We have developed a sensitive, novel laser heterodyne radiometer using a fiber-coupled distributed feedback laser as the local oscillator to measure Fe(I) Fraunhofer lines Doppler-shifted by the rotational motion of the Sun. The radiometer repetitively measures the Doppler shift of an Fe(I) Fraunhofer line at a vacuum wavelength of 1559.252 nm induced by the Sun’s rotation on its eastern and western

In this paper, we develop a method of simulations of using the broadband Green’s function (BBGF) in the Korringa Kohn Rostoker (KKR) method. The merit of the method is broadband such that once the initial setup is completed, the calculation at every frequency is calculated rapidly. The broadband Green’s function consists of a frequency-independent spatial summation and a spectral summation that has

A lossy mode resonance (LMR) based fiber optic refractive index (RI) sensor utilizing a layer of fluorine-doped tin oxide (FTO) over the unclad core of the fiber is theoretically analyzed. To enhance its sensitivity, the thickness of the FTO layer is optimized. For further sensitivity enhancement, an over-layer of two different materials, ${{\rm{TiO}}_2}$ and ${\rm{Hf}}{{\rm{O}}_2}$, is used. The sensitivity

We conducted a study on the thermal effects in chirped volume Bragg gratings (CVBGs) used as optical compressors in high-power lasers. A simulation code was developed to predict the distortion of the pulses by the thermal effects. The types and significance of the thermal distortion were analyzed using an Yb:YAG laser with an average power of 250 W. The temperature distribution in the CVBG, the thermal

Thermal management for the continuous wave (CW) operation of large-area double-lattice photonic-crystal surface-emitting lasers (PCSELs) is discussed. Thermal analysis is conducted to calculate the temperature of PCSELs under CW operation with heat dissipation. We assemble a double-lattice PCSEL in a water-cooling package with a highly thermally conductive sub-mount for heat dissipation. We measure

A novel noncollinear phase-matching (PM) scheme was proposed by introducing a small tunable angle between two pump beams to maximize the effective nonlinear coefficient (${d_{\rm{eff}}}$) in tunable terahertz wave difference frequency generation in the ${{\rm ZnGeP}_2}$ crystal. Compared with the collinear PM condition, the noncollinear geometry transfers the PM angle to be around $\theta = {90}^\circ$

We propose low-power designs of electrotunable absorption- and transmission-mode color filters and optical switches based on a metal–dielectric–metal structure. By applying voltage across an electro-optic polymer, used as a dielectric layer, tunable color filtering is achieved over a voltage range of ${-}10 \; {\rm{V}}$ to $+{{10}}\;{\rm{V}}$. Moreover, by adjusting each layer thickness, such designs

We present a cascaded side-coupled silicon-on-insulator (SOI) photonic crystal nanobeam cavities (PCNCs) sensor for simultaneous sensing of the refractive index (RI) and temperature. Two types of PCNCs are designed for increasing the demodulation coefficient: the low-index mode cavity exposed to water directly (${{\rm cav}_1}$) and the high-index mode cavity covered with SU-8 cladding (${{\rm cav}_2}$)

The spontaneous emissions of a quantum emitter near three different samples, namely, graphene-covered hexagonal boron nitride (hBN) bulk (monocell), graphene/hBN/graphene sandwich (sandwich), and graphene/hBN/graphene/hBN (double-cell), are investigated in detail. The spontaneous emission decay rate near the graphene/hBN samples can be increased by several orders of magnitude because of the hyperbolic

We provide experimental characterization of stimulated Brillouin scattering at 2-µm wavelength in step-index optical fibers made of various types of infrared materials. Our results show that the main characteristics of the Brillouin process such as the frequency shift, spectral linewidth, and gain can be widely tuned through the index-controlled guiding of both acoustic and optical waves as well as

A theoretical model for all-optical modulation format conversion from amplitude-shift keying (ASK) to phase-shift keying (PSK) has been proposed using a reflective vertical cavity semiconductor saturable absorber (R-VCSSA). The R-VCSSA is a nonlinear device. The phase response of the device has been studied numerically with different input intensities. It has been observed from the simulated result

The properties of the photonic spin Hall effect (PSHE) excited in a prism-coupling waveguide with hyperbolic metamaterial (HMM) are investigated theoretically. The proposed waveguide is composed of four layers including a prism, HMM, thin metal, and air. Both type I and type II HMMs can be created through multilayer realization comprising alternating subwavelength layers of plasma and dielectric or

Layered semiconductor hyperbolic metamaterials (HMMs) are composite materials composed of alternating subwavelength-doped (metal) and undoped (dielectric) semiconductor layers. These materials support the propagation of light with large wave vectors through modes called volume plasmon polaritons (VPPs). In this paper, we use finite-element modeling and effective medium analysis (EMA) to investigate

The study of photonic crystals, artificial materials whose dielectric properties can be tailored according to the stacking of their constituents, remains an attractive research field, and it is the basis of photonic devices based on the generation, processing, and storage of photons. In this paper, we employ a transfer-matrix treatment to study the propagation of light waves in periodic, quasiperiodic

We present robust control of superposition of spatial modes in a photonic crystal cavity arising from incorporating a weak localized perturbation. As expected, this perturbation breaks the symmetry of the underlying photonic crystal structure, resulting in a frequency shift of the cavity eigen modes. Engineering of the perturbation leads us to discover the comprehensive mathematical structure of the

We theoretically and numerically investigate the dynamics of a time truncated finite energy Airy pulse (FEAP) under longitudinally varying group velocity dispersion (GVD), which significantly influences the Airy dynamics. Realistic waveguide geometries are proposed that offer linear and oscillating GVD profiles through which one can efficiently control the ballistic Airy trajectory. We observe that

Control of the nonlinear response of nanostructures via path interference effects, i.e., Fano resonances, has been studied extensively. In such studies, a frequency conversion process takes place near a hot spot. Here, we study the case where the frequency conversion process takes place along the body of a nonlinear crystal. Metal nanoparticle–quantum emitter dimers control the down-conversion process

A stretchable chiral metamaterial with Au nanoslits and L-shaped and T-shaped Au patterns (SCMM-NLT), which can simultaneously produce circular dichroism (CD) and asymmetric transmission (AT) effects for circularly polarized waves in the mid-infrared region, is proposed. The peak values of CD and AT effects reach 20.4% and ${-}{20.4}\%$ at the resonance wavelength of 23.4 µm, respectively, which originate

This publisher’s note corrects the funding and acknowledgment sections in J. Opt. Soc. Am. B 37, 2805 (2020). [CrossRef]

Africa has a long history in optics, but decades of turmoil have seen optical science in Africa advance only slowly, punching far below its weight. But a younger generation of scientists hold promise for the brighter future, addressing continental issues with photonics. In this Feature Issue on Optics in Africa we capture some of the exciting optical research from across the continent in 51 research

Fast and secure sharing of information is among the prime concerns of almost any communication system. While commonly used cryptographic algorithms cannot provide unconditional security, high-dimensional (HD) quantum key distribution (QKD) offers an exceptional means to this end. Here, we provide a tutorial to demonstrate that HD QKD protocols can be implemented in an effective way using optical elements

Recent advances in the availability of intense, carrier-envelope phase-stabilized few-cycle lasers have led to the active study of the control of electrons using a light field in atoms, molecules, and solids. The field-driven ultrafast current in solids by strong fields is of far-reaching importance in view of ultrafast devices. Recent ab initio time-dependent density functional theory calculations

Laguerre–Gaussian beams with vortex structure, as a special type of electromagnetic wave, can carry energy, momentum, and angular momentum, which is crucial for understanding of dynamical processes concerning light–matter interaction phenomena. In this paper, we theoretically investigate the local dynamical characteristics of Laguerre–Gaussian vortex beams upon reflection and refraction. Using a hybrid

We consider transformation of quantum intensity correlations of light, observed by direct photodetection, by a single-lens temporal imaging scheme with magnification factor $M$. We prove that such an imaging scheme performs noiseless stretching or contraction of the second-order intensity correlation function without deteriorating such nonclassical features as antibunching and sub-Poissonian statistics

We present a topology optimization method for a 1D dielectric metasurface, coupling the classical fluctuations-trend analysis (FTA) and diamond-square algorithm (DSA). In classical FTA, a couple of device distributions termed fluctuation or mother and trends or father, with specific spectra, is initially generated. The spectral properties of the trend function allow one to efficiently target the basin

A proposal for cooling the translational motion of optically levitated magnetic nanoparticles is presented. The theoretical cooling scheme involves the sympathetic cooling of a ferromagnetic YIG nanosphere with a spin-polarized atomic gas. The particle–atom cloud coupling is mediated through the magnetic dipole–dipole interaction. When the particle and atom oscillations are small compared to their

We report on trapping and cooling $^6{\rm Li}$ atoms in a monolithic ring bowtie cavity. To make the cavity insensitive to magnetic fields used to tune atomic interactions, we constructed it entirely from fused silica and Zerodur. The components were assembled using hydroxide bonding, which we show can be compatible with ultra-high vacuum. Backscattering in high-finesse ring cavities readily causes

We conducted a theoretical study on the potential use of amorphous hydrogenated silicon (a-Si:H) as the high-index material in quarter-wave-stack Bragg mirrors for cavity quantum electrodynamics applications. Compared to conventionally employed ${\rm{T}}{{\rm{a}}_2}{{\rm{O}}_5}$, a-Si:H provides a much higher-index contrast with ${\rm{Si}}{{\rm{O}}_2}$, thus promising significantly reduced layer-number

The transmittance fluctuation resulting from free space optics will impart the continuous-variable quantum key distribution (CV-QKD). In this paper, we study the CV-QKD over free space by taking practical transmittance fluctuation into account. The transmittance is modeled following the Gaussian distribution, which reflects the most realistic fluctuation since all sources of perturbation are required

A cost-effective, compact, and portable optical system using multi-angle illumination for retrieval of the amplitude and phase of a sample is implemented in this paper. The system consists of a matrix of LED followed by a mask, a USAF resolution chart, and a detector in a column. The sample information is collected by the detector directly without any objective lens. The sample information is encoded

By leveraging cross-like hybrid plasmonic waveguides (HPWs) and subwavelength gratings, a silicon-based ultracompact ${{\rm{TE}}_0}$- and ${{\rm{TE}}_1}$-${\rm{pass}}/{{\rm{TM}}_0}$- and ${{\rm{TM}}_1}$-stop dual-mode polarizer for 1.55/2 µm dual-wavelength is proposed and analyzed in detail. The HPWs are located above the bottom Si waveguide to form a hybrid plasmonic silicon nitride waveguide (HPSNW)

The localized modes of one-dimensional photonic crystals without inversion symmetry are calculated by using linear combinations of Wannier functions. A closed form is given for the phase of the Bloch function leading to maximally localized Wannier functions. The defect consists of changing the refractive index of one layer in a single unit cell. The results for the frequencies and magnetic-field profiles

We study numerically and experimentally the impact of temporal randomness on the formation of analog optical blast waves in nonlinear fiber optics. The principle of operation is based on a two-components nonlinear interaction occurring between a partially coherent probe wave co-propagating in a normally dispersive optical fiber together with an orthogonally polarized intense short pulse. The cross-polarized

A compact and broadband three-dimensional (3D) quasi-${{\rm TE}_0}$ and quasi-${{\rm TE}_1}$ mode (de)multiplexer [(De)MUX] is proposed via an asymmetric slot-strip coupler, in which the optimally lateral displacement between the bottom silicon slot waveguide and the upper poly-silicon strip-waveguide can enable the vertical mode-coupling efficiently. The design of the proposed 3D mode (De)MUX is based

The so-called terahertz band of the electromagnetic spectrum falls in a spectral region where traditional electronic technologies fail to operate owing to the extremely short switching times required. In this paper, we demonstrate the design of three optical logic gates fabricated by three-dimensional printing, which can perform the OR, AND, and XOR logic operations at 130 GHz. In order to optimize

The propagation of guided TE and TM modes through graded-index planar waveguides is reported in this paper. Both a real-valued and complex-valued position-dependent refractive index are supposed for a film layer. It is possible to set various refractive index profiles based on five distribution parameters. For the position-dependent refractive index, the governing equations are transformed to Heun’s

Optical tweezers are noncontact and noninvasive force transducers. Techniques for multiple optical trapping are of much interest. In this paper, we investigate, numerically, optical trapping of multiple particles using so-called petal beams by trapping every single particle in a separate petal of the focused beam. We have used the generalized Lorenz–Mie theory to compute the optical trapping forces

Absorption, scattering, and turbulence experienced in underwater channels severely limit the range of quantum communication links. In this paper, as a potential solution to overcome range limitations, we investigate a multi-hop underwater quantum key distribution (QKD) where intermediate nodes between the source and destination nodes help the key distribution. We consider the deployment of passive

We have developed a theory for the one-photon and two-photon fluorescence of a nanohybrid composite comprised of an ensemble of quantum dots encased in a matrix of polymer. The quantum dots are comprised of four-level quantum emitters encased within a coating of dielectric material. The fluorescence of the quantum dot system is calculated using the master equation method where dipole–dipole interaction

In plasmonic guided waves, material absorption is generally an unwanted shortcoming that degrades the quality of plasmon modes by greatly curtailing their propagation distance. In this work, we explore the general features of the modal properties supported by 2D anisotropic materials and elucidate how the material’s in-plane anisotropy can offer a previously untenable level of control or tailoring

Diagnostics tools are the underpinnings for the experimental study of combustion phenomena. The inherent dynamic and three-dimensional (3-D) nature of turbulent flames has imposed strict requirements to the measurement techniques, which should provide both temporally and spatially resolved information of the target flames. Time-resolved volumetric tomography is one of such methods that meet the stringent

In this paper, a double-layer structure of ultra-bandwidth cross-polarization converter (PC) has been devised in line with the rationale of the metasurface. The project can bring about a superior 90° conversion effect of the incident wave when it is perpendicularly incident. This PC is an improvement and majorization of the single-layer PC with a bowknot surface structure, which can hit the mark of

Optical metasurfaces with an ultra-thin, planar structure can easily adjust the phase and polarization of light waves. Based on the principle of the resonant phase, a cubic nanopillar is designed to construct the polarization-insensitive metalens in the visible light range. By simulating the phase and transmission efficiency of a cubic nanopillar with a width of ${50}\sim{200}\;{\rm nm}$, the optimized

We analyze the Kerr index, associated critical power, and focal length for nodal semimetals in a Weyl, Dirac, and gapped semimetal phase. Our model produces a Kerr index of ${10^{- 15}} - {10^{- 20}}\;{{\rm{m}}^2}/{\rm{W}}$ in the micro-meter wavelength range. Novel dependence of the Kerr index, critical power, and focal length on temperature, chemical potential, bandgap, and node separation are readily

We present a novel and straightforward Fibonacci lens, which is created by binarizing and adding a spiral phase to its radial phase function. It is shown that this new element yields a pair of petal-like modes due to several segments of the Fibonacci lens, where each segment is phase shifted by $\pi$ compared to its adjacent segment. Also, the generated petals have highly controllable rotation, and

The possibility to perform time-resolved spectroscopic studies in the molecular fingerprinting region or extending the cutoff wavelength of high-harmonic generation has recently boosted the development of efficient mid-infrared (mid-IR) ultrafast lasers. In particular, fiber lasers based on active media such as thulium or holmium are a very active area of research since they are robust, compact, and

In this paper, we present a fabricated cladless optical fiber sensor to analyze distilled water solution polluted with methylene blue (MB). The fabricated sensor is based on evanescent wave absorption by the surrounding medium at the core–liquid cladding interface. The response of the optical fiber sensor is mainly related to the MB concentration as well as its refractive index. A theoretical and experimental

Dithizone, with its derivatives and complexes, is characterized by seven classes of chromic reactions, which make it a remarkable candidate for diverse sensor applications. We now present dithizone’s chromic response to experimental photoexcitation as studied by ultrafast laser spectroscopy, density functional theory (DFT), and complete active space self-consistent field (CASSCF) calculations. After

Propagation of few-cycle optical pulses in nonlinear optical Kerr (cubic) and non-Kerr (quintic) type metamaterials, exhibiting frequency-dependent dielectric susceptibility and magnetic permeability, is considered. Considering the theory of electromagnetic waves from Maxwell’s equations, a new nonlinear evolution equation describing the combined influences of higher-order nonlinearities and higher-order

We report on simultaneous sum-frequency mixing and doubling of C-band and ${\sim}{980}\;{\rm nm}$ laser sources using a single segmented periodically poled lithium niobate (PPLN) crystal in a single-pass configuration. Our theoretical analysis on the spectral outputs show that a proper design of a five-segment single PPLN crystal has potential to generate violet, blue, green, and orange wavelengths

The field of nonlinear optics has been investigated extensively since its beginning in 1961. This development is in both the theory of nonlinear effects and the theory of nonlinear interactions in nonlinear media, and in the applications of nonlinear devices. The mathematical basis of nonlinear optics is Maxwell’s system of equations governing propagation of electromagnetic waves in a material medium

The ${\rm ZnO} {-} {{\rm ZrO}_2}$ nanocomposites were prepared using varying concentrations of ${{\rm Ho}^{3 +}}$ ions through the solution combustion method. Zirconium butoxide and zinc nitrate were used as the precursor solutions with citric acid as a fuel. The synthesis was done at a low temperature of 80°C and then the samples calcined at 600°C for 2 h, before characterization. Rietveld refinement

An optimized H1 photonic crystal (PhC) microcavity with a high quality factor ($\!Q$), small mode volume, wide measurement range, and high sensitivity is proposed, and its possibility in spectroscopic gas sensing is theoretically demonstrated. In the proposed structure, we have taken advantage of the air holes surrounding the defect region to optimize the resonance characteristics so as to detect the

As available spectrum gets congested by different applications, spectral efficiency can be enhanced through spectrum sharing and coexistence. In this paper, we demonstrate the idea of spectrum sharing and coexistence by using optical heterodyning as a flex-spectrum photonic RF transmitter. Flexibility was achieved by tuning the RF carrier frequency from 1–5 GHz, frequencies around two spectra from

We present an improvement on the signal-to-background of single-beam coherent anti-Stokes Raman scattering (SB-CARS) spectroscopy measurements for systems employing ultrafast supercontinuum sources based on all-normal dispersion photonic crystal fibers. Improvements to the signal-to-background arise in the use of a new pulse-reconstruction algorithm based on temporal ptychography, ${{\rm{i}}^2}{\rm{PIE}}$

Plasmon coupling between the dipolar localized surface plasmons of a nanoegg and the longitudinal dipolar localized surface plasmons of a nearby gold nanorod is investigated within a dipolar-quasistatic limit. This was achieved by varying the core-offset of the nanoegg for different nanorod sizes at a fixed coupling distance. With respect to the plasmon peaks of the isolated nanoegg, we studied blue

Nonlinear microscopy has evolved over the last few decades to become a powerful tool for imaging and spectroscopic applications in biological sciences. In this study, ${{\rm i}^2}{\rm PIE}$, a novel spectral phase control technique, was implemented in order to compress broad-bandwidth supercontinuum light pulses generated in an all-normal-dispersion (ANDi) photonic crystal fiber (PCF). The technique

Synthetic mesh lattice (SML) with temporally controlled potential is a versatile platform for realizing wave dynamics associated with physical areas of optics and quantum physics. Here, discrete optics in one-dimensional synthetic photonic lattice is investigated systematically, in which the light behavior is highly analogous to that in evanescently coupled one-dimensional discrete waveguides. Such

Waveguides based on metamaterials may exhibit strongly frequency-dependent nonlinearities. In this work, we focus on the phenomenon of modulation instability in this type of waveguide, departing from a new modeling equation that ensures strict conservation of both the energy and photon number of the parametric process. In particular, we analyse the case of a waveguide with a linearly frequency-dependent

A novel scheme to implement an optical single-sideband (OSSB) polarization modulator (PolM) is proposed and theoretically demonstrated in this paper. The proposed OSSB-PolM is based on the phase modulation technique in two consecutive Sagnac interferometers (SIs). It is shown that by applying four equal-power radio frequency (RF) signals with appropriate phases to electro-optic modulators and aligning