Publications by authors named "Chunlei Guo"

116 Publications

Resonance-enhanced high harmonic in metal ions driven by elliptically polarized laser pulses.

Opt Lett 2021 May;46(10):2372-2375

Resonance enhancement of a single order harmonic has been a main attractive feature in high-harmonic generation from laser ablated plumes of metals. Although it has been extensively investigated experimentally and theoretically, studies so far have focused only on linearly polarized driving fields. In this Letter, we study the dependence of the resonant harmonic yield in tin ions on the driving laser ellipticity. We find that the resonance leads to a less rapid decay of the harmonic yield as a function of driving ellipticity, and it is qualitatively reproduced by quantum mechanical simulations. To the best of our knowledge, our findings provide a new type of evidence for supporting previously proposed mechanisms for enhancement.
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http://dx.doi.org/10.1364/OL.425495DOI Listing
May 2021

Comparative transcriptomic analysis highlights contrasting levels of resistance of Vitis vinifera and Vitis amurensis to Botrytis cinerea.

Hortic Res 2021 May 1;8(1):103. Epub 2021 May 1.

State Key Laboratory of Crop Stress Biology in Arid Areas, College of Horticulture, Northwest A&F University, 712100, Yangling, Xianyang, Shaanxi, China.

Botrytis cinerea is a major grapevine (Vitis spp.) pathogen, but some genotypes differ in their degree of resistance. For example, the Vitis vinifera cultivar Red Globe (RG) is highly susceptible, but V. amurensis Rupr Shuangyou (SY) is highly resistant. Here, we used RNA sequencing analysis to characterize the transcriptome responses of these two genotypes to B. cinerea inoculation at an early infection stage. Approximately a quarter of the genes in RG presented significant changes in transcript levels during infection, the number of which was greater than that in the SY leaves. The genes differentially expressed between infected leaves of SY and RG included those associated with cell surface structure, oxidation, cell death and C/N metabolism. We found evidence that an imbalance in the levels of reactive oxygen species (ROS) and redox homeostasis probably contributed to the susceptibility of RG to B. cinerea. SY leaves had strong antioxidant capacities and improved ROS homeostasis following infection. Regulatory network prediction suggested that WRKY and MYB transcription factors are associated with the abscisic acid pathway. Weighted gene correlation network analysis highlighted preinfection features of SY that might contribute to its increased resistance. Moreover, overexpression of VaWRKY10 in Arabidopsis thaliana and V. vinifera Thompson Seedless enhanced resistance to B. cinerea. Collectively, our study provides a high-resolution view of the transcriptional changes of grapevine in response to B. cinerea infection and novel insights into the underlying resistance mechanisms.
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http://dx.doi.org/10.1038/s41438-021-00537-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8087793PMC
May 2021

High-speed femtosecond laser plasmonic lithography and reduction of graphene oxide for anisotropic photoresponse.

Light Sci Appl 2020 Apr 26;9(1):69. Epub 2020 Apr 26.

State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 130033, Changchun, China.

Micro/nanoprocessing of graphene surfaces has attracted significant interest for both science and applications due to its effective modulation of material properties, which, however, is usually restricted by the disadvantages of the current fabrication methods. Here, by exploiting cylindrical focusing of a femtosecond laser on graphene oxide (GO) films, we successfully produce uniform subwavelength grating structures at high speed along with a simultaneous in situ photoreduction process. Strikingly, the well-defined structures feature orientations parallel to the laser polarization and significant robustness against distinct perturbations. The proposed model and simulations reveal that the structure formation is based on the transverse electric (TE) surface plasmons triggered by the gradient reduction of the GO film from its surface to the interior, which eventually results in interference intensity fringes and spatially periodic interactions. Further experiments prove that such a regular structured surface can cause enhanced optical absorption (>20%) and an anisotropic photoresponse (~0.46 ratio) for the reduced GO film. Our work not only provides new insights into understanding the laser-GO interaction but also lays a solid foundation for practical usage of femtosecond laser plasmonic lithography, with the prospect of expansion to other two-dimensional materials for novel device applications.
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http://dx.doi.org/10.1038/s41377-020-0311-2DOI Listing
April 2020

Spectrally resolved wedged reversal shearing interferometer.

Opt Lett 2021 Apr;46(8):1796-1799

In this Letter, we introduce a technique to fully determine the spatio-temporal electric field (,,) of an arbitrary ultrashort pulse. By passing the beam through a wedged reversal shearing interferometer followed by a scanning Michelson interferometer, the field autocorrelation of the shearing interferograms is measured. The spectrum of the shearing interferograms is obtained after a Fourier transform by the Whittaker-Shannon sampling theorem, yielding the amplitude and wavefront information at every wavelength. With the addition of the phase information of a single point, we are able to directly reconstruct the spatio-temporal electric field (,,) of an arbitrary ultrashort pulse.
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http://dx.doi.org/10.1364/OL.417997DOI Listing
April 2021

Ultrabroadband, compact, polarization independent and efficient metasurface-based power splitter on lithium niobate waveguides.

Opt Express 2021 Mar;29(6):8160-8170

We propose a metasurface-based Lithium Niobate waveguide power splitter with an ultrabroadband and polarization independent performance. The design consists of an array of amorphous silicon nanoantennas that partially converts the input mode to multiple output modes creating multimode interference such that the input power is equally split and directed to two branching waveguides. FDTD simulation results show that the power splitter operates with low insertion loss (< 1dB) over a bandwidth of approximately 800 nm in the near-infrared range, far exceeding the O, E, S, C, L and U optical communication bands. The metasurface is ultracompact with a total length of 2.7 µm. The power splitter demonstrates a power imbalance of less than 0.16 dB for both fundamental TE and TM modes. Our simulations show that the device efficiency exhibits high tolerance to possible fabrication imperfections.
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http://dx.doi.org/10.1364/OE.415676DOI Listing
March 2021

The prevalence and distribution of human papillomavirus among 10,867 Chinese Han women.

Infect Agent Cancer 2021 Mar 25;16(1):21. Epub 2021 Mar 25.

Department of Obstetrics and Gynecology, Peking University Shenzhen Hospital, No. 1120, Lianhua Road, Shenzhen, Guangdong, 518036, PR China.

Objective: To assess the prevalence and distribution of HPV genotypes among Chinese Han women, and to explore the risk of high-grade cervical lesions associated with individual hr-HPV genotypes.

Methods: Genotyping and histopathology data from the Chinese Multi-Center Screening Trial (CHIMUST) and its pilot screening trial, from 6 regions across mainland China, were re-analyzed. The data from physician- and self-collected samples from 10,867 Chinese Han women (ages 30-69) were used to determine the prevalence and distribution of hr-HPV and to explore the risk association between hr-HPV genotypes and precancerous lesions.

Results: 9.2% of the study population tested hr-HPV positive in physician-collected sample. The prevalence varied regionally from the lowest in Guangdong (6.3%) to the highest in Inner Mongolia (13.0%). The most prevalent genotypes found were HPV-52 (21.7%), HPV-16 (19.2%), HPV-58 (15.0%), HPV-39 (8.9%), and HPV-51 (8.2%). The overall odds ratios for CIN2+ and CIN3+ for the presence of HPV-16 was 58.6 (95% CI 39.2-87.5) and, 91.6 (95%CI 54.3-154.6), respectively and remained the highest odds ratio for CIN3+ in all 6 regions.

Conclusion: Geographical variation exists in the prevalence and distribution of hr-HPV in mainland China. HPV-16/52/58 were the most prevalent genotypes, and HPV-16 had the highest risk for high-grade cervical lesions.

Trial Registration: CHIMUST, Registration number: ChiCTR-EOC-16008456 . Registered 11 May 2016.
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http://dx.doi.org/10.1186/s13027-021-00360-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7993460PMC
March 2021

Significantly enhanced electrocatalytic activity of copper for hydrogen evolution reaction through femtosecond laser blackening.

Int J Hydrogen Energy 2021 Mar;46(18):10783-10788

The Institute of Optics, University of Rochester, Rochester, NY 14627, United States.

In this work, we report on the creation of a black copper via femtosecond laser processing and its application as a novel electrode material. We show that the black copper exhibits an excellent electrocatalytic activity for hydrogen evolution reaction (HER) in alkaline solution. The laser processing results in a unique microstructure: microparticles covered by finer nanoparticles on top. Electrochemical measurements demonstrate that the kinetics of the HER is significantly accelerated after bare copper is treated and turned black. At -0.325 V (v.s. RHE) in 1 M KOH aqueous solution, the calculated area-specific charge transfer resistance of the electrode decreases sharply from 159 Ω cm for the untreated copper to 1 Ω cm for the black copper. The electrochemical surface area of the black copper is measured to be only 2.4 times that of the untreated copper and therefore, the significantly enhanced electrocatalytic activity of the black copper for HER is mostly a result of its unique microstructure that favors the formation and enrichment of protons on the surface of copper. This work provides a new strategy for developing high-efficient electrodes for hydrogen generation.
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http://dx.doi.org/10.1016/j.ijhydene.2020.12.174DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7939068PMC
March 2021

Fano-resonant ultrathin film optical coatings.

Nat Nanotechnol 2021 Apr 4;16(4):440-446. Epub 2021 Feb 4.

The Institute of Optics, University of Rochester, Rochester, NY, USA.

Optical coatings are integral components of virtually every optical instrument. However, despite being a century-old technology, there are only a handful of optical coating types. Here, we introduce a type of optical coatings that exhibit photonic Fano resonance, or a Fano-resonant optical coating (FROC). We expand the coupled mechanical oscillator description of Fano resonance to thin-film nanocavities. Using FROCs with thicknesses in the order of 300 nm, we experimentally obtained narrowband reflection akin to low-index-contrast dielectric Bragg mirrors and achieved control over the reflection iridescence. We observed that semi-transparent FROCs can transmit and reflect the same colour as a beam splitter filter, a property that cannot be realized through conventional optical coatings. Finally, FROCs can spectrally and spatially separate the thermal and photovoltaic bands of the solar spectrum, presenting a possible solution to the dispatchability problem in photovoltaics, that is, the inability to dispatch solar energy on demand. Our solar thermal device exhibited power generation of up to 50% and low photovoltaic cell temperatures (~30 °C), which could lead to a six-fold increase in the photovoltaic cell lifetime.
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http://dx.doi.org/10.1038/s41565-020-00841-9DOI Listing
April 2021

Phase change material based hot electron photodetection.

Nanoscale 2021 Jan;13(2):1311-1317

The Institute of Optics, University of Rochester, Rochester, New York 14627, USA.

We introduce a phase change material (PCM) based metal-dielectric-metal (MDM) cavity of gold (Au)-antimony trisulfide (Sb2S3)-Au as a hot electron photodetector (HEPD). Sb2S3 shows significant contrast in the bandgap (Eg) upon phase transition from the crystalline (Cry) (Eg = 2.01 eV) to the amorphous (Amp) (Eg = 1.72 eV) phase and forms the lowest Schottky barrier with Au in its Amp phase compared to conventional semiconductors such as Si, MoS2, and TiO2. The proposed HEPD is tunable for absorption and responsivity in the spectral range of 720 nm < λ < 1250 nm for the Cry phase and 604 nm < λ < 3542 nm for the Amp phase. The single resonance cavity and thus the sensitivity of the designed HEPD device can be changed to the double resonance cavity via the Cry to Amp phase transition. The maximum predicted responsivities for the single and double cavities are 20 and 24 mA W-1, respectively, at 950 nm and 1050 nm wavelengths which is the highest among all previously proposed planar HEPD devices. An anti-symmetric resonance mode at a higher wavelength is observed in the double cavity with 100% absorption. Owing to a high index of Sb2S3, an ultrathin ∼40 nm (∼λ/15) MDM cavity supports a critical light coupling to achieve high-efficiency HEPDs. Furthermore, a reversible and ultrafast (∼70 ns) Cry to Amp phase transition of Sb2S3 makes it suitable for many tunable photonics applications ranging from the visible to near-infrared region. Finally, we have introduced a novel scheme to switch between the single and double cavity by exploiting a semiconductor to metal phase transition in a PCM called VO2. The integration of VO2 as a coupling medium in the double cavity has increased the responsivity up to 50% upon phase transition to the metal phase. The proposed design can be used in optical filters, optical switches, ultrathin broad or narrow band solar absorbers, and other energy applications such as water splitting.
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http://dx.doi.org/10.1039/d0nr06456dDOI Listing
January 2021

Rapid fabrication of anti-corrosion and self-healing superhydrophobic aluminum surfaces through environmentally friendly femtosecond laser processing.

Opt Express 2020 Nov;28(24):35636-35650

The development of superhydrophobic metals has found many applications such as self-cleaning, anti-corrosion, anti-icing, and water transportation. Recently, femtosecond laser has been used to create nano/microstructures and wetting property changes. However, for some of the most common metals, such as aluminum, a relatively long aging process is required to obtain stable hydrophobicity. In this work, we introduce a combination of femtosecond laser ablation and heat treatment post-process, without using any harsh chemicals. We turn aluminum superhydrophobic within 30 minutes of heat treatment following femtosecond laser processing, and this is significantly shorter compared to conventional aging process of laser-ablated aluminum. The superhydrophobic surfaces maintain high contact angles greater than 160° and low sliding angles smaller than 5° over two months after the heat treatment. Moreover, the samples exhibit strong superhydrophobicity for various types of liquids (milk, coffee, CuPc, R6G, HCl, NaOH and CuCl). The samples also show excellent self-healing and anti-corrosion properties. The mechanism for fast wettability conversion time is discussed. Our technique is a rapid process, reproducible, feasible for large-area fabrication, and environment-friendly.
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http://dx.doi.org/10.1364/OE.400804DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7771893PMC
November 2020

Optical-field driven charge-transfer modulations near composite nanostructures.

Nat Commun 2020 Dec 1;11(1):6150. Epub 2020 Dec 1.

CNRS-Ewha International Research Center, Ewha Womans University, Seoul, South Korea.

Optical activation of material properties illustrates the potentials held by tuning light-matter interactions with impacts ranging from basic science to technological applications. Here, we demonstrate for the first time that composite nanostructures providing nonlocal environments can be engineered to optically trigger photoinduced charge-transfer-dynamic modulations in the solid state. The nanostructures explored herein lead to out-of-phase behavior between charge separation and recombination dynamics, along with linear charge-transfer-dynamic variations with the optical-field intensity. Using transient absorption spectroscopy, up to 270% increase in charge separation rate is obtained in organic semiconductor thin films. We provide evidence that composite nanostructures allow for surface photovoltages to be created, which kinetics vary with the composite architecture and last beyond optical pulse temporal characteristics. Furthermore, by generalizing Marcus theory framework, we explain why charge-transfer-dynamic modulations can only be unveiled when optic-field effects are enhanced by nonlocal image-dipole interactions. Our demonstration, that composite nanostructures can be designed to take advantage of optical fields for tuneable charge-transfer-dynamic remote actuators, opens the path for their use in practical applications ranging from photochemistry to optoelectronics.
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http://dx.doi.org/10.1038/s41467-020-19423-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7708636PMC
December 2020

Phase change material-based nano-cavity as an efficient optical modulator.

Nanotechnology 2021 Feb;32(9):095207

The Institute of Optics, University of Rochester, Rochester, NY 14627, United States of America.

Structural phase transition induced by temperature or voltage in phase change materials has been used for many tunable photonic applications. Exploiting reversible and sub-ns fast switching in antimony trisulfide (SbS) from amorphous (Amp) to crystalline (Cry), we introduced a reflection modulator based on metal-dielectric-metal structure. The proposed design exhibits tunable, perfect, and multi-band absorption from visible to the near-infrared region. The reflection response of the system shows >99% absorption of light at normal incidence. The maximum achievable modulation efficiency with a narrow line width is ∼98%. Interestingly, the designed cavity supports critical resonance in an ultrathin (∼λ/15) SbS film with perfect, broadband, and tunable absorption. Finally, we proposed a novel hybrid cavity design formed of Cry and Amp SbS thin films side-by-side to realize an optical modulator via relative motion between the incident light beam and cavity. The proposed lithographic free structure can be also used for filtering, optical switching, ultrathin photo-detection, solar energy harvesting, and other energy applications.
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http://dx.doi.org/10.1088/1361-6528/abcb7aDOI Listing
February 2021

Compositional Engineering Study of Lead-Free Hybrid Perovskites for Solar Cell Applications.

ACS Appl Mater Interfaces 2020 Nov 20;12(44):49636-49647. Epub 2020 Oct 20.

The Guo Photonics Laboratory, Changchun Institute of Optics, Fine Mechanics, and Physics, Chinese Academy of Sciences, Changchun 130033, China.

Hybrid organic-inorganic perovskite solar cells (HOIPs), especially CHNHPbI (MAPbI), have received tremendous attention due to their excellent power conversion efficiency (25.2%). However, two fundamental hurdles, long-term stability and lead (Pb) toxicity, prevent HOIPs from practical applications in the solar industry. To overcome these issues, compositional engineering has been used to modify cations at A- and B-sites and anions at the X-site in the general form ABX. In this work, we used the density functional theory (DFT) to incorporate Rb, Cs, and FA at the A-site to minimize the volatile nature of MA, while the highly stable Ca and Sr were mixed with the less stable Ge and Sn at the B-site to obtain a Pb-free perovskite. To further enhance the stability, we mixed the X-site anions (I/Br). Through this approach, we introduced 20 new perovskite species to the lead-free perovskite family and 7 to the lead-containing perovskite family. The molecular dynamic (MD) simulations, enthalpy formation, and tolerance and octahedral factor study confirm that all of the perovskite alloys we introduced here are as stable as pristine MAPbI. All Pb-free perovskites have suitable and direct band gaps (1.42-1.77 eV) at the Γ-point, which are highly desirable for solar cell applications. Most of our Pb-free perovskites have smaller effective masses and exciton binding energies. Finally, we show that the introduced perovskites have high absorption coefficients (10 cm) and strong absorption efficiencies (above 90%) in a wide spectral range (300-1200 nm), reinforcing their significant potential applications. This study provides a new way of searching for stable lead-free perovskites for sustainable and green energy applications.
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http://dx.doi.org/10.1021/acsami.0c14595DOI Listing
November 2020

Construction of a simple and intelligent DNA-based computing system for multiplexing logic operations.

Acta Biomater 2020 12 6;118:44-53. Epub 2020 Oct 6.

The Institute of Optics, University of Rochester, Rochester, New York, 14627, United States.

Over the past few decades, DNA-based computing technology has become a rapidly developing technology and shown remarkable capabilities in handling complex computational problems. However, most of the logical operations that DNA computer can achieve are still very basic or using large-scale operations to realize complex functions, especially in mathematics. Graphene oxide (GO) is an ideal nanomaterial for biological computing, which has been used in our previous work to perform basic logic operations. Here, we utilize GO to implement far more complex and large-scale logical computing. For the first time, in this work, we utilize the unique interaction between GO and a variety of classified single-stranded DNAs as the reaction platform, by segmenting and encoding the DNA sequences, and programming the interactions between inputs and between the inputs and reaction platform, two relative large-scale logic operations, 6-bit square-root and 9-bit cube-root logical circuits are realized. This study provides a simple but efficient method for advanced and large-scale logical mathematic operations in biotechnology, opening a new horizon for building biocomputer-based innovative functional devices.
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http://dx.doi.org/10.1016/j.actbio.2020.09.054DOI Listing
December 2020

Multipronged heat-exchanger based on femtosecond laser-nano/microstructured Aluminum for thermoelectric heat scavengers.

Nano Energy 2020 Sep;75:104987

The Institute of Optics, University of Rochester, Rochester, NY, 14627, USA.

Femtosecond (fs) laser processing can significantly alter the optical, thermal, mechanical, and electrical properties of materials. Here, we show that fs-laser processing transforms aluminum (Al) to a highly efficient and multipronged heat exchanger. By optimizing the formed surface nano- and microstructures, we increase the Al emissivity and surface area by 700% and 300%, respectively. Accordingly, we show that fs-laser treated Al (fs-Al) increases the radiative and convective cooling power of fs-Al by 2100% and 300%, respectively, at 200 °C. As a direct application, we use fs-Al as a heat sink for a thermoelectric generator (TEG) and demonstrate a 280% increase in the TEG output power compared to a TEG with an untreated Al heat exchanger at 200 °C. The multipronged enhancement in fs-Al heat exchange properties lead to an increase in the TEG output power over a wide temperature ( ) range ( ). Conversely, a simple radiative cooling heat exchanger increases the TEG output power within a limited temperature range . We investigate the laser processing parameters necessary to maximize the spectral emissivity and surface area of fs-Al. Fs-Al promises to be a widely used and compact heat exchanger for passive cooling of computers and data centers as well as to increase the efficiency of TEGs incorporated in sensors and handheld electronics.
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http://dx.doi.org/10.1016/j.nanoen.2020.104987DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7453914PMC
September 2020

Plasmonic analogue of geometric diodes realizing asymmetric optical transmission.

Opt Lett 2020 Jul;45(14):3937-3940

Geometric diodes represent a relatively new class of diodes used in rectennas that rely on the asymmetry of a conducting thin film. Here, we numerically investigate a plasmonic analogue of geometric diodes to realize nanoscale optical asymmetric transmission. The device operates based on spatial symmetry breaking that relies on a unique property of surface plasmon polaritons (SPPs), namely, adiabatic nanofocusing. We show that the structure can realize on-chip asymmetric electromagnetic transmission with a total dimension of ∼2µ×6µ. We demonstrate a signal contrast of 0.7 and an asymmetric optical transmission ratio of 4.77 dB. We investigate the origin of the asymmetric transmission and show that it is due mainly to asymmetric out-coupling of SPPs to far-field photons. We highlight the role of evanescent field coupling of SPPs in undermining the asymmetric transmission efficiency and show that by adjusting the plasmonic waveguide dimensions, a signal contrast of 0.94 and an asymmetric optical transmission ratio of 5.18 dB can be obtained. Our work presents a new paradigm for on-chip nanoscale asymmetric optical transmission utilizing the unique properties of SPPs.
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http://dx.doi.org/10.1364/OL.397601DOI Listing
July 2020

Modulating the optical and electrical properties of MAPbBr single crystals via voltage regulation engineering and application in memristors.

Light Sci Appl 2020 30;9:111. Epub 2020 Jun 30.

The Guo Photonics Laboratory, State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 130033 Changchun, China.

Defect density is one of the most significant characteristics of perovskite single crystals (PSCs) that determines their optical and electrical properties, but few strategies are available to tune this property. Here, we demonstrate that voltage regulation is an efficient method to tune defect density, as well as the optical and electrical properties of PSCs. A three-step carrier transport model of MAPbBr PSCs is proposed to explore the defect regulation mechanism and carrier transport dynamics via an applied bias. Dynamic and steady-state photoluminescence measurements subsequently show that the surface defect density, average carrier lifetime, and photoluminescence intensity can be efficiently tuned by the applied bias. In particular, when the regulation voltage is 20 V (electrical poling intensity is 0.167 V μm), the surface defect density of MAPbBr PSCs is reduced by 24.27%, the carrier lifetime is prolonged by 32.04%, and the PL intensity is increased by 112.96%. Furthermore, a voltage-regulated MAPbBr PSC memristor device shows an adjustable multiresistance, weak ion migration effect and greatly enhanced device stability. Voltage regulation is a promising engineering technique for developing advanced perovskite optoelectronic devices.
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http://dx.doi.org/10.1038/s41377-020-00349-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7327067PMC
June 2020

All-optical logic gates using dielectric-loaded waveguides with quasi-rhombus metasurfaces.

Opt Lett 2020 Jul;45(13):3769-3772

Nanostructure and nanoantenna-based all-optical (AO) devices have attracted significant research interests in recent years due to their small size, high information capacity, ultrafast processing, low power consumption, and overall practicality. Here, in this Letter, we propose a novel metasurface having quasi-rhombus-shaped antennas to modulate optical modes in a dielectric-loaded waveguide for the realization of a complete family of logic gates including NOT, AND, OR, XOR, NAND, NOR, and XNOR. These logic operations are realized using destructive and constructive interferences between the input optical signals. The high contrast ratios of about 33.39, 27.69, and 33.11 dB are achieved for the NAND, NOR, and XNOR logic gates, respectively, with the speed as high as 108 Gb/s.
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http://dx.doi.org/10.1364/OL.396978DOI Listing
July 2020

Rotationally symmetric colorization of metal surfaces through omnidirectional femtosecond laser-induced periodic surface structures.

Opt Lett 2020 Jul;45(13):3414-3417

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 across the laser spot and create OD-LSFLs by raster scanning fs laser pulses. We also show that the period of the OD-LSFL orientation rotation can be controlled with the defocused distance, and OD-LSFLs can significantly expand the viewing angle of the structural colors in the azimuthal direction without noticeable color degradations.
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http://dx.doi.org/10.1364/OL.396375DOI Listing
July 2020

Spatial Wavefunction Characterization of Femtosecond Pulses at Single-Photon Level.

Research (Wash D C) 2020 15;2020:2421017. Epub 2020 Jun 15.

The Institute of Optics, University of Rochester, Rochester, New York 14627, USA.

Reading quantum information of single photons is commonly realized by quantum tomography or the direct (weak) measurement approach. However, these methods are time-consuming and face enormous challenges in characterizing single photons from an ultrafast light source due to the stringent temporal mode matching requirements. Here, we retrieve the spatial wavefunction of indistinguishable single photons from both a continuous wave source and a femtosecond light source using a self-referencing interferometer. Our method only requires nine ensemble-averaged measurements. This technique simplifies the measurement procedure of single-photon wavefunction and automatically mode matches each self-interfering single photon temporally, which enables the measurement of the spatial wavefunction of single photons from an ultrafast light source.
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http://dx.doi.org/10.34133/2020/2421017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7312785PMC
June 2020

High-efficiency non-diffractive generator of arbitrary vectorial optical fields with minimal optical elements.

Opt Commun 2020 May;463:125443

The Institute of Optics, University of Rochester, Rochester, NY, 14627, USA.

Tailoring electromagnetic waves has a wide range of applications, such as optical trapping, focus engineering, imaging, laser cutting, and optical communication. To do so, the spatial distribution of at least one of the four degrees of freedom of electromagnetic waves, amplitude, phase, polarization ratio, and retardance, must be modified. Arbitrary vectorial optical fields (VOF) can be engineered by spatially modulating all four degrees of freedom simultaneously. However, existing dynamic vectorial optical field generators (VOF-Gens) require intensive alignment and many optical elements in order to achieve high efficiency. Here, we design a dynamic VOF-Gen that can generate arbitrary VOFs using only five optical elements. Experimentally, we demonstrated an efficiency of 72%, the highest ever demonstrated.
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http://dx.doi.org/10.1016/j.optcom.2020.125443DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7097970PMC
May 2020

Back-Reflected Performance-Enhanced Flexible Perovskite Photodetectors through Substrate Texturing with Femtosecond Laser.

ACS Appl Mater Interfaces 2020 Jun 1;12(23):26614-26623. Epub 2020 Jun 1.

State Key Laboratory for Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.

Recently, enhancing the performance of flexible perovskite photodetectors through facile and effective means has gained greater attention. In contrast to typical approaches through modifying light-active materials, we present here a simple but effective design by improving light-matter interactions through near-field optical interference on a back-reflected substrate, whose architecture includes a morphologically flat top surface and a backscattering surface textured with micro/nanostructures by the femtosecond laser direct writing. A CHNHPbI perovskite film and poly(ethylene terephthalate) are selected as the light-active and base materials, respectively. Under a 1 V bias voltage actuation and 532 nm laser irradiation at an intensity of 10 mW cm, the flexible device exhibits excellent performance in photoresponsivity (47.1 mA W), detectivity (3.7 × 10 Jones), and on/off ratio (4600). Due to the near-field optical enhancement of the substrate and the strong light-matter interaction, the above performance parameters are enhanced by at least 5 times over a wide spectral range of 220-780 nm. Such enhancement behaviors are independent of active material properties and therefore can be compatible with other operations such as crystalline transformation, doping, and interface modification. Moreover, the alteration of stress distribution on the structured substrate facilitates the bending robustness and stability. These features highlight the potential of back-reflected design in the development of flexible perovskite photoelectric devices, which are especially suitable for large-scale industrial production.
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http://dx.doi.org/10.1021/acsami.0c04124DOI Listing
June 2020

Thin-film perfect infrared absorbers over single- and dual-band atmospheric windows.

Opt Lett 2020 May;45(10):2800-2803

A thin-film perfect electromagnetic absorber with a tunable response in the infrared (IR) region is proposed using a metal-dielectric-metal configuration, which consists of a Ti top layer and a Ge spacer layer on a Ti substrate. The thin-film structure simplifies the absorber design by tuning the thicknesses of the two layers, which is suitable for large-scale fabrication by matured deposition technologies. The absorber supports perfect IR absorption with tunability from 3 µm to over 15 µm. Furthermore, the total thickness is much smaller than the wavelength, and the absorption has small iridescence. Based on this design, we demonstrated two samples with one supporting single-band absorption in the atmospheric absorption window (5-8 µm) and the other one supporting dual-band absorption in the two atmospheric transmission windows (3-5 and 8-13 µm). These absorption signatures can find applications in IR invisibility and radiative cooling.
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http://dx.doi.org/10.1364/OL.392651DOI Listing
May 2020

A Highly Sensitive Single Crystal Perovskite-Graphene Hybrid Vertical Photodetector.

Small 2020 Jun 14;16(25):e2000733. Epub 2020 May 14.

The Guo Photonics Laboratory, State Key Laboratory of Applied Optics Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences (CAS), Changchun, 130033, P. R. China.

Organolead trihalide perovskites have attracted significant attention for optoelectronic applications due to their excellent physical properties in the past decade. Generally, both grain boundaries in perovskite films and the device structure play key roles in determining the device performance, especially for horizontal-structured device. Here, the first optimized vertical-structured photodetector with the perovskite single crystal MAPbBr as the light absorber and graphene as the transport layer is shown. The hybrid device combines strong photoabsorption characteristics of perovskite and high carrier mobility of flexible graphene, exhibits excellent photoresponse performance with high photoresponsivity (≈1017.1 A W ) and high photodetectivity (≈2.02 × 10 Jones) in a low light intensity (0.66 mW cm ) under the actuations of 3 V bias and laser irradiation at 532 nm. In particular, an ultrahigh photoconductive gain of ≈2.37 × 10 is attained because of fast charge transfer in the graphene and large recombination lifetime in the perovskite single crystal. The vertical architecture combining perovskite crystal with highly conductive graphene offers opportunities to fulfill the synergistic effect of perovskite and 2D materials, is thus promising for developing high-performance electronic and optoelectronic devices.
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http://dx.doi.org/10.1002/smll.202000733DOI Listing
June 2020

Boosting Perovskite Photodetector Performance in NIR Using Plasmonic Bowtie Nanoantenna Arrays.

Small 2020 Jun 14;16(24):e2001417. Epub 2020 May 14.

The Guo Photonics Laboratory, State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033, P. R. China.

Triple-cation mixed metal halide perovskites are important optoelectronic materials due to their high photon to electron conversion efficiency, low exciton binding energy, and good thermal stability. However, the perovskites have low photon to electron conversion efficiency in near-infrared (NIR) due to their weak intrinsic absorption at longer wavelength, especially near the band edge and over the bandgap wavelength. A plasmonic functionalized perovskite photodetector (PD) is designed and fabricated in this study, in which the perovskite ((Cs FA MA )Pb(I Br ) ) active materials are spin-coated on the surface of Au bowtie nanoantenna (BNA) arrays substrate. Under 785 nm laser illumination, near the bandedge of perovskite, the fabricated BNA-based plasmonic PD exhibits ≈2962% enhancement in the photoresponse over the Si/SiO -based normal PD. Moreover, the detectivity of the plasmonic PD has a value of 1.5 × 10 with external quantum efficiency as high as 188.8%, more than 30 times over the normal PD. The strong boosting in the plasmonic PD performance is attributed to the enhanced electric field around BNA arrays through the coupling of localized surface plasmon resonance. The demonstrated BNA-perovskite design can also be used to enhance performance of other optoelectronic devices, and the concept can be extended to other spectral regions with different active materials.
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http://dx.doi.org/10.1002/smll.202001417DOI Listing
June 2020

Dynamic control of spontaneous emission rate using tunable hyperbolic metamaterials.

Opt Lett 2020 Apr;45(7):1671-1674

We numerically investigate the dynamic control over the spontaneous emission rate of quantum emitters using tunable hyperbolic metamaterials (HMMs). The dispersion of a metal-dielectric thin-film stack at a given frequency can undergo a topological transition from an elliptical to a hyperbolic dispersion by incorporating a tunable metal or dielectric film in the HMM. This transition modifies the local density of optical states of the emitter and, hence, its emission rate. In the visible range, we use an HMM consisting of TiN and ${{\rm Sb}_2}{{\rm S}_3}$SbS and show considerable tunability in the Purcell enhancement and quantum efficiency as ${{\rm Sb}_2}{{\rm S}_3}$SbS phase changes from amorphous to crystalline. Similarly, we show tunable Purcell enhancement in the telecommunication wavelength range using a ${\rm TiN}/{{\rm VO}_2}$TiN/VO- HMM. Finally, tunable spontaneous emission rate in the mid-IR range is obtained using a ${\rm graphene}/{\rm MgF}_2$graphene/MgF HMM by modifying the graphene conductivity through changing its chemical potential. We show that using a metal nitride (for the visible and NIR HMMs) and a fluoride (for the mid-IR HMM) is important to get an appreciable change in the effective permittivity of the thin-film multilayer stack.
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http://dx.doi.org/10.1364/OL.385844DOI Listing
April 2020

What and How Can Physical Activity Prevention Function on Parkinson's Disease?

Oxid Med Cell Longev 2020 13;2020:4293071. Epub 2020 Feb 13.

Laboratory of Brain Function and Disease, Institute for Brain Sciences Research, School of Life Sciences, Henan University, China.

Aim: This study was aimed at investigating the effects and molecular mechanisms of physical activity intervention on Parkinson's disease (PD) and providing theoretical guidance for the prevention and treatment of PD.

Methods: Four electronic databases up to December 2019 were searched (PubMed, Springer, Elsevier, and Wiley database), 176 articles were selected. Literature data were analyzed by the logic analysis method.

Results: (1) Risk factors of PD include dairy products, pesticides, traumatic brain injury, and obesity. Protective factors include alcohol, tobacco, coffee, black tea, and physical activity. (2) Physical activity can reduce the risk and improve symptoms of PD and the beneficial forms of physical activity, including running, dancing, traditional Chinese martial arts, yoga, and weight training. (3) Different forms of physical activity alleviate the symptoms of PD through different mechanisms, including reducing the accumulation of -syn protein, inflammation, and oxidative stress, while enhancing BDNF activity, nerve regeneration, and mitochondrial function.

Conclusion: Physical activity has a positive impact on the prevention and treatment of PD. Illustrating the molecular mechanism of physical activity-induced protective effect on PD is an urgent need for improving the efficacy of PD therapy regimens in the future.
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http://dx.doi.org/10.1155/2020/4293071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7042542PMC
October 2020

Creating superhydrophobic and antibacterial surfaces on gold by femtosecond laser pulses.

Appl Surf Sci 2020 Mar;506:144952

The Institute of Optics, University of Rochester, Rochester, NY 14627, USA.

Femtosecond laser-induced surface structuring is a promising technique for the large-scale formation of nano- and microscale structures that can effectively modify materials' optical, electrical, mechanical, and tribological properties. Here we perform a systematic study on femtosecond laser-induced surface structuring on gold (Au) surface and their effect on both hydrophobicity and bacterial-adhesion properties. We created various structures including subwavelength femtosecond laser-induced periodic surface structures (fs-LIPSSs), fs-LIPSSs covered with nano/microstructures, conic and 1D-rod-like structures ( 6 μm), and spherical nanostructures with a diameter 10 nm, by raster scanning the laser beam, at different laser fluences. We show that femtosecond laser processing turns originally hydrophilic Au to a superhydrophobic surface. We determine the optimal conditions for the creation of the different surface structures and explain the mechanism behind the formed structures and show that the laser fluence is the main controlling parameter. We demonstrate the ability of all the formed surface structures to reduce the adhesion of Escherichia coli (E. coli) bacteria and show that fs-LIPSSs enjoys superior antibacterial adhesion properties due to its large-scale surface coverage. Approximately 99.03% of the fs-LIPSSs surface is free from bacterial adhesion. The demonstrated physical inhibition of bacterial colonies and biofilm formation without antibiotics is a crucial step towards reducing antimicrobial-resistant infections.
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http://dx.doi.org/10.1016/j.apsusc.2019.144952DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7043332PMC
March 2020

Memories in the photoluminescence intermittency of single cesium lead bromide nanocrystals.

Nanoscale 2020 Mar 17;12(12):6795-6802. Epub 2020 Mar 17.

Université de Bordeaux, LP2N, Talence, France.

Single cesium lead bromide (CsPbBr) nanocrystals show strong photoluminescence intermittency, with on- and off- dwelling times following power-law distributions. We investigate the correlations for successive on-times and successive off-times, and find a memory effect in the photoluminescence intermittency of such inorganic perovskite nanocrystals. This memory effect is not sensitive to the nature of the surface capping ligand and the embedding polymer. These observations suggest that photoluminescence intermittency and its memory are mainly controlled by intrinsic traps in the nanocrystals. Our findings will help optimizing light-emitting devices based on these perovskite nanocrystals.
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http://dx.doi.org/10.1039/d0nr00633eDOI Listing
March 2020

Producing anomalous uniform periodic nanostructures on Cr thin films by femtosecond laser irradiation in vacuum.

Opt Lett 2020 Mar;45(6):1301-1304

We report on producing unprecedentedly uniform periodic structures on chromium thin films in vacuum conditions with irradiation of femtosecond laser pulses. In sharp contrast to the observations in air, the achieved surface structures of the ablated groove arrays are surprisingly found to have not only an extraordinarily uniform distribution but also a deep-subwavelength period of 360 nm. The measured both width and depth of the ablated periodic grooves are 150 and 120 nm, respectively, showing a large depth-to-width ratio and sharp-edge profiles. Remarkably, such well-organized nanostructures can be enabled to robustly extend into an infinitely long range via the sample scanning and even have a large-area production with a cylindrical lens. Raman spectral analyses reveal that the regular formation of such nanostructures benefits from avoiding the material oxidation and thermal disturbance of the air plasma on the sample surface.
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http://dx.doi.org/10.1364/OL.382322DOI Listing
March 2020