• Opt. Lett. (IF 3.714) Pub Date : 2020-06-19
Thibault Wildi, Marcell Kiss, and Niels Quack

We demonstrate the design, fabrication, and experimental characterization of near-field binary phase transmission diffractive optical elements (DOEs) in single crystal diamond. Top-hat and arbitrary pattern DOE beam shapers were numerically optimized using an iterative Fourier transform algorithm (IFTA). Commercially available single crystal diamond plates (${{3}}\;{\rm{mm}} \times {{3}}\;{\rm{mm}} 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-22 S. M. A. Hosseini-Saber, Ehsan A. Akhlaghi, and Ahad Saber In this Letter, we investigate the Fresnel diffraction of vortex beams from a phase plate and propose a novel (to the best of our knowledge) method to determine the fractional part of the topological charge of vortex beams. When a vortex beam with a fractional topological charge illuminates the edge region of a transparent plate, the visibility of the diffraction pattern on two sides of the beam is 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-29 Lauris Talbot, Daniel Richter, Maximilian Heck, Stefan Nolte, and Martin Bernier We report on what we believe are the first volume Bragg gratings written inside bulk multicomponent fluoride glasses. The gratings inscribed with tightly focused infrared (IR)-femtosecond pulses in combination with the phase-mask technique exhibit refractive index modulations of up to$5 \times {10^{- 4}}$with reflectivities up to 90% at a wavelength near 2.8 µm. Such highly compact and narrowband 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-22 Oleksandr Kotlyar, Maryna Pankratova, Morteza Kamalian-Kopae, Anastasiia Vasylchenkova, Jaroslaw E. Prilepsky, and Sergei K. Turitsyn We propose a method to improve the performance of the nonlinear Fourier transform (NFT)-based optical transmission system by applying the neural network post-processing of the nonlinear spectrum at the receiver. We demonstrate through numerical modeling about one order of magnitude bit error rate improvement and compare this method with machine learning processing based on the classification of the 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-23 Lior Blech, Cristian Antonelli, Antonio Mecozzi, Yonina C. Eldar, and Mark Shtaif We report a scheme for reconstructing the complex envelope of an optical signal from two decorrelated measurements of its intensity. The decorrelation is achieved by splitting the received optical signal into two copies, and by dispersing one of the copies prior to photo detection. The reconstructed complex-valued signal is obtained by means of an iterative algorithm that requires only a few tens of 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-25 Runzhou Zhang, Hao Song, Haoqian Song, Zhe Zhao, Giovanni Milione, Kai Pang, Jing Du, Long Li, Kaiheng Zou, Huibin Zhou, Cong Liu, Karapet Manukyan, Nanzhe Hu, Ahmed Almaiman, Jeffery Stone, Ming-Jun Li, Brittany Lynn, Robert W. Boyd, Moshe Tur, and Alan E. Willner We experimentally demonstrate the utilization of adaptive optics (AO) to mitigate intra-group power coupling among linearly polarized (LP) modes in a graded-index few-mode fiber (GI FMF). Generally, in this fiber, the coupling between degenerate modes inside a modal group tends to be stronger than between modes belonging to different groups. In our approach, the coupling inside the${{\rm LP}_{11}}$更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-29 Xiaodong He, Jiajing Tu, Xiaowen Wu, Shecheng Gao, Lei Shen, Chenglong Hao, Yuanhua Feng, Weiping Liu, and Zhaohui Li The third-order orbital angular momentum (${{\rm OAM}_{\pm 3}}$) guided mode generation is demonstrated for the first time, to the best of our knowledge, by employing an asymmetric long-period fiber grating (AS-LPFG). The proposed AS-LPFG is modeled by coupled local-mode theory, which is extended to the coupling of core modes and is fabricated by multicycle scanning ablation with increasing power in 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-30 Bowen Zhang, Yushi Chu, Xinghu Fu, Shuen Wei, Jiaying Wang, Yanhua Luo, and Gang-Ding Peng Bismuth/erbium co-doped optical fiber fabricated through 3D silica lithography is thermally treated with various conditions. Then the thermal treatment effect on bismuth active centers (BACs) in this fiber is investigated. The thermal bleaching of the BAC associated with Al and the BAC associated with Si is observed after thermal treatment at high temperatures (300°C–800°C). It is found that the absorption 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-24 Manuel P. Fernández, Luis Romero Cortés, Saikrishna R. Konatham, Benjamin Crockett, Laureano A. Bulus-Rossini, Pablo A. Costanzo-Caso, and José Azaña We report a novel, to the best of our knowledge, all-optical discrete multilevel time-lens (DM-TL) design based on cross-phase modulation (XPM). In this approach, the pump is synthesized such as the quadratic phase modulation is applied to the probe in constant-level time-bins with a maximum phase excursion of${2}\pi$. As a result, a considerable reduction in the required pump power is achieved in 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-17 Chelsea Carlson, Andreas Knorr, and Stephen Hughes We study the near-field energy transfer rates between two finite size quantum dot disks, generalizing the result of Förster coupling between two point dipoles. In particular, we derive analytical results for the envelope of the electronic wave function for model potentials at the boundaries of quantum dot disks and demonstrate how the Förster interaction is screened as the size of the dots becomes 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-17 Andrzej Gajewski, Daniel Gustaw, Nor Roshidah Yusof, Norshamsuri Ali, Karolina Słowik, and Piotr Kolenderski This work is a proposition of an experimental platform to observe quantum fictitious anticentrifugal force. We present an analytical and numerical treatment of a rectangular toroidal dielectric waveguide. Solving the Helmholtz equation, we obtain analytical solutions for transverse spatial modes and estimate their number as a function of system characteristics. On top of that, the analysis of the structure 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-24 Dmitry A. Bykov, Leonid L. Doskolovich, and Evgeni A. Bezus We propose a multiscale approach for designing mirrors generating prescribed irradiance distributions in the far field. Our design method is based on calculating a ray mapping from a Monge–Kantorovich mass transportation problem and on reducing this problem to a linear assignment problem (LAP). The proposed multiscale formulation of the LAP allows one to efficiently calculate freeform mirror surfaces 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-17 Kibum Nam and Jung-Hoon Park Focusing through scattering media is a subject of great interest due to its direct impact in the field of biomedical optics. However, the greatest barrier currently limiting direct applications is the fact that most scattering media that we wish to deliver light through are dynamic. To focus or deliver light through dynamic scattering media, using a digital micromirror device (DMD) has been demonstrated 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-18 Nathaniel Hai and Joseph Rosen Optical, spatial, or temporal multiplexing is a well-known approach to optimize the performance of imaging systems. Following the recent discovery about the capability to record a coherent hologram in an interferenceless working mode, we propose a motionless method to spatially multiplex more than one hologram in a single camera exposure. Using the rather simple multiplexing framework based on coded 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-17 Yeon-Gyeong Ju, Myeong-Ho Choi, Pengyu Liu, Brandon Hellman, Ted L. Lee, Yuzuru Takashima, and Jae-Hyeung Park Occlusion of a real scene by displayed virtual images mitigates incorrect depth cues and enhances image visibility in augmented reality applications. In this Letter, we propose a novel optical scheme for the occlusion-capable optical-see-through near-eye display. The proposed scheme uses only a single spatial light modulator, as the real-scene mask and virtual image display simultaneously. A polarization-based 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-18 Sylwia M. Kolenderska, Frédérique Vanholsbeeck, and Piotr Kolenderski Intensity levels allowed by safety standards (ICNIRP or ANSI) limit the amount of light that can be used in a clinical setting to image highly scattering or absorptive tissues with optical coherence tomography (OCT). To achieve high-sensitivity imaging at low intensity levels, we adapt a detection scheme—which is used in quantum optics for providing information about spectral correlations of photons—into 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-22 Benjamin Le Teurnier, Xiaobo Li, Matthieu Boffety, Haofeng Hu, and François Goudail Full Stokes polarimetric images can be obtained from two acquisitions with a microgrid polarization camera equipped with a retarder. When the retardance is imperfectly known, it can be calibrated from the measurements, but this requires three image acquisitions and may cause divergence of estimation variance at a low signal-to-noise ratio. We determine closed-form equations allowing one to decide in 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-29 Elias Scharf, Jakob Dremel, Robert Kuschmierz, and Jürgen Czarske Lensless fiber endoscopes are of great importance for keyhole imaging. Coherent fiber bundles (CFB) can be used in endoscopes as remote phased arrays to capture images. One challenge is to image at high speed while correcting aberrations induced by the CFB. We propose the combination of digital optical phase conjugation, using a spatial light modulator, with fast scanning, for which a 2D galvo scanner 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-07-01 Anhu Li, Xingsheng Liu, and Zusheng Zhao We present a three-dimensional (3D) computational imaging architecture based on the imaging principle of a dynamic virtual camera, which enables the spatial reconstruction using a single camera and a compact wedge prism device. By rotating the prism for camera boresight adjustment, the proposed system can capture an object from different viewpoints. Each captured image appears to be recorded directly 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-17 José Manuel Luque-González, Alaine Herrero-Bermello, Alejandro Ortega-Moñux, Marina Sánchez-Rodríguez, Aitor V. Velasco, Jens H. Schmid, Pavel Cheben, Íñigo Molina-Fernández, and Robert Halir On-chip polarization splitters are key elements for coherent optical communication systems and polarization diversity circuits. These devices are often implemented with directional couplers that are symmetric for one polarization and strongly asymmetric for the other polarization. To achieve this asymmetry, highly dissimilar waveguides are used in each coupler arm, often requiring additional material 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-24 Angeleene S. Ang, Alexander S. Shalin, and Alina Karabchevsky Tuning the near field using all-dielectric nano-antennas offers a promising approach for trapping atoms, which could enable strong single-atom–photon coupling. Here we report the numerical study of an optical trapping of a single Cs atom above a waveguide with a silicon nano-antenna, which produces a trapping potential for atoms in a chip-scale configuration. Using counter-propagating incident fields 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-29 Matthew Garrett, Yang Liu, Pan Ma, Duk-Yong Choi, Stephen J. Madden, and Benjamin J. Eggleton We present a high-performance radio frequency (RF) photonic bandpass filter enabled by combining on-chip Brillouin scattering with a suppressed carrier phase modulation scheme. We achieve a low RF loss of 5 dB and a large stopband rejection of more than 40 dB, which represents a significant improvement of 20 dB to the RF passband gain and 31 dB to the RF rejection ratio over traditional modulation 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-07-01 Qiang Zhang, Hui Yu, Penghui Xia, Zhilei Fu, Xiaofei Wang, and Jianyi Yang In this Letter, we demonstrate an ultra-high linearity silicon carrier-depletion-based modulator by integrating a dual-parallel Mach–Zehnder modulator (DP-MZM) with a${{1}} \times {{2}}$thermo-optical switch. The operation principle is to manipulate power distributions of RF and optical signals among the two sub-MZMs, so their third-order nonlinearities can cancel each other. Spurious-free dynamic 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-07-01 Yaotian Zhao, Xuhan Guo, Yong Zhang, Jinlong Xiang, Kangnian Wang, Hongwei Wang, and Yikai Su Ultra-compact mode-order converters with dielectric slots are demonstrated on a silicon-on-insulator platform. We propose a mode converter that converts the TE0 mode into the TE1 mode with an ultra-small footprint of only${0.8} \times {1.2}\;{{\unicode{x00B5}}}{{\rm{m}}^2}$. The measured insertion loss is less than 1.2 dB from 1520 nm to 1570 nm. To reduce the insertion loss, we further optimize the 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-17 Thomas Gretzinger, Toney T. Fernandez, Simon Gross, Alexander Arriola, and Michael J. Withford The formation of femtosecond laser direct-written waveguides in gallium lanthanum sulfide (GLS) chalcogenide glass with a peak index contrast of$\Delta {n_{\max}} = 0.023$and an average positive refractive index change of$\Delta {n_{\rm waveguide}} = 0.0049$is explained for the first time, to the best of our knowledge. Evidence of structural change and ion migration is presented using Raman spectroscopy 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-17 Hanwei Zhang, Hu Xiao, Xiaolin Wang, Pu Zhou, and Xiaojun Xu Yb-Raman fiber amplifier (YRFA) is a compact setup that can be applied to achieve high-power narrow linewidth or special wavelength lasers. In this Letter, we realized a high-power YRFA with seed wavelengths of 1090 nm and 1150 nm, tandem-pumped by a 1018 nm fiber laser. The dynamic of mode interaction has been carefully studied. The beam cleanup effect in the large mode area, step-index fiber has 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-17 Taek Yong Hwang, Heedeuk Shin, Hai Joong Lee, Hyo Soo Lee, Chunlei Guo, and Byounghwak Lee Following femtosecond (fs) laser pulse irradiation, the formation of a new type of low-spatial-frequency laser-induced periodic surface structure (LSFL) patterns, namely, omnidirectional LSFLs (OD-LSFLs) with the periodic ordering of their orientations, are investigated on Ni in this Letter. Using a liquid crystal polymer patterned depolarizer, we periodically rotate the polarization of fs laser pulses 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-19 Dmitry A. Zezyulin and Vladimir V. Konotop An array of non-Hermitian optical waveguides can operate as a laser or as a coherent perfect absorber, which corresponds to a spectral singularity of the underlying discrete complex potential. We show that all lattice potentials with spectral singularities are characterized by the universal form of the gain-and-loss distribution. Using this result, we systematically construct potentials characterized 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-22 Thomas Zacharias and Alon Bahabad Using a superposition of shifted Bessel beams with different longitudinal wave vectors and orbital angular momenta, we realize an optical beam having simultaneous axial, angular, and radial focusing narrower than the Fourier limit. Our findings can be useful for optical particle manipulation and high-resolution microscopy. 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-24 E. Di Gaetano, S. Watson, E. McBrearty, M. Sorel, and D. J. Paul A distributed feedback GaAs-based semiconductor laser with a laterally coupled grating is demonstrated at a wavelength of 780.24 nm with up to 60 mW power. A mode expander and aluminum-free active layers have been used to reduce the linewidth to 612 kHz while maintaining high output power. The laser demonstrates over 40 dB side-mode suppression ratio with${\gt}{0.3}\;{\rm nm}$of tuning suitable for 更新日期：2020-07-02 • Opt. Lett. (IF 3.714) Pub Date : 2020-06-24 Pengfei Wang, Yating Yi, Xin Wang, Angzhen Li, Shijie Jia, Yaxian Fan, Gilberto Brambilla, Shunbin Wang, and Haiyan Zhao In this Letter, we report lasing at 2.3 µm in${\text{Tm}^{3 +}}$-single-doped and${\text{Tm}^{3 +}}/{\text{Ho}^{3 +}}$-codoped fluorotellurite glass microsphere resonators. By employing a 793 nm diode laser as a pump and exploiting whispering gallery mode microresonators (WGMRs), dual-wavelength lasing at 1.9 and 2.3 µm and triple-wavelength lasing at 1.9, 2.07, and 2.3 µm are achieved in${\text{Tm}^{3

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-24
Can Liu, Pengfei Zhang, Mingwen Xiang, Xiang Ma, Chun Jiang, Bao Tang, Qiaoyin Lu, and Weihua Guo

We propose and experimentally demonstrate an 850 nm single-mode surface-emitting distributed feedback laser based on the surface grating. The laser composes a second-order grating section sandwiched by two first-order grating sections. The second-order grating provides not only surface emission, but also phase shift to remove the emission degeneracy. A high side-mode suppression ratio of 47 dB has

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-29
Sergey Magnitskiy, Dmitriy Agapov, and Anatoly Chirkin

We present an experimental implementation of the ghost polarimetry concept in unpolarized light, which allows obtaining complete information on the spatial distribution of polarization properties of objects with linear dichroism. It is theoretically shown that it is possible to restore the spatial distribution of the azimuth and a value of anisotropy of such objects. The developed technique allows

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-29
Sinan Gündoğdu, Juzar Thingna, and Daniel Leykam

Topological lasers are of growing interest as a way to achieve disorder-robust single-mode lasing using arrays of coupled resonators. We study lasing in a two-dimensional coupled resonator lattice exhibiting transitions between trivial and topological phases, which allows us to systematically characterize the lasing modes throughout a topological phase. We show that, unlike conventional topological

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-30
ChaoYong Chen, Qing Wang, Shuai Huang, Xu Zhang, KaiXin Wang, MingWei Gao, and ChunQing Gao

We present an injection-seeding $Q$-switched 1645 nm Er:YAG ceramic laser with high frequency stability and energy stability by combining the injection-seeding technique and Pound–Drever–Hall technique. 10.31 mJ single-frequency pulses with optimal frequency stability (525 kHz) and relative energy stability (0.52%) at a high pulse repetition rate of 1 kHz are obtained. To the best of our knowledge

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-30
Stirling Scholes and Andrew Forbes

Laser brightness is crucial in many optical processes, and is optimized by high power, high beam quality (low ${M^2}$) beams. Here we show how to improve the laser beam quality factor (reducing the ${M^2}$) of arbitrary structured light fields in a lossless manner using continuous phase-only elements, thus allowing for the increase in brightness by a simple linear optical transformation. We demonstrate

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-07-01
In-Goo Lee, Chang-Hwan Yi, Ji-Won Lee, Jinhyeok Ryu, Sunjae Gwak, Kwang-Ryong Oh, and Chil-Min Kim

We study a lasing of mode groups in a fully chaotic rounded D-shape InGaAsP semiconductor microcavity laser when an electrode is smaller than a cavity (inward gap). Although there are numerous unstable periodic orbits supporting resonances, a mode group localized on period-5 unstable periodic orbit is more competitive than the others for our laser configuration of the inward gap. By means of theoretical

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-07-01
Rui Ma, Zhao Wang, Hua Hui Zhang, Wei Li Zhang, and Yun Jiang Rao

Memory-effect-based speckle correlation is one of the most practical techniques for imaging through scattering opaque media, where a light source with low spatial coherence and moderate bandwidth plays a pivotal role. Usually, a rapidly rotating diffuser is applied to make the light source spatially decoherent. Here, an all-fiber-based low-spatial-coherence light source is proposed and demonstrated

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-17
Subhajit Karmakar, Deepak Kumar, Ravendra K. Varshney, and Dibakar Roy Chowdhury

We explore an inherent connection between two fundamental concepts of physics–resonance (eigen mode) hybridization and lattice effect in sub-wavelength periodic structures. Our study reveals that coupling with lattice mode is the prime deciding factor to determine the nature, position, and line shape of the hybridized states. Modulating lattice modes can effectively control mode hybridization and tune

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-17
Giorgio Biasiol and Simone Zanotto

Symmetry principles and theorems are of crucial importance in optics. Indeed, from one side, they allow obtaining direct insights into phenomena by eliminating unphysical interpretations; from the other side, they guide the designer of photonic components by narrowing down the parameter space of design variables. In this Letter, we illustrate a significant departure from the Babinet spectral complementarity

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-23
Ruoxing Wang, Jin Han, Jianlong Liu, Hao Tian, Weimin Sun, Li Li, and Xianzhong Chen

We propose a reflective terahertz (THz) metalens with four focal points for polarization detection of THz beams. The metalens is composed of ${{Z}}$-shaped resonators with spatially variant orientations, a reflective gold layer, and a dielectric spacer between them. The polarization states of the focal points include left circular polarization, right circular polarization, an incident polarization

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-25
Hasan Kocer, Yılmaz Durna, Hamza Kurt, and Ekmel Ozbay

Beam splitters are an indispensable part of optical measurements and applications. We propose a dynamic beam splitter incorporating all-dielectric metasurface in an elastic substrate under external mechanical stimulus of stretching. The optical behavior at 720 nm wavelength shows that it can be changed from a pure optical-diode-like behavior to a dynamic beam splitter. Although the structure is designed

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-29
Fengwei Zhan and Yu-Sheng Lin

We present a design of a tunable infrared (IR) resonator by using complementary circular metamaterial (CCM). CCM is composed of concentric rings. It exhibits superior characteristics of narrow multiresonance generated by the coupling between two adjacent concentric rings in the IR wavelength range. An effective modulation of reflection spectra can be realized by changing the height of each concentric

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-29
Evgenij Travkin, Thomas Kiel, Sergey Sadofev, Sascha Kalusniak, Kurt Busch, and Oliver Benson

We demonstrate experimentally and computationally an intricate cavity size dependence of the anomalous near-infrared mode spectrum of an ordinary optical resonator that is combined with a ZnO:Ga-based hyperbolic metamaterial (HMM). Specifically, we reveal the existence of a resonance in subwavelength-sized cavities and demonstrate control over the first-order cavity mode dispersion. We elaborate that

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-30
Qi Dai, Zile Li, Liangui Deng, Nan Zhou, Juan Deng, Jin Tao, and Guoxing Zheng

Under the government of Malus’s law, metasurfaces composed of anisotropic nanostructures acting as nano-polarizers have shown their precise optical manipulation of polarization profile of incident light at the nanoscale. The orientation degeneracy implied in Malus’s law provides a new design degree of freedom for polarization multiplexing, which can be employed to design amplitude-modulated multiplexing

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-17
L. Colombo, M. Pagliazzi, S. Konugolu Venkata Sekar, D. Contini, T. Durduran, and A. Pifferi

Time-domain diffuse correlation spectroscopy (TD-DCS) is a newly emerging optical technique that exploits pulsed, yet coherent light to non-invasively resolve the blood flow in depth. In this work, we have explored TD-DCS at longer wavelengths compared to those previously used in literature (i.e., 750–850 nm). The measurements were performed using a custom-made titanium-sapphire mode-locked laser,

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-22
Zhenyue Chen, Quanyu Zhou, Justine Robin, and Daniel Razansky

Imaging of cerebral vasculature is impeded with the existing fluorescence microscopy methods due to intense light scattering in living tissues and the need for highly invasive craniotomy procedures to resolve structures on a capillary scale. We propose a widefield fluorescence localization microscopy technique for high-resolution transcranial imaging and quantitative assessment of cortical perfusion

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-26
Hyeon-Cheol Park, Honghua Guan, Ang Li, Yuanlei Yue, Ming-Jun Li, Hui Lu, and Xingde Li

Fiber-optic-based two-photon fluorescence endomicroscopy is emerging as an enabling technology for in vivo histological imaging of internal organs and functional neuronal imaging on freely-behaving animals. However, high-speed imaging remains challenging due to the expense of miniaturization and lack of suited fast beam scanners. For many applications, a higher imaging speed is highly desired, especially

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-26
Yi Sun, Ethan W. Chen, Jalen Thomas, Yuan Liu, Haohua Tu, and Stephen A. Boppart

Extracellular vesicles (EVs) have emerged as potential biomarkers in cancer research and for clinical diagnosis. Little is known, however, about their spatial distributions in tissue and the different subpopulations that may exist. Here we report the use of label-free nonlinear optical imaging techniques to provide spatially resolved chemical information of EVs within untreated tissues. A multimodal

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-30
Xu Cao, Cuiping Yao, Shudong Jiang, Jason Gunn, Austin C. Van Namen, Petr Bruza, and Brian W. Pogue

Fluorescence imaging is severely limited by the background and autofluorescence of tissues for in vivo detection of circulating tumor cells (CTCs). Time-gated luminescence (TGL) imaging, in combination with luminescent probes that possess hundreds of microsecond emission lifetimes, can be used to effectively suppress this background, which has predominantly nanosecond lifetimes. This Letter demonstrates

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-22
Pengming Song, Ruihai Wang, Jiakai Zhu, Tianbo Wang, Zichao Bian, Zibang Zhang, Kazunori Hoshino, Michael Murphy, Shaowei Jiang, Chengfei Guo, and Guoan Zheng

We report an angle-tilted, wavelength-multiplexed ptychographic modulation approach for multispectral lensless on-chip microscopy. In this approach, we illuminate the specimen with lights at five wavelengths simultaneously. A prism is added at the illumination path for spectral dispersion. Thus, lightwaves at different wavelengths hit the specimen at slightly different incident angles, breaking the

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-26
P. Pozzi, M. Quintavalla, A. B. Wong, J. G. G. Borst, S. Bonora, and M. Verhaegen

In this Letter, we present a solution for simple implementation of adaptive optics in any existing laser scanning fluorescence microscope. Adaptive optics are implemented by the introduction of a multiactuator adaptive lens between the microscope body and the objective lens. Correction is performed with a sensorless method by optimizing the quality of the images presented on screen by the microscope

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-30
Guan-Yu Zhuo, Po-Lin Tsai, Hsien-Yi Wang, and Ming-Che Chan

Based on a rigid square fiber for wave vector delivery, we present a novel (to the best of our knowledge) wave-vector-encoded nonlinear-optical endomicroscopy (WENE). WENE overcomes three tangled issues, including femtosecond pulse broadening induced signal degradation, complexity of packaging miniaturized scanners in the distal end, and pixel-like images, which cannot be fully addressed by current

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-30
Md Rasedujjaman, Kévin Affannoukoué, Nicolas Garcia-Seyda, Philippe Robert, Hugues Giovannini, Patrick C. Chaumet, Olivier Theodoly, Marie-Pierre Valignat, Kamal Belkebir, Anne Sentenac, and Guillaume Maire

Biomedical imaging lacks label-free microscopy techniques able to reconstruct the contour of biological cells in solution, in 3D and with high resolution, as required for the fast diagnosis of numerous diseases. Inspired by computational optical coherence tomography techniques, we present a tomographic diffractive microscope in reflection geometry used as a synthetic confocal microscope, compatible

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-30
Lejia Hu, Shuwen Hu, Wei Gong, and Ke Si

The conventional Shack–Hartmann wavefront sensor (SHWS) requires wavefront slope measurements of every micro-lens for wavefront reconstruction. In this Letter, we applied deep learning on the SHWS to directly predict the wavefront distributions without wavefront slope measurements. The results show that our method could provide a lower root mean square wavefront error in high detection speed. The performance

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-30
Yiming Li, Elena Buglakova, Yongdeng Zhang, Jervis Vermal Thevathasan, Joerg Bewersdorf, and Jonas Ries

Interferometric single-molecule localization microscopy (iPALM, 4Pi-SMS) uses multiphase interferometry to localize single fluorophores and achieves nanometer isotropic resolution in 3D. The current data analysis workflow, however, fails to reach the theoretical resolution limit due to the suboptimal localization algorithm. Here, we develop a method to fit an experimentally derived point spread function

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-17
Antoine F. J. Runge, Tristram J. Alexander, Joseph Newton, Pranav A. Alavandi, Darren D. Hudson, Andrea Blanco-Redondo, and C. Martijn de Sterke

We study the propagation of ultrashort pulses in optical fiber with gain and positive (or normal) quartic dispersion by self-similarity analysis of the modified nonlinear Schrödinger equation. We find an exact asymptotic solution, corresponding to a triangle-like ${T^{4/3}}$ intensity profile, with a ${T^{1/3}}$ chirp, which is confirmed by numerical simulations. This solution follows different amplitude

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-17
Youhei Okawa and Kazuo Hotate

We propose and demonstrate a novel method for controlling stimulated Brillouin scattering with light in a phase-sensitive manner. Our results indicate that Brillouin gain can be enhanced or suppressed in a polarization-maintaining fiber via acoustic wave interference by controlling the relative phase of orthogonally polarized light, which induces acoustic waves. This method paves the way for the all-optical

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-24
M. I. Bakunov, E. S. Efimenko, S. D. Gorelov, N. A. Abramovsky, and S. B. Bodrov

A nonlinear structure for efficient Cherenkov-type terahertz emission from ultrashort laser pulses is proposed, modeled, and experimentally demonstrated. The structure comprises a thin (a few tens of micrometers thick) layer of lithium niobate sandwiched between two silicon prisms. A focused-to-a-line laser pulse propagates in the layer and generates a Cherenkov wedge of terahertz radiation in the

更新日期：2020-07-02
• Opt. Lett. (IF 3.714) Pub Date : 2020-06-24
Etienne Genier, Amar N. Ghosh, Swetha Bobba, Patrick Bowen, Peter M. Moselund, Ole Bang, John M. Dudley, and Thibaut Sylvestre

We demonstrate broadband supercontinuum generation in an all-normal dispersion polarization-maintaining photonic crystal fiber and report the observation of a cross-phase modulation instability sideband generated outside of the supercontinuum bandwidth. We demonstrate that this sideband is polarized on the slow axis and can be suppressed by pumping on the fiber’s fast axis. We theoretically confirm

更新日期：2020-07-02
Contents have been reproduced by permission of the publishers.

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