4,229 results match your criteria induced refractive


Observation of the Pockels Effect in Ionic Liquids and Insights into the Length Scale of Potential-Induced Ordering.

Langmuir 2021 Apr 22. Epub 2021 Apr 22.

Department of Chemistry, Graduate School of Science and Technology, Kwansei Gakuin University, Sanda 669-1337, Japan.

Ionic liquids (ILs) under electric fields play essential roles in the electrochemical utilization of ILs. Recently, long-range organization of ILs in the vicinity of charged (and even neutral) surfaces has been revealed, but experimental evidence for such an ordering is still limited and its spatial length scale remains controversial. Here, we use confocal Raman microspectroscopy to investigate the effect of an applied electric potential on the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and its analogues in a space-resolved manner. Read More

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Assessment of Long-Term Anterior and Posterior Topographic Changes in the Cornea After Ptosis Surgery Using Fourier Harmonic Analysis.

Cornea 2021 Apr;40(4):440-444

*Department of Ophthalmology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan; and †Department of Ophthalmology, Keio University Hospital, Tokyo, Japan.

Purpose: We aimed to assess the corneal refractive changes induced by ptosis surgery in patients with acquired ptosis using Fourier harmonic analysis.

Methods: This retrospective observational study enrolled consecutive patients who underwent levator aponeurotic surgery for acquired ptosis at the Department of Ophthalmology in the University of Tokyo Hospital from May 2016 to January 2018. Best corrected visual acuity, central corneal thickness, average keratometric corneal power (AvgK), corneal astigmatism, and topographic data using Fourier analysis were analyzed preoperatively and 6 months postoperatively. Read More

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Nonlinear increase, invisibility, and sign inversion of a localized fs-laser-induced refractive index change in crystals and glasses.

Light Sci Appl 2020 Apr 20;9(1):64. Epub 2020 Apr 20.

Centre d'Optique, Photonique et Laser, 2375 Rue de la Terrasse, Université Laval, G1V 0A6, Québec, QC, Canada.

Multiphoton absorption via ultrafast laser focusing is the only technology that allows a three-dimensional structural modification of transparent materials. However, the magnitude of the refractive index change is rather limited, preventing the technology from being a tool of choice for the manufacture of compact photonic integrated circuits. We propose to address this issue by employing a femtosecond-laser-induced electronic band-gap shift (FLIBGS), which has an exponential impact on the refractive index change for propagating wavelengths approaching the material electronic resonance, as predicted by the Kramers-Kronig relations. Read More

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Temporal evolution of the biological response to laser-induced refractive index change (LIRIC) in rabbit corneas.

Exp Eye Res 2021 Apr 14:108579. Epub 2021 Apr 14.

The Institute of Optics, University of Rochester, Rochester, NY, 14627, USA; The Center for Visual Science, University of Rochester, Rochester, NY, 14627, USA; The Flaum Eye Institute, University of Rochester, Rochester, NY, 14642, USA. Electronic address:

Laser induced refractive index change (LIRIC) is a new, non-incisional, non-ablative, femtosecond photo-modification technique being developed for vision correction in humans. Prior, ex-vivo studies showed intra-tissue refractive index change to induce minimal cell death, restricted to the laser focal zone in the corneal stroma, and with no observable damage to the epithelium or endothelium. Here, we used live rabbits to ascertain longer-term consequences of LIRIC in vivo. Read More

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Femtosecond laser induced thermophoretic writing of waveguides in silicate glass.

Sci Rep 2021 Apr 16;11(1):8390. Epub 2021 Apr 16.

Laser Processing Group, Institute of Optics (IO, CSIC), Serrano 121, 28006, Madrid, Spain.

Here in, the fs-laser induced thermophoretic writing of microstructures in ad-hoc compositionally designed silicate glasses and their application as infrared optical waveguides is reported. The glass modification mechanism mimics the elemental thermal diffusion occurring in basaltic liquids at the Earth's mantle, but in a much shorter time scale (10 times faster) and over a well-defined micrometric volume. The precise addition of BaO, NaO and KO to the silicate glass enables the creation of positive refractive index contrast upon fs-laser irradiation. Read More

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A Phase-Shifted Surface Plasmon Resonance Sensor for Simultaneous Photoacoustic Volumetric Imaging and Spectroscopic Analysis.

ACS Sens 2021 Apr 16. Epub 2021 Apr 16.

Nanophotonics Research Center, Shenzhen Key Laboratory of Micro-Scale Optical Information Technology, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.

For biomedical photoacoustic applications, an ongoing challenge in simultaneous volumetric imaging and spectroscopic analysis arises from ultrasonic detectors lacking high sensitivity to pressure transients over a broad spectral bandwidth. Photoacoustic impulses can be measured on the basis of the ultrafast temporal dynamics and highly sensitive response of surface plasmon polaritons to the refractive index changes. Taking advantage of the ultra-sensitive phase shift of surface plasmons caused by ultrasonic perturbations instead of the reflectivity change [as is the case for traditional surface plasmon resonance (SPR) sensors], a novel SPR sensor based on phase-shifted interrogation was developed for the broadband measurement of photoacoustically induced pressure transients with improved detection sensitivity. Read More

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Ultra-broadband supercontinuum generation in gas-filled photonic-crystal fibers: the epsilon-near-zero regime.

Opt Lett 2021 Apr;46(8):1959-1962

In this Letter, we show theoretically that the nonlinear photoionization process of a noble gas inside a hollow-core photonic-crystal fiber can be exploited in obtaining broadband supercontinuum generation via pumping close to the mid-infrared regime. The interplay between the Kerr and photoionization nonlinearities is strongly enhanced in this regime. Photoionization continuously modifies the medium dispersion, in which the refractive index starts to significantly decrease and approach the epsilon-near-zero regime. Read More

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Inverse design of a single-frequency diffractive biosensor based on the reporter cleavage detection mechanism.

Opt Express 2021 Mar;29(7):10780-10799

Vertically interrogated porous silicon (PSi) interferometric biosensors have shown high potential for sensing bio-molecules as they combine high detection sensitivity with simplicity of fabrication, functionalization, optical coupling, and interfacing with microfluidic systems. However, most interferometric sensor designs require either broadband or wavelength-tunable light sources as well as wide-angle detection schemes, increasing their complexity and cost for point-of-care biosensing applications. The limit of detection of such sensors is also constrained by the small size and low refractive index of biological molecules, making it hard to detect very low concentrations of pathogens. Read More

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Effect of convergent beam array on reducing scintillation in underwater wireless optical communications with pointing errors.

Opt Express 2021 Mar;29(7):9846-9860

In this paper, we propose the convergent beam array to reduce scintillation induced by oceanic turbulence in underwater wireless optical communications (UWOCs) between misaligned transceivers. In the proposed convergent beam array, the propagation directions of beams are slanted inwards and different from each other. First, we present the convergent beam array system and analyze spatial relationships between the transmitter and the individual beam in beam array systems. Read More

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Corneal neuromediator profiles following laser refractive surgery.

Neural Regen Res 2021 Nov;16(11):2177-2183

Tissue Engineering and Cell Therapy Group, Singapore Eye Research Institute; Department of Cornea and External Eye Disease, Singapore National Eye Centre; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore.

Laser refractive surgery is one of the most commonly performed procedures worldwide. In laser refractive surgery, Femtosecond Laser in Situ Keratomileusis and Refractive Lenticule Extraction have emerged as promising alternatives to microkeratome Laser in Situ Keratomileusis and Photorefractive Keratectomy. Following laser refractive surgery, the corneal nerves, epithelial and stromal cells release neuromediators, including neurotrophins, neuropeptides and neurotransmitters. Read More

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November 2021

Fast Fabrication of Fishnet Optical Metamaterial Based on Femtosecond Laser Induced Stress Break Technique.

Nanomaterials (Basel) 2021 Mar 16;11(3). Epub 2021 Mar 16.

Laboratory of Thin Film Optics, Shanghai Institute of Optics and Fine Mechanics, No. 390 Qinghe Road, Jiading District, Shanghai 201800, China.

To speed up the fabrication of optical metamaterials by making use of the fast speed advantage of femtosecond laser preparation, a metamaterial appropriate for femtosecond laser processing was designed, and the interaction between femtosecond laser and metal-dielectric-metal fishnet stacks was investigated in detail. Two kinds of processing mechanisms, thermal melting and stress break, were revealed during the fabrication. The thermal melting process, dominated by the interaction of femtosecond laser with metals, makes the upper and lower metal layers adhere to each other, which leads to the magnetic resonance impossible. Read More

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The development of and recovery from form-deprivation myopia in infant rhesus monkeys reared under reduced ambient lighting.

Vision Res 2021 Jun 30;183:106-117. Epub 2021 Mar 30.

College of Optometry, University of Houston, Houston, TX, United States; Brien Holden Vision Institute, Sydney, NSW, Australia. Electronic address:

Although reduced ambient lighting ("dim" light) can cause myopia in emmetropizing chicks, it does not necessarily lead to myopic changes in emmetropizing rhesus monkeys. Because myopia is rarely spontaneous, a question remained whether dim light would hasten the progression of visually induced myopia. To determine the effects of dim light on the development of and recovery from form-deprivation myopia (FDM), seven 3-week-old infant rhesus monkeys were reared under dim light (mean ± SD = 55 ± 9 lx) with monocular diffuser spectacles until ~154 days of age, then maintained in dim light with unrestricted vision until ~337 days of age to allow for recovery. Read More

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Measurement of the refractive index of lenses from the maximum phase difference of the total internal reflection with a polarization camera.

Appl Opt 2021 Apr;60(10):B106-B112

The proposed total internal reflection (TIR)-based technique can be used for measuring the refractive index of lenses. Distribution of the phase difference between the - and -polarization states of the reflected light induced by TIR can be obtained by a polarization camera. The refractive index of the lens can be determined from the detected maximum phase difference, with the specific measurement equation. Read More

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Comparison of penetrating femtosecond laser-assisted astigmatic keratotomy and toric intraocular lens implantation for correction of astigmatism in cataract surgery.

Sci Rep 2021 Apr 1;11(1):7340. Epub 2021 Apr 1.

Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-Ro, Gangnam-gu, Seoul, 06351, Republic of Korea.

This study tried to compare the clinical outcomes of femtosecond laser-assisted astigmatic keratotomy (FSAK) and toric intraocular lens (IOL) implantation for astigmatism correction and identify factors affecting the efficacy of FSAK and toric IOL implantation in astigmatism correction. This retrospective case series comprised patients with corneal astigmatism ranging between 0.5 D and 4. Read More

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Comparison of corneal aberrations and refractive outcomes after small-incision lenticule extraction and femtosecond-assisted laser-assisted in situ keratomileusis.

Int Ophthalmol 2021 Mar 30. Epub 2021 Mar 30.

Joint Shantou International Eye Center of Shantou University, The Chinese University of Hong Kong, Shantou, 515041, China.

Purposes: To retrospectively compare the short-term refractive outcomes and corneal aberrations after small-incision lenticule extraction (SMILE) and femtosecond-assisted laser-assisted in situ keratomileusis (FS-LASIK) combined with smart pulse technology (SPT) in patients with compound myopic astigmatism.

Methods: A total of 91 eyes (91 patients) were included, 43eyes in FS-LASIK group and 48 eyes in the SMILE group. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refractive results and corneal topography were evaluated 1 and 3 months postoperatively. Read More

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High Refractive Index Photopolymers by Thiol-Yne "Click" Polymerization.

ACS Appl Mater Interfaces 2021 Apr 29;13(13):15647-15658. Epub 2021 Mar 29.

Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, Colorado 80309, United States.

A scalable synthesis of high refractive index, optically transparent photopolymers from a family of low-viscosity multifunctional thiol and alkyne monomers via thiol-yne "click" is described herein. The monomers designed to incorporate high refractive index cores consisting of aryl and sulfide groups with high intrinsic molar refraction were synthesized starting from commercially available low-cost raw materials. The low-viscosity (<500 cP) thiol-yne resins formulated with these new multifunctional monomers and a phosphine oxide photoinitiator underwent efficient thiol-yne polymerizations upon exposure to 405 nm light at 30 mW/cm. Read More

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CLEAR - Contact lens complications.

Cont Lens Anterior Eye 2021 Apr 25;44(2):330-367. Epub 2021 Mar 25.

School of Optometry, Aston University, Birmingham, UK.

Contact lens-related complications are common, affecting around one third of wearers, although most are mild and easily managed. Contact lenses have well-defined anatomical and physiological effects on the ocular surface and can result in other consequences due to the presence of a biologically active material. A contact lens interacts with the tear film, ocular surface, skin, endogenous and environmental microorganisms, components of care solutions and other antigens which may result in disease specific to contact lens wear, such as metabolic or hypersensitivity disorders. Read More

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Total keratometry for determination of true corneal power after myopic small incision lenticule extraction.

J Cataract Refract Surg 2021 Feb 24. Epub 2021 Feb 24.

1 University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany 2 SMILE Eyes Clinic, Linz, Austria 3 SMILE Eyes Clinic, Munich, Germany 4 Prof. Kook & Partner, Private Practice, Graefelfing, Germany.

Purpose: To gauge the value of total keratometry (TK) to estimate corneal power change in eyes that underwent SMILE for treatment of myopia or myopic astigmatism.

Setting: Department of Ophthalmology, Ludwig-Maximilians-University and SMILE Eyes Clinic Munich Airport, Munich, Germany.

Design: Prospective cross-sectional trial. Read More

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February 2021

Title.

J Cataract Refract Surg 2021 Feb 24. Epub 2021 Feb 24.

1 Humanitas San Pio X Hospital, Milan, Italy 2 The School of Engineering, University of Liverpool, Liverpool, United Kingdom 3 Department of Ophthalmology, the Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil 4 Department of Ophthalmology, the Federal University of São Paulo (UNIFESP), São Paulo, Brazil 5 Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing, 100083, China 6 NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, UK 7 ELZA Institute, Dietikon/Zurich, Switzerland 8 Faculty of Medicine, University of Geneva, Geneva, Switzerland 9 USC Roski Eye Institute, Miller School of Medicine, Los Angeles, CA 10 School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China 11 Eyereum Eye Clinic, Seoul, Korea 12 Augenklinik am Neumarkt, Cologne, Germany 13 Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan 14 School of Medicine and Health Sciences, University of Antwerp, Wilrijk, Belgium 15 Emmetropia Mediterranean Eye Institute, Heraklion, Greece 16 Department of Cornea & Refractive Surgery, Medical Research Foundation, Chennai, India 17 Department of Ophthalmology & Visual Science, Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA 18 Center for Refractive Surgery Muenster, Hohenzollernring 70, Muenster, Germany 19 University Eye-Clinic, Ruhr-University, Bochum, Germany 20 Eye Care, Miami, FL, USA 21 Humanitas University, Department of Biomedical Sciences, Via Rita Levi Montalcini 4, 20090 Pieve Emanuele, Milan, Italy 22 Humanitas Clinical and Research Center - IRCCS, via Manzoni 56, 20089 Rozzano (Mi) Italy.

Purpose: To validate and evaluate the use of a new biomechanical index known as the CBI-LVC (Corvis Biomechanical Index-Laser Vision Correction) as a method for separating stable post-LVC eyes from post-LVC eyes with ectasia.

Setting: Patients were included from 10 clinics/9 countries.

Design: Retrospective, multi-center, clinical study. Read More

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February 2021

Stratifin in ocular surface squamous neoplasia and its association with p53.

Acta Ophthalmol 2021 Mar 26. Epub 2021 Mar 26.

Ophthalmoplasty Service, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.

Purpose: Sunlight-induced p53 mutations are known to contribute towards increased risk of ocular surface squamous neoplasia (OSSN). Stratifin (14-3-3σ)/HEM (human epithelial marker) is a p53-mediated inhibitor of cell cycle progression and has been shown to be a target of epigenetic deregulation in various carcinomas. In the present study, Stratifin expression, its promoter methylation status as well as expression of mutant p53 in early and advanced AJCC stages (8th edition) of OSSN, was evaluated. Read More

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LASIK versus PRK for high astigmatism.

Int Ophthalmol 2021 Mar 22. Epub 2021 Mar 22.

Department of Ophthalmology, Barzilai Medical Center, Ashkelon, Israel.

Purpose: To compare the refractive outcomes of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for myopic astigmatism of 3 diopters (D) or more.

Study Design: Retrospective matched comparative study.

Methods: This study include consecutive myopic patients (SE 0 to -10 D) undergoing LASIK or PRK between 2007 and 2016 with astigmatism of 3 to 6 D, and postoperative follow-up of at least 30 days for LASIK and 60 days for PRK, compared outcomes of LASIK and PRK eyes. Read More

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Protective effects of riboflavin-UVA-mediated posterior sclera collagen cross-linking in a guinea pig model of form-deprived myopia.

Int J Ophthalmol 2021 18;14(3):333-340. Epub 2021 Mar 18.

Tianjin Key Laboratory of Retinal Functions and Diseases, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin 300384, China.

Aim: To evaluate the effect of posterior sclera collagen cross-linking induced by riboflavin-ultraviolet A (UVA) on form-deprived myopia in guinea pigs.

Methodes: Twenty-five pigmented guinea pigs of 3-week-old were randomly assigned into 4 groups that included normal control (NOR, =7), form-deprived (FDM, =7), normal with riboflavin-UVA cross-linking (NOR+CL, =5) and form-deprived with cross-linking (FDM+CL, =6). The NOR+CL group and the FDM+CL group received the riboflavin-UVA induced cross-linking at day 0. Read More

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Deoxypodophyllotoxin Inhibits Non-Small Cell Lung Cancer Cell Growth by Reducing HIF-1α-Mediated Glycolysis.

Front Oncol 2021 24;11:629543. Epub 2021 Feb 24.

Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Chengdu Medical College, Chengdu, China.

Cancer cell proliferation is a metabolically demanding process that requires high rate of glycolysis to support anabolic growth. Deoxypodophyllotoxin (DPT) is a natural flavonolignan with various pharmacological activities, including antitumor effect. However, whether DPT affects the metabolic reprogramming of cancer cells is unknown. Read More

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February 2021

Enhanced optical pulse broadening in free-space optical links due to the radiative effects of atmospheric aerosols.

Opt Express 2021 Jan;29(2):865-876

Propagation through turbulent media produces complex amplitude fluctuations and temporal spreading of narrow optical pulses. Light-absorbing aerosols present in the atmospheric transmission path will perturb the refractive index structure parameter (Cn2) through atmospheric heating. The consequent enhancement in broadening and attenuation of ultrashort (femtosecond) optical pulses has been calculated by combining multi-satellite observations, radiosonde profiles and computational radiative transfer. Read More

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January 2021

Balanced-detection interferometric cavity-assisted photothermal spectroscopy employing an all-fiber-coupled probe laser configuration.

Opt Express 2021 Mar;29(5):7794-7808

The interferometric cavity-assisted photothermal spectroscopy (ICAPS) method has been proven highly suitable for sensitive and compact gas detection by application of an optical cavity as transducer for photothermal spectroscopy. This work reports on the implementation of an overall fiber-coupled probe laser configuration detecting the reflectance of the individual interferometers in a balanced-detection ICAPS system. The layout greatly improves the overall sensor system robustness. Read More

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Tree shrews do not maintain emmetropia in initially-focused narrow-band cyan light.

Exp Eye Res 2021 Mar 10;206:108525. Epub 2021 Mar 10.

Dept. of Optometry and Vision Science, University of Alabama at Birmingham (UAB), 1716 University Blvd., Birmingham, AL, United States. Electronic address:

We asked if emmetropia, achieved in broadband colony lighting, is maintained in narrow-band cyan light that is well focused in the emmetropic eye, but does not allow for guidance from longitudinal chromatic aberrations (LCA) and offers minimal perceptual color cues. In addition, we examined the response to a -5 D lens in this lighting. Seven tree shrews from different litters were initially housed in broad-spectrum colony lighting. Read More

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Effect of defocus combined with rotation on the optical performance of trifocal toric IOLs.

Eur J Ophthalmol 2021 Mar 11:11206721211002121. Epub 2021 Mar 11.

Faculty of Optics and Optometry, Complutense University of Madrid, Spain.

Purpose: To objectively analyze the optical quality of the FineVision Toric intraocular lens (IOL) with two cylinder powers when different combinations of rotations and residual refractive errors are induced.

Methods: This study assessed the FineVision Toric IOL with two different cylinder powers: 1.5 and 3. Read More

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Electrically Tunable Singular Phase and Goos-Hänchen Shifts in Phase-Change-Material-Based Thin-Film Coatings as Optical Absorbers.

Adv Mater 2021 Apr 10;33(15):e2006926. Epub 2021 Mar 10.

Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.

The change of the phase of light under the evolution of a nanomaterial with time is a promising new research direction. A phenomenon directly related to the sudden phase change of light is the Goos-Hänchen (G-H) shift, which describes the lateral beam displacement of the reflected light from the interface of two media when the angles of incidence are close to the total internal reflection angle or Brewster angle. Here, an innovative design of lithography-free nanophotonic cavities to realize electrically tunable G-H shifts at the singular phase of light in the visible wavelengths is reported. Read More

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Fiber-optic sensor measuring spatial distributions of refractive index and temperature.

Appl Opt 2021 Feb;60(5):1428-1433

In this work, we present a fiber sensor designed to measure simultaneously spatial inhomogeneities of the refractive index and temperature in liquid media, for example, induced by biochemical reactions. The sensor's constituent elements are Fabry-Perot microresonators fabricated in standard single-mode optical fibers by diamond blade dicing. To allow simultaneous measurements of different refractive indices, the sensor comprises two open cavities approximately 2 mm apart. Read More

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February 2021

Rolling angle recovery of flowing cells in holographic tomography exploiting the phase similarity.

Appl Opt 2021 Feb;60(4):A277-A284

Holographic tomography allows the 3D mapping of the refractive index of biological samples thanks to reconstruction methods based on the knowledge of illumination directions or rotation angles of the imaged sample. Recently, phase contrast tomographic flow cytometry by digital holography has been demonstrated to reconstruct the three-dimensional refractive index distribution of single cells while they are flowing along microfluidic channels. In this system, the illumination direction is fixed while the sample's rotation is not deterministically known a priori but induced by hydrodynamic forces. Read More

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February 2021