Long range phase-sensitive optical time domain reflectometer (φ-OTDR) sensing mainly employs distributed amplification in the fiber. It requires light to be injected into both ends of fiber, which reduces degree freedom embedding fiber structures. To overcome this problem, key factors that affects signal-to-noise ratio (SNR) φ-OTDR system based on matched filter is analyzed thoroughly, and a single-ended long-range does not require proposed. In system, two techniques are adopted for SNR...

We simulate the motion of spherical particles in a phase-separating binary mixture. By combining cell dynamical equations with Langevin dynamics for particles, we show that addition hard significantly changes both speed and morphology phase separation. At late stage spinodal decomposition process, slow down domain growth, qualitative agreement earlier experimental data.

Resonant transmission of light has been observed in symmetric Fibonacci TiO2/SiO2 multilayers, which is characterized by many perfect peaks. The dramatically decreases when the mirror symmetry multilayer structure deliberately disrupted. Actually, feature peaks can be considered as general evidence for dielectric multilayers with internal structure. It opens a unique way to control propagation.

A novel low-profile, ultra-lightweight, high-efficient circularly polarized (CP) planar patch antenna array is reported for Ku-band satellite TV reception applications. The basic radiating element of the realized by a 2 × corner-removed subarray. This subarray centerfed rectangular coupling aperture etched on top surface substrate-integrated-waveguide cavity. compact sequential rotation feeding technique adopted to broaden operating bandwidth without occupying additional area. 2×2 CP can be...

In this paper, we investigate transmission of electromagnetic wave through aperiodic dielectric multilayers. A generic feature shown is that the mirror symmetry in system can induce resonant transmission, which originates from positional correlations (for example, presence dimers) system. Furthermore, be manipulated at a specific wavelength by tuning structures with internal symmetry. The theoretical results are experimentally proved optical observation...

A compact and high-gain SIW-fed circularly polarized (CP) slot-antenna array with a stacked feed structure is presented for the application of Ku-band high-data-rate satellite communications. First, novel probe-fed SIW cavity four slots etched on top surface proposed as radiating element array. The in act 2 x array, its directivity 2.15 1.43 dB greater than that cavity-backed antenna same size using ring slot split slot, respectively. Second, 1-4 power divider designed exciting subarray....

We propose a novel technique to enhance the dynamic range of coherent slope-assisted Brillouin optical time domain analysis. A multi-tone probe and reference wave are launched into fiber under test (FUT); after interacting with pump pulse, gain, as well phase shift each tone, can be demodulated simultaneously. In light this, strain information determined by phase-gain ratio tone. experiment, three-tone 60 MHz interval is used; effective measurement frequency span larger than 180 verified in...

Abstract Accurate prediction of the engine's remaining useful life (RUL) is essential to ensure safe operation aircraft because. However, traditional deep‐learning based methods for RUL has been limited by interpretability and adjustment hyperparameters in practical applications due intricate potential relations during degradation process. To address these dilemmas, an improved multi‐strategy tuna swarm optimization‐assisted graph convolutional neural network (IMTSO‐GCN) developed achieve...

We present in this letter the observation of optical resonant transmission Thue-Morse (TM) dielectric multilayers. For first time frequency trifurcation feature has been experimentally demonstrated. This effect can be analogous to electronic energy spectrum a TM system, which not yet directly obtained experiments. The originates from positional correlation basic units and is sensitive modulation thickness. experimental results are good agreement with theoretical analysis.

We report here the reflection of electromagnetic waves in self-similar Thue-Morse dielectric multilayers, which presents features multiple omnidirectional photonic bandgaps (PBGs). The number and width PBG depend on ratio refraction indexes thicknesses materials. theoretical result is partly verified by optical observation TiO2/SiO2 multilayers with visible near-infrared light. Our investigations provide a new approach to achieve frequency ranges. With this progress, application mirrors can...

All-optical controlling provides the burgeoning, precise, and compact access in photonics optoelectronics with tunable performance. Through tuning physical parameters of optical-controlled devices, such as effective index, bandwidth dispersion, output characteristics free-running lasers can be manipulated for widespread applications spectroscopy laser biology. Among which flexible optical-thermal tunability graphene introduces an advantageous avenue enhancement photosensitivity devices to...

A quad‐band filter with compact size and high skirt selectivity utilising stub‐loaded nested dual‐open loop resonators is presented. By loading open‐ended stubs at the centre of two resonators, odd modes as well even can be independently adjusted to realise a flexible filtering response. Moreover, both pair zero‐degree feed lines frequency transformation method are adopted introduce multiple transmission zeroes, which rightly enhance out‐of‐band selectivity. According topology circuit design...

Planar waveguides have been fabricated in Nd- or Ho-doped gallium lanthanum sulfide laser glasses by 60 MeV Ar 20 N ion implantation. The refractive index profiles were reconstructed based on the results of prism coupling. implanted exhibit an approximate steplike distribution, while ones show a "well + barrier" type. This difference can be attributed to much lower dose ions. After annealing, support two modes at 1539 nm and low propagation loss, which makes them candidates for novel...

We present a fast distributed Brillouin optical fiber sensor based on pump frequency modulation. The shift of the probe is fixed, while scanned using an arbitrary waveform generator (AWG). Thus, bandwidth requirement AWG reduced to several hundred megahertz without any expense acquiring speed. Combining with differential pulse width pair (DPP) technology, vibration measurement implemented in 230-m polarization-maintaining sampling rate 2.6 kHz and 50 cm spatial resolution. A signal up 31 Hz...

Multiple perfect transmissions of electromagnetic waves are found in the photonic band gap symmetric dielectric heterostructures (SDH) constructed as (AB)nBm(BA)n, where A and B stand for different materials, m n repeating numbers units. The frequency mode number resonant therein can be manipulated by varying m, quality factor Q transmission peak increases exponentially with increasing n. These features experimentally demonstrated a SDH TiO2/SiO2 visible near infrared light. possible...

We report on the fabrication of neodymium-doped lithium niobate active planar waveguides based generation non-overlapping nano-tracks by ultralow-fluence swift heavy ions. A combination confocal luminescence, Raman and surface second harmonic investigations have evidenced simultaneous presence partial amorphization, damage local compression network along ion path, with these effects being at basis refractive index modification. The potential application obtained in multi-functional laser...

Characterized by non-amplification in sensing fiber and coherent fading free, an φ-OTDR vibration system is experimentally validated with 80 km range, 2.5 m spatial resolution, 49.6 dB dynamic 45 phase demodulation SNR.

A novel six‐band triplexer based on short‐ and open‐ended stub‐loaded stepped impedance resonators (SLSIRs) is presented. The stub added at the centre of SIR introduces a flexible even mode close to first odd mode, realising dual‐band response with nearby passbands wide stop band. Three second‐order channels combined common T‐shaped feed line form compact size, low insertion loss high isolation. practical operating 1.9/2.4, 3.5/4.2 5.2/5.8 GHz designed realised proposed multi‐band...

The self-assembled type-II GaSb quantum dots (QDs) are successfully grown on semi-insulting GaAs (100) matrix by liquid phase epitaxy technique. topography of QDs with high growth temperature is characterized atomic force microscopy (AFM). cap layer, which needed for the device fabrication, obtained only some tens nanometers. non-resonant Raman spectra applied to investigate GaSb-like optical phonons localized in and confirm convincingly existence QDs.

A circularly polarized (CP) substrate integrated waveguide (SIW) cavity-backed slot antenna is proposed. split ring (SSR) etched on the top metal surface of an SIW resonator employed to generate right-handed (RHCP) wave. The proposed excited directly by a coaxial probe with proper distance from symmetric axis SSR resonator. prototype CP at center frequency 10 GHz manufactured. As result, exhibits advantages both conventional planar antennas and metallic cavity backed antennas, including...

A dual-band microstrip filter utilizing zero-degree coupled SIR feed linewith high frequency selectivity is presented. The first two resonant modes of stepped impedance resonators (SIRs) are chosen as the center frequencies. pair folded SIRs to form a second-order filter. Meanwhile, surrounded by lines which introduce five transmission zeros. Two zeros realized source-load coupling, another created line; last one due third harmonic effect line. To demonstrate this technique, selective...