We demonstrate 1.37 m coherent near-infrared light generation via self-seeded parametric four-wave mixing (FWM) process in Rb atomic vapor. Two lasers (780 nm and 776 nm) in the co-propagating configuration, drive the Rb atoms from the 5S1/2 ground state to the 5D5/2 excited state. The parametric FWM around the 5P3/2–5D5/2–6P3/2–6S1/2–5P3/2 transition loop is effectively established under phase matching

Laser speckle contrast imaging has been widely used for quantifying blood perfusion. In this letter, we propose a rapid, wide-field laser speckle angiography technique for noninvasive imaging of retinal and choroidal vessels. The field of view (FOV) reaches ∼50∘ while the acquisition time was less than 1 s. Larger FOV (∼90∘) can be further improved by mosaicking. The results were comparatively studied

Several hydrodynamic models of the atomic Bose–Einstein condensate (BEC) obtained beyond the mean-field approximation are discussed together from a single point of view. All these models are derived from the microscopic quantum description. The derivation is made within the many-particle quantum hydrodynamics method suggested by L Kuz’menkov. The derivation is demonstrated and discussed for the mean-field

In conventional linear accelerators, the beam is accelerated with a synchronous harmonic of the radio frequency field where the electric field component is collinear with the beam direction. This approach requires the design of complex accelerating structures, especially for low-energy heavy ions. If the beam motion were sustainably coupled to transverse electromagnetic fields, this could significantly

To improve the security of encryption systems, we propose a multiple-image encryption method via Toeplitz matrix ghost imaging and elliptic curve cryptography. Specifically, each unencrypted image is firstly compressed using wavelet transformation. Compressed images are merged into a single image via spatial multiplexing technology. Then, based on the ghost imaging, the phase mask matrix of the speckle

The sensitivities of optical magnetometers, atomic clocks and atom interferometers and other quantum metrology devices, whose signals are linear in the number N of active atoms, have practically arrived at their theoretical limit. Further enhancement of the sensitivities of such devices requires the introduction of new physical processes to improve on their present achievements. Many-body collective

We present a simple and efficient experimental approach to synchronized dual-wavelength pulsed operation in an all-fiber laser. Four different dual-wavelength emissions of synchronized picosecond pulses are generated through simple adjustments of a wave retarder. Autocorrelation traces exhibit modulation profiles corresponding to dual-wavelength emissions with wavelength separations ranging over one

A Tm3+:Lu2O3 ceramics laser with the L-shaped cavity in-band pumped by a fiber laser at 1670 nm was studied in CW and passively Q-switched multi-wavelength regimes. The CW laser operated at 2066 nm at the weak pump power and self-tuned to 1966 nm and further to 1940 nm at higher pump power. The maximum power in the CW regime at 1940 nm reached 9.5 W, while the average power of 3.6 W was registered

For the first time, a complete set of decay parameters, due to collisions of 174Yb atoms with noble gas atoms and with ytterbium atoms, was experimentally found for the 174Yb (6s6p) 3P1 level. The method of stimulated photon echo with special angles between the polarization vectors of light pulses forming an echo at the 174Yb (6s2) 1S0—(6s6p) 3P1 transition (type ) is used. For each buffer gas of He

We investigate the nonlocal advantage of quantum coherence (NAQC) for two qubits coupled via the Heisenberg interaction and embedded in their respective thermal and dephasing reservoirs. Unlike the case of two uncoupled qubits, we showed that in the presence of the Heisenberg interaction, the decay rate of the NAQC can be reduced and the strength of the NAQC can be enhanced for certain initial states

A single-photon qudit encoded in more than one degree of freedom (DOF) can effectively enlarge a single photon’s capacity and has great potential for applications in future high-capacity quantum communication fields. During the photon transmission in practical noisy channels, photon qudits may suffer from photon transmission loss, which largely limits their application. In this paper, we propose a

A four-party deterministic single-qubit operation sharing scheme is proposed by using a generalized seven-qubit Brown state in a given qubit distribution as the quantum channel. Its security is confirmed via analyses. The sharing determinacy and the sharer symmetry of the scheme are identified. The experimental feasibility of the scheme is confirmed through discussions. Moreover, the scheme is compared

We study steering-induced coherence (SIC) in local decoherence channels. Two types of channels are considered in this work, one is the amplitude damping channel under rotating-wave approximation (RWA) and the other the non-RWA channel. Unlike the amplitude damping channel, the system-environment interaction of the non-RWA channel is treated without RWA. We use the hierarchy equation method to calculate

The interaction between spin and orbital components of the angular momentum of an elliptically polarized beam with helicoidal phase profile and arbitrary axially symmetric intensity profile in the third-harmonic generation process is investigated. The third-harmonic beam is generated in an isotropic medium with cubic nonlinearity within undepleted pump approximation. The conservation of the total projections

The latest breakthroughs in quantum technologies, such as satellite quantum communications, present new challenges, imposing stringent restrictions on weight, size, and power consumption of quantum information systems. Here, we show that nonlinear and quantum optics provides powerful resources to confront these challenges by offering attractive solutions for photon-pair counting and quantum-entanglement

This article focuses on the resonant high-energy spontaneous bremsstrahlung of ultrarelativistic electrons with considerable energies GeV in the field of a nucleus and a quasimonochromatic laser wave with an intensity 1017 W cm−2. Under resonant conditions within the light field the intermediate virtual electron transformed into a real particle. Therefore, the initial second order process in accordance

We propose an efficient scheme to control Goos–Hnchen (GH) shifts of the reflected and transmitted beams in a cavity containing Er3 + -doped yttrium-aluminum-garnet (YAG) crystal with a four-level Er3 +  ionic system. It is found that both the values and signs of the reflected and transmitted GH shifts can be coherently controlled by tuning the relevant optical parameters, such as the incoherent pumping

We study the distribution and monogamous relations of quantum coherence for three-qubit systems under the influence of local amplitude-damping, phase-damping and random unitary channels, respectively. We find that under the influence of the considered channels, the W state has both global and bipartite coherence, and its monogamy is always equal to zero. For the Greenberger–Horne–Zeilinger) state,

A dual-wavelength 532/1064 nm optoacoustic (OA) imaging system allows 3D visualizations of arteriovenous anastomoses (AVAs) with an acoustic spatial resolution (50 m) at depths of up to 2 mm in vivo in rabbit ears. Both structural and spectral information from the OA data are employed to analyze the anatomical locations of the blood vessels and to distinguish between veins and arteries in the zone

The orthogonality time is examined for different initial states settings interacting locally with different types of spin interaction: XX, Ising and anisotropic models. It is shown that the number of orthogonality increases, and consequently the time of orthogonality decreases as the environment qubits increase. The shortest time of orthogonality is displayed for the XX chain model, while the largest

Based on the Markoff approximation, we find the photon power spectrum of high harmonic generation from the irradiation of atoms using an intense laser field.

The paper provides a complete analytical proof of the secrecy of the quantum key distribution for the single-photon quantum states in the case of different quantum efficiency of detectors. Taking into account the imperfect and different quantum efficiency of detectors is fundamentally important for ensuring the secrecy of keys in practical systems of quantum cryptography.

In this work, the temperature (strain) properties of As2Se3 π-phase-shift fiber Bragg gratings (π-PSFBGs) are numerically investigated. The sensing sensitivities are 0.0665 nm C−1 (0.8598 pm μϵ −1) at 1.55 μm, 0.1546 nm C−1 (1.9968 pm μϵ −1) at 3.6 μm, 0.2717 nm C−1 (3.51 pm μϵ −1) at 6.328 μm, and 0.4551 nm C−1 (5.8796 pm μϵ −1) at 10.6 μm, and the sensitivities are improved with the increasing Bragg

Symmetric quantum correlations and properties have been often investigated earlier in the process of quantum decoherence. However, the asymmetric quantum features, such as steering, have been rarely considered in this context. In this work, we study Einstein–Podolsky–Rosen steering, measured by steering robustness R, for two-qubit systems under asymmetric noise channels. For the one-sided asymmetric

We propose a potentially practical scheme for constructing a quantum network based on a system where three waveguides are coupled to two two-level atoms. In the case of chiral couplings between the waveguides and atoms, we realize a directed single-photon router and the efficiency of single-photon routing reaches 100%. In addition, in this network, the photon input from one port of the channel can

We propose the design of a high-power fiber oscillator with chirped and tilted fiber Bragg gratings (CTFBGs) to suppress the stimulated Raman scattering within the fiber cavity and in the delivery fibers. A high-power single-mode fiber oscillator system was constructed for demonstration. With a CTFBG inserted into the fiber cavity, obvious Raman suppression was observed and the output signal laser

We report the laser-ablative fabrication of antibacterial nanostructures, combining mechanical and chemotoxic effects, by femto- and nanosecond laser ablation and their testing on Staphylococcus aureus and Pseudomonas aeruginosa strains. A Ti surface, covered with nanospikes and periodical surface ripples, provides a strong anti-biofilm effect, and the addition of cytotoxic nanoparticles (NPs) (Ag

Optoacoustic (OA) angiography allows high-contrast three-dimensional (3D) visualization of hemoglobin-containing structures ranging from micrometers to millimeters. However, due to the large amount of 3D data acquired by modern high-throughput OA systems the resulting OA vasculature images might be difficult to analyze visually. This problem is especially relevant for monitoring of angiogenesis of

In this paper we study quantum correlation (QC) swapping between two different kinds of quantum-correlated states. To be concrete, one is the famous Werner state while another is a kind of separable state. We employ measurement-induced disturbance (Luo 2008 Phys. Rev. A 77 02230) as the quantifier to characterize and quantify QC. We work out QCs in all the concerned states and concretely analyze their

In this paper an off-axis holography is put forward based on the Sagnac interferometer. The holograms of alumina-dust aerosol particles, an United States Air Force 1951 resolution plate and paramecium were recorded in the experiment. The diffraction integral of a plane hole derived from quantum theory is illustrated by the variation of the thickness of interference fringes. We use an angular spectrum

In this work, we report a tunable mode-locked fiber laser that can produce ultrashort laser pulses with polarization vortex. Two vortex wave plates (VWPs) are employed in this laser to convert the intracavity beam states between the Gaussian mode and cylindrical vector mode. By adjusting the angle between a diffraction grating and the light beam in the cavity, the center wavelength of the mode-locked

We present the results of investigation of total internal reflection of a femtosecond light filament in a LiF crystal in the regime of anomalous group velocity dispersion. We measure the Goos–Hnchen shift of the filament in the vicinity of the critical angle for a single femtosecond pulse using the laser coloration method. The obtained experimental values are compared to several existing theoretical

In this paper, we consider the relationship between C Shannon’s unicity distance, which is determined by the number of symbols of the encrypted message required to uniquely find the encryption key of the cryptosystem in information-theoretical sense, ε-secrecy criterion in quantum cryptography and Holevo information. A lower bound for the unicity distance for ε-secret keys in quantum cryptography is

Experimentalists have long sought a method that allows them to control the branching ratios of an unstable particle decay and direct some decay to follow one specific desired channel without another. The powerful laser could make this a reality. In this letter and within the framework of the standard electroweak model, we investigate theoretically the laser effect on the branching ratios of different

Facial nerve palsy involves paralysis of unknown origin caused by trauma, infectious disease or metabolic disorders. The aim of this study was to employ low-level laser therapy (LLLT) in the recovery of two patients with facial nerve palsies due to trauma and Bell’s palsy (BP), respectively. LLLT was used with a gallium aluminum arsenide laser (780 nm) in the first case and in the second case LLLT

We describe a method that allows accumulation in a Paul trap of a large number of ions obtained from multiple laser ablation pulses, and therefore solving the problem of a single pulse that usualy gives rise to final trapping of too few ions. The proposed method of the cumulative trap loading was based on interaction with a buffer gas that provided a friction force. The method was applied to triply

Within the frame of electrodynamic and nonlinearly Thomson scattering, we study the motion and spatial radiation features of a static electron irradiated by circularly polarized tightly focused laser with different laser intensities. Combining the existing and our novel 3D Oxyz coordinate analysis, we find the azimuthal divergence and peak radiation azimuth decrease at varied speeds with laser intensity

An analysis of weak quantum fluctuations of a spatial soliton in a laser with fast saturable absorption in the possible presence of weak holding radiation is carried out. In the c-number representation with adiabatic elimination of atomic variables, the master Heisenberg–Langevin equation is linearized in the vicinity of a stable classical (in the absence of fluctuations) laser soliton. The linearized

Increasing the conversion efficiency of second harmonic generation (SHG) is an area of interest in research. We report a high-efficiency 532 nm laser generation, with a conversion efficiency of 94.04 0.115% from the pump depletion of 98.1% 0.1%, by accurately quantifying the round-trip loss and the transmissivity of the input mirror using our proposed scheme. The optimal conversion efficiency of the

This article investigates the performance of a free space optical (FSO) communication link by incorporating the device parameters that influence the optical output power of the quantum cascade laser (QCL). The transmitter side of the FSO link consists of gain-switched QCL operating at 9 m. Short optical pulses possessing minimum full width half maximum (FWHM) and peak power as a result of ON-OFF keying

The article demonstrates the fundamental possibility of creating microstructures for various functional purposes using the capabilities of the two-photon femtosecond polymerization method. The developed technological approach for creating a micro-optical holder for standard single-mode and multimode fibers is demonstrated. This type of holder can be used to manufacture a unit for optical matching of

Thin films of zinc oxide and those doped with terbium (at concentrations of 0.1–5.0 mol%) were synthesized on glass substrates using the sol–gel method. The UV–Vis transmission spectra showed that transparency increases from 60% to 86% with an increase of Tb content. All terbium-doped samples exhibit a rise in Eg from 3.37 eV for zinc oxide to 3.827 eV for doped films. The photoluminescence (PL) of

By using the Lyapunov control approach—an optimization algorithm, we propose a dissipative scheme for efficiently preparing the three-dimensional entangled state of two Rydberg atoms, which subject to Rydberg–Rydberg interactions at the antiblockade regime. The steady target state is the unique dark state of the two-atom system, and is achieved with high fidelity under the Rydberg pumping and the atomic

Transmission versus intensity in 100 μm CaF2 and UV fused silica samples at a wavelength of 473 nm for different durations of the initial pulse was studied. Fitting the experimental data with a model based on the solution of the nonlinear Schrdinger equation and taking into account multiphoton absorption and absorption by the plasma, as well as the Kerr nonlinearity, diffraction and dispersion of the

A quantum digital signature (QDS) is guaranteed by the laws of quantum physics and can provide unconditional security to authenticate classical messages. Previous QDS protocols that shared secret keys could be realized using discrete-variable quantum key distribution (DV-QKD), for which the DV-QKD relied on extreme requirements like single-photon detection and extremely weak pulses of light. QDS protocols

Vortex beams have wide applications in optical tweezers, optical communications and so on. Long period fiber gratings, mode selective couplers, few mode fiber Bragg gratings or specially designed fibers are often used to generate vortex beams from fiber lasers. New methods of mode selection in fiber lasers are always attractive. When transverse modes propagate along a multimode fiber, the polarization

The long-term hydrodynamics of laser generated plasma regions are dictated by the spatial distribution of the deposited laser energy. Using an integrated chemical-optical solver to track energy deposition from single and dual nanosecond laser pulses, we show that self-defocusing results in a biased growth of the plasma region towards the focusing lens. This displacement of energy deposition scales

Single-pixel imaging (SPI) uses point detectors instead of expensive array sensors to capture images under low light conditions. It therefore provides a solution in detecting objects with weak signals. In this research, we propose a non-line-of-sight (NLOS) 2D transparent object inspection system based on SPI technique. The 2D shape of the transparent object is reconstructed using Total Variation Augmented

Optical frequency combs (OFCs) generated in microresonators with whispering gallery modes are attractive for different applications and basic science. The effects associated with Raman nonlinearity are constantly being discovered and investigated experimentally and theoretically expanding the capabilities of microresonator OFCs. Here we obtain experimentally Raman-assisted nested OFCs in two different

We present the closed-loop controlled compensation of the thermally induced lens in a high-power thin-disk oscillator to obtain fundamental-mode operation over a wide range of pump powers. The radius of the oscillating beam was measured in real time at the position of the thin-disk crystal. This signal was used by the control system to adapt the curvature of a spherically deformable mirror to maintain

An ensemble of thorium-229 ions embedded by pulsed laser implantation into a matrix of a broadband dielectric-silicon oxide is studied. The results of the experimental investigation of thorium ions’ lifetime as charged components of the Th+/SiO2/Si system formed immediately after laser implantation are presented. The modelled theoretical description takes into account the instantaneous charging of

We investigate polarization-locked vector solitons (PLVSs) arising in an all-polarization-maintaining (PM) soliton fiber laser mode-locked by a carbon nanotube. The laser can operate stably in both Q-switched and mode-locked states with different pump power. Under the PLVS condition, we observe a string of peak-dip-pair sidebands after polarization-resolving measurement, indicating the strong and regular

Temperature sensors based on photonic crystal fibers (PCFs) have attracted considerable attentions due to their desirable advantages. However, the real-time temperature sensing in the temporal region is rarely studied. Here, an all-fiber real-time high-sensitivity temperature sensor is fabricated based on the high-order soliton compression process. A 1560 nm femtosecond fiber laser is used as the injected

The application of metasurface in invisibility technology is mainly based on its phase control function, which provides a new choice for the design of ultra-thin carpet cloaking devices with arbitrary shape. At present, most of the carpet cloaking devices mainly focus on metal structure metasurfaces. The Ohmic loss of metallic materials seriously affects the efficiency of cloaking devices. To reduce

The formation of entanglement between the electronic and vibrational subsystems of two interacting molecules localized between tunneling contact leads was theoretically analyzed using the Keldysh diagram technique. The time evolution of concurrence after ‘switching on’ the coupling between the molecules was investigated. It was revealed that non-zero concurrence can be present in the system in the

In this work we report on a tandem pumped gain-switched Yb-doped fiber laser. We used an amplified dissipative soliton resonance mode-locked fiber laser with the wavelength of 1030 nm as a source of high repetition rate pulsed pump, incorporated with a CW diode laser at the wavelength of 976 nm in hybrid pump scheme. Sub-nanosecond narrow line-width gain-switched pulses with peak power of 10 kW at

A single-resonant beta barium borate crystal optical parametric oscillator with high pulse energy output at the H-β Fraunhofer line of 486.1 nm was demonstrated. Pumped by a single-frequency 355 nm ultraviolet pulsed laser at 10 Hz repetition rate with maximum pulse energy of 411 mJ, maximum output energy of 162 mJ blue laser pulse at 486.1 nm was successfully obtained from a plano-concave cavity with

We examine two types of information loss function encountered in optical neural recording—the uncertainty of neural states encoding an external stimulus and the incompleteness of information that laser-excited fluorescence can read out from these neural states. We show that, even though these uncertainties are of distinctly different nature, they can be treated on an equal footing against the Fisher

We study the generation of terahertz (THz) radiation from a dual-color filament in air for a Ti:sapphire pump and with different wavelengths of the seed pulse using the unidirectional pulse propagation equation (UPPE). The local transient photocurrent model indicates that the most efficient THz generation corresponds to the seed with either halved or doubled pump frequency compared with the other seed

In this paper, an asymmetric multiple-image cryptosystem is proposed using LUP decomposition (LUPD) in the spherical diffraction (SpD) domain. To the best of our knowledge, the SpD transform is applied to the optical encryption for the first time. In the proposed cryptosystem, multiple grayscale images are encoded into a sparse and binary amplitude distribution with the cascaded LUPD and SpD transform