32,968 results match your criteria Optics Letters [Journal]


All-optically controlled beam splitting through asymmetric polarization-based holography.

Opt Lett 2019 Apr;44(8):2129-2132

All-optically controlled beam splitting is demonstrated by a tunable split ratio through polarization modulation. The beam splitters are essentially holographic gratings recorded by means of the interference of two 532 nm beams with asymmetric polarization states in an azobenzene liquid crystal film. It is found that the intensity ratio between zero and the first diffraction order is adjustable through the polarization manipulation of the recording light. Read More

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http://dx.doi.org/10.1364/OL.44.002129DOI Listing

Sub-micrometer resolution liquid level sensor based on a hollow core fiber structure.

Opt Lett 2019 Apr;44(8):2125-2128

Liquid level measurement in lab on a chip (LOC) devices is a challenging task due to the demand for a sensor with ultra-high resolution but miniature in nature. In this Letter, we report a simple, compact in size, yet highly sensitive liquid level sensor based on a hollow core fiber (HCF) structure. The sensor is fabricated by fusion splicing a short section of HCF between two singlemode fibers (SMFs). Read More

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http://dx.doi.org/10.1364/OL.44.002125DOI Listing

Optical network solution to the synchronization of distributed coherent aperture radar.

Opt Lett 2019 Apr;44(8):2121-2124

Distributed coherent aperture radar (DCAR) is an important direction for next-generation radar due to its high sensitivity. The challenge to realize DCAR is the synchronization among geographically distributed radar units. We propose an optical network for DCAR synchronization. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-2121
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http://dx.doi.org/10.1364/OL.44.002121DOI Listing
April 2019
1 Read

Correlated spatially resolved two-dimensional electronic and linear absorption spectroscopy.

Opt Lett 2019 Apr;44(8):2117-2120

A multimodal method for correlating linear and nonlinear optical spectra with a spatial resolution is presented. Using a partially collinear pump-probe geometry and two-frame phase-cycling, ultrafast two-dimensional electronic spectroscopy (2DES) was performed with transverse-spatial and temporal resolutions of 17 μm and 80 fs, respectively. Time-resolved 2DES maps were spatially correlated with linear extinction spectra obtained in the same imaging platform, enabling the examination of state-resolved dynamics of spatially heterogeneous materials. Read More

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http://dx.doi.org/10.1364/OL.44.002117DOI Listing

Mid-infrared dual-comb spectroscopy with interband cascade lasers.

Opt Lett 2019 Apr;44(8):2113-2116

Two semiconductor optical frequency combs, consuming less than 1 W of electrical power, are used to demonstrate high-sensitivity mid-infrared dual-comb spectroscopy in the important 3-4 μm spectral region. The devices are 4 mm long by 4 μm wide, and each emits 8 mW of average optical power. The spectroscopic sensing performance is demonstrated by measurements of methane and hydrogen chloride with optical multi-pass cell sensitivity enhancement. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-2113
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http://dx.doi.org/10.1364/OL.44.002113DOI Listing
April 2019
1 Read

Pulse compression irrespective of fiber dispersion using chirp of transistor lasers.

Opt Lett 2019 Apr;44(8):2109-2112

The voltage modulation of transistor lasers (TLs) through Franze-Keldysh absorption can impose an unconventional chirp on optical signals. In this Letter, we model this chirp effect and demonstrate how the output Gaussian pulse is reshaped through optical fibers. It is shown that pre-chirped pulses of TLs may be compressed in fibers with both normal and anomalous dispersions. Read More

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http://dx.doi.org/10.1364/OL.44.002109DOI Listing

Freestanding metasurfaces for optical frequencies.

Opt Lett 2019 Apr;44(8):2105-2108

We present freestanding metasurfaces operating at optical frequencies with a total thickness of only 40 nm. The metasurfaces are fabricated by focused ion beam milling of nanovoids in a carbon film followed by thermal evaporation of gold and plasma ashing of the carbon film. As a first example, we demonstrate a metasurface lens based on resonant V-shaped nanovoids with a focal length of 1 mm. Read More

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http://dx.doi.org/10.1364/OL.44.002105DOI Listing

Tracer-free liquid-vapor imaging using lifetime-filtered planar laser-induced fluorescence.

Opt Lett 2019 Apr;44(8):2101-2104

The separation of liquid phase and vapor phase laser-induced fluorescence (LIF) signals using tracer species suffers from uncertainties in tracer-fuel coevaporation, as well as a disparity in liquid and vapor signals. This work demonstrates the use of a simple technique, referred to as lifetime-filtered LIF, to help separate the liquid and vapor signals of fuel sprays in oxygen-free environments without the use of added tracers. This is demonstrated for a common aviation fuel, Jet-A, using prompt detection of the liquid phase and time-delayed detection of the vapor phase. Read More

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http://dx.doi.org/10.1364/OL.44.002101DOI Listing
April 2019
2 Reads

Noise suppression technique for distributed Brillouin sensing with polymer optical fibers.

Opt Lett 2019 Apr;44(8):2097-2100

We develop a new noise suppression technique to perform distributed strain and temperature sensing based on a higher-speed configuration of Brillouin optical correlation-domain reflectometry even when a polymer optical fiber (POF) is used as a sensing fiber. We acquire the spectral difference between with and without reference light, leading to selective observation of the beat signal of Brillouin-scattered light and reference light, which is effective for distributed sensing. After experimentally showing the usefulness of this technique, we demonstrate POF-based distributed temperature sensing and dynamic strain sensing. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-2097
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http://dx.doi.org/10.1364/OL.44.002097DOI Listing
April 2019
1 Read

Hexagonal vector field of polarization singularities with a gradient basis structure.

Opt Lett 2019 Apr;44(8):2093-2096

The coherent superposition of vector fields can yield interesting field distributions. For example, the superposition of two right-handed polarization singularities can result in left-handed polarization singularities. Unlike the coherent superposition of scalar fields which modulate resultant intensity, the vector field superposition can modulate additional parameters such as ellipticity and azimuth in the field distribution. Read More

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http://dx.doi.org/10.1364/OL.44.002093DOI Listing

Lop-sided Raman-Nath diffraction in PT-antisymmetric atomic lattices.

Opt Lett 2019 Apr;44(8):2089-2092

Two-dimensional (2D) optical lattices of driven cold atoms can provide a useful platform to construct 2D electromagnetically induced grating (EIG) with parity-time (PT) antisymmetry. This atomic grating is achieved by the spatial modulations of the atomic density and frequency detunings in the four-level double-Λ atomic system. Gain-assisted PT antisymmetry allows us to realize lop-sided Raman-Nath diffraction with high diffraction efficiency at the exception point. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-2089
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http://dx.doi.org/10.1364/OL.44.002089DOI Listing
April 2019
2 Reads

Spectral phase and amplitude retrieval and compensation technique for measurement of pulses.

Opt Lett 2019 Apr;44(8):2085-2088

In this Letter, an in-line, compact, and efficient quantitative pulse compensation and measurement scheme is demonstrated. This simple system can be readily deployed in multiphoton imaging systems and advanced manufacturing where multiphoton processes are exploited. Read More

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http://dx.doi.org/10.1364/OL.44.002085DOI Listing

Optical signatures of Mott-superfluid transition in nitrogen-vacancy centers coupled to photonic crystal cavities.

Opt Lett 2019 Apr;44(8):2081-2084

Detecting optical signatures of quantum phase transitions (QPT) in driven-dissipative systems constitutes a new frontier for many-body physics. Here we propose a practical idea to characterize the extensively studied phenomenon of photonic QPT, based on a many-body system composed of nitrogen-vacancy centers embedded individually in photonic crystal cavities, by detecting the critical behaviors of mean photon number, photon fluctuation, photon correlation, and emitted spectrum. Our results bridge these observables to the distinct optical signatures in different quantum phases and serve as good indicators and invaluable tools for studying dynamical properties of dissipative QPT. Read More

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http://dx.doi.org/10.1364/OL.44.002081DOI Listing

Optical computing optical coherence tomography with conjugate suppression by dispersion.

Opt Lett 2019 Apr;44(8):2077-2080

For all imaging techniques, such as optical coherence tomography (OCT), fast imaging speed is always of high demand. Optical computing OCT (OCT) has achieved ultrahigh speed for real time 3D imaging without post data processing, but its spatial resolution is lowered down due to an imperfect Fourier transformation in the optical computing process. In this Letter, we illustrate the theory of OCT and prove that the dispersion imbalance between reference arm and sample arm may be introduced to improve the resolution. Read More

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http://dx.doi.org/10.1364/OL.44.002077DOI Listing

Broadband space-time wave packets propagating 70  m.

Opt Lett 2019 Apr;44(8):2073-2076

The propagation distance of a pulsed beam in free space is ultimately limited by diffraction and space-time coupling. "Space-time" (ST) wave packets are pulsed beams endowed with tight spatio-temporal spectral correlations that render them propagation-invariant. Here we explore the limits of the propagation distance for ST wave packets. Read More

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http://dx.doi.org/10.1364/OL.44.002073DOI Listing

Spatiotemporal observations of light propagation in multiple polarization states.

Opt Lett 2019 Apr;44(8):2069-2072

Real-time imaging techniques involving light propagation are commonly applied in the fields of physics, chemistry, and biomedicine. However, conventional techniques provide only the intensity change associated with light propagation. Here, we propose an imaging technique to visualize the ultrafast behavior of the polarization state of a propagating light pulse with four different linear polarization components. Read More

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http://dx.doi.org/10.1364/OL.44.002069DOI Listing

High-dimensional Stokes vector direct detection over few-mode fibers.

Opt Lett 2019 Apr;44(8):2065-2068

Direct detection attracts much attention for its simplicity compared with coherent detection. In this Letter, we propose for the first time, to the best of our knowledge, a high-dimensional Stokes vector direct detection (HD-SVDD) receiver for mode-division multiplexing transmission in few-mode fibers where the coupled modes can be recovered without resorting to coherent detection. To the best of our knowledge, the first high-dimensional Stokes vector reception based on the proposed HD-SVDD receiver has been successfully demonstrated with a dual-spatial and dual-polarization mode at 60 Gb/s over a 200 m two-mode fiber. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-2065
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http://dx.doi.org/10.1364/OL.44.002065DOI Listing
April 2019
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In-plane near-field optical barrier on a chip.

Opt Lett 2019 Apr;44(8):2061-2064

Nanoparticles trapped on resonant near-field structures engraved on a metallic substrate experience forces due to the engravings, as well as the image-like interaction with the substrate. In the case of normally incident optical excitation, the force due to the substrate is solely perpendicular to its surface. Numerical simulations are presented to demonstrate that under the combined influence of the aforementioned forces, a plasmonic nanoparticle can be repelled from the engraving along the substrate, while attracting it towards the substrate along its normal. Read More

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http://dx.doi.org/10.1364/OL.44.002061DOI Listing
April 2019
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DC carpet cloak designed by topology optimization based on covariance matrix adaptation evolution strategy.

Opt Lett 2019 Apr;44(8):2057-2060

Optimal designs of direct current (DC) carpet cloaks are obtained using topology optimization based on the covariance matrix adaptation evolution strategy. The cloaking structures are expressed using an immersed boundary-level set method visualized as gray-scale-free configurations and composed simply of homogeneous materials. These cloaks successfully hide bumps made electrically invisible through topology optimization by minimizing the difference in voltage distributions around the cloaked bump and over the flat surface in the absence of the bump. Read More

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http://dx.doi.org/10.1364/OL.44.002057DOI Listing

Quantum beam splitter for orbital angular momentum of light: quantum correlation by four-wave mixing operated in a nonamplifying regime.

Opt Lett 2019 Apr;44(8):2053-2056

Nondegenerate four-wave mixing (FWM) process based on a double-Λ scheme in hot alkali metal vapor is a versatile tool in quantum state engineering, quantum imaging, and quantum precision measurements. In this Letter, we investigate the generation of quantum correlated twin beams which carry nonzero orbital angular momentums (OAMs) based on the FWM process in hot cesium vapor. The amplified probe beam and the newly generated conjugate beam in the FWM process have the same and opposite topological charge as the seed beam, respectively. Read More

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http://dx.doi.org/10.1364/OL.44.002053DOI Listing

Strong interaction of quantum emitters with a WS layer enhanced by a gold substrate.

Opt Lett 2019 Apr;44(8):2049-2052

We investigate the spontaneous emission (SE) effects of a two-level quantum emitter (QE) near a WS layer. The QE is placed above the WS layer in a host medium with constant dielectric permittivity. The material below the WS layer is either the same as the host medium or Au. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-2049
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http://dx.doi.org/10.1364/OL.44.002049DOI Listing
April 2019
2 Reads

Brillouin instantaneous frequency measurement with an arbitrary response for potential real-time implementation.

Opt Lett 2019 Apr;44(8):2045-2048

We demonstrate an arbitrary-response Brillouin instantaneous frequency measurement (IFM) based on the principle of the frequency-to-power mapping in stimulated Brillouin scattering (SBS), which is named Brillouin IFM. The arbitrary response is realized by periodically sweeping the frequency of the local pump lightwave, and the response's amplitude depends on the sweeping slope. The Brillouin IFM is achieved by the control of the sweeping period lower than the double of the flight-of-time in the SBS interaction length. Read More

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http://dx.doi.org/10.1364/OL.44.002045DOI Listing

Ultracompact integrated polarizers using bent asymmetric coupled waveguides.

Opt Lett 2019 Apr;44(8):2040-2043

A new type of integrated polarizer based on bent coupled optical waveguides is proposed. The simplicity of the device geometry permits its realization using only basic standard fabrication steps. A deep-etched waveguide silicon nitride TE-pass implementation is numerically investigated. Read More

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http://dx.doi.org/10.1364/OL.44.002040DOI Listing

Construction of robust Rydberg controlled-phase gates.

Opt Lett 2019 Apr;44(8):2036-2039

One scheme is presented to construct the robust multi-qubit arbitrary-phase controlled-phase gate (CPG) with one control and multiple target qubits in Rydberg atoms using the Lewis-Riesenfeld (LR) invariant method. The scheme is not limited by adiabatic condition while preserves the robustness against control parameter variations of adiabatic evolution. Comparing with the adiabatic case, our scheme does not require very strong Rydberg interaction strength. Read More

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http://dx.doi.org/10.1364/OL.44.002036DOI Listing

Linear space-variant optical cryptosystem via Fourier ptychography.

Opt Lett 2019 Apr;44(8):2032-2035

An optical cryptosystem via Fourier ptychography with double random phase masks is proposed. The encryption process cannot be precisely simulated except by optical experiment due to vignetting, which is space variant and can act as a one-way function from the perspective of pure optics and improve the security of our system. In addition, the encryption for a high-resolution, large field-of-view, and complex-valued image is achievable. Read More

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http://dx.doi.org/10.1364/OL.44.002032DOI Listing

Wave representation for asymmetric elliptic vortex beams generated from the astigmatic mode converter.

Opt Lett 2019 Apr;44(8):2028-2031

An analytical wave representation is derived to express the asymmetric elliptic vortex beams generated by using an astigmatic mode converter to transform the asymmetric Hermite-Gaussian modes. The effect of the spatial asymmetry on the elliptic vortex beam can be straightforwardly considered in the analytical wave representation. A detailed comparison with experimental intensity patterns and phase structures is made. Read More

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http://dx.doi.org/10.1364/OL.44.002028DOI Listing

Spectral singularities of a potential created by two coupled microring resonators.

Opt Lett 2019 Apr;44(8):2024-2027

Two microring resonators, one with gain and one with loss, coupled to each other and to a bus waveguide, create an effective non-Hermitian potential for light propagating in the waveguide. Due to geometry, the coupling for each microring resonator yields two counter-propagating modes with equal frequencies. We show that such a system enables implementation of many types of scattering peculiarities. Read More

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http://dx.doi.org/10.1364/OL.44.002024DOI Listing

Mode coupling in a terahertz multi-mode whispering-gallery-mode resonator.

Opt Lett 2019 Apr;44(8):2020-2023

We investigate mode-coupling effects of terahertz whispering-gallery modes (WGMs) in a multi-mode resonator using an extended transfer matrix method. Coupling effects between two WGMs are successfully observed on a well-designed high-Q terahertz Teflon ring resonator that supports low-order WGMs. The extended transmission matrix method is adopted to model, analyze, and reproduce terahertz single-band resonance and asymmetric dual-band resonances caused by mode coupling. Read More

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http://dx.doi.org/10.1364/OL.44.002020DOI Listing

Near-infrared supercontinuum source by intracavity silica-based highly-nonlinear fiber.

Opt Lett 2019 Apr;44(8):2016-2019

Near-infrared supercontinuum generation by using silica-based highly-nonlinear fiber placed inside of the ring-cavity of an erbium-doped fiber laser pulsed by mode-locking is experimentally demonstrated. Only one erbium-doped fiber amplifier is employed to generate supercontinuum with a spectral width as long as 830 nm (from 1205 to 2035 nm) and a spectral power higher than -30  dBm/nm. To generate supercontinuum, it is not necessary a second amplifier to raise the power of the laser pulses coupled into the nonlinear fiber. Read More

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http://dx.doi.org/10.1364/OL.44.002016DOI Listing

Photonic-based microwave hybrid combiner with arbitrarily tunable phase shift and power combining ratio.

Opt Lett 2019 Apr;44(8):2012-2015

We report a broadband photonic-based microwave hybrid combiner (PMHC) using a dual-polarization dual-parallel Mach-Zehnder modulator. The broadband PMHC with arbitrarily tunable phase shift and power combining ratio can overcome several limitations of conventional microwave combiners in terms of tunability and bandwidth. By simply adjusting the biases of the modulator, the phase shift and power ratio of the two combined microwave signals are independently, continuously, and freely tunable. Read More

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http://dx.doi.org/10.1364/OL.44.002012DOI Listing
April 2019
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Increased reverse energy flux area when focusing a linearly polarized annular beam with binary plates.

Opt Lett 2019 Apr;44(8):2008-2011

We suggest an annular field with linear polarization and a binary sectored phase for the formation of the inverse energy flux with an increased area of action. The possibility of the formation of a reverse energy flux over large areas in the focal domain at tight focusing of a linearly polarized field with the binary phase is shown theoretically and numerically. Moreover, the area increases with the number m. Read More

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http://dx.doi.org/10.1364/OL.44.002008DOI Listing

Frequency comb generation through the locking of domain walls in doubly resonant dispersive optical parametric oscillators.

Opt Lett 2019 Apr;44(8):2004-2007

In this Letter we theoretically investigate the formation of localized temporal dissipative structures, and their corresponding frequency combs in doubly resonant dispersive optical parametric oscillators. We derive a nonlocal mean field model, and show that domain wall locking allows for the formation of stable coherent optical frequency combs. Read More

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http://dx.doi.org/10.1364/OL.44.002004DOI Listing

System design of a single-shot reconfigurable null test using a spatial light modulator for freeform metrology.

Opt Lett 2019 Apr;44(8):2000-2003

We report the simulation of an adaptive interferometric null test using a high-definition phase-only spatial light modulator (SLM) to measure form and mid spatial frequencies of a freeform mirror with a sag departure of 150 μm from its base sphere. A state-of-the-art commercial SLM is modeled as a reconfigurable phase computer generated hologram (CGH) that generates a nulling phase function with close to an order of magnitude higher amplitude than deformable mirrors. The theoretical uncertainty in form measurement arising from pixelation and phase quantization of the SLM is 50. Read More

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http://dx.doi.org/10.1364/OL.44.002000DOI Listing

Three-wave radial shearing interferometer.

Opt Lett 2019 Apr;44(8):1996-1999

We propose a simple and compact three-wave radial shearing interferometer (TWRSI). This interferometer is constructed by a Gabor zone plate (GZP) and a charge-coupled device (CCD). The nominal plane wavefront under test is diffracted by the GZP into three orders (i. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-1996
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http://dx.doi.org/10.1364/OL.44.001996DOI Listing
April 2019
1 Read

Phase noise measurement of an optoelectronic oscillator based on the photonic-delay line cross-correlation method.

Opt Lett 2019 Apr;44(8):1992-1995

Phase noise measurement of a dual-loop optoelectronic oscillator (OEO) based on a dual- photonic-delay line cross-correlation method is proposed and experimentally demonstrated. The dual-loop OEO and the phase noise measurement system are combined by sharing the transmitter of the optical link, which makes the structure of the system simpler. In part of the dual-loop OEO, the 10 km long fiber is shared by the two loops of the OEO utilizing a wavelength division multiplexing technique. Read More

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http://dx.doi.org/10.1364/OL.44.001992DOI Listing

Enabling both time-domain and frequency-domain photoacoustic imaging by a fingertip laser diode system.

Opt Lett 2019 Apr;44(8):1988-1991

Photoacoustic imaging has attracted increasing research interest in recent years, due to its unique merit of combining light and sound. Enabling deep tissue imaging with high ultrasound spatial resolution and optical absorption contrast, photoacoustic imaging has been applied in various application scenarios including anatomical, functional and molecular imaging. However, the bulky and expensive laser source is one of the key bottlenecks that needs to be addressed for further compact system development. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-1988
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http://dx.doi.org/10.1364/OL.44.001988DOI Listing
April 2019
5 Reads

Transverse-load, strain, temperature, and torsion sensors based on a helical photonic crystal fiber.

Opt Lett 2019 Apr;44(8):1984-1987

In this Letter, we demonstrate a fabrication method of a helical photonic crystal fiber (HPCF) and an inflated HPCF (IHPCF) by use of an inflation-assisted hydrogen-oxygen flame heating technique. The transverse load, strain, temperature, and mechanical torsion properties of the HPCF and IHPCF were investigated experimentally to develop high-sensitivity sensors. The experimental results show that the transverse-load sensitivity could be greatly enhanced by means of enlarging the size of the air holes in the IHPCF; that is, the transverse-load sensitivity, i. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-1984
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http://dx.doi.org/10.1364/OL.44.001984DOI Listing
April 2019
1 Read

Multipass active stretcher with large chirp for high-flux ultra-intense lasers.

Opt Lett 2019 Apr;44(8):1980-1983

We demonstrate a novel active multipass stretcher that can deliver pulses with large chirp, adjustable chirped pulse duration, and great beam quality for a high-flux chirped-pulse amplification system. The stretcher is based on a Martinez-type stretcher and a regenerative amplifier structure, and the laser pulses can be amplified while they are stretched in the cavity. By controlling the round trip of the pulses running in the cavity, chirped pulses with more than 10 ns, even scaling to 30 ns, pulse duration and 20 nm bandwidth can be obtained very easily, which indicates a chirp rate of 0. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-1980
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http://dx.doi.org/10.1364/OL.44.001980DOI Listing
April 2019
1 Read

Field-portable quantitative lensless microscopy based on translated speckle illumination and sub-sampled ptychographic phase retrieval.

Opt Lett 2019 Apr;44(8):1976-1979

We report a compact, cost-effective, and field-portable lensless imaging platform for quantitative microscopy. In this platform, the object is placed on top of an image sensor chip without using a lens. We use a low-cost galvo scanner to rapidly scan an unknown laser speckle pattern on the object. Read More

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http://dx.doi.org/10.1364/OL.44.001976DOI Listing
April 2019
3.292 Impact Factor

Directional scattering cancellation for an electrically large dielectric sphere.

Opt Lett 2019 Apr;44(8):1972-1975

We demonstrate the directional scattering cancellation for a dielectric sphere of radius up to 10 times the incident wavelength, by coating it with a surface of finite conductivity. Specifically, the problem of determining the values of surface conductivity that guarantee destructive interference among hundreds of multipolar scattering orders at the prescribed angular direction is reduced to the determination of the zeros of a polynomial, whose coefficients are analytically known. Read More

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http://dx.doi.org/10.1364/OL.44.001972DOI Listing
April 2019
5 Reads

Generation of spirally accelerating optical beams.

Opt Lett 2019 Apr;44(8):1968-1971

We developed a generalized spectral phase superposition approach for generating accelerating optical beams along arbitrary trajectories. Such beams can be customized by predefining an appropriate superimposed phase pattern that consists of multiple sub-phases. We generated a spirally accelerating beam in a three-dimensional space and developed an algorithm to improve the uniformity of the intensity along the trajectory by introducing phase-shift factors. Read More

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http://dx.doi.org/10.1364/OL.44.001968DOI Listing

Diffusion-based single-shot diffraction tomography.

Opt Lett 2019 Apr;44(8):1964-1967

Holographic microscopy is a powerful technique for noninvasive label-free biomedical imaging. Most holographic methods utilize reference light and/or multiple measurements to observe both the amplitude and phase of a light wave passing through a specimen. However, such fundamental requirements degrade the spatial resolution due to the use of a reference carrier, cause difficulties for real-time imaging of dynamic biological events, and make the optical setups bulky. Read More

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http://dx.doi.org/10.1364/OL.44.001964DOI Listing

High-efficiency and broadband photonic polarization rotator based on multilevel shape optimization.

Opt Lett 2019 Apr;44(8):1960-1963

We report on a novel photonic polarization rotator design obtained by multilevel shape optimization. The numerical method consists of a topological optimization scheme, improving iteratively the efficiency of the component by modifying its shape on two discrete levels along the etching direction. We numerically show that, compared to state-of-the-art single-level shape optimization, the performances can be drastically improved for a given device length. Read More

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http://dx.doi.org/10.1364/OL.44.001960DOI Listing

Light-emitting-diode-pumped active Q-switched Nd:YLF laser.

Opt Lett 2019 Apr;44(8):1956-1959

An active Q-switching light-emitting diode (LED)-pumped laser is demonstrated by Nd:YLF crystal with acousto-optic modulation for the first time. The spectrum-band pump characteristic is grasped to describe the essential difference between an LED pump and single-absorption-peak matching of laser-diode pump or no matching of lamp pump. An effective absorption spectrum concept is proposed to characterize the absorption features of the gain material with LED-band pumping. Read More

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http://dx.doi.org/10.1364/OL.44.001956DOI Listing
April 2019
2 Reads

Fourier-domain mode-locked laser combined with a master-oscillator power amplifier architecture.

Opt Lett 2019 Apr;44(8):1952-1955

Originally introduced in 2005 for high-speed optical coherence tomography, the rapidly wavelength-swept Fourier-domain mode-locked (FDML) laser still, to this day, enables highest imaging speeds through a very high-speed spectral tuning capability. The FDML laser achieves a tuning bandwidth of over 1/10th of its center wavelength and can sweep this entire bandwidth in less than a microsecond. Interestingly, even though it covers a very broad spectral range, instantaneously it has a narrow spectral linewidth that puts it in a unique space compared to other high-speed broadband laser sources, e. Read More

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https://www.osapublishing.org/abstract.cfm?URI=ol-44-8-1952
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http://dx.doi.org/10.1364/OL.44.001952DOI Listing
April 2019
1 Read

Photonics-based dual-functional system for simultaneous high-resolution radar imaging and fast frequency measurement.

Opt Lett 2019 Apr;44(8):1948-1951

A photonics-based dual-functional system is proposed that can simultaneously implement high-resolution radar imaging and fast frequency measurement. In this system, the radar is realized based on photonic frequency doubling and de-chirp receiving, and the frequency measurement is achieved by a novel frequency-to-time mapping method. In the experimental demonstration, the radar works in Ku band with a bandwidth of 6 GHz (12-18 GHz), through which inverse synthetic aperture radar imaging with a resolution as high as ∼2. Read More

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http://dx.doi.org/10.1364/OL.44.001948DOI Listing

Ultraviolet polarized light emitting and detecting dual-functioning device based on nonpolar n-ZnO/i-ZnO/p-AlGaN heterojunction.

Opt Lett 2019 Apr;44(8):1944-1947

We report on the demonstration of a 386 nm light emission and detection dual-functioning device based on nonpolar a-plane n-ZnO/i-ZnO/p-AlGaN heterojunction under both forward and reverse bias. The electroluminescence intensity under reverse bias is significantly stronger than that under forward bias, facilitated by carrier tunneling when the valence band of p-AlGaN aligns with the conduction band of i-ZnO under reverse bias. Also amid reverse bias, the photodetection was observed and applied in a duplex optical communication device. Read More

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http://dx.doi.org/10.1364/OL.44.001944DOI Listing

Fabrication and characterization of super-polished wedged borosilicate nano-cells.

Opt Lett 2019 Apr;44(8):1940-1943

We report on the fabrication of an all-glass vapor cell with a thickness varying linearly between (exactly) 0 and ∼1  μm. The cell is made in Borofloat glass that allows state-of-the-art super polish roughness, a full optical bonding assembling and easy filling with alkali vapors. We detail the challenging manufacture steps and present experimental spectra resulting from fluorescence and transmission spectroscopy of the cesium D1 line. Read More

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http://dx.doi.org/10.1364/OL.44.001940DOI Listing
April 2019
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Compressive Raman imaging with spatial frequency modulated illumination.

Opt Lett 2019 Apr;44(8):1936-1939

We report a line scanning imaging modality of compressive Raman technology with spatial frequency modulated illumination using a single pixel detector. We demonstrate the imaging and classification of three different chemical species at line scan rates of 40 Hz. Read More

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http://dx.doi.org/10.1364/OL.44.001936DOI Listing
April 2019
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