For the past decades, the applicability of distributed optical fibre sensor (DOFS) technology has been widely explored to assess the structural health and integrity. The DOFS has distinctive features compared to traditional sensors, including the ability to provide long-distance monitoring of temperature, strain, and vibration with a single mode of cable. Moreover, it has high durability and low maintenance

A high-sensitive optical fiber humidity sensor based on in-line Michelson interferometer (MI) is proposed and demonstrated. The MI is formed by an asymmetric dual-core fiber (DCF) spliced with a short section of multimode fiber (MMF). The MMF serves as fiber coupler, while the DCF creates a strong intermodal interference to strengthen the interaction between light and ambient moisture. The sensor presents

A new and simple fabrication technique was successfully demonstrated in the fabrication of a novel multistructured flat fiber in the form of a doped flat fiber with dual airholes. This proof of concept fabrication technique uses only a drawing tower where an arrangement of solid rods and capillaries were attached inside a preform using a simple holder. The fabricated doped flat fiber with dual airholes

The industry is considering redesigning the architecture of optical access networks (PONs) to address the challenges of 5G developments. One of the major challenges is to achieve low communication delay. To better address this challenge, PONs not only need to be improved from the perspective of underlying facilities, but also need to combine with effective resource allocation strategies. This paper

We present a method to fabricate Fresnel zone plate (FZP) on the multimode fiber (MMF) tip by combining femtosecond laser direct writing with coating, polishing and chemical etching. After laser processing, the fiber tip coated by gold was polished to obtain a clear unprocessed region with high transmittance and a processed area filled with gold. By launching an 850 nm laser into the MMF, the light

Fabrication and characterization of a fiber optic surface plasmon resonance (SPR) based potassium ion (K+) sensor utilizing the coating of dicyclohexeno-18-crown-6 ionophore incorporated in plasticized PVC membrane along with lipophilic pH sensitive dye chromoionophore-I over the silver coated unclad core of the fiber have been carried out. The interaction between ion selective cocktail layer and incoming

Dark pulses are optical structures with fascinating fundamental physics and have a great wealth of optical properties yet to be better explored. Since the earliest demonstration of a dark pulse, its generation was very limited, depending on specific experimental setups for its observation. However, the development of new saturable absorber (SA) materials with exceptional nonlinear optical properties

For the cavity length demodulation of fiber-optic Fabry-Perot (FP) sensors, a frequency-doubled self-correlation algorithm was proposed. Since the frequency doubling can make the self-correlation peak sharper, the peak positioning accuracy can be effectively improved for the cavity length extraction. The feasibility and performances of the proposed algorithm was investigated by both simulation and

A hybrid bidirectional orthogonal frequency division multiplexing–millimeter wave over fiber (OFDM-MMWOF) transport system based on mixed quadrature amplitude modulation (QAM) format using dual-mode colorless laser diode and reflective semiconductor optical amplifier for next-generation 5G based networks is proposed and experimentally demonstrated. Here, an orthogonal quadruple frequency MMW is generated

A glucose sensor based on a helical long-period grating (HLPG) coupling to a high-order cladding mode is demonstrated, which is composed of an optical fiber with the fiber surface modified by poly (4-vinylphenylboronic acid). The sensor has a linear response to glucose (0.18 ~ 3 mg/mL) with a sensitivity of 1.115 nm·(mg/mL)−1 at pH 7.4 and 3.259 nm·(mg/mL)−1 at pH 9, respectively.

We report on the generation and transmission of millimeter-wave (MMW) beat-tone at 28 GHz from an external injection-locked InAs/InP quantum-dash laser-based comb source emitting in mid L-band. The MMW beat-tone exhibited a narrow linewidth, and low phase noise of ~ −122 dBc/Hz at 1.0 MHz offset frequency, thus demonstrating superior characteristics. Thereafter, we achieved a successful transmission

Compared with traditional uniform fiber, the long tapered fiber has the advantage of suppressing nonlinear effects and maintaining excellent beam quality. Both the cladding size and core size of the long tapered fiber reported so far vary simultaneously in a constant core-to-cladding diameter ratio (CCDR) along the length. In this work, we propose a technique for preparing cladding uniform core tapered

In this paper, we investigate a novel improved Particle Swarm Optimization (IPSO) algorithm to enhance the coupling precision between a laser diode and a single-mode fiber. It mainly relies on the nonlinear adjustment of inertia weight. Several variations of PSO are used as references. The simulated and experimental results show that the proposed strategy has an excellent search success rate with few

We designed and demonstrated a compact all-fiber dissipative soliton (DS) fiber laser. The proposed Erbium doped fiber laser is mode-locked by nonlinear amplified loop mirror (NALM), which has a typical figure-of-9 structure and operates in normal net-cavity dispersion regime. The NALM-based fiber laser is constructed by only three polarization maintaining fiber components, which can generate long-term

In this paper, a high-performance parallel pipelined hardware structure of Volterra decision feedback equalizer (Volterra-DFE) for 4-level pulse amplitude modulation (PAM-4) transmission is derived and implemented for the first time. For feed-forward portion, an approach based on multi-level register banks is employed, and the feedback portion is pipelined by converting complex calculation in the loop

A vibration sensor based on Sagnac interferometer and fiber ring laser (FRL) is proposed for fault diagnosis of bearing, and a sensing system of vibration is demonstrated experimentally. In the sensing system, the Sagnac interferometer based on single mode fiber- polarization maintaining fiber-single mode fiber (SPS) as a sensor is connected to FRL which performs as a filter. Because the transmission

Based on the intensity model of few-mode erbium-doped fiber amplifiers (FM-EDFAs), we put forward a semi-analytic method for efficiently calculating the signal mode gains by solving the analytical expression for the average population inversion over each fiber segment. Our studies show that, the semi-analytic method can offer a desirable calculation accuracy, very close to that of the full approach

cncnA contactless high temperature in-situ sensing system based on fiber Bragg grating(FBG) is proposed to implement accurate temperature measurements of bearing bushing, which is the core component of reciprocating compressor(RC). The system consists of a sensing probe of a FBG putting in a metal capillary to eliminate the cross-sensitivity problem and a pair of optical fiber collimators to send the

Ultrashort pulses have a crucial role in the evolution of different areas of science such as ultra fast imaging, femtochemistry and high harmonic spectroscopy and therefore, diagnosing and reconstructing ultrashort pulses is important. The interplay of dispersion and nonlinear effects gives rise to a wide variety of pulse dynamics. On the other hand, dispersion, linear and nonlinear effects have proven

In this paper, we successfully demonstrate the generation and reception of faster-than-Nyquist (FTN) orthogonal frequency-division multiplexing (OFDM) signals with coherent detection. We can improve the spectrum efficiency by using higher order QAMs. However, we believe that the realization of super-Nyquist channel has the following advantages to improve spectral efficiency: Firstly, when we use higher

We report on the influence of the average nonlinear coefficient on noise-like pulse (NLP) in a figure-of-eight erbium-doped fiber laser. Since the nonlinear switching point of nonlinear amplifying loop mirror (NALM) shifts with distinct laser configurations, through changing the length of highly nonlinear fiber (HNLF) in NALM, properties of output pulse have been compared and analyzed. The spectral

Half etched fiber Bragg grating (HEFBG) is designed and studied by spectral properties under applied axial force. To design the HEFBG, a half-length of a given FBG is thinned down to 12μm diameter through the chemical corrosion with hydrofluoric acid. Under an applied axial force, the Bragg wavelengths due to etched and unetched parts of the HEFBG encounter different peak shifts and sensitivity. The

We report a watt-level yellow random laser at 589 nm. The laser is generated by single-pass second harmonic generation of a half-open random Raman fiber laser at 1178 nm in a periodically poled stoichiometric lithium tantalite crystal. The major limitation on power scaling is the usual broad linewidth of random Raman fiber lasers. By counter pumping instead of common co-pumping, and using narrower

Optical fiber-tip ball resonators are inexpensive devices characterized by a rapid, repeatable, and reliable fabrication process through a fiber splicer. The spectral features of a ball resonator appear as low-finesse interferometer, with an optical backscatter reflectometer (OBR) interrogator. The spectrum changes in amplitude when the external refractive index (RI) varies. In this work, we present

A simple single-fiber (SF) Mach-Zehnder interferometer (MZI) based technique for identifying any known/unknown organic/inorganic substance, has been proposed. The suggested process involves the quantification of the contribution of tapered and un-tapered sections of SF-MZI in its optical interference length by modifying the existing expression of its free spectral range (FSR). Each chemical/biological

In this study, we investigated plastic optical fiber (POF) pressure sensors embedded in mattresses to measure respiration and heart rate for sleep performance monitoring. The signal is amplified in the circuit using a two-stage amplification scheme to collect weak respiration and heart rate signals while an algorithm was designed to obtain respiration and heart rate. We also propose a good reliability

New design of FBG-based strain sensor is reported. Fiber with two Bragg gratings is reeled up on a ring-shaped base. Main design feature is eliminated glue effects on FBG reflection spectrum. In addition, design reduces errors of strain measurements caused by temperature variations. Analytical estimations and experimental results are presented.

Elastic optical networking is an attractive technology for the next generation of backbone networks, because it can flexibly provide spectrum resources to connection requests. In elastic optical networks, spectrum resources are generally split into frequency slices with finer granularity and each connection request can use several frequency slices according to its bandwidth requirement. In the process

Peak-to-average power ratio (PAPR) is the main challenge of the conventional and optical orthogonal frequency division multiplexing (OFDM) systems. In this paper, we implement the clipping technique to reduce the high PAPR of DC-biased optical OFDM (DCO-OFDM) signals. Then, the clipped peaks are sent to the receiver as extra data because of possessing valuable information to reconstruct the original

Thanks to characteristics such as high beam qualities and high average powers, largely founded on the outstanding characteristics of fibers as an active medium, fiber lasers have become one of the most popular laser technologies. Although most of the advantages of fiber lasers stem from their geometry, the same geometry is the main source of the limitations. In this study, we focused on managing the

A new method of reducing coherent Rayleigh noise (CRN) by using Phase Shift Keying (PSK) pulse coding is characterized and demonstrated theoretically and experimentally. A phase modulator driven by an arbitrary function generator is employed to encode pulses with PSK modulation, the traces obtained by coded pulses with different coding orders are superposed and averaged to reduce CRN. The experimental

We propose orbital angular momentum (OAM) mode generation using an all-fiber coupler based on hollow-core circular photonic crystal fibers (PCF). Using the mode-matching method, we calculated the coupling efficiency of high-order vector modes excited by the OAM coupler. The coupler’s structure with optimal parameters was designed to achieve high mode purity and good coupling efficiency for broadband

A temperature sensitive hybrid interferometer is developed and tested experimentally. The hybrid interferometer consists of a Michelson interferometer (MI) cascaded with a Fabry-Perot interferometer (FPI). It is fabricated by successively fusion splicing a single-mode fiber (SMF), a small section of multi-mode fiber (MMF), double side hole fiber (DSHF) and hollow Core fiber (HCF) together. The end

A polar code over One-Coincidence-coded optical code-division multiplexing (OCDM) network is proposed, which is suitable for the multi-access optical fiber network. The excellent error correction ability of Polar code was applied to build a low error rate performance of network system. The proposed architecture not only supports lots of users by OCDM technology with spectral amplitude coding scheme

In this paper, lawsone (2-hydroxy-1,4-naphthoquinone), a natural dye material is proposed and demonstrated as a saturable absorber (SA) for passive Q-switching operation in Erbium-doped fiber laser (EDFL) cavity. The lawsone-based SA was fabricated using a liquid-phase exfoliation technique. A tiny piece of the lawsone film was then cut and slot-in between two fiber ferrules so that it can easily be

A solid unobtrusive fiber-optic sensor based on modal interference in dual mode fiber (DMF) embedded in a thin mat is proposed and investigated theoretically and experimentally, realizing real-time vital signs and activity monitoring. The whole sensing setup only consists of one laser diode, one section of DMF, one photo-detector and few standard single mode fibers (SMFs). The DMF fiber is sandwiched

We propose and demonstrate a fibre surface plasmon resonance (SPR) sensor based on a microsphere structure. By employing the microsphere fibre, the cladding mode of the fibre is excited and provides an evanescent field for the SPR sensing structure. The relationship between the diameter of the microsphere, the diameter of the fibre core, the types of fibres, and the sensing performance of the sensing

We propose and experimentally demonstrate a wide tuning range triple frequency spacing multi-wavelength Brillouin erbium fibre laser (MBEFL). The laser can be tuned in the C- and L-bands of the optical communication windows. At a Brillouin pump power of 3 dBm and 1480-nm pump power of 195 mW, the proposed MBEFL generates up to five triple spacing Brillouin Stokes lines that can be tuned over 60 nm

We present a study of ultrafast solitonic all-optical switching in the C-band using dual-core optical fibers fabricated in-house. The two soft glasses used for the fiber express high contrast of refractive index at the level of 0.4. The core was made of a highly nonlinear lead-silicate glass, which, combined with the anomalous dispersion, allowed the solitonic propagation at low pulse energies. A convincing

An inline time division multiplexed (TDM) fiber Bragg grating (FBG) interferometric sensor array for low frequency bands was presented. The length of the sensing fiber for each element was 58.78 m and the TDM number was 8, both of which are the largest to the best of our knowledge. Besides, in order to pick up phases stably in this ultra-long array with low background noise, a polarization switching

Fiber Wireless (FiWi) access network is a promising next generation broadband access network as it provides high bandwidth, better stability and anywhere-anytime connection at lower cost to the users. It integrates the wireless access network and optical access network at front-end and back-end respectively. Optimizing the ONUs position plays an important role in FiWi network as it affects the network

Stretchable strain sensors are urgently needed in measurement field. This paper reports a no-core polydimethylsiloxane (PDMS) optical sensor, which is suitable for large scale strain and concentration measurement with high sensitivity. The proposed no-core PDMS fiber is composed of polydimethylsiloxane and curing agent in a certain propotion. The output spectrum loss of the no-core PDMS fiber varies

The continuous growth in mobile network traffic driven by the extensive range of new user applications, for instance, interactive e-learning, social networking sites, remote medical service and machine-to-machine communication has pushed the mobile network operators to enhance their network capacity. The main solution to deal with this problem is to deploy thousands of low power small cell base stations

It has been seen that there is a growing demand for the production of micron size grooves with a uniform flat surface, minimal heat-affected zone (HAZ) thickness, debris deposition, microcrack, microcavity, and recast layer thickness on orthopedic implants. In the present study, a multi-response optimization approach is adopted for fiber laser-based micro engraving to enhance groove characteristics

Hydroxyl groups (OH) penetrate the surface of the fiber preforms as a result of preform processing in the oxy-hydrogen flame. Designing double-clad fibers (DCFs) that have a complex noncircular inner-cladding shape with concave and convex edges are possible by shaping their optical preforms thermally with a CO2 laser. Unlike the mechanical technique, the thermal shaping via CO2 laser has paved the

The explosive growth of users’ requirements promotes the development of optical network function virtualization (ONFV) over elastic optical networks (EON). Through optical network virtualization, network services can be provided by sharing physical resources in terms of virtual optical network (VON), which can simplify optical-layer resource management and promote the flexibility of multi-dimensional

Based on conservation laws, kinetic equations for changes in ion populations in different energy states are written down, as well as equations how optical radiation intensity (and power) is changing in the optical fiber core is sequentially derived. Physical limitations of the given approach are also considered. A comparison of the results of a numerical analysis of the formation of luminescence in

We report on a new method for fabrication of saturable absorbers for operation in ring fiber lasers as a mode-locking element taking advantages of the manufacturing technologies of fiber couplers and microfiber tapers coated with carbon nanotubes. It is demonstrated in the experiment that the transmittance of the fabricated saturable absorber increases with an increase of the input radiation power

Different from the use of IQ modulator or a dual-drive Mach-Zehnder modulator, we investigate an optical vestigial sideband orthogonal frequency division multiplexing (OVSB-OFDM) transmission system using a low-cost directly modulated laser. Precoding techniques and Kramers-Kronig (KK) algorithm are employed to enhance the bit error rate (BER) performance. The KK receiver is applied to eliminate the

This paper proposes a methodology E-S-RSCA to integrate energy efficiency with spectrum efficient design of crosstalk aware routing, spectrum and core assignment (RSCA) schemes for offline traffic in space division multiplexed elastic optical network (SDM-EON) while allocating traffic in selected multiple cores in SDM-EON. Mixed Integer Linear Programming (MILP) model has been formulated for the scheme

Fiber Bragg grating (FBG) based sensors have been extensively used to monitor the deformation of structures (i.e., aircrafts, ocean platforms, bridges, tunnels, pavements and high-speed railways), for the advantages of absolute measurement, anti-electromagnetic interference, high precision, multiplexing and integration of sensing network over other sensors. However, due to the temperature-sensitive

The stress distribution in an optical fiber with single stress element is calculated and analyzed. The stress oscillation magnitudes related to mode coupling are characterized. The coupling ability between the fundamental mode HE11 and other modes is demonstrated and compared. The strongest coupling is occurred between the fundamental modes HE11+andHE11-. The coupling strength fromHE11-HE21, HE11-HE22

The performance of Raman-based distributed temperature sensors is strongly dependent on the receiver system employed since the signal carrying the temperature information has extremely low intensity. Therefore, a noisy receiver can easily generate noise levels that overlap the signal strength, unable to detect changes in this signal due to temperature variations. The present study will address a theoretical

In this study, temperature detection with distributed fibers was used to obtain data for a laboratory model of seepage heat in an embankment dam, and the temperature was monitored using optical frequency domain reflection (OFDR) technology with high temporal and spatial accuracies. First, the temperature field in the infiltrated region of the dam body during the seepage test showed changes similar

This paper proposes the interferometric method for arrays inscription of type I Bragg gratings on the unified segment of the standard telecommunication single-mode optical fiber, using preliminary inscription of the gratings with low diffraction efficiency. The accuracy of setting the Bragg resonance wavelength of each individual diffraction structure is at least 50 pm with the reflection coefficient

A two-wavelength pump–probe technique to measure the gain recovery time of an erbium-doped fiber amplifier is reported. In the measurement, pulse fields and quasi-continuous-wave fields generated from a single-distributed-feedback laser array are respectively used as the pump and probe light. To distinguish the probe field from spontaneous emissions from the amplifier, a circulator and fiber Bragg

We propose a technique for determining whether mechanically transferable (MT) connectors are flooded. The proposed technique is based on the return loss measurements at several wavelengths using an optical time domain reflectometer (OTDR). We define the effective return loss at the MT connector as the average of the return losses measured at several wavelengths. The effective return loss makes it possible

In this paper, a new hygrometer sensor based on a taper-photonic crystal fiber (PCF)-dislocation structure coated with polyvinyl alcohol/graphene oxide (PVA/GO) composite film is proposed and analyzed by the beam propagation method (BPM) method and experimental measurement. Due to the moisture absorption characteristic, the refractive index (RI) of the PVA/GO composite film changes linearly, so the

The multi-core fiber (MCF) plays an important role in expanding capacity. The geometrical parameters and its changes will greatly influence the transmission characteristics of the fiber and the performance of the MCF based devices. The traditional denoising method for analyzing geometrical parameters of the fiber is complex, and the high quality of the fiber image is demanded, which result in poor

A compact optical fiber sensor (OFS) based on an inline Mach-Zehnder interferometer for simultaneous measurement of liquid level and the temperature is proposed and demonstrated experimentally. The proposed sensor is formed by fusion splicing a thin core fiber (TCF) with an ultra-thin fiber (UTF) with core offset, then TCF and UTF are sandwiched between two standards of single mode fibers (SMFs). The