Using numerical simulation, we investigate the formation of noise-like pulses with an extremely broadband spectrum in passively mode-locked fiber lasers. The mechanism of spectral broadening is due to the Kerr nonlinearity of the fibers making up the laser cavity. It is found that optimization of the nonlinear-dispersion parameters of the fiber cavity can lead to the generation of noise-like pulses

We develop an analytic approach for reflection of light at a temporal boundary inside a dispersive medium and derive frequency-dependent expressions for the reflection and transmission coefficients. Using the analytic results, we study the temporal reflection of an optical pulse and show that our results agree fully with a numerical approach used earlier. Our approach provides approximate analytic

Theoretical study of arrays of graphene ribbons is currently of high interest due to its potential application in beam splitters, absorbers, and polarizers. In this paper, an analytical method is presented for diffraction analysis of graphene ribbon arrays. Previous analytical studies were carried out in the regime where the lateral separation between the ribbons is much smaller than the wavelength

Numerical analysis of optical biosensors made of very short-pillar (only one or two lattice constants high) liquid-infiltrated photonic crystals is presented. The small pillar height makes these photonic crystals amenable to fabrication by techniques such as nanoimprinting. Our biosensors can detect at least three different analytes (disease markers), individually or combinatorially in a single spectroscopic

We study the peculiarities of light pulse propagation in the quasi-parity-time (quasi-${\cal P}{\cal T}$) symmetric periodic media in the Bragg geometry. Our focus is the investigation of the competition between the Bragg reflection and the ${\cal P}{\cal T}$ symmetry contribution provided different pulse duration. The mechanisms of nonsymmetric interaction between the counterpropagating waves are

Resonant electromagnetic scattering with particles is a fundamental problem in electromagnetism that has been thoroughly investigated through the excitation of localized surface plasmon resonances (LSPR) in metallic particles or Mie resonances in high refractive index dielectrics. The interaction strength between electromagnetic waves and scatterers is limited by maximum and minimum physical bounds

We theoretically design and study a structure of graphene/intrinsic amorphous-silicon Schottky junction solar cell (Gr/i-a-Si_SJSC) with top core/shell quantum dots (CSQDs). A physical model incorporated with optoelectrical characteristics is developed to optimize the structure’s electrical performance by modifying the graphene work function, temperature, and CSQD radius. Simulations show that the

Frequency combs downconvert absolute optical frequency references and thereby can significantly advance time and frequency precision in satellite-based navigation systems, fundamental science, earth observation, and many other spaceborne applications. We have developed a compact and vacuum compatible double comb system, thereby minimizing volume, mass, and power consumption compared to its precursor

We demonstrate tunable broadband two-mode power dividers based on a wavelength-insensitive coupler for a mode-division multiplexing system. Ultra-small ${{\rm{TE}}_0} {-} {{\rm{TE}}_1}$ and ${{\rm{TE}}_0} {-} {{\rm{TE}}_2}$ mode dividers based on Si-wire waveguides are designed based on the coupled-mode theory. Tunability is achieved by using the thermo-optic effect. In both dividers, arbitrary branching

This work reports on the use of a gain-switched vertical cavity surface-emitting laser (VCSEL) optical frequency comb (OFC) to generate multiple optical carriers for applications in future wavelength-division multiplexing (WDM) passive optical network (PON) systems. The VCSEL-based OFC system was tested for its ability to simultaneously transmit error-free data signals up to 30 Gbps, and a 50 MHz clock

A crystalline silicon thin-film solar cell (c-Si TFSC) with a trapezoidal grating is newly introduced and analyzed. The three-dimensional (3D) finite-difference time-domain (FDTD) method is employed to optimize the geometrical parameters of the trapezoidal grating and hence maximize the light absorption. The proposed trapezoidal grating TFSC offers an optical ultimate efficiency ($\eta$) of 32.3%,

The lack of a systematic design strategy to precisely control bending and guiding of photons in three dimensions, as well as the requirement of advancements in the fabrication technology for realizing large-area, defect-free three-dimensional (3D) photonic crystals, has been the main hurdle toward exploiting the potential of three-dimensional photonic crystals. Here, we demonstrate a new, to the best

Laser diodes, in general, are sensitive to optical feedback, especially with regard to maintaining single-frequency operation. Until now, however, the feedback sensitivity of high-power devices such as single-frequency distributed Bragg reflector (DBR) tapered laser diodes has not been investigated in quantitative detail. In this paper, we analyze the impact of very weak optical feedback between $

In this paper, we present a novel, to the best of our knowledge, 3D ultra-broadband tunable metamaterial absorber (TMA), which is innovatively tuned by the gravity field with changing the position of the liquid metal (eutectic gallium-indium) in theory. The given TMA consists of a 3D glass cavity filled with the liquid metal, two-layer high-impedance surfaces, two dielectric layers, and a metallic

In this paper, an electromagnetically induced transparency metamaterial simultaneously coupled with the incident electric and magnetic fields is designed and presented theoretically, whereas its reconfigurability, slow-wave effect, low-loss, and polarization insensitivity are analyzed and discussed principally. Based on the tunable solid-state plasma, there is a transmission peak with a 92.06% transmission

We investigate magnon statistics in a qubit-magnon hybrid quantum system in which an effective appreciable qubit-magnon coupling can be realized by exchanging virtual cavity photons. A conventional magnon blockade and two types of unconventional magnon blockades are proposed, respectively, based on three different physical mechanisms. We verify theoretically that a magnon blockade can occur in strong

We investigate Raman scattering from optically deformed droplets both theoretically and experimentally. Using a dual-beam optical trap, single aqueous aerosol microdroplets are held in an environmentally controlled cell and deformed, while both input and output resonances are simultaneously excited. Our systematic investigation shows that, depending on the scattering angle and whispering gallery mode

In this work, we propose a novel broadband terahertz (THz) metamaterial absorber (MMA) based on double-spiral structures, including discrete and continuous ones. The gradient ring resonators are in a discrete spiral topological distribution to expand the absorption band. By stacking two layers with a certain proportion, the proposed THz MMA can further enhance the energy loss to achieve absorption

We show an adaptive deep-learning algorithm that recovers the distorted broadband signals of defective microwave photonic (MWP) receiving systems. With data-driven supervised training, the adopted neural network automatically learns the end-to-end distortion effects of the photonic analog links and recovers the received signals in the digital domain. Through changing the training data sets and retraining

A recent work devoted to the longitudinal optical forces exerted by circularly symmetric Bessel beams on point-like particles in the Rayleigh regime of the generalized Lorenz–Mie theory (GLMT) confirmed the existence of nonstandard forces (named axicon forces in the context of Bessel beams) that seemingly cannot be expressed in terms of scattering and gradient forces traditionally discussed in the

We proposed a theoretical modeling of a “giant” colloidal core–shell quantum dot with a strain-adapting alloyed interfacial layer between the core and shell materials for solar cell applications. The recently modified detailed balance model [J. Appl. Phys. 125, 174302 (2019) [CrossRef] ] is further modified in this paper to obtain a more realistic conversion efficiency (CE) of the ${\rm CdSe}/{{\rm

We demonstrate a reduction of THz material parameter estimation errors by a factor of 40, using a time-domain material-model-based extraction method, in comparison with the respective frequency-domain approach. Based on simulated and experimentally measured THz time-domain spectroscopy data with different levels of the signal-to-noise ratios (SNR), an improved robustness of the time-domain scheme with

A second-order transfer function analysis is performed on plasmonic modes with disparate quality factors. This generalized analysis technique is applied to the coupling of modes in metal–insulator–metal structures in the mid-wave infrared, which are systematically studied, both experimentally and with computational modeling. Coupling between these disparate modes is observed from the asymmetric Fano-like

The optical parametric amplification of spectrally incoherent signals is analyzed and simulated using a set of normalized equations describing phase-matched three-wave nonlinear mixing. Varying the amplifier’s properties and the seeding conditions reveals different amplification regimes. In particular, the relative temporal walk-off of the signal, idler, and pump has a strong impact on the temporal

A two-fluid hydrodynamic model is employed to model the spatial dispersion when both electrons and holes in semiconductors are considered. Within the two-fluid hydrodynamic model, analytical solutions to the nonlocal responses of cylindrical multilayered concentric and eccentric nanowires are obtained using the Mie theory and the scattering matrix method, which are also validated by finite element

For the realization of a quantum network and efficient transfer of information between its nodes, many challenges should be resolved. One of these challenges is related to controlling photons, in that receiving and resending data in a real-time process should be reliable. The uncontrollable and time asymmetry shape of the photon wave packets emitted by quantum sources creates obstacles for reliable

This article corrects a misprint in Eqs. (4) and (6) of J. Opt. Soc. Am. B 32, 2025 (2015) [CrossRef] .

We make use of two well-known numerical approaches of nonlinear pulse propagation, namely, the unidirectional pulse propagation equation and the multimode generalized nonlinear Schrödinger equation, to provide a detailed comparison of ultrashort pulse propagation and possible conical emission in the context of multimode optical fibers. We confirm the strong impact of the frequency dispersion of the

Mamyshev oscillators can generate high-power femtosecond pulses, but starting a mode-locked state has remained a major challenge due to the suppression of continuous-wave lasing. Here, we study the starting dynamics of a linear Mamyshev oscillator designed to generate high-power femtosecond pulses while avoiding component damage. Reliable starting to stable mode-locking is achieved with a combination

The Langevin noise approach for quantization of macroscopic electromagnetics for three-dimensional, inhomogeneous environments is compared with normal-mode quantization. Recent works on the applicability of the method are discussed, and several examples are provided showing that for closed systems the Langevin noise approach reduces to the usual cavity mode expansion method when loss is eliminated

Terahertz time-domain spectroscopy is employed to investigate temperature-dependent properties of bulk chalcopyrite crystals (${{\rm CdGeP}_2}$, ${{\rm ZnGeP}_2}$, and ${{\rm CdSiP}_2}$). The complex spectra provide refraction and absorption as a function of temperature, from which electron–phonon coupling and average phonon energies are extracted and linked to the mechanics of the A- and B-site cations

A nanophotonic waveguide based on engineered horizontal and vertical slots is proposed. The proposed engineered structure is composed of three silicon ribs forming two vertical slots, and on top a gold cover in the shape of microchannel forms horizontal slot regions. We are able to increase the bulk sensitivity in TM mode by 1.5 times with the gold cover. The bulk sensitivity for TE and TM mode is

Radiation of charged particles moving in the presence of dielectric targets is of essential importance for various applications in accelerator and beam physics. As a rule, the sizes of these targets are much larger than the wavelengths under consideration. This fact gives an obvious small parameter of the problem and allows developing approximate methods for analysis. Here we apply one such method

Nanocavity lasers are commonly characterized by the spontaneous coupling coefficient $\beta$ that represents the fraction of photons emitted into the lasing mode. While $\beta$ is conventionally discussed in semiconductor lasers where the photon lifetime is much shorter than the carrier lifetime (class-B lasers), little is known about $\beta$ in atomic lasers where the photon lifetime is much longer

The twin-field quantum key distribution (TF-QKD) protocol has been studied widely to overcome the linear bound, and several variations of the TF-QKD protocol have been proposed to improve security and practicality. One variation called the phase-matching QKD (PM-QKD) protocol develops an optical-mode-based security; simultaneously, it has a quadratic improvement of key rate without either basis choice

We consider theoretically the power spectral density ${S_E}(\nu)$ of an otherwise periodic optical pulse train with optical field $E(t)$, i.e., the optical frequency comb, in the presence of noise in the pulse-to-pulse carrier-envelope phase slip in carrier-envelope-stabilized optical pulse trains. The spectrum is a frequency comb where the comb line shape is Gaussian. To obtain these results, we implement

The nonlinear process of orbital angular momentum (OAM) beams in multimode fiber has attracted renewed interest due to its enhanced intermodal nonlinear interactions. Here, we designed and simulated a novel photonic crystal fiber (PCF) based on ${{\rm As}_2}{{\rm Se}_3}$ glass that supports stable OAM modes. By optimizing the structure parameters of the fiber, both the effective index separation and

We present our experimental results on electric field poling of X-cut thin-film lithium niobate with poling periods of 1–4 µm. We used polarization contrast microscopy combined with digital image processing to study the impact of the experimental parameters of the poling process such as electric field strength, poling pulse duration, and layout of metal electrodes on the domain growth and quality of

The construction of millimeter-structured surface beams by superimposing scalar Bessel beams has proven to be a powerful technique for creating visual two-dimensional (2D) images in lossless media. In the present paper, we show that surface frozen waves can indeed be designed even in media having non-zero extinction ratios. Examples are provided for specific surface intensity patterns, revealing that

In this paper, a two-level atom coupled with a double Lorentzian spectrum is solved by pseudomode theory, and an analytic representation of the density operator is obtained. Second, the paper investigates the entanglement witness and entropy uncertainty, and gets the analytical representation of entanglement, uncertainty, and their relationship. The environmental effects of the double Lorentzian spectrum

Losing the information contained in evanescent waves scattered from an object limits the best achievable resolution in far-field optical imaging systems to about half of the wavelength. This limitation is known as the diffraction limit. In this paper, we propose a new holography-based far-field imaging technique to go beyond the diffraction limit and achieve super-resolution images. In the proposed

Topology optimization (TopOpt) methods for inverse design of nano-photonic systems have recently become extremely popular and are presented in various forms and under various names. Approaches comprise gradient- and non-gradient-based algorithms combined with more or less systematic ways to improve convergence, discreteness of solutions, and satisfaction of manufacturing constraints. We here provide

We provide a compact 200 line MATLAB code demonstrating how topology optimization (TopOpt) as an inverse design tool may be used in photonics, targeting the design of two-dimensional dielectric metalenses and a metallic reflector as examples. The physics model is solved using the finite element method, and the code utilizes MATLAB’s fmincon algorithm to solve the optimization problem. In addition to

With the advances in the field of plasmonics, techniques for trapping and localizing light have become more feasible at the nanoscale. Several works have shown that plasmonics-based photovoltaic devices have yielded an improved absorption capability, enabling the design of thin-layered photovoltaic absorbers. In this review, we shed light on recent advances that employ plasmonics and nano-sized structures

We theoretically investigate the generation of dissipative solitons (DSs) and interactions between them in a fiber laser with higher-order dispersion and nonlinearity, multiphoton absorption, and gain dispersion or spectral filtering. A random component of the group-velocity dispersion (GVD) is taken into account too. The DSs are stabilized by the dynamical balance of the dispersion terms by the cubic–quintic

Erbium-doped ZBLAN (Er:ZBLAN) is a commonly used glass for mid-infrared fiber lasers. Quantifying the energy dynamics of the erbium ions is important for improving the performance of mid-infrared fiber lasers. Previous studies have found a discrepancy between the strength of inter-ion energy transfer measured in bulk Er:ZBLAN and the strength required to explain current fiber laser performance. We

We recently predicted [J. Opt. Soc. Am. B 35, 558 (2018) [CrossRef] ] that large radial gradients of the refractive index induced by the pump beam in the heated gain medium of diode-pumped alkali lasers (DPALs) could lead to improved DPAL beam quality. This effect depends on the composition of the buffer gas in the cell. We report here on verifying this counterintuitive finding by careful measurements

We report a correlation between periodic patterns of cold-atom density and field polarization that gives new insight into a nearly 30 year old question about the role of optical phases in laser cooling. The laser field of three intersecting pairs of counter-propagating ${\sigma ^ +} - {\sigma ^ -}$ beams is widely used for cooling of atoms in magneto-optical traps and optical molasses. This six-beam

We report an ultrabroadband perfect metamaterial absorber, comprising a two-dimensional array of a hemi-ellipsoid shaped metallo-dielectric multilayered structure. What we believe, to the best of our knowledge, is an unprecedented average absorbance of ${\sim}99\%$ is theoretically demonstrated in the 300 to 4500 nm spectral range at normal incidence. We use 20 pairs of molybdenum–germanium metallo-dielectric

In this paper, we discuss the Fano response from a hybrid trimer composed of gold and silicon nanospheres. This allows the structure to exhibit plasmonic properties while having a versatile spectral tuning of its Fano response. We analyze the Fano response from the point of view of the individual subsystem as well as the coupling of supermodes of the structure. The coupling between the sustained non-orthogonal

Inspired by the reflectarray concept, we propose a polarization beam splitter (PBS) using orthogonally oriented slotted graphene patches configured in a two-layer metasurface, which bidirectionally deflects the incident wave depending on its polarization in the terahertz (THz) regime. Our device employs slotted graphene patch resonators as plasmonic dipoles to provide a nearly 360° phase shift for

In this paper, we discuss the isotropic chiroptical response of two-layered metasurfaces with $n$-fold dihedral symmetries of resonators (${D_n}$) in the terahertz (THz) range. The analysis of numerical calculations is based on the homogenization model through effective polarizability approximation. We reveal the impact of resonator symmetry on circular dichroism and polarization anisotropy of the

While usually negligible in standard optical fibers, the group velocity dispersion of acoustic waves may in some cases play a significant role in the dynamics of stimulated Brillouin scattering (SBS) in propagation media with more complex structures, such as microstructured fibers. The usual three-wave coherent model of SBS can be adapted to take perturbative acoustic dispersion into account, but the

We derive an analytical formulation of the Raman-induced frequency shift experienced by a fundamental soliton. By including propagation losses, self-steepening, and dispersion slope, the resulting formulation is a high-order (HO) extension of the well-known Gordon’s formula for soliton self-frequency shift (SSFS). The HO-SSFS formula agrees closely with numerical results of the generalized nonlinear

We demonstrate the existence of a dynamical phase transition in the quasi-one-dimensional photonic condensate system formed in an axially symmetric optical cavity filled with a suitable thermalizing medium. The dynamical transition is observed to occur between the periodically modulated superfluid phase and the superfluid droplets phase. The parameter domains and conditions leading to such a dynamical

In this report, we investigate the statistical temporal distribution of nonlinear upconverted photoluminescence emitted by gold and silver nanostructures excited by focused near-infrared laser pulses. We systematically observe a clear signature of photon bunching regardless of the nano-object’s geometry, material’s crystalline arrangement, and electronic band structure. The similarity of the data obtained

We report on highly efficient and power-scalable laser operation in a thulium-doped high-phonon-energy crystal [monoclinic double tungstate, ${\rm KLu}{({{\rm WO}_4})_2}$] on the ${^3{{\rm H}}_4} \to {^3{{\rm H}}_5}\;{{\rm Tm}^{3 +}}$ transition giving rise to the short-wave infrared emission at ${\sim}{2.3}\;\unicode{x00B5}{\rm m}$. A 3 at. % Tm-doped crystal generated a maximum continuous-wave output

Imaging through a multimode fiber (MMF) is a promising strategy for in vivo endoscopy due to its nature of simultaneously realizing high spatial resolution and minimal invasiveness. In MMF-based speckle imaging systems, a spatial light modulator (SLM) with a large number of pixels is commonly employed to enable independent controls of all the linearly polarized (LP) modes inside the MMF. Here, instead

This paper proposes a method for shaping a light spiral with the desired intensity and phase distributions based on the addition of an angular-dependent amplitude distribution to the phase transmission function of a generalized spiral phase plate. An expression for the amplitude distribution of the illuminating beam, which provides a given intensity distribution in the focal plane along the light spiral

In this paper, a simple, analytical, and very efficient method capable of providing control of an optical beam’s intensity over an arbitrary curvilinear (planar) trajectory is developed. The same method also provides the possibility of managing branchings of the optical beam. The results presented here can have valuable applications in fields like optical tweezers, optical lithography, atom optical