modes than the unmyelinated one and the myelin sheath operates in a single-mode condition for wavelengths longer than 1980 nm. This article determines light propagation characteristics of nerve fibers for a range of wavelengths, making it very useful for future INS designs. This study can also be useful in the field of interfacing brain using light.

Biography:

Andrei Kotkov has his expertise in Laser Physics. He received his MS degree from the Moscow Physical-Technical Institute (State University) in 1982 and his PhD degree from the P N Lebedev Physical Institute (LPI) in 2001. He is Associate Professor focusing on Laser Physics at the LPI.

Abstract:

In mid-IR range molecular gas lasers can simultaneously emit dozens or hundreds of spectral lines. The spectral lines of gas lasers are quite narrow, but they are located relatively rare. A carbon dioxide CO₂ laser can emit dozens spectral lines in the wavelength range from 9 to 11 microns. A carbon monoxide (CO) laser operating on fundamental and first-overtone vibrational transitions has an extremely broad emission spectrum consisting of more than a thousand spectral lines in the wavelength range from 2.5 to 8.2 microns. However, all laser lines do not cover entirely specified spectral ranges. To enrich and expand the laser spectra, it is worth to apply the frequency conversion in nonlinear crystals. To enrich CO laser spectrum, frequency conversion in ZnGeP₂ (ZGP) crystal was applied. Hundreds of new spectral lines were obtained due to sum-frequency generation (SFG) as the first stage and difference-frequency generation (DFG) as the second stage of two-stage frequency conversion. The ZGP crystal is a very efficient nonlinear crystal but it is transparent only up to 12 mm. Then for mixing CO and CO₂ laser light we used AgGaSe₂ (AGSe), GaSe, and PbIn₆Te₁₀ (PIT) crystals. Application of AGSe crystal as a frequency converter of CO and CO₂ laser radiation resulted in 16.6 mm DFG. The conversion efficiency of DFG under mixing CO and CO₂ laser light in AGSe appeared to be 20 times that of GaSe, which probably is related to high birefringence of the latter resulting in high spatial walk-off effect. We believe that the developed laser system can be a prototype for the development of IR laser systems and would be useful in a variety of researches and applications.

Biography:

Xiaoyi Bao is the Canada Research Chair Professor (Tier I) in Fiber Optics and Photonics in Center for Research in Photonics, Physics Department, University of Ottawa, Canada. Her research interests range from study of nonlinear effects in fibers to make fiber device, lasers and sensors. She has co-authored over 260 refereed journals and 210 conference proceeding papers, 9 book chapters, and 6 IPs/patents from her group have been transferred to industries. She is a Fellow of Royal Society of Canada (RSC), OSA and SPIE.

Abstract:

Random fiber lasers (RFLs) with unique frequency and phase properties have attracted much attention. Comparing with the fixed cavity length lasers, RFLs rely on a scattering medium, where multiple scattering lights due to spatial inhomogeneity is captured by the fiber waveguide and amplified through different gain media leading to one-dimensional lasers with good directionality. The frequency, phase and intensity noises of RFLs have strong dependency on the free mean length (Δl) of the scattering medium. Through our experiments, we observed three different cases relative to the fiber length L, wavelength λ: (1) when Δl>λ, the frequency jitter is the highest, although relative intensity noises (RIN) and the linewidth (<5 kHz) is comparable to the phase locked laser. The random feedback can be realized by writing random grating at sub-mm spacing; (2) when Δl~λ; the linewidth can be <100 Hz with long fiber (L≥5 km), RIN is increased due to large number of the random modes, while the frequency noise is reduced; (3) Δl<λ, the RIN and frequency noise are the lowest, and the linewidth is ~10 Hz, which can be used as reference for laser linewidth characterization. The gains of the RFLs are: Er-doped fiber (EDF), Brillouin and Raman amplification and SOA. The high RIN in RFLs can be used for the random number generators (RNGs) at high speed (MHz to GHz). The distributed feedback allows multiple wavelengths operation in the laser without phase matching condition of 2 πm (m is integer) constraint in the wavelength selection, and hence it can be used as tunable microwave generator. For the Brillouin scattering, the random mode injection acts as the mode selection element, which allows single mode operation and high order Brillouin frequencies with the high contrast and narrow linewidth (1 kHz). The random gratings can be used as random feedback and sensing head to achieve high sensitivity thanks to the lasing gain for large dynamic range. The temperature, strain and refractive index and ultrasound sensing has been demonstrated.

Biography:

Etsuji Ohmura is a Professor of the Osaka University, Japan. His main field of research is intelligent laser processing systems, especially theoretical analysis and computer simulation to gain deeper understanding of the complicated physical phenomena in laser material processing, influence of laser optics, and nonlinear optical phenomena.

Abstract:

The purpose of this study is elucidation of the process mechanism in the microprocessing of glass by an ultrashort pulse laser. In order to achieve this purpose, the plasma behavior due to femtosecond laser irradiation was observed by a high-speed camera, and laser absorption by plasma was investigated. In the experiments, pulse duration was 290 fs@1028 nm, repetition frequency was 20 kHz, traveling speed was 3 mm/s, and pulse energy was 3.8 µJ, 4.5 µJ and 5.4 µJ. The experimental results showed that there are three patterns of the plasma behavior depending on the pulse energy. Plasma is generated and disappears periodically when the pulse energy is 3.8 µJ. For pulse energy 4.5 µJ, plasma exists always and the lower part of plasma vibrates little by little. When the pulse energy is 5.4 µJ, the plasma is divided, rises to a constant depth, and then the top lump of plasma disappears. These processes are repeated periodically during several tens of pulses. The threshold fluence of laser absorption by plasma was estimated comparing rising of plasma with change of the laser fluence on the optical axis. Then the relationship between rising velocity of plasma and fluence on the optical axis was investigated. Absorption energy increases as the fluence on the optical axis becomes large and the rising velocity of plasma increases. From these series of observation of plasma behavior and investigation of plasma absorption, a simple laser absorption model by the plasma was proposed. This absorption model was applied to the plasma behavior observed, and the energy absorbed in each of divided plasma was estimated. The estimated absorptance was compared with the absorptance measured in the internal processing experiment. For different pulse energy, the estimated absorptances agreed comparatively well with the experimental values, and the validity of the proposed absorption model was confirmed.

Figure 1: Schematic chart of one period of plasma behavior obtained by high-speed video analysis (upper), and estimated energy which is absorbed by each plasma (lower). E(z) is laser energy at the depth z and E_a(x) is energy absorbed by each plasma at the traveling distance x.

Biography:

Lap Van Dao is a Professor and Leader of Ultrafast Laser Science Group at Centre for Quantum and Optical Science, Swinburne University of Technology. His research activities are the development and application of ultrafast and high power laser for imaging and ultrafast time-resolved laser spectroscopy in semiconductor quantum structures and biological systems

Abstract:

The high-order harmonic generation process provides methods to produce short pulses of coherent radiation in the extreme ultraviolet and soft X-ray region. Soft x-ray light sources will provide new nonlinear spectroscopic tools that can be used to reveal core-level electronic resonances and their interactions, and permit the creation of no stationary electronic wave-packets and monitoring their dynamics.  We investigate the creations of coherent extreme ultraviolet sources with phase-matched generation, wave-mixing and amplification process where two multiple-cycle pulses with incommensurate frequencies (at 1400 nm and 800 nm) are used. A 800 nm, 10 mJ, 30 fs, 1 kHz repetition rate laser beam is split into two beams, with pulse energies of 6 mJ and 4 mJ. The 6 mJ beam is used to pump a three-stage optical parametric amplifier (OPA) system to generate an infrared (IR) pulse at 1400 nm with energy ~2 mJ and duration 40 fs. The 4 mJ beam (800 nm) is used to mix with the 1400 nm field. The high intensity pulse (1400 nm or 800 nm) is used for phase-matched generation of XUV pulses and the other pulse (800 nm or 1400 nm respectively), which is used to control the HHG output and for generation of mixing fields or amplification, is aligned collinear or at a very small angle (<10⁰) to the direction of the high intensity beam by a dichroic mirror. The time delay between the two pulses is controlled by a motorized delay stage with 0.1 fs resolution. The spectrum and intensity of the XUV radiation generated by the first pulse varies markedly with the influence of the second pulse. The coherence of free electron wave-packet can be obtained by time evolution of mixing fields.

Biography:

Jianlang Li is a Professor at Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences, and his research is in the field of Laser Sciences. He has the interest in the development of high-power vector and vortex laser. As a pioneer, he developed the first radially polarized fiber laser, and thereafter extended it to the high-power and pulsed operation. Until now, he has been playing a leading role in the field of Vector Fiber Laser. He also revealed the efficient and high-power excitation of both radial and azimuthal polarizations in solid-state laser by combining the end-pumped microchip laser geometry with the photonic crystal grating mirror. In recent years, he developed highly efficient vector and vortex solid-state laser. Most recently, He invented the maglev and optically-driven rotary disk laser.

Abstract:

Statement of the Problem: The Laguerre- Gaussian (LG) beam is known as doughnut-shaped cross section and spiral phase wavefront. The exponential term exp(−imφ) in its amplitude expression grants an orbit angular momentum to the beam photon, and such the vortex beam on LG modes becomes valuable for numerous applications such as optical manipulation, super-resolution microscopy, quantum communication, gravitational-wave detection, etc. Presently Ti-doped sapphire laser is one of the most common types of solid-state laser, which can generate femtosecond pulses with high peak power up to terawatt or petawatt level and be used in the fields of plasma physics, ion acceleration, etc. A new and interesting line for this laser is to generate vortex laser emission, which would be undoubtedly much more valuable for various kinds of applications in fields like the strong-field laser physics, etc. Nevertheless, the concern on vortex Ti: sapphire laser is much inferior to those in Nd: YAG and Yb: YAG lasers.

Methodology & Theoretical Orientation: We fabricated several spot defect spatial filters (SDSFs) with different sizes (i.e. diameters), then inserted them into an ever-built Ti: sapphire laser. The SDSF was antireflection coated glass plate containing a laser-treated opaque region of a circular shape. By inserting the SDSF into the laser cavity, the effect of the sizes of SDSF on the transverse laser mode and laser power was analyzed.

Findings: The Ti: sapphire laser emitted vortex LG₀₁ mode at proper size of SDSF and pump power. When applying a spot defect with 140-mm diameter, the power of vortex LG₀₁ mode reached 135 mW and the slope efficiency of the laser was 17.7%.

Conclusion & Significance: In summary, this study reported the first vortex LG₀₁-mode Ti: sapphire laser. By using SDSF as intracavity mode selector, we demonstrated a vortex Ti: sapphire laser that emitted 800-nm and LG₀₁-mode vortex light. The next investigation will focus on the mode-locked operation of the vortex Ti: sapphire laser by applying intracavity spot defect for spatial filtering.

Biography:

Jianqiang Zhu is working as a Senior Professor of Shanghai Institute of Optics and Fine Mechanics (SIOM), Chinese Academy of Sciences (CAS). He has been devoted to the long-term study in the fields of high-power laser system. This includes laser device design, optical engineering, optical beam propagation and control etc. As a Chief Scientist, he was responsible for several major projects such as Shenguang-II (SG-II) laser facility, SG-II multifunction high-energy laser systems, upgrading SG-II laser device, 3ps petawatt and 30fs multi-petawatt laser facilities, which has contributed immensely to the establishment and development of high-power laser system for ICF study in China. “SG-II multifunction high-energy laser systems” has won the National Science and Technology Progress Award in 2013. He has published 320 papers on international journals and holds 50 patents where including 4 patents in USA and Japan. And more than 50 Doctoral theses were completed under his supervision.

Abstract:

National Laboratory on High Power Laser and Physics (CAS) has long been committed to the researches on high-power laser system and high-energy density physics. The SG-II facility in the lab is of great importance in advancing national strategic high-tech innovation, basic science and innovation at the frontiers of interdisciplinary science. High power laser device is an ultra-precision optical system running under the condition of high flux, which contains thousands of large-aperture optical components. Optical component performance will directly or indirectly affect the overall performance of the laser system. To ensure stable operation of the system, a set of optical component technical specifications are established, including laser characteristics, wavefront characteristics, loss characteristics and characteristics of the damage. In this presentation, we analyses the character for high power laser optics components, and give the technique to manufacture. We provide a reference for improving the surface defect standard and optimizing the design of high-power laser system.