A hybrid biomimetic imaging system combining the advantages of a fish eye and a compound eye is proposed. It uses a single ball lens as objective lens followed by an array of microcameras, which makes it possible to achieve high resolution in a wide field of view (FOV). Unlike conventional monocentric designs, a single ball lens is enough for the purpose of intermediate imaging. Its geometric aberrations

We present a new scheme of dual-core THz fiber for tunable polarization splitter based on the mode coupling theory. Each elliptical polymer core is modified with two elliptical air holes, which is helpful for high modal birefringence and low transmission loss. Due to different coupling lengths for x and y polarizations, the two orthogonal polarizations can be easily separated in an appropriate transmission

The results of a study of the nonlinear frequency response of a silicon micro-ring resonator (MRR) manufactured using silicon-on-insulator technology are presented. Appearance of optical bistability caused by the frequency shift of the MRR resonant spectrum under continuous wave pumping is experimentally demonstrated. The experimental results are explained in the framework of an original theory, which

In this study, we investigate an optical modulation of the focusing mirror based on photonic jet effect working in the reflection mode The photonic jet effects excited by surface plasmon polariton (SPP) in the near-field on the front-side of different core–shell micro-cuboids positioned on a substrate are presented. The core–shell micro-cuboid consists of a metallic shell (silver or gold) and a dielectric

This paper focuses on fabrication of submicron structures onto photoresist films by use of a continuous wave (CW) laser. Conventional CW laser fabrication has low accuracy, because the laser beam affects the periphery of a beam exposed area; it is unsuitable for three-dimensional submicrofabrication. Therefore, we have developed a high-accuracy exposure method with CW lasers that use controlling the

In this paper, we experimentally explore using both mode and space (i.e., aperture) diversity to improve system reliability and performance of a free-space optical (FSO) link under atmospheric turbulence. When a system has a limited number of transmitter and receiver apertures, introducing mode diversity to the existing space diversity scheme might further enhance the system performance. We utilize

This paper reports an elaborated study of a graphene-based transmittive-type triple-band linear to circular polarization converter (TTLCPC) within the lower mid infrared (MIR) region, covering the terahertz gap. The linearly polarized incident electromagnetic wave undergoes conversion into the circular polarization at three distinct frequencies viz., 5.72 THz, 13.49 THz and 18.90 THz. The axial ratios

The paper presents the research results of operation features of the copper bromide brightness amplifier in the monostatic laser monitor with frame-by-frame imaging. The dependence of the gain on the input signal level is determined. The small-signal gain reaches 0.22 cm−1 without the hydrogen-containing additive. It is proposed to estimate the sensitivity of a laser monitor based on the analysis of

A novel scheme to achieve a back reflector based on two-dimensional dielectric-metal graded metasurface is proposed, which presents high-efficiency over a broad range of incident solid angles and wavelengths. The remarkable performance is achieved by an effective optimization by searching the maximum reflection and the lowest deviation angle at a certain diffraction order. The optimized structure,

We present sub-aperture scanning Fourier transform system, a method for fast Bidirectional reflection distribution function (BRDF) measurements. A single lens is used for Fourier transform, and the scattering light field is measured by sub aperture scanning of the Fourier transform lens. Through Fourier transform, a single measurement can obtain multi-angle scattering data, and sub-aperture scanning

Axion remains the most convincing solution to the strong-CP problem and a well-motivated dark matter candidate, causing the search for axions and axion-like particles(ALPs) to attract attention continually. The exchange of such particles may cause anomalous spin-dependent forces, inspiring many laboratory ALP searching experiments based on the detection of macroscopic monopole–dipole interactions between

Single-longitudinal-mode gain-coupled distributed feedback (DFB) lasers based on high-order gain-coupled surface gratings emitting at 770 nm window are implemented. The periodic surface metal p-contact with insulated grating grooves realizes a gain coupled mechanism. Our devices provided a single longitudinal mode with the maximum CW output power up to 116.8 [email protected] mA with facet coated (HR>99%

An all-solid-state Nd:YVO4 laser producing dual-wavelength of 1064/1342 nm was designed, which took a plan of double RTP (RbTiOPO4) electro-optic Q-switch of 1064 nm and 1342 nm, by controlling the voltage of double RTP crystals to control the output laser power ratio of dual-wavelength. When the repetition rate is 10 kHz, the 1064/1342 nm dual wavelength laser output with 1.6/1.6 W, power ratio of

Asymmetric nonlinear gain in tunable three sections distributed Bragg reflector (3s-DBR) laser is theoretically studied with multimode rate equations. It is found, with a special design, anomalous interaction between adjacent modes can be used to enhance modulation bandwidth of the 3s-DBR laser. Tuning characteristics and direct modulation response of a designed laser are simulated and analyzed. Results

The AlGaAs material platform has been intensively used to develop nonlinear photonic devices on-a-chip, thanks to its superior nonlinear optical properties. We propose a new AlGaAs waveguide geometry, called half-core etched, which represents a compromise between two previously studied geometries, namely the nanowire and strip-loaded waveguides, combining their best qualities. We performed tunable

The coupling resonance effect between surface plasmon polariton (SPP) and multi-mode magnetic polariton (MP) is very complicated. In this study, we propose a complex trapezoidal grating solar absorber (CTGSA) with nanoscale structure, which is made of two tungsten trapezoids and a silicon dioxide spacer lying on the tungsten substrate, to study the coupling resonance between SPP and multi-mode MP in

The paper presents the results of the research and development the brightness amplifier excited by longitudinal capacitive discharge with a pulse repetition frequency (PRF) up to 24 kHz for using in systems with optical signal amplification. The amplification features of the active element were experimentally studied. The results of the use the designed brightness amplifier in the MOPA system and in

A double-side polished fiber (DSPF) is fabricated for the passive generation of mode-locked pulses in an optical fiber ring cavity. The DSPF is made using a modified wheel polishing technique and coated with a cobalt oxide (Co3O4) solution as a saturable absorber (SA) to induce mode-locked operation by evanescent field interaction. The laser uses a thulium-holmium-doped fiber (THDF) for lasing in the

In this paper, we propose a generalized kind of partially coherent vector beams with an off-axis vortex, named partially coherent radially polarized (PCRP) off-axis vortex beam for considering such a case in which laser beam passes through a spiral phase plate (SPP) but slightly deviates from the vortex core due to the experimental misoperation. The influences of such off-axis vortex phase on the focusing

In this paper, we study the multi-granularity switching of SDM optical network. We design and demonstrate a novel multi-granularity SDM ROADM. The optical node is a simple two-layer architecture, which has the functions of all-optical multi-granularity switching, business convergence, traffic grooming, channel add/drop and online monitoring. We demonstrate MCF-level switching, fiber-level granularity

The Kramers-Kronig (KK) receiver has been used for dispersion compensation in direct detection systems employing external-modulator-based transmitters. In this paper, we investigate the use of the KK receiver for dispersion compensation in a direct detection system based on a directly-modulated laser. We show the validity of the KK receiver by considering a linear contribution to the optical phase

It is theoretically shown that the distribution of the average intensity of Gaussian optical vortex in the focal plane of a spherical lens scattered by random phase screen has the form of a ring with non-zero value on the optical axis. The radius of the ring depends on the topological charge of the optical vortex and the scattering power of the diffuser. Therefore the topological charge can not be

This paper presents a compact dual-mode polarization beam splitter (PBS) based on silicon on insulator platform. The proposed PBS separates two lowest-order transverse magnetic (TM) modes from two lowest-order transverse electric (TE) ones by employing an optimized tapered directional coupler. To the best of our knowledge, this is the first PBS with the ability of separating two sets of modes with

Due to the complexity and strong fluctuations of atmosphere turbulence, it is always a challenging task to mitigate atmospheric turbulence effects in space optical communications. In this paper, we demonstrate a shared local oscillator (LO) spatial diversity polarization multiplexing coherent optical orthogonal frequency division multiplexing (PM-CO-OFDM) system based on group timing synchronization

This paper proposes a wavelength diversity decode-and-forward (DF) serial relay orthogonal frequency division multiplexing (OFDM) free-space optical (FSO) communication system. The proposed system performance is evaluated by the quadrature phase-shift keying (QPSK) as an OFDM signal subcarrier mapping method, considering the maximum ratio combining (MRC) and equal gain combing (EGC) schemes, over exponentiated

We theoretically investigate a plasmonic nanostructure, which comprises a groove and aperture-coupled slot resonators integrated on a metal–dielectric–metal (MDM) waveguide. The interference between the mode of the slot resonator and groove give rise to the Fano resonances which can be easily tuned by changing the parameters of the slot. Furthermore, this structure can be extended to generate double

A cost-effective optical signal-to-noise ratio (OSNR) monitoring scheme with large chromatic dispersion (CD) tolerance is proposed. By leveraging the low-bandwidth coherent detecting with both highly sensitive optical to electrical conversion and small bulk wavelength scanning, no CD compensation and the random forest trained with asynchronous amplitude histograms, the proposed technique could serve

We propose and numerically investigate a fiber-optic sensor comprised by core-offset splicing up to 20 equal-length single-mode fiber (SMF) segments, which is used for the high-sensitivity refractometric sensing owing to the open cavities with much light propagating outside the optical fiber. The emergence of high-order modes in the silica cladding and air enhances the multi-mode interference, therefore

In this work, we put forward the length design principle of the dual-injection integrated Ge-on-Si photodetectors based on the characteristics of the light field distribution. When the length of the absorption layer makes the maximum intensity of the incident light from both ends are alternately distributed, the light field distribution is more uniform. Based on this principle, the shorter photodetector

Flexible terahertz fibers were designed for terahertz wave applications. In this paper, new terahertz fiber structures using polymer tube bundles were proposed. A triangle structure fiber with three-tube core and a hexagonal structure fiber with mono-tube core were considered. Mode field distributions in the proposed terahertz fibers and their propagation losses were numerically calculated using the

The existence of three generalized mirrors (Martinelli and Martelli, 2017) that compensate for the effects of birefringence in retracing optical circuits allows to develop a parallel with the time reversal properties. The Wigner time reversal operator for the photon spin is considered and three pseudo time reversal operators borrowed from this original operator are introduced and analyzed. Their application

Using the Richards–Wolf formula focusing of a circularly polarized plane wave with wavelength 532 nm by an aplanatic lens with high numerical aperture was investigated numerically. We have investigated the behavior of the spin angular momentum (SAM) and the Poynting vector at the focal spot. It was shown that the direction of rotation of the transverse component of the SAM at the focus does not depend

Hybrid free-space optical (FSO) and millimeter wave (mmWave) systems have emerged as promising candidates for high data rate wireless transmissions due to their unique complementary properties with respect to different channel and environment conditions. A main issue in hybrid FSO-mmWave systems is the mechanism followed to activate one of the links. Most of the proposed selection mechanisms suffer

We have designed two CMOS compatible plasmonic electro-absorption modulators (EAMs) based on vanadium dioxide (VO2) and indium tin oxide (ITO). Their performance matrices have been improved in terms of insertion loss (IL), extinction ratio (ER), and figure of merit (FOM). Rigorous Finite Element Method (FEM) has been used to optimize output parameters based on the input device parameters. The IL, ER

We report on the generation of high-order solitons with order continuously adjustable in an erbium-doped fiber laser mode-locked by a graded index multimode fiber–step index multimode fiber–graded index multimode fiber (GIMF–SIMF–GIMF) saturable absorber (SA). The SA has advantages of high damage threshold, easy fabrication and low cost. The fundamental soliton to eleventh-order soliton were obtained

In this paper we introduce novel time-resolved photoluminescence spectroscopy called femtosecond two pulses induced stimulated emission spectroscopy, in which the generated nonlinear photoluminescence signal was used to identify the ultrafast dynamics of stimulated emission process in the semiconductor material. By employing two collinear fundamental femtosecond laser beams, we systematically investigated

Based on Fresnel–Kirchhoff diffraction theory, the effect of high order nonlinearities and saturable Kerr media in Z-scan experiments are theoretically investigated. Analytical expressions were obtained for the Z-scan curve, which can be strongly affected by the pump intensity. Moreover, empirical relationships were found to describe the intensity dependence of the peak-valley distance and the transmittance

Light reflection among surfaces of an optical system and coherent waves superposition can lead to interference resulting in undesirable fringes. Such optical fringes cause distortions of transmission spectrum of the experimental setup. Analysis of the interference reduction by wavelength modulation is presented. The method was applied for minimizing fringes in an experiment with multipass absorption

In this paper, a multi-segment bonded crystal model of YAG/Tm:YAG/ YAG/Tm:YAG/YAG structure is proposed firstly and the thermal effect of LD double-end pumped multi-segment bonded Tm:YAG crystal is investigated. The thermal distribution is simulated and the thermal focal length of the multi-segment bonding is calculated and measured, which comfirms that it can effectively alleviate the thermal effect

Raman spectroscopy is a non-destructive testing technology that has been widely used in biomedicine and other fields. However, the spontaneous Raman signal is weak. Therefore, the data collection is very time consuming, which has seriously hindered the application of Raman imaging technology in the fast dynamic system. At present, the reconstruction of Raman spectra based on multi-channel measurements

Characterizing polarization of skin pathologies is still an interested issue for the dermatology community. In a previous study, the present group proposed a Stokes-Mueller matrix polarimetry for differentiating between squamous cell carcinoma tissue and normal healthy tissue in mice. The present study extends our method to the detection of squamous cell carcinoma, basal cell carcinoma and melanoma

Study on the excitation process of magnesium atom has been conducted in microwave-assisted laser plasma. Experimentally, an Nd:YAG laser (532 nm, 5 mJ) was directed into the magnesium oxide (MgO) sample in various gases of helium, argon, and air at a reduced pressure to induce a luminous plasma. The plasma emission was significantly enhanced when a microwave (2.45 GHz, 400W) was introduced into the

The spectra, the phase shifts, and the phase difference between TE and TM waves upon reflection from a one-dimensional photonic crystal (1D PC) containing negative-zero-positive index metamaterials (NZPIMs) have been investigated. It is found that there exist a zero-n̄ gap and a dirac point (DP) band gap, which can be adjusted by the incident angle, the thickness ratio, and the scaling factor. Furthermore

In this paper, a two-position rotating grating compressed sensing spectrometer is proposed, which can expand the spectrum measurement range nearly twice without losing high resolution. In the entire measurement process, two compressed sensing samples are taken for two spectral segments respectively, but through mathematical transformation, only one calculation is performed to reconstruct the whole

A unidirectional vertical coupling structure is designed based on optical through-silicon vias (TSVs) and gratings to couple and steer the optical interconnects in 3D optoelectronic integrated circuits. The optical TSVs provide high-speed vertical optical data transmission over short distances. The grating coupler structure achieves efficient coupling between an optical TSV and a planar Si waveguide

In order to perform a simple design of topological edge states, we construct two-dimensional triangular lattices with reversed scatterers and matrix materials. As the p and d orbits in the two lattices are reversed, the topologically trivial and non-trivial states can directly be formed without any intermediate transition. The topological edge states occur at the interface between the two lattices

The types of aerosols are essential for estimating radiative forcing effects, improving the lidar retrieval algorithms, and identifying aerosol sources. However, it is difficult to categorize the aerosols with similar optical properties based on lidar techniques. In this study, an approach was proposed to distinguish desert dust (DD), mineral dust (MD), air pollution aerosols (APA), and their mixtures

The possibility to perform the tomography of irregularly-shaped rough particles in a flow using multi-view interferometric imaging is investigated. Combining three perpendicular angles of views, we reconstruct a family of possible 3D-shapes from speckle patterns. The estimation of an error parameter enables the elimination of erroneous 3D-shapes to obtain a more accurate estimation of the particle’s

Black objects are sometimes associated with black carbon, while shiny, highly reflecting surfaces are typically associated with metals. Here, we discuss several objects in everyday life that upon use take on a black color that is unlikely to be due to black carbon. We propose that this black color is caused by the formation of metallic nanoparticles from abrasion processes. We support this hypothesis

In this paper, a non-volatile polarization-insensitive 1×2 silicon optical switch utilizing phase-change materials is presented. The presented device is composed of three polarization beam combiners/splitters, two directional couplers with phase change materials, and a polarization-insensitive waveguide crossing. By adjusting the phase state of phase-change material, polarization-insensitive switching

Based on the aberration theory of plane-symmetric optical system, this paper develops a method for calculating the wave aberration of the field curvature and color aberrations of each optical surface in an ultrawide-angle optical system, which enables us to analyze, like Seidel aberration theory, the contribution and balance of these aberrations between different optical surfaces. We then apply the

We present the exact equations for designing a stigmatic singlet lens that meets Abbe’s sine condition for each ray. These lenses are designed from the solution of a system of nonlinear equations. We test the results and method by ray-tracing techniques with a very high accuracy.

In this study, a new dielectric loaded plasmonic waveguide is proposed by inserting a vertical graphene layer into the dielectric ridge in order to realize propagation of SPP waves symmetrically on both sides of the graphene. This waveguide is numerically analyzed for sensing applications at the wavelength of 1550 nm. The effective refractive indices of its guided modes are calculated by the full-wave

A distributed fiber-optic sensor based on a hybrid configuration of dual-Sagnac interferometer is proposed and demonstrated. The polarization compensation module is used to stabilize the polarization state of Sagnac interferometer so that it can be used for sensing. Through the time delay estimation algorithm, two signals with a time delay can be constructed, and the vibration position can be obtained

There is presently an increased research activity in understanding the nature of optical force when ultrashort pulsed excitation is used to trap and manipulate objects with sizes ranging from micrometers down to nanometers. Such a ‘nonlinear laser tweezer’ is peculiarly promising because the nature of the force can be dramatically tuned owing to optical nonlinearity. However, accurate measurement of

In the present study, a brief, efficient and synchronous 3D (three-dimensional) deformation measurement method based on digital speckle pattern interferometry (DSPI) and digital shear speckle interference (DSSPI) was proposed. Comparing with traditional multi-laser and multi-CCD DSPI methods, this method used a single CCD and two lasers to capture the speckle patterns from three sensitive directions

Optical sensors based on surface plasmon resonance are widely used in several applications. The structure to obtain the resulting polarization in the resonance of the surface plasmon in the Kretschmann configuration was investigated, a silver film acts as coating, in addition there is a dielectric layer which is deposited on the silver film, water is also used as substrate, using a source of λ=633 nm

An efficient generation of red emission at 620 nm from an artificial diamond crystal based on the second-order stokes design is demonstrated. According to the cascaded stokes theory, the second-order stokes laser is crucial for controlling the output of the multi-stokes laser. In this work, applying a microcavity with the integrated coating design, the Raman red laser can be achieved the highest average

In recent years, polarized light navigation has been widely used for the application of the autonomous heading measurement of small unmanned combat platforms to satellite navigation rejection. However, current techniques of polarized light navigation yield low accuracy when measuring the heading angle in dynamic environments, and the use of a single source of navigation has some shortcomings as well

Plasma is commonly existing in pulsed laser drilling and it has an important impact on drilling results. The effects include plasma absorption and defocusing effect caused by plasma. This paper studied the influence of plasma on laser drilling by a combination method of numerical simulation and experiment. Based on the combination of computational fluid dynamics (CFD), fluid–solid coupling theory,