Showing papers on "Dispersion-shifted fiber published in 2013"
22 Apr 2013
TL;DR: A thulium doped fiber amplifier designed for optical communications providing high gain and low noise figure over 1910nm-2020nm with a maximum saturated output power of more than 1W is reported.
Abstract: We report the realization of a thulium doped fiber amplifier designed for optical communications providing high gain (>35dB) and low noise figure (<;6dB) over 1910nm-2020nm with a maximum saturated output power of more than 1W.
271 citations
TL;DR: An optical fiber magnetic field sensor based on the single-mode-multimode-single-mode (SMS) structure and magnetic fluid (MF) is proposed and demonstrated and investigated.
Abstract: An optical fiber magnetic field sensor based on the single-mode-multimode-single-mode (SMS) structure and magnetic fluid (MF) is proposed and demonstrated. By using a piece of no-core fiber as the multimode waveguide in the SMS structure and MF sealed in a capillary tube as the magnetic sensitive media, which totally immersing the no-core fiber, an all-fiber magnetic sensor was fabricated. Interrogation of the magnetic field strength can be achieved either by measuring the dip wavelength shift of the transmission spectrum or by detecting the transmission loss at a specific wavelength. A demonstration sensor with sensitivities up to 905 pm/mT and 0.748 dB/mT was fabricated and investigated. A theoretical model for the design of the proposed device was developed and numerical simulations were performed.
218 citations
TL;DR: In this article, nondegenerate four-wave mixing (FWM) between waves belonging to different spatial modes of a 5 km-long few-mode fiber (FMF) has been experimentally demonstrated.
Abstract: We experimentally demonstrate nondegenerate four-wave mixing (FWM) between waves belonging to different spatial modes of a 5-km-long few-mode fiber (FMF). Of the three inter-modal FWM (IM-FWM) processes possible, two have been experimentally observed. These IM-FWM processes are found to be phase-matched over very large frequency separations of several Terahertz between the waves. In contrast to FWM in single-mode fibers that require operating near the zero-dispersion wavelength to achieve phase matching, IM-FWM in a FMF can be fully phase matched in the presence of large chromatic dispersion in each spatial mode.
161 citations
TL;DR: Graphene is a promising and reliable saturable absorber for mid-infrared pulse generation at 3 μm and is demonstrated to be stable Q-switched for passively Q switched operation.
Abstract: We report a diode-pumped 2.78 μm Er3+-doped ZBLAN fiber laser passively Q switched by a graphene saturable absorber, which was directly deposited onto a fiber dichroic mirror by the method of optically driven deposition. Stable Q-switched operation with a pulse duration of 2.9 μs and a pulse energy of 1.67 μJ was achieved in a 10 m long gain fiber. The pulse duration was reduced to 1 μs when the gain fiber length was shortened to 2 m. This Letter demonstrates that graphene is a promising and reliable saturable absorber for mid-infrared pulse generation at 3 μm.
159 citations
TL;DR: The first in-band diode-pumped TDFAs operating in the 2 µm wavelength region are presented and their suitability as high performance amplifiers in potential future telecommunication networks is tested.
Abstract: We present the first in-band diode-pumped TDFAs operating in the 2µm wavelength region and test their suitability as high performance amplifiers in potential future telecommunication networks. We demonstrate amplification over a 240nm wide window in the range 1810 - 2050nm with up to 36dB gain and noise figure as low as 4.5dB.
146 citations
TL;DR: In this paper, an analytical model that predicts the impact of the Kerr nonlinearity in optical communication systems when the signal spectrum is wide and the accumulated dispersion during propagation is large is discussed.
Abstract: We discuss an analytical model that predicts the impact of the Kerr nonlinearity in optical communication systems when the signal spectrum is wide and the accumulated dispersion during propagation is large. A detailed derivation of this model is given for a generalized system by means of a perturbation analysis of the Manakov equation with attenuation, gain, and third order dispersion included. As in the case with previous studies, three simplifying assumptions are necessary. These are that (i) the nonlinearity is weak, (ii) the input signal is of a given specific form, and (iii) the signal-noise interaction can be neglected. Under these assumptions, the result is found exactly. We also discuss the accuracy of the analytical result and show that third order dispersion has a small impact in practice.
138 citations
TL;DR: The supercontinuum (SC) generation in a suspended-core As(2)S(3) chalcogenide microstructured optical fiber (MOF) is demonstrated and the generalized nonlinear Schrödinger equation agrees well with the experiment.
Abstract: We demonstrate the supercontinuum (SC) generation in a suspended-core As2S3 chalcogenide microstructured optical fiber (MOF) The variation of SC is investigated by changing the fiber length, pump peak power and pump wavelength In the case of long fibers (20 and 40 cm), the SC ranges are discontinuous and stop at the wavelengths shorter than 3500 nm, due to the absorption of fiber In the case of short fibers (13 and 24 cm), the SC ranges are continuous and can extend to the wavelengths longer than 4 μm The SC broadening is observed when the pump peak power increases from 024 to 132 kW at 2500 nm The SC range increases with the pump wavelength changing from 2200 to 2600 nm, corresponding to the dispersion of As2S3 MOF from the normal to anomalous region The SC generation is simulated by the generalized nonlinear Schrodinger equation The simulation includes the SC difference between 13 and 24 cm long fiber by 2500 nm pumping, the variation of SC with pump peak power in 24 cm long fiber, and the variation of SC with pump wavelength in 13 cm long fiber The simulation agrees well with the experiment
134 citations
TL;DR: A high-efficiency 1480 nm cascaded Raman fiber laser is demonstrated with an output power of 301 W, comparable to record power levels achieved with rare-earth-doped fiber lasers in the 1.5 μm wavelength region.
Abstract: High-power fiber lasers operating at the 1.5 μm wavelength region have attractive features, such as eye safety and atmospheric transparency, and cascaded Raman fiber lasers offer a convenient method to obtain high-power sources at these wavelengths. A limitation to power scaling, however, has been the lower conversion efficiency of these lasers. We recently introduced a high-efficiency architecture for high-power cascaded Raman fiber lasers applicable for 1.5 μm fiber lasers. Here we demonstrate further power scaling using this new architecture. Using numerical simulations, we identify the ideal operating conditions for the new architecture. We demonstrate a high-efficiency 1480 nm cascaded Raman fiber laser with an output power of 301 W, comparable to record power levels achieved with rare-earth-doped fiber lasers in the 1.5 μm wavelength region.
122 citations
TL;DR: A photonic crystal fiber (PCF) long-period grating (LPG) humidity sensor has been developed with high sensitivity and selectivity for nondestructive detection of moisture ingression into structures that can potentially lead to corrosion as mentioned in this paper.
Abstract: A photonic crystal fiber (PCF) long-period grating (LPG) humidity sensor has been developed with high sensitivity and selectivity for nondestructive detection of moisture ingression into structures that can potentially lead to corrosion. We have proposed two types of nanofilms to be coated on the surface of air channels in the grating region by electrostatic self-assembly deposition processing. The primary nanofilm does not affect LPG properties such as resonance wavelength or transmission intensity which can impact sensing characteristics; however it increases the sensitivity by changing the refractive index of the surrounding material. The secondary nanofilm is used for selectively adsorbing analyte molecules of interest. The experimental results reveal that, compared to the conventional fiber LPGs and exterior nanofilm-coated PCF-LPG, the interior nanofilm-coated PCF-LPG humidity sensors have both the most sensitive resonance intensity change of 0.00022%/10 −3 dBm from relative humidity (RH) of 38% to 39% and average wavelength shift of 0.0007%/pm for a relative humidity variation from 22% to 29%. The proposed sensor shows excellent thermal stability as well.
120 citations
TL;DR: Narrow-band emission of spectral width down to ~0.05 nm line-width is achieved in the random distributed feedback fiber laser employing narrow-band fiber Bragg grating or fiber Fabry-Perot interferometer filters.
Abstract: Narrow-band emission of spectral width down to ~0.05 nm line-width is achieved in the random distributed feedback fiber laser employing narrow-band fiber Bragg grating or fiber Fabry-Perot interferometer filters. The observed line-width is ~10 times less than line-width of other demonstrated up to date random distributed feedback fiber lasers. The random DFB laser with Fabry-Perot interferometer filter provides simultaneously multi-wavelength and narrow-band (within each line) generation with possibility of further wavelength tuning.
120 citations
TL;DR: The limits of attenuation of silica hollow core negative curvature fibers in the wavelength range from 800 nm up to 4.5 µm are discussed and good agreement is shown.
Abstract: In this paper we discuss the limits of attenuation of silica hollow core negative curvature fibers in the wavelength range from 800 nm up to 4.5 µm. Both numerical and experimental results are presented and show good agreement. A minimum attenuation of 24.4 dB/km was measured at around 2400 nm wavelength, while 85 dB/km was measured at 4000 nm.
TL;DR: This paper describes the implementation of a coherent beacon source placed at the distal tip of the multimode fiber, which can be used to compensate for the effects of bending and demonstrates focusing even when the fiber is bent by dynamically compensating for it.
Abstract: Multimode fiber endoscopes have recently been shown to provide sub-micrometer resolution, however, imaging through a multimode fiber is highly sensitive to bending. Here we describe the implementation of a coherent beacon source placed at the distal tip of the multimode fiber, which can be used to compensate for the effects of bending. In the first part of this paper, we show that a diffraction limited focused spot can be generated at the distal tip of the multimode fiber using the beacon. In the second part, we demonstrate focusing even when the fiber is bent by dynamically compensating for it. The speckle pattern at the proximal fiber end, generated by the beacon source placed at its distal end, is highly dependent on the fiber conformation. We experimentally show that by intensity correlation, it is possible to identify the fiber conformation and maintain a focus spot while the fiber is bent over a certain range. Once the fiber configuration is determined, previously calibrated phase patterns could be stored for each fiber conformation and used to scan the distal spot and perform imaging.
TL;DR: Detailed analysis of the optical modes and their propagation along the fiber, carried out using a time-of-flight technique in conjunction with spatially and spectrally resolved (S2) imaging, provides clear evidence that the HC-PBGF can be operated as quasi-single mode even though it supports up to four mode groups.
Abstract: The first demonstration of a hollow core photonic bandgap fiber (HC-PBGF) suitable for high-rate data transmission in the 2 µm waveband is presented. The fiber has a record low loss for this wavelength region (4.5 dB/km at 1980 nm) and a >150 nm wide surface-mode-free transmission window at the center of the bandgap. Detailed analysis of the optical modes and their propagation along the fiber, carried out using a time-of-flight technique in conjunction with spatially and spectrally resolved (S2) imaging, provides clear evidence that the HC-PBGF can be operated as quasi-single mode even though it supports up to four mode groups. Through the use of a custom built Thulium doped fiber amplifier with gain bandwidth closely matched to the fiber's low loss window, error-free 8 Gbit/s transmission in an optically amplified data channel at 2008nm over 290m of 19 cell HC-PBGF is reported.
TL;DR: A 170 W all-fiber linearly-polarized single-frequency sing-mode ytterbium amplifier at 1064 nm with an optical efficiency of 80% is demonstrated and 7 times increase of the stimulated Brillouin scattering threshold is achieved.
Abstract: A 170 W all-fiber linearly-polarized single-frequency sing-mode ytterbium amplifier at 1064 nm with an optical efficiency of 80% is demonstrated. 3.9 m long ytterbium-doped polarization maintaining fiber with a core diameter of 10 μm is used as the gain fiber, which guarantees a diffraction-limited output with a measured M(2) of 1.02. To suppress the stimulated Brillouin scattering, longitudinally varied strains are applied on the gain fiber according to the signal power evolution and the temperature distribution. 7 times increase of the stimulated Brillouin scattering threshold is achieved.
TL;DR: In this article, a highly birefringent photonic crystal fiber based on a modified octagonal structure for broadband dispersion compensation covering the S, C, and L-communication bands is proposed.
TL;DR: It was experimentally shown that an all-fiberized thulium-holmium (Tm-Ho)-codoped fiber ring laser with reduced cavity length can produce stable femtosecond pulses by incorporating a graphene oxide-deposited side-polished fiber.
Abstract: An in-depth experimental investigation was conducted into the use of a graphene oxide-based saturable absorber implemented on a side-polished fiber platform for femtosecond pulse generation in the 2 μm region. First, it was experimentally shown that an all-fiberized thulium-holmium (Tm-Ho)-codoped fiber ring laser with reduced cavity length can produce stable femtosecond pulses by incorporating a graphene oxide-deposited side-polished fiber. Second, the measurement accuracy issue in obtaining a precise pulse-width value by use of an autocorrelator together with a silica fiber-based 2 μm-band amplifier was investigated. It showed that the higher-order soliton compression effect caused by the combination of anomalous dispersion and Kerr nonlinearity can provide incorrect pulse-width information. Third, an experimental investigation into the precise role of the graphene oxide-deposited side-polished fiber was carried out to determine whether its polarization-dependent loss (PDL) can be a substantial contributor to mode-locking through nonlinear polarization rotation. By comparing its performance with that of a gold-deposited side-polished fiber, the PDL contribution to mode-locking was found to be insignificant, and the dominant mode-locking mechanism was shown to be saturable absorption due to mutual interaction between the evanescent field of the oscillated beam and the deposited graphene oxide particles.
TL;DR: In this article, a compact low-crosstalk multi-ring fiber transmitting multiple orbital angular momentum (OAM) modes is presented, which can be used for high-density space-division multiplexing.
Abstract: A compact low-crosstalk multi-ring fiber transmitting multiple orbital angular momentum (OAM) modes is presented. The multi-OAM-mode multi-ring fiber (MOMRF) consists of 7 rings, each supporting 22 modes with 18 OAM ones (i.e., 154 channels in total), which can be used for high-density space-division multiplexing. The employed high-contrast-index ring structure benefits tight light confinement and large effective refractive index difference of different OAM modes , featuring both low-level inter-ring crosstalk ( 30 dB for a 100-km-long fiber) and intermode crosstalk over a wide wavelength range (1520-1580 nm). The designed MOMRF is also compatible with wavelength-division multiplexing technique (e.g., 75 ITU-grid wavelengths from 1520.25 to 1579.52 nm with 100-GHz spacing) and advanced multilevel amplitude/phase modulation formats (e.g., 16-ary quadrature amplitude modulation), which might be used to achieve petabit-per-second total transmission capacity and hundred bits-per-second-per-hertz aggregate spectral efficiency.
TL;DR: Picosecond and nanosecond pulse delivery have been demonstrated in fiber-based laser micro-machining of fused silica, aluminum and titanium and have been successfully delivered through the NCF with a coupling efficiency of 92%.
Abstract: We present high average power picosecond and nanosecond pulse delivery at 1030 nm and 1064 nm wavelengths respectively through a novel hollow-core Negative Curvature Fiber (NCF) for high-precision micro-machining applications. Picosecond pulses with an average power above 36 W and energies of 92 µJ, corresponding to a peak power density of 1.5 TWcm⁻² have been transmitted through the fiber without introducing any damage to the input and output fiber end-faces. High-energy nanosecond pulses (>1 mJ), which are ideal for micro-machining have been successfully delivered through the NCF with a coupling efficiency of 92%. Picosecond and nanosecond pulse delivery have been demonstrated in fiber-based laser micro-machining of fused silica, aluminum and titanium.
TL;DR: In this paper, the authors demonstrate a fiber-to-cavity coupling of light from an optical fiber to a silicon photonic crystal optomechanical cavity using a compact (L ~ 25 um) intermediate adiabatic coupler.
Abstract: We demonstrate highly efficient coupling of light from an optical fiber to a silicon photonic crystal optomechanical cavity. The fiber-to-cavity coupling utilizes a compact (L ~ 25 um) intermediate adiabatic coupler. The optical coupling is lithographically controlled, broadband, relatively insensitive to fiber misalignment, and allows for light to be transferred from an optical fiber to, in principle, any photonic chip with refractive index greater than that of the optical fiber. Here we demonstrate single-sided cavity coupling with a total fiber-to-cavity optical power coupling efficiency of 85%.
TL;DR: A high-energy Q-switched double-clad thulium-doped fiber laser (TDFL) using a graphene-oxide-deposited tapered fiber device as a saturable absorber operating at a wavelength of 2 μm for the first time is demonstrated.
Abstract: We have demonstrated a high-energy Q-switched double-clad thulium-doped fiber laser (TDFL) using a graphene-oxide-deposited tapered fiber (GODTF) device as a saturable absorber operating at a wavelength of 2 μm for the first time. Because of the side-interaction of the graphene-oxide with the evanescent field on the taper waist, the GODTF devices have potential for offering high laser damage threshold. Using a 788 nm laser diode as the pump source, the TDFL generated stable single transverse mode Q-switched pulses with a single pulse energy of 6.71 μJ (corresponding to an average power of 302 mW) at a wavelength of 2032 nm. This is significantly higher than the highest pulse energy/average power from any rare-earth-doped fiber lasers employing a graphene or graphene-oxide based Q-switch so far. The demonstrated TDFL in this paper represents an encouraging step towards the practical applications of graphene or graphene-oxide based Q-switched 2 μm TDFLs.
TL;DR: Tapered mode-selective couplers are shown to allow for ultra-broadband mode-division multiplexing of few-mode optical fiber as discussed by the authors, using appropriate three-core configurations, modes of arbitrary spatial orientation can be demultiplexed.
Abstract: Tapered mode-selective couplers are shown to allow for ultra-broadband mode-division multiplexing of few-mode optical fiber. Using appropriate three-core configurations, modes of arbitrary spatial-orientation can be demultiplexed. The successful fabrication of these wavelength-insensitive couplers would represent the realization of compact low-loss mode-multiplexers for use in high-bandwidth few-mode fiber networks.
TL;DR: A multi-wavelength Erbium-doped fiber (EDF) laser based on four-wave-mixing is proposed and experimentally demonstrated and the lasing stability is investigated.
Abstract: A multi-wavelength Erbium-doped fiber (EDF) laser based on four-wave-mixing is proposed and experimentally demonstrated. The 5 km single mode fiber in the cavity enhances the four-wave-mixing to suppress the homogenous broadening of the erbium-doped fiber and get the stable multi-wavelength comb. The lasing stability is investigated. When the pump power is 300 mW, the fiber laser has 5-lasing lines and the maximum fluctuation of the output power is about 3.18 dB. At the same time, a laser with 110 m high nonlinear fiber (HNFL) is demonstrated. When the pump power is 300 mW, it has 7-lasing lines (above -30 dBm) and the maximum fluctuation is 0.18dB.
TL;DR: A supercontinuum spanning well over an octave of measurable bandwidth from about 1 to 3.7 μm in a 2.1 mm long As₂S₃ fiber taper is reported using the in situ tapering method.
Abstract: We report a supercontinuum spanning well over an octave of measurable bandwidth from about 1 to 3.7 μm in a 2.1 mm long As2S3 fiber taper using the in situ tapering method. A sub-100-fs mode-locked thulium-doped fiber laser system with ∼300 pJ of pulse energy was used as the pump source. Third-harmonic generation was observed and currently limits the pump pulse energy and achievable spectral bandwidth.
TL;DR: A high pulse energy and high average power Q-switched Tm-doped large-pitch fiber oscillator, which allows for large core diameters in combination with effective single-mode operation.
Abstract: We report on a high pulse energy and high average power Q-switched Tm-doped fiber oscillator. The oscillator produces 2.4 mJ pulses with 33 W average power (at a repetition rate of 13.9 kHz) and nearly diffraction-limited beam quality. This record performance is enabled by a Tm-doped large-pitch fiber, which allows for large core diameters in combination with effective single-mode operation.
TL;DR: This paper uses the Volterra series transfer function (VSTF) method to define impairment characteristic coefficients that capture intersymbol interference, and investigates the impact of system parameters, namely, duty cycle, spectral efficiency, frequency chirp, and span length, on the RoI for long-haul DWDM systems.
Abstract: In long-haul dense wavelength-division multiplexing (DWDM) systems with periodic dispersion compensation and amplification, system performance is adversely affected by severe physical impairments due to fiber losses, dispersion and nonlinearity. Fiber modeling is a prerequisite for the development of physical impairment mitigation techniques to improve system performance. The distance between two interacting symbols in time and wavelength, i.e., the range of influence (RoI) of each physical impairment, plays an important role in the development of these mitigation techniques. In this paper, we use the Volterra series transfer function (VSTF) method to define impairment characteristic coefficients that capture intersymbol interference (ISI), self phase modulation (SPM), intrachannel cross phase modulation (IXPM), intrachannel four wave mixing (IFWM), cross phase modulation (XPM) and four wave mixing (FWM), to characterize the impact of these impairments individually on the system output. We then investigate the impact of system parameters, namely, duty cycle, spectral efficiency, frequency chirp, and span length, on the RoI for long-haul DWDM systems.
TL;DR: By intentionally combining the porous fiber and the air-core photonic bandgap fiber, a kind of porous core photonic Bandgap fiber for guiding terahertz (THz) wave is proposed in this paper.
09 Jun 2013
TL;DR: In this article, the authors demonstrate modally pure propagation over a record number (12) of modes in an optical fiber, and achieve mode purities >10dB over 2m for all states and >20dB after 1km for a 2 state subset.
Abstract: We demonstrate modally pure propagation over a record number (12) of modes in an optical fiber. An air-core fiber enables this by supporting OAM states. We achieve mode purities >10dB over 2m for all states and >20dB after 1km for a 2 state subset.
TL;DR: In this article, the design of an index guided photonic crystal fiber which promises to yield very large birefringence (~2.22 ×10-2) was presented.
Abstract: This paper presents the design of an index guided photonic crystal fiber which promises to yield very large birefringence (~2.22 ×10- 2). Important optical properties, such as birefringence, single modeness, optical confinement, fiber dispersion, walk-off, etc., have been studied employing numerical simulation through finite difference time domain scheme. The fiber also promises a very small walk-off near optical communication wavelength.
TL;DR: In this paper, a Raman cascade spanning the wavelength range of 523 to 1750 nm was generated in a standard telecommunication graded-index multimode optical fiber, and the Raman peaks were generated in specific modes of the fiber, confirming substantial beam cleanup during the stimulated Raman scattering process.
Abstract: We report on the generation of a Raman cascade spanning the wavelength range of 523 to 1750 nm wavelength range, in a standard telecommunication graded-index multimode optical fiber. Despite the highly multimode nature of the pump, the Raman peaks are generated in specific modes of the fiber, confirming substantial beam cleanup during the stimulated Raman scattering process.
TL;DR: A low noise single-frequency and single-polarization distributed Bragg reflector fiber laser is presented by using a 1.8 cm long newly developed ytterbium-doped phosphate single mode glass fiber.
Abstract: We present a low noise single-frequency and single-polarization distributed Bragg reflector fiber laser at 1083 nm by using a 1.8 cm long newly developed ytterbium-doped phosphate single mode glass fiber. The maximum output power is more than 100 mW with a slope efficiency of >29.6%. The signal to noise ratio is higher than 61 dB and the laser linewidth of less than 2 kHz is estimated. The obtained relative intensity noise for frequencies of over 4.0 MHz is less than −150 dB/Hz, which approaches the shot noise limit. The achieved linear polarization extinction ratio is more than 30 dB.