The network for stable radio frequency dissemination is evolving from point-to-point to point-to-multipoint. For a long-distance dissemination network with multiple access sites, the amplifier is one of the most important components which is used to compensate for power loss caused by optical fibers and optical couplers when the RF reference propagates through dissemination networks. However, the amplifier

A novel fiber Bragg grating (FBG) accelerometer is proposed. The accelerometer is based on a compact symmetrical structure consisting of a Y-shaped beam and an FBG. The mechanical model and sensing principle of the accelerometer are well illustrated. Then, the structural parameters are numerically studied. In experiment, the measured resonant frequency is 700 Hz, and the stable working frequency range

We propose a novel mode selective directional coupler based on microstructured cane for higher order modes excitation. The coupler is composed by a single mode fiber (SMF) and a few mode fiber (FMF) inserted in a periodic air-silica microstructured cane (ASMC) on either side of the central hole. The internal geometry of the cane is adjusted to satisfy the phase matching condition between the selected

Because inclined cracks are more harmful to pressurized tanks than parallel cracks, the existing ultrasonic testing methods cannot meet the needs of on-line monitoring for pressure vessels. Therefore, in this paper, inclined cracks in a pressure vessel are studied by using optical fiber ultrasonic sensor technology. The relationship between the oblique angle of the inclined cracks, the time when the

A sensitivity enhanced temperature sensor with cascaded Sagnac loops based on harmonic Vernier effect has been proposed and verified by experiments. The harmonic Vernier effect can be achieved, through controlling the polarization-maintaining fiber (PMF) length of one Sagnac loop to be an integral multiple of the other with a small deviation. The experimental results show that in temperature range

In this paper, we present a mode demultiplexing algorithm based on robust independent component analysis (ICA) in electrical domain. Multi-mode fiber (MMF) based spatial division multiplexing system is modeled as a behavioral model. Different modes can carry the data to increase the system capacity with the proposed algorithm. In the system, two orthogonal frequency division multiplexing (OFDM) signals

The determination of overburden failure volume is a great challenge because of the complexity and concealment of mining fractures. Taking the 61,601 working face of Longwanggou Coal Mine as the engineering background, this paper established a two-dimensional model of 3000 mm × 200 mm × 1350 mm (length × width × height) in the laboratory. By adopting the Brillouin optical time-domain analysis (BOTDA)

We experimentally find a practical stimulated Brillouin scattering (SBS) threshold for broadband high-performance fiber optical parametric devices relying on dispersion-stable GeO2-doped silica highly nonlinear fibers. We demonstrate that SBS limits the nonlinear phase shift in such fibers to ~0.3 rad per pump unless the SBS is mitigated in some way. We consequently derive corresponding limits on signal

In recent years, the construction of urban highway through slope excavation becomes more and more widespread. However, the surcharge loading induced by dense buildings is often neglected. For a better understanding of the deformation characteristics and associated failure mechanism of such slopes, a series of model tests have been carried out using distributed strain sensing (DSS) technology. The coupling

We measured the transmission of tapered and untapered optical fibres as a function of input beam numerical aperture at 635 nm. The tapered fibres were fabricated with an adiabatic tapering process from graded and step-index fibres with 50 μm core diameters to form a 100 mm long taper with 5:1 taper ratio. We tested tapered graded-index and step-index fibres fabricated from commercial Thorlabs products

A hybrid cascade structure composed of two Mach–Zehnder interferometers (MZI) is proposed and demonstrated to measure gas pressure and temperature, simultaneously. The key sensing components of the two MZIs are all based on a tapered single mode fiber (TSMF) spliced between two multimode optical fibers. The difference is that one of the TSMFs is covered with PDMS material, while the other one is exposed

The non-Hermitian symmetric optical orthogonal frequency division multiplexing (NHS-OFDM) system exhibits lower hardware implementation complexity and power consumption as maintaining the same bandwidth granularity, compared to the conventional Hermitian symmetric optical OFDM (HS-OFDM) system. Also, NHS-OFDM can obtain a similar peak-to-average power ratio as well as bit error rate (BER) performance

Versatile structures of wavelength-dependent bound solitons are obtained based on nonlinear polarization rotation (NPR) mode-locked technology in an anomalous-dispersion fiber laser. After optimizing the intra-cavity birefringence and finely adjusting the operating wavelength of the laser, both the conventional soliton and loosely bound-state soliton pairs can be generated and switched under different

A multi-wavelength single-longitudinal-mode optical fiber laser using fiber Bragg grating (FBG) as wavelength selector and FBG based Fabry-Perot filters as frequency selector is studied. The optical fiber laser includes several fiber laser resonators and there is a length of erbium-doped fiber used as gain medium in each resonator. Each of the laser resonators uses a FBG as wavelength selector and

Hybrid immediate request (IR) and advanced reservation (AR) is an inevitable traffic model for future SDM-EONs to accommodate uncertainty and abundance of services. Different from the traditional IR handling instant services like chat messaging, AR can balance the traffic load by postponing allocation to delay-tolerant requests such as cloud computing, e-science, IPTV etc. Although IR/AR mixed traffics

A high sensitivity FBG humidity sensor coated with polyimide and graphene films is proposed. The sensing probe is based on a fiber Bragg grating coated with an inner polyimide film and an outer graphene film. The sensor shows the high humidity sensitivity and experimental results show that its sensitivity is 1.80 times that of the sensor coated with only polyimide film. Within the humidity range of

To produce polymer optical fibers in research environments, a flexible cladding material-application process is required. Further, to functionalize the waveguide, the fiber core-production step needs to be separated from the cladding application, contrasting conventional polymer optical fiber production processes. In this study, we developed a solution using continuous dip-coating technique to apply

We demonstrate optical to radio frequency (RF) locking technique using all-fiber phase shifter. Phase shift at 1030 nm was achieved by pumping Er-doped fiber incorporated in the resonator. Pump induced refractive index change was fast enough to stabilize optical pulse repetition rate of ultrafast Yb-doped fiber oscillator and achieve sub-200 fs timing jitter. We also investigate the source of phase

This study presents a theoretical model that enables a fast and precise calculation of a sampled apodized fiber Bragg grating and the related sensor. Transfer matrix method was used since there is no analytical solution due to the complex refractive index profile. Errors brought by the uniform refractive index profile approximation were compensated, which allows a smaller number of divided segments

Optical multiple-input multiple-output (MIMO) technology is introduced into optical space division multiplexing (SDM) communication as an effective solution for the crosstalk issue. Unfortunately, this application is limited because all the channel information over the transmission link must be transmitted to MIMO receivers for complete crosstalk compensation, which indicates difficulty in applying

Wavelength-division multiplexing passive optical network (WDM-PON) is considered as a mainstream solution for 5G fronthaul transmission system to cope with the rapidly increasing bandwidth demand. In such a multi-wavelength system, nonlinear effects limit the achievable transmission distance and channel capacity. Therefore, in this paper, the impact of nonlinear effects on a multi-wavelength transmission

A high-sensitivity optical fiber temperature sensor based on the Vernier effect of cascaded fiber Sagnac interferometer (FSI) and Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated. The FSI is composed of a 3 dB four-port coupler and a section of polarization maintaining fiber, which has high sensitivity and good stability as the sensing part. As the filtering part, MZI is

In this paper, we report an ultra-compact reflective SPR microtip temperature probe, which can achieve 2-D spatial resolution of several microns. The pencil-shaped all-fiber microtip proposed by us is a SO2 cone-cylinder with a length of 40 μm and a gradient diameter of 2 μm-10 μm, which can be used to develop multi-type tiny functionalized sensors. Due to the strong evanescent field of the ultra-fine

A high-reliability acceleration sensor based on fiber Bragg grating (FBG) that can be used in downhole for a long time is proposed, which is aimed at solving the problem of low-reliability of existing optical fiber acceleration sensors in the field of petroleum and natural gas resources exploration. The acceleration sensor uses the inertial force generated by the mass to make the symmetrically tilting

This paper reported the experimental and theoretical analysis of a non-contact fiber optics displacement sensor for the concentration measurement of opaque dye solution. This sensor was able to detect the concentration without having to dilute the opaque solution. Brilliant Blue FCF dye was used to demonstrate the sensor. The displacement curves of dye solutions with various concentrations were taken

Machine learning methods are being successfully applied in various domains of human activity, including optics. Can they become a universal instrument capable of improving user aspect of photonic devices? Is their application a necessary element of such improvement? Answers to fundamental questions arising from application of machine learning methods in ultrashort-pulsed lasers are discussed. Future

In the recent years, there has been an increasing demand for effective ethanol sensor in the pharmaceutical and food industries where there is a need to constantly monitor and maintain the permissible level of ethanol. In this study, we report the development of a fiber optic sensor based on Lossy Mode Resonance (LMR) technique using tin oxide (SnO2) thin film over the unclad core of the optical fiber

Packaging technology is a key factor in fiber Bragg grating (FBG) sensing, which can greatly affect the sensing performance of FBG sensors. In this paper, a pre-stressed packaging method for FBG sensors is proposed. The method enables the pre-stress applied on the FBG to be continuously and accurately adjusted when the FBG sensor is packaged, thereby ensuring the stability of the pre-stress. In order

A simple approach is proposed for determining peak frequencies, stress heights, stress lengths, full-width at half-maximum (FWHM), broadening and symmetry properties, of a composite Brillouin Gain Spectrum (BGS) which is obtained for the pulse lengths longer than the embedded stress lengths. The composite BGS is thus reconstructed in terms of extracted components. It is validated that the method is

The upstream transmission performance was experimentally investigated to consider the practical deployment of a photonics-based terahertz (THz)-band indoor network. An experimental setup was established using several off-the-shelf THz and optical components, to evaluate the technical feasibility of the uplink. Two commercialized THz mixers were used to build the THz wireless link, and a cost-effective

This paper proposes the use of the fiber Bragg grating (FBG) temperature sensors array to estimate the fluid level. The tank is 100 cm in height and 30 cm in width, with 9 FBG sensors distributed along with the tank height. This work proposes level estimation in two steps: level detection (classification) and level estimation (regression). The level detection consists of finding under which FBG the

We propose and demonstrate the fiber optic Surface Plasmon Resonance (SPR) for hydrogen sensing based on Ag/TiO2 at the telecommunications wavelength of 1550 nm . The sensor using TiO2 as a sensitive layer for hydrogen detection consists of a multilayer film of 45 nm Ag/110 nm TiO2 deposited on the coupling prism substrate. An intensity interrogation SPR with Kretschmann configuration is designed,

A novel method of flow measurement in oil well based on turbulence vibration principle and fiber laser vibration sensor is proposed. The constitutive equations of flow velocity and pipe wall vibration were established, and a kind of optical fiber laser vibration sensor based on hinge structure was designed and installed on the outer wall of oil pipe to measure the fluid flow velocity inside oil pipe

Through filling the liquid crystal E7 into the defect position of the photonic crystal fiber (PCF) which possesses full circular air hole structure, a PCF with adjustable optical performance is designed. The effect of external temperature and magnetic field on its optical properties is analyzed by adopting the finite element method. The results reveal that its confinement loss is reduced, and the dispersion

This work reports some important optical characteristics of porous core photonic crystal fiber (PC-PCF) for four different core structures which are elliptical, circular, square, and hexagonal. Numerical analysis based on the finite element method (FEM) shows that for the same core area, an elliptical core demonstrates the highest birefringence that ensures reliable polarization-maintaining applications

We demonstrated a compact fiber sensor for the Refractive Index (RI) and temperature measurement based on a balloon-shaped Mach-Zehnder interferometer (MZI) with no need of special fibers or coating sensitizer material. To enhance the sensitivity and structural stability of the sensor, a spherical structure is added on both sides of the balloon-shaped single mode fiber (SMF). The fiber length between

Recent research demonstrates that promising gas sensing materials are called metal-organic frameworks (MOFs) and their products due to their tunable form, high surface area, highly porous structure, and physisorption towards gases with relatively low temperature. In this report, recent developments in transition-metal (Zn, Mn, Cu)-based MOFs and their derivatives were synthesized as sensing materials

In this paper, we proposed a 40Gbps 16QAM-OFDM polarization insensitive all-optical wavelength conversion (AOWC) system based on self-pumping structure of wide optical comb. In this scheme, the carrier suppression modulation is carried out by a laser with Mach-Zehnder modulator (MZM) to generate a wide comb with only 3 dB odd sidebands flatness. By changing the frequency selection of the optical comb

A novel temperature sensor based on microfiber (MF) interferometer with low-cost, long-term reliability and high repeatability was developed. The experimental results indicate that the unsymmetrical U-shaped MF has particularly advantages of a thinner waist diameter and better sensing stability compared with symmetrical U-shaped MF in terms of structure and spectrum. The air temperature sensitivity

A novel half-side PDMS-coated photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) is proposed for simultaneous detection of seawater salinity and temperature. The plasmonic material gold is coated on the outer surface of the PCF to measure the seawater salinity by exciting SPR effect. Moreover, the polydimethylsiloxane (PDMS) layer is coated on the upper half-side of the surface

A multi-frequency fiber optic acoustic sensor (FOAS) based on graphene-oxide Fabry-Perot microcavity (GO-FPM) is proposed and demonstrated. The micrometer-size FP cavity is formed by a single-mode-fiber end surface and a layer of GO diaphragm. The GO diaphragm is used as the acoustic sensitive diaphragm to realize the acoustic signal detection. The performance of the GO-FPM FOAS for single-frequency

In this paper, a cost-effective 50-W-level all-fiber oscillator operating near 980 nm is demonstrated with the 20-μm core-diameter double-cladding Yb-doped fiber (DCYF) firstly, to the best of our knowledge. By using the 15-degree angle-cleaved output fiber end-facet, the record 54.8-W output power is obtained with the slope efficiency about 15.6%. It is revealed that increasing the cleaved angle (or

This paper proposes a biosensor based on side-hole fibers (SHF) formed by the structure of single-mode fiber (SMF)-coreless fiber (CLF)- SHF-CLF-SMF for the detection of bovine serum albumin (BSA). Among the fibers, the SHF’s misalignment splicing makes one hole exposed, which is very sensitive to the change of the external environment. Due to the unique structure of the SHF, two Mach-Zehnder interferences

In this work, we address the phonon dynamics in the stimulated Brillouin scattering process. There exists a wide consensus on the fact that the slowly varying approximation for the acoustic field cannot be invoked in the transient subphonon regime. We present an analysis where we set the precise limits of validity of this approximation. Our study shows that the resonant behavior of the Stokes interaction

In this paper, a multi-core fiber with 22 air holes and 15 conventional cores is proposed. The fiber can realize dual-mode operation of fundamental mode HE11 and second-order mode HE21 under certain conditions. The relationship between performance of the fiber and the structural parameters that include core pitch, refractive index difference between core and cladding, and fiber core radius is investigated

In this work, a temperature sensor based on an asymmetric core-offset Mach-Zehnder Interferometer (MZI) coated with aluminum is proposed and experimentally demonstrated. The interferometer is fabricated by core-offset splicing three sections of single mode fiber, and by coating it with aluminum using a thermal evaporation technique. The temperature sensitivity of the device increases by a factor of

The effectiveness of sensor networks depends largely on the coverage provided by sensor deployment schemes. In order to improve the coverage rate of sensor network, it is necessary to optimize the sensor layout. In this paper, an optimized layout method of fiber Bragg grating (FBG) sensor network based on modified artificial fish swarm algorithm (MAFSA) is proposed. Firstly, the elliptical sensing

We experimentally demonstrate Kerr beam self-cleaning in 90 m long standard graded-index (GRIN) multimode fiber (MMF) for normal and oblique launching conditions. Sub-nanosecond pump pulses are launched in the normal dispersion regime of the GRIN MMF. We measure the simultaneous evolution of the near field modal profile and the output spectrum for various pump powers under different launching conditions

In this work, we obtained chirped Bragg gratings by post-coating uniform poly (methylmethacrylate) (PMMA) microstructured polymer optical fiber Bragg gratings (POFBGs) with an UV cure adhesive. The main advantage of the proposed method consists on being a cost-effective and simple solution, since no special phase mask, additional etching or gradient thermal annealing are required. A comparison between

In order to reduce the measurement error of Raman-based distributed temperature sensor (RDTS) caused by random noise, we have proposed an effective noise reduction method, which can reduce the time consumption of data processing due to the low time complexity of the method. We classified the signal as five models based on the waveform types, thus to filter the raw data according to the waveform types

Vanadium carbide (V2C), a member of the MXene family, promises numerous possibilities in ultrafast laser technology with substantial applications in various optical industries. In this work, MXene V2C was deposited onto a tapered fiber using the drop-casting technique and incorporated into a thulium/holmium doped fiber laser cavity for generating mode-locked outputs in the 2.0 µm region. The fabricated

Cracks are the most common lesion in water-wading structures such as dams and sluices, which have an important impact on the durability of concrete materials and the safety of structures. The emergence of cracks is also regarded as a precursor to the destruction of buildings. However, the randomness and concealment of cracks are strong, which bring great difficulty to real-time and accurate capture

This work utilizes an experimentally designed erbium-doped fiber-based tunable dual-wavelength laser (EDFL) to generate phase-stable millimeter waves over a wide-band of ≈ 12–110 GHz and their transmission over the radio-over-fiber (RoF) link. The generated fiber-laser-based millimeter waves are transmitted over a RoF link, including an optical link of 20 km and a wireless link of 50 m, which is carried

Passive optical network (PON) with online polling-based dynamic bandwidth allocation (DBA) algorithms effectively reduces the granting and back-off delays as well as the overall end-to-end delay of the PON with offline polling-based DBA schemes. However, in the online polling-based DBA schemes, distribution of excess bandwidths from the lightly loaded optical network units (ONUs) to the highly loaded

As the conventional fiber Mach-Zehnder (M−Z) interference structure being sensitive to temperature variation and mismatching of arm length in Differential Phase Shift Keying (DPSK) system, we proposed a modulation and demodulation system of DPSK based on novel M−Z interference structure. This novel M−Z interference structure has some advantages of higher temperature stability, better robustness and

A novel blind equalization scheme based on a machine learning algorithm called artificial neural network (ANN) is proposed and experimentally demonstrated to compensate for the dynamic nonlinear behavior of a 10-G class 1310-nm directly modulated laser (DML) in pulse amplitude modulated (PAM)-4 signal transmissions. The dynamic nonlinearity is often seen as the major limiting factor against the transmission

The time scheduled traffic in spectrally efficient elastic optical networks (EONs) is periodic and exhibits non uniform pattern, in both, the time as well as the requested bandwidth. In time domain, it remains heavy during the office hours and slacks during the non-office hours; while in the bandwidth domain, it is distributed non-uniformly along the network links and also, may vary from few Gbps to