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Showing papers on "Dispersion-shifted fiber published in 2018"


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a novel strategy for designing a highly birefringent photonic crystal fiber (PCF) with near zero flattened dispersion properties by applying elliptical air holes in the core area.

75 citations


Journal ArticleDOI
TL;DR: In this paper, an optical fiber pH sensor based on a polyaniline coating deposited on the surface of a tilted fiber Bragg grating was reported, which was synthesized by in situ chemical oxidative polymerization keeping track of the deposition time in order to optimize the sensor response.
Abstract: In this paper, we report an optical fiber pH sensor based on a polyaniline coating deposited on the surface of a tilted fiber Bragg grating. The pH-sensitive film was synthesized by in situ chemical oxidative polymerization keeping track of the deposition time in order to optimize the sensor response. As a result, the sensor reacts to pH changes in the range of 2–12 with a fast response and its sensitivity is directly related to the film thickness. The main advantages of this PAni-TFBG pH sensor are its biochemical compatibility, temperature independence, long-term stability and remote real-time multipoint sensing features.

58 citations


Journal ArticleDOI
TL;DR: In this article, the authors demonstrate switchable dual-wavelength CVB generation from a passively mode-locked fiber laser using carbon nanotubes as saturable absorber for mode-locking and a home-made mode-selective coupler as both mode converter and birefringence filter.
Abstract: Cylindrical vector beams (CVBs) with axial symmetry in both polarization and field intensity have attracted much attention because of their unique optical properties. Conventional methods to obtain CVBs including direct modulation of light beams in free space and high-order mode excitation by offset splicing single-mode fiber with few-mode fiber usually works at single wavelength with rather narrow bandwidth. Here, for the first time to the best of our knowledge, we demonstrate switchable dual-wavelength CVB generation from a passively mode-locked fiber laser using carbon nanotubes as saturable absorber for mode-locking and a home-made mode-selective coupler as both mode converter and birefringence filter. In experiments, the mode-locked fiber laser delivers CVB pulses of dual-wavelength (1532.5 nm and 1555.5 nm) and corresponding single wavelength with duration of hundreds of femtosecond, respectively. Moreover, the output polarization status is switchable between radially and azimuthally polarized states. The mode-locked CVBs with wavelength and polarization flexibility may have potential applications in mode-division multiplexing optical fiber communication, nanoparticle manipulation, material processing, nonlinear optics, and so on.

45 citations


Journal ArticleDOI
TL;DR: In this paper, a highly sensitive optical fiber curvature sensor based on cascaded fiber interferometers (CFIs) is demonstrated theoretically and experimentally, and the authors show that the scheme of CFI can be regarded as an equivalent fiber inter-ferometer with longer interference length and narrower FSR.
Abstract: A highly sensitive optical fiber curvature sensor based on cascaded fiber interferometers (CFIs) is demonstrated theoretically and experimentally. Theoretical results show that the scheme of cascaded fiber interferometers can be regarded as an equivalent fiber interferometer with longer interference length and narrower FSR. It serves as a curvature sensor with sensitivity up to 4.362 nm/m−1 within the measurement range of 0–1.134 m−1. Compared to the single fiber modal interferometer, the curvature sensitivity of the CFI is almost doubled. In addition, simultaneous curvature and temperature measurement is achieved using the coefficient matrix method, eliminating the issue of temperature cross sensitivity.

45 citations


Journal ArticleDOI
TL;DR: In this article, a high-power Yb-doped fiber laser at 1064 nm with improved temporal stability was developed as the pump source for the 9th-order cascaded random Raman fiber laser.
Abstract: High-order random Raman fiber lasers are investigated for generating high-power widely wavelength-tunable light sources. By cascaded random Raman lasing and adjusting pump laser wavelength, continuous wavelength tuning from 1 to 1.9 μm is reported. For power scaling, a high-power Yb-doped fiber laser at 1064 nm with improved temporal stability is developed as the pump source. The ninth-order cascaded random Raman fiber laser with a spectral purity of 86.6% is achieved at 1806 nm. Up to 100.1-W inband power is obtained with an optical efficiency of 38.4% from 1064 nm and 27.2% from 915 nm. The results prove that cascaded random Raman fiber laser is a versatile technology to generate high-power fiber laser at wavelength outside the rare earth emission bands.

43 citations


Journal ArticleDOI
TL;DR: In this article, a novel fiber design based on hexagonal shaped holes incorporated within the core of a Kagome lattice photonic crystal fiber (PCF) is presented, and the modal properties of the proposed fiber are evaluated by using a finite element method (FEM) with a perfectly matched layer as boundary condition.

39 citations


Journal ArticleDOI
TL;DR: In this paper, a 2-μm mode-locked Tm-doped fiber laser with a fundamental repetition rate of up to 1.6 GHz was proposed and demonstrated.
Abstract: We propose and demonstrate a compact passively mode-locked $\text{Tm}^{\text{3+}}\hbox{--}\text{doped}$ fiber laser with a fundamental repetition rate up to 1.6 GHz. A 5.9 cm home-made, heavily $\text{Tm}^{\text{3+}}\hbox{--}\text{doped}$ barium gallo-germanate glass fiber with a gain coefficient of 2.3 dB/cm at 1950 nm is employed as gain medium. The compact Fabry-Perot (FP) laser cavity contains a fiber mirror by directly coating the SiO2/Ta2O5 dielectric films on a fiber ferrule. The miniature FP laser pumped by a 793-nm laser diode is passively mode-locked by a semiconductor saturable absorber mirror. Stable self-started mode-locking is successfully achieved at a low pump threshold of 107 mW. The mode-locked operation at the central wavelength of 1959.7 nm has a spectral bandwidth of 12.2 nm, and the pulse duration of 7.2 ps. In particular, the pulse repetition frequency of the fundamental mode-locking can be as high as 1.6 GHz. Moreover, numerical simulation for the 2-μm mode-locked Tm-doped fiber lasers is performed using the lumped model, and the numerical results are in good agreement with the experimental ones. This is, to the best of our knowledge, the highest fundamental repetition frequency for the 2-μm mode-locked fiber lasers.

39 citations


Journal ArticleDOI
TL;DR: In this article, a saddle-shaped Yb-doped fiber design for high power generation in the spectral range near 0.976 nm was proposed, and a monolithic 976-nm single-mode continuous wave laser based on the proposed fiber was created.
Abstract: We propose a novel saddle-shaped Yb-doped fiber design for high power generation in the spectral range near 0.976 $\mu \text{m}$ . The fiber has a central single-mode part with a core diameter of approximately $12~\mu \text{m}$ and an ultra-thin silica clad of approximately $49~\mu \text{m}$ . At both ends of the fiber, the core/clad diameters were adiabatically increased up to 20/80 $\mu \text{m}$ to be compatible with ordinary passive fibers. A monolithic 976-nm single-mode continuous wave laser based on the proposed fiber was created. The laser’s power was a record high compared with all-fiber laser schemes, with an output power of 10.6 W. Utilization of a photodarkening-free core glass matrix has allowed us to demonstrate perfect long-term stability (without any power degradation) of the developed laser over 45 h.

36 citations


Journal ArticleDOI
TL;DR: In this article, a switchable multi-wavelength erbium-doped fiber ring laser, based on a core-off Mach-Zehnder interferometer (MZI) with non-zero dispersion shifted fiber (NZ-DSF), is proposed and experimentally demonstrated.
Abstract: In this paper, a switchable multi-wavelength erbium-doped fiber ring laser, based on a core-offset Mach-Zehnder interferometer (MZI) with non-zero dispersion shifted fiber (NZ-DSF), is proposed and experimentally demonstrated. Here, the core-offset MZI was implemented by fusion splicing a segment of a NZ-DSF between two single-mode fiber sections. In the proposed ring cavity design, the core-offset MZI is acting as a wavelength selective filter and it is optimized in order to achieve a single-mode suppression ratio (SMSR) of about of 56 dB. In addition, the laser is capable of emitting a single, double, or triple line, which can be switched from 1546 to 1564 nm by controlling its polarization states. Finally, this laser fiber offers a high output power stability at room temperature, compactness, robustness and low implementation cost.

34 citations


Journal ArticleDOI
TL;DR: In this article, a wavelength-tunable all-fiber Erbium-doped mode-locked fiber laser based on carbon nanotubes and 45° tilted fiber grating (TFG) is demonstrated.

31 citations


Journal ArticleDOI
TL;DR: In this paper, the thermomechanical behavior of a standard singlemode fiber with different coating materials is theoretically analyzed under different temperature conditions, and it is shown that the thermal expansion/shrinkage of the fiber coating introduces an extra strain on the optical fiber and can modify its thermal response.
Abstract: The thermomechanical behavior of a standard single-mode fiber with different coating materials is theoretically analyzed under different temperature conditions. Results show that the thermal expansion/shrinkage of the fiber coating introduces an extra strain on the optical fiber and can modify its thermal response. Distributed fiber sensors based on coherent Rayleigh and Brillouin scatterings are employed to characterize the impact of different coatings on the temperature sensitivity. The standard coating with dual-layer demonstrates a little influence on the thermal response at room temperature due to the softness of primary coating, but it increases the temperature sensitivity by some 50% at ∼220 K as the primary coating becomes stiffer at low temperature. Optical fibers with aluminum and Ormocer coatings are also experimentally tested. All the measured results agree well with the theoretical analysis.

Journal ArticleDOI
TL;DR: In this article, a hybrid Erbium-Raman random fiber laser was proposed to realize low-threshold, high-efficiency 1.5 μ m random lasing.
Abstract: In this paper, we proposed a novel approach to realize low-threshold, high-efficiency 1.5 μ m random fiber laser by taking advantage of hybrid Erbium–Raman gain. The numerical model is established to optimize the proposed Erbium–Raman random fiber laser, revealing the route to generate high-efficiency random lasing. The experiment is conducted to verify the concept, in which the threshold of 1.55 μ m random lasing has been reduced to 75 mW and its optical conversion efficiency has reached record high (65.5%). This simple and efficient random fiber laser could provide a platform for development of novel 1.5 μ m light sources for diverse applications where stable random lasing output with high-efficiency is essential.

Journal ArticleDOI
TL;DR: In this article, the authors designed and developed tapered suspended-core fibers of high-purity As39Se61 glass for supercontinuum generation in the mid-IR with a standard fiber laser pump source at 2μm.
Abstract: We designed and developed tapered suspended-core fibers of high-purity As39Se61 glass for supercontinuum generation in the mid-IR with a standard fiber laser pump source at 2 μm. It was shown that microstructuring allows shifting a zero dispersion wavelength to the range shorter than 2 μm in the fiber waist with a core diameter of about 1 μm. In this case, supercontinuum generation in the 1–10 μm range was obtained numerically with 150-fs 100-pJ pump pulses at 2 μm. We also performed experiments on wavelength conversion of ultrashort optical pulses at 1.57 μm from Er: fiber laser system in the manufactured As-Se tapered fibers. The measured broadening spectra were in a good agreement with the ones simulated numerically.

Journal ArticleDOI
TL;DR: In this paper, a deadband-free, high-resolution microwave frequency measurement scheme based on undersampling the microwave signal by three pulse sequences generated from a triple-wavelength mode-locked fiber laser is proposed and demonstrated.
Abstract: Microwave photonic solutions of frequency measurement have advantages in broad frequency coverage, but achieving high-resolution measurement remains a challenge. Those schemes based on optical frequency combs could achieve high-resolution measurement over a broad frequency range. Here, a dead-band-free, high-resolution microwave frequency measurement scheme based on undersampling the microwave signal by three pulse sequences generated from a triple-wavelength mode-locked fiber laser is proposed and demonstrated. The triple-wavelength ultrashort pulses generated in one laser cavity have slightly different repetition rates due to chromatic dispersion. This eliminates the needs of multiple mode-locked lasers and frequency control between them and drastically reduces the system complexity. The absolute frequency of the microwave signal can be determined based on three down-converted low-frequency beat notes of the microwave signal with the nearest comb lines without ambiguity. A 10–10 relative measurement precision at a sampling speed of 100 Hz is demonstrated from 1 to 20 GHz, and the measurement accuracy remains within 0.3 Hz. Microwave signal with an RF power as low as −75 dBm can be measured with a 10 Hz precision at 10 GHz by using RF frontend amplifiers. The simple and compact triple-comb fiber laser would enable the development of low-complexity, high-performance microwave characterization instrument.

Journal ArticleDOI
TL;DR: In this paper, a switchable narrow linewidth single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser with LP 11 transverse mode output was demonstrated.
Abstract: We experimentally demonstrate a switchable narrow linewidth single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser with LP 11 transverse mode output. The laser is based on a mode selective all-fiber fused coupler which is composed of a single-mode fiber (SMF) and a two-mode fiber (TMF). By controlling the polarization state of the output light, the laser can provide narrow linewidth SLM output with LP 11 transverse mode at two specific wavelengths, which correspond to two transmission peaks of the chirped moire fiber grating (CMFBG). The 20 dB linewidth of the fiber laser for each wavelength is approximately 7.2 and 6.4 kHz.

Journal ArticleDOI
TL;DR: In this article, experimental and simulation results of the zero-dispersion shift in photonics crystal fibers infiltrated with water-ethanol mixture were presented, showing that the flattened part of the dispersion shifts from anomalous to the normal regime at temperatures below −70°C.

Journal ArticleDOI
01 Mar 2018-Optik
TL;DR: An annular core photonic quasi-crystal fiber with ultra-flat dispersion, low confinement loss and small effective mode area covering O, E, S, C, L and U bands was proposed in this paper.

Journal ArticleDOI
TL;DR: In this article, a long-period fiber grating sensor induced by electric-arc discharge has been fabricated and demonstrated for the simultaneous measurement of temperature and strain, which is promising for applications for which simultaneous measurement is required.
Abstract: A long-period fiber grating sensor induced by electric-arc discharge has been fabricated and demonstrated for the simultaneous measurement of temperature and strain. The proposed sensor was fabricated by inscribing a sing-mode fiber with periodic electric-arc discharge technology that was produced from a commercial fusion splicer. The resonance dips formed by the coupling between cladding modes and core mode have different sensitivity responses, so the simultaneous measurement for multiple parameters was realized by monitoring the wavelength shifts of the resonance dips. Because of the easy fabrication and low cost, the sensor is promising for applications for which simultaneous measurement of temperature and strain is required.

Journal ArticleDOI
01 Mar 2018-Optik
TL;DR: In this paper, a dual concentric core dispersion compensating photonic crystal fiber (DCC-DCPCF) with all solid structure and low index difference is proposed.

Journal ArticleDOI
TL;DR: In this paper, the residual strain pattern distributed on composite cylinders after impacts was detected using optical fibers for the first time, using phase modulation and single side band modulation methods, using sensing optical fiber was implemented on the composite cylinders using aluminum (Al)-coated optical fiber, polyimide-coated fiber, or standard single mode fiber of polymer-coating.

Journal ArticleDOI
01 Feb 2018-Optik
TL;DR: In this article, a germanium doped hexagonal photonic crystal fiber is presented to obtain highly nonlinear coefficient with flat dispersion property for supercontinuum generation applications.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate simultaneous stabilization of optical and microwave signals on an optical-fiber link by independently stabilizing two optical signals that are separated by a nominated microwave frequency.
Abstract: We demonstrate simultaneous stabilization of optical and microwave signals on an optical-fiber link by independently stabilizing two optical signals that are separated by a nominated microwave frequency. This system can be implemented on conventional stabilized optical frequency transfer networks without degrading the stability of the optical signal, increasing the scope of applications of existing and future large-scale frequency transfer networks. For a 30 km optical-fiber link, we demonstrate a 193 THz optical carrier transfer absolute frequency stability of $4.9\times 10^{-5}$ Hz at $10^{3}$ s, and a 10.02 GHz microwave signal transfer absolute frequency stability of $1.3\times 10^{-4}$ Hz at $10^{3}$ s.

Journal ArticleDOI
TL;DR: In this article, a fiber-based photon-pair source in the telecom C-band is proposed for quantum information science including quantum communications, where photon pairs exhibit strong temporal correlation with each other and excellent heralded anti-bunching property.
Abstract: A fiber-based photon-pair source in the telecom C-band is suitable for quantum information science including quantum communications. Spontaneous four-wave mixing effects are known to create photon pairs that are slightly detuned from the pump wavelength only in the anomalous group-velocity-dispersion (GVD) regime. Here, we achieve high-quality photon-pair generation slightly detuned from the pump wavelength in the normal GVD regime through a dispersion shifted fiber, for the first time. The photon pairs in C-band exhibit strong temporal correlation with each other and excellent heralded anti-bunching property. This photon-pair generation scheme can be exploited as telecom-band quantum light sources for quantum information applications.

Journal ArticleDOI
TL;DR: In this paper, a coherent Pound-Drever-Hall (PDH) technique was proposed for detection of very weak probe light, in which the probe beam is coherent detected with a strong local oscillator.
Abstract: The Pound–Drever–Hall (PDH) technique has been widely adopted in high-resolution fiber-optic sensors, but its performance degenerates as the probe power drops. In this work, we develop a coherent PDH technique for detection of very weak probe light, in which the probe beam is coherent detected with a strong local oscillator. Assisted with an analog frequency doubler and a band-pass filter, the configuration of proposed coherent PDH technique is highly compatible with classical PDH technique. The influence of fiber dispersion is also assessed. In the demonstrational experiments, the signal-to-noise ratio of the extracted PDH signal is dramatically improved compared with classical PDH technique, especially under weak probe power. Using a π-phase shifted fiber Bragg grating as the sensing element, a ne-order strain resolution is achieved at a low probe power down to –43 dBm, which is about 15-dB lower compared with classical PDH technique. The proposed technique has great potentials in high-resolution large-scale fiber sensor networks.

Journal ArticleDOI
01 Dec 2018-Optik
TL;DR: In this article, an effective full-duplex radio-over-fiber (ROF) system was proposed, which only used a single light source at central station (CS) Frequency quadrupling modulation scheme was employed to generate 100 GHz optical millimeter wave (mm-wave) for downlink transmission while the central optical carrier was reused at BS for uplink connection.

Journal ArticleDOI
TL;DR: In this article, the effect of wavelength filtering on pulse dynamics of a wavelength-tunable Erbium-doped fiber Q-switched laser in a ring configuration is investigated.
Abstract: We present a numerical simulation, validated by experimental analysis, of the effect of wavelength filtering on pulse dynamics of a wavelength-tunable Erbium-doped fiber Q-switched laser in a ring configuration. Travelling wave time-dependent model is implemented using finite difference time domain (FDTD) method to accurately simulate the population dynamics and the pulse evolution in the ring laser. Such a model is experimentally validated for a wavelength tunable Q-switched fiber laser and stable Q-switched pulses are obtained over a wavelength tuning range of ∼30 nm in the C-band.

Journal ArticleDOI
TL;DR: In this article, the authors reported a 166 W burst mode pulse fiber amplifier seeded by a Q-switched mode-locked all-fiber laser at 1064 nm based on a fiber-coupled semiconductor saturable absorber mirror.
Abstract: We report a 166 W burst mode pulse fiber amplifier seeded by a Q-switched mode-locked all-fiber laser at 1064 nm based on a fiber-coupled semiconductor saturable absorber mirror. With a pump power of 230 W at 976 nm, the output corresponds to a power conversion efficiency of 74%. The repetition rate of the burst pulse is 20 kHz, the burst energy is 8.3 mJ, and the burst duration is ∼ 20 μ s, which including about 800 mode-locked pulses at a repetition rate of 40 MHz and the width of the individual mode-locked pulse is measured to be 112 ps at the maximum output power. To avoid optical damage to the fiber, the initial mode-locked pulses were stretched to 72 ps by a bandwidth-limited fiber bragg grating. After a two-stage preamplifier, the pulse width was further stretched to 112 ps, which is a result of self-phase modulation of the pulse burst during the amplification.

Journal ArticleDOI
TL;DR: In this article, a strain-independent torsion and displacement fiber sensor using acoustically-induced fiber grating (AIFG) in dual-mode fiber (DMF) is presented.
Abstract: We present a strain-independent torsion and displacement fiber sensor using acoustically-induced fiber grating (AIFG) in dual-mode fiber (DMF). By tuning the radio frequency of driving signal, LP01 and LP11 modes generated by the AIFG can be exploited to measure the dynamic displacement and torsion variations, respectively. Both the twist angle and the twist direction can be monitored via image detection facility at the end of DMF. Between torsion angles of −80° and 80°, the highest twist sensitivity reaches 15 pixel/°. The average displacement sensitivity is 5 pixel/µm within the recorded two-dimensional movement of 100um × 80um. The stable property of sensor is verified when the strain is varied from 100 μe to 1500 μe.

Journal ArticleDOI
TL;DR: In this article, the authors explore the properties of a novel stimulated Raman scattering (SRS) filtering fiber for high average or high peak optical power delivery applications, which is based on a series of circularly arranged high index rods embedded in a leaky silica cladding.
Abstract: We explore the properties of a novel stimulated Raman scattering (SRS) filtering fiber for high average or high peak optical power delivery applications. The fiber geometry is based on a series of circularly arranged high index rods embedded in a leaky silica cladding. The operation principle relies on the resonant coupling of the core and rod modes and the wavelength-dependent leaking of the structure. The fabricated fiber demonstrated wide transmission window and filtering of SRS with extinction in excess of 20 dB at the Raman Stokes wavelength, excellent robustness with bending, and high output beam quality. The fiber has been tested as a beam delivery fiber of a commercial pulsed fiber laser system in order to explore the filtering performance and its limitations.

Journal ArticleDOI
01 Feb 2018-Optik
TL;DR: In this article, an all fiber self-mode-locked Tm-doped double-clad fiber ring laser is experimentally demonstrated, where a piece of ∼95m SMF-28 was inserted into the cavity to enhance the nonlinearity and bring in a large net anomalous dispersion.