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https://www.readbyqxmd.com/read/29791400/temperature-independent-hygrometry-using-micromachined-photonic-crystal-fiber
#1
Pan Zhang, Hangzhou Yang, Kok-Sing Lim, Harith Ahmad, Qiangzhou Rong, Qin Tian, Xiangzi Ding
An in-fiber Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated for relative humidity (RH) and temperature measurements. The MZI is formed by a grapefruit-shaped photonic crystal fiber (G-PCF) cascaded with a short section of multimode fiber that serves as a mode coupler. To enhance sensitivity to humidity, femtosecond laser micromachining was performed to remove a portion of cladding of the G-PCF to expose its core to the ambient medium. The output interference spectrum is fast Fourier transformed to produce a spatial frequency spectrum that describes the intensity composition of the cladding modes in the MZI...
May 20, 2018: Applied Optics
https://www.readbyqxmd.com/read/29791336/optimization-of-optical-properties-of-photonic-crystal-fibers-infiltrated-with-carbon-tetrachloride-for-supercontinuum-generation-with-subnanojoule-femtosecond-pulses
#2
Quang Ho Dinh, Jacek Pniewski, Hieu Le Van, Aleksandr Ramaniuk, Van Cao Long, Krzysztof Borzycki, Khoa Dinh Xuan, Mariusz Klimczak, Ryszard Buczyński
A photonic crystal fiber (PCF) made of fused silica glass, infiltrated with carbon tetrachloride (CCl4 ), is proposed as a new source of supercontinuum (SC) light. Guiding properties in terms of effective refractive index, attenuation, and dispersion of the fundamental mode are studied numerically. As a result, two optimized structures are selected and verified against SC generation in detail. The dispersion characteristic of the first structure has the zero-dispersion wavelength at 1.252 μm, while the dispersion characteristic of the second structure is all-normal and equals -4...
May 10, 2018: Applied Optics
https://www.readbyqxmd.com/read/29791328/silicon-microsphere-whispering-gallery-modes-excited-by-femtosecond-laser-inscribed-glass-waveguides
#3
Hüseyin Ozan Çirkinoğlu, Mustafa Mert Bayer, Ulaş Sabahattin Gökay, Ali Serpengüzel, Belén Sotillo, Vibhav Bharadwaj, Roberta Ramponi, Shane Michael Eaton
We report on the coupling of whispering gallery modes in a 500-μm-radius silicon microsphere to a femtosecond-laser-inscribed glass optical waveguide. The shallow glass waveguide with a large mode field diameter in the near-infrared is written at a depth of 25 μm below the glass surface, resulting in a high excitation impact parameter of 525 μm for the microsphere. The excited whispering gallery modes of the silicon microsphere have quality factors of approximately 105 in the 90° elastic scattering and 0° transmission...
May 10, 2018: Applied Optics
https://www.readbyqxmd.com/read/29789157/comparison-of-fibrotic-response-in-the-human-lens-capsular-bag-after-femtosecond-laser-assisted-cataract-surgery-and-conventional-phacoemulsification
#4
Christian M Wertheimer, Mehdi Shajari, Thomas Kohnen, Annabel von Studnitz, Stefan Kassumeh, Socrates Dimitriou, Ralf Lieberz, Imad Hakim, Siegfried G Priglinger, Wolfgang J Mayer
PURPOSE: To compare the effect of different laser pulse energy settings in femtosecond laser-assisted cataract surgery with that of standard phacoemulsification and no energy at all used on posterior capsule opacification (PCO) in vitro. SETTING: Cell and Molecular Biology Research Laboratory, Department of Ophthalmology, Ludwig-Maximilians-University Munich, Real Eyes, Ophthalmology Center, Munich, and Institute for Clinical Pathology, Goethe University Frankfurt, Frankfurt, Germany...
May 19, 2018: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/29785998/acute-full-thickness-macular-hole-after-uneventful-femtosecond-assisted-cataract-surgery-and-its-spontaneous-closure
#5
Deepak Bhojwani, Shail Vasavada, Aditya Sudhalkar, Viraj Vasavada, Abhay R Vasavada
No abstract text is available yet for this article.
June 2018: Indian Journal of Ophthalmology
https://www.readbyqxmd.com/read/29785082/control-matched-comparison-of-refractive-and-visual-outcomes-between-small-incision-lenticule-extraction-and-femtosecond-laser-assisted-lasik
#6
Takahiro Kataoka, Tomoya Nishida, Azusa Murata, Mayuka Ito, Naoki Isogai, Rie Horai, Takashi Kojima, Yoko Yoshida, Tomoaki Nakamura
Purpose: This retrospective case-matched study aimed to compare visual and refractive outcomes between small incision lenticule extraction (SMILE) and LASIK. Patients and methods: Patients who underwent SMILE (34 eyes of 23 patients) or LASIK (34 eyes of 24 patients) were enrolled and matched according to preoperative manifest refractive spherical equivalents. The mean preoperative manifest refractive spherical equivalent was -4.69±0.6 and -4.67±0.64 D in the SMILE and LASIK groups, respectively...
2018: Clinical Ophthalmology
https://www.readbyqxmd.com/read/29784166/opinions-on-corrective-refractive-surgery
#7
Helen Chung, Emi Sanders, Jamie Bhamra
OBJECTIVE: To investigate public perception that ophthalmologists are hesitant to undergo refractive surgery by determining the personal opinions of ophthalmologists on different surgical options. DESIGN: Prospective cross-sectional survey. PARTICIPANTS: Members of the American Society of Cataract and Refractive Surgery electronic mailing list. METHODS: An online survey administered from July to August 2014. RESULTS: There were 396 (5...
June 2018: Canadian Journal of Ophthalmology. Journal Canadien D'ophtalmologie
https://www.readbyqxmd.com/read/29781929/femtosecond-laser-assisted-graft-preparation-for-descemet-membrane-endothelial-keratoplasty
#8
Hamish D McKee, Vishal Jhanji
PURPOSE: To describe a technique of using a femtosecond laser to assist with graft preparation for Descemet membrane endothelial keratoplasty (DMEK). METHODS: A femtosecond laser was used to assist in graft preparation for 3 DMEK procedures. The donor cornea is mounted on a proprietary artificial anterior chamber. A partial thickness deep circular cut is made with the femtosecond laser through the endothelium, Descemet membrane, and posterior stroma. Graft preparation is then completed without the use of a corneal trephine...
May 16, 2018: Cornea
https://www.readbyqxmd.com/read/29779377/how-does-the-surface-of-al-itq-hb-2d-mof-condition-the-intermolecular-interactions-of-an-adsorbed-organic-molecule
#9
Elena Caballero-Mancebo, Jose Maria Moreno, Avelino Corma, Urbano Díaz, Boiko Cohen, Abderrazzak Douhal
In this work, we unravel how the 2D-Al-ITQ-HB metal organic framework changes the interactions of Nile Red (NR) adsorbed on its surface. Time-resolved emission experiments indicate the occurrence of energy transfer between adsorbed NR molecules, in abnormally long time constant of 2-2.5 ns, getting shorter (~0.25 ns) when the concentration of the surface adsorbed NR increases. We identify the emission from local excited state of aggregates, and charge-transfer and energy transfer between adsorbed molecules...
May 21, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29776767/-visual-outcomes-5-years-after-small-incision-lenticule-extraction-smile-surgery-on-spherocylindrical-myopia-eyes-from-616-eyes
#10
J Burazovitch, H Ferguene, D Naguszewski
OBJECTIVE: Determine if the visual criteria of the technique of surgery refractive by Femtosecond Laser-assisted duckweed Extraction - Small Lenticule Extraction (FLEx-Smile® ), realized in the laser femtosecond VisuMax® (Carl Zeiss Meditec, Jena, Germany), are stable, secure, effective and predictable in the long term, to the nearsighted and astigmatic. MODEL OF THE STUDY: Retrospective study, monocentric with data collected between March 2012 and March 2017...
May 15, 2018: Journal Français D'ophtalmologie
https://www.readbyqxmd.com/read/29776312/on-the-prospects-of-using-high-intensity-thz-pulses-to-induce-ultrafast-temperature-jumps-in-liquid-water
#11
Pankaj Kr Mishra, Vincent Bettaque, Oriol Vendrell, Robin Santra, Ralph Welsch
Ultrashort, high-intensity THz pulses, e.g., created at free-electron laser facilities, allow for direct investigation as well as the driving of intermolecular modes in liquids like water and thus will deepen our understanding of the hydrogen bonding network. In this work, the temperature-jump (T-jump) of water induced by THz radiation is simulated for ten different THz frequencies in the range from 3 to 30 THz and five different pulse intensities in the range from 1 × 1011 to 5 × 1012 W/cm2 employing both ab initio molecular dynamics (AIMD) and force field molecular dynamics (FFMD) approaches...
May 18, 2018: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29775354/mapping-the-complete-reaction-path-of-a-complex-photochemical-reaction
#12
Adam D Smith, Emily M Warne, Darren Bellshaw, Daniel A Horke, Maria Tudorovskya, Emma Springate, Alfred J H Jones, Cephise Cacho, Richard T Chapman, Adam Kirrander, Russell S Minns
We probe the dynamics of dissociating CS_{2} molecules across the entire reaction pathway upon excitation. Photoelectron spectroscopy measurements using laboratory-generated femtosecond extreme ultraviolet pulses monitor the competing dissociation, internal conversion, and intersystem crossing dynamics. Dissociation occurs either in the initially excited singlet manifold or, via intersystem crossing, in the triplet manifold. Both product channels are monitored and show that, despite being more rapid, the singlet dissociation is the minor product and that triplet state products dominate the final yield...
May 4, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29773798/probing-femtosecond-lattice-displacement-upon-photo-carrier-generation-in-lead-halide-perovskite
#13
Giovanni Batignani, Giuseppe Fumero, Ajay Ram Srimath Kandada, Giulio Cerullo, Marina Gandini, Carino Ferrante, Annamaria Petrozza, Tullio Scopigno
Electronic properties and lattice vibrations are expected to be strongly correlated in metal-halide perovskites, due to the soft fluctuating nature of their crystal lattice. Thus, unveiling electron-phonon coupling dynamics upon ultrafast photoexcitation is necessary for understanding the optoelectronic behavior of the semiconductor. Here, we use impulsive vibrational spectroscopy to reveal vibrational modes of methylammonium lead-bromide perovskite under electronically resonant and non-resonant conditions...
May 17, 2018: Nature Communications
https://www.readbyqxmd.com/read/29773458/outcomes-of-conventional-phacoemulsification-versus-femtosecond-laser-assisted-cataract-surgery-in-eyes-with-fuchs-endothelial-corneal-dystrophy
#14
Dagny C Zhu, Parth Shah, William J Feuer, Wei Shi, Ellen H Koo
PURPOSE: To compare the outcomes in eyes with Fuchs endothelial corneal dystrophy after standard phacoemulsification with those of femtosecond laser-assisted cataract surgery. SETTING: Bascom Palmer Eye Institute, Miami, Florida, USA. DESIGN: Retrospective case series. METHODS: Charts from patients diagnosed with Fuchs endothelial corneal dystrophy who had phacoemulsification cataract surgery at Bascom Palmer Eye Institute between January 1, 2014, and January 1, 2017, were reviewed...
May 15, 2018: Journal of Cataract and Refractive Surgery
https://www.readbyqxmd.com/read/29772169/multiphoton-up-conversion-emission-from-diamond-single-crystals
#15
Yunfeng Wang, Wenfei Zhang, Chao-Nan Lin, Pengpeng Ren, Ying-Jie Lu, Chongxin Shan, Siu Fung Yu
Room-temperature up-conversion emission up to eight-photon absorption is demonstrated from diamond single crystals under femtosecond laser excitation for the first time. The low concentration of defects and impurities is attributed to the support of free excitons emission at 235 nm. Nonlinear optical properties are also investigated by using an open aperture Z-scan technique. The corresponding three-, five- and eight-photon absorption coefficients of the diamonds are found to be 1.8×10-2 cm3/GW2, 5×10-9 cm7/GW4 and 1...
May 17, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29772050/combined-femtosecond-laser-assisted-cataract-surgery-and-small-gauge-pars-plana-vitrectomy-using-different-devices-a-new-trend-for-vitreoretinal-surgery
#16
Bruno de Queiroz Alves, Oswaldo Ferreira Moura Brasil, Cristiano Toesca Espinhosa, Ricardo Miguel Japiassu, Mariana Batista Gonçalves, Otaviano Magalhães Júnior, André Maia, Emmerson Badaró, Paula Serraino, Arturo Alezzandrinni, Mauricio Maia
BACKGROUND AND OBJECTIVE: To report the efficacy, safety, and benefits of femtosecond laser-assisted cataract surgery (FLACS) combined with sutureless 23-gauge pars plana vitrectomy (PPV). PATIENTS AND METHODS: This multicenter, retrospective study evaluated patient records and videos of 43 cases with retinal pathologies and cataract who underwent the combined procedure. RESULTS: In 44.2% and 55.8% of cases, respectively, the LenSx Laser (femtosecond machine; Alcon, Fort Worth, TX) and the Constellation (vitreous cutter; Alcon, Fort Worth, TX), and the Victus (femtosecond machine; Bausch + Lomb, Rochester, NY) and Stellaris PC (vitreous cutter; Bausch + Lomb, Rochester, NY) were used...
May 1, 2018: Ophthalmic Surgery, Lasers & Imaging Retina
https://www.readbyqxmd.com/read/29771882/-morphological-changes-of-cornea-in-children-with-hyperopia-in-the-immediate-and-remote-postoperative-period-after-laser-keratomieleusis-according-to-confocal-microscopy-data
#17
I L Kulikova, N P Pashtaev, O V Shlenskaya
Studying morphological changes of cornea in the remote postoperative period is becoming increasingly relevant with refractive surgeries being adapted for children. PURPOSE: comparative analysis of keratocyte density and hystomorphologic changes of cornea after laser in situ keratomieleusis (LASIK) and femtosecond laser-assisted LASIK (FS-LASIK) in children with hyperopia. MATERIAL AND METHODS: 109 patients aged 6-17 years in 2 groups were examined with 'Confoscan-4' confocal microscope...
2018: Vestnik Oftalmologii
https://www.readbyqxmd.com/read/29771112/uv-photochemistry-of-the-disulfide-bond-evolution-of-early-photoproducts-from-picosecond-x-ray-absorption-spectroscopy-at-the-sulfur-k-edge
#18
Miguel Ochmann, Abid Hussain, Inga von Ahnen, Amy A Cordones, Kiryong Hong, Jae Hyuk Lee, Rory Ma, Katrin Adamczyk, Tae Kyu Kim, Robert W Schoenlein, Oriol Vendrell, Nils Huse
We have investigated dimethyl disulfide as the basic moiety for understanding the photochemistry of disulfide bonds, which are central to a broad range of biochemical processes. Picosecond time-resolved X-ray absorption spectroscopy at the sulfur K-edge provides unique element-specific insight into the photochemistry of the disulfide bond initiated by 267 nm femtosecond pulses. We observe a broad but distinct transient induced absorption spectrum which recovers on at least two time scales in the nanosecond range...
May 17, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29769600/x-ray-based-virtual-histology-allows-guided-sectioning-of-heavy-ion-stained-murine-lungs-for-histological-analysis
#19
Jonas Albers, M Andrea Markus, Frauke Alves, Christian Dullin
Examination of histological or immunohistochemically stained 2D sections of embedded tissue is one of the most frequently used tools in biomedical research and clinical routine. Since to date, targeted sectioning of specific regions of interest (ROI) in the sample is not possible, we aimed at developing a guided sectioning approach based on x-ray 3D virtual histology for heavy ion stained murine lung samples. For this purpose, we increased the contrast to noise ratio of a standard benchtop microCT by 5-10-fold using free-propagation phase contrast imaging and thus substantially improved image quality...
May 16, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29769544/towards-a-petawatt-class-few-cycle-infrared-laser-system-via-dual-chirped-optical-parametric-amplification
#20
Yuxi Fu, Katsumi Midorikawa, Eiji J Takahashi
Expansion of the wavelength range for an ultrafast laser is an important ingredient for extending its range of applications. Conventionally, optical parametric amplification (OPA) has been employed to expand the laser wavelength to the infrared (IR) region. However, the achievable pulse energy and peak power have been limited to the mJ and the GW level, respectively. A major difficulty in the further energy scaling of OPA results from a lack of suitable large nonlinear crystals. Here, we circumvent this difficulty by employing a dual-chirped optical parametric amplification (DC-OPA) scheme...
May 16, 2018: Scientific Reports
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