Showing papers on "Fiber laser published in 2007"
TL;DR: In this paper, a model-ocked fiber laser is designed to have strong pulse-shaping based on spectral filtering of a highly-chirped pulse in the laser cavity, without a dispersive delay line or anomalous dispersion in the cavity.
Abstract: A modelocked fiber laser is designed to have strong pulse-shaping based on spectral filtering of a highly-chirped pulse in the laser cavity. The laser generates femtosecond pulses without a dispersive delay line or anomalous dispersion in the cavity.
653 citations
TL;DR: In this article, the effect of the shifting of consecutive single vectors on the process of forming the first layer was studied and the optimal parameters of layer thickness and power input per unit speed for SLS/SLM were determined.
551 citations
TL;DR: Experimental results from Yb-doped fiber lasers agree with the trends of numerical simulations, and stable and self-starting pulses are generated with energies above 20 nJ, and these can be dechirped to <200 fs duration.
Abstract: We report a study of the scaling and limits to pulse energy in an all-normal-dispersion femtosecond fiber laser. Theoretical calculations show that operation at large normal cavity dispersion is possible in the presence of large nonlinear phase shifts, owing to strong pulse shaping by spectral filtering of the chirped pulse in the laser. Stable pulses are possible with energies of tens of nanojoules. Experimental results from Yb-doped fiber lasers agree with the trends of numerical simulations. Stable and self-starting pulses are generated with energies above 20 nJ, and these can be dechirped to <200 fs duration. Femtosecond pulses with peak powers near 100 kW are thus available from this simple and practical design.
424 citations
TL;DR: Godard et al. as discussed by the authors reviewed the main technologies, restricted to continuous-wave (CW) and nanosecond pulsed sources emitting in the 2-12 µm range, and discussed the pros and cons of these technologies in the context of several selected applications.
355 citations
TL;DR: In this article, an improved curvature loss formula for optical waveguides is presented, which is shown to accurately predict the bend loss of both single-mode and multimode fibers.
Abstract: This paper presents an improved curvature loss formula for optical waveguides, which is shown to accurately predict the bend loss of both single-mode and multimode fibers. The formula expands upon a previous formula derived by Marcuse, greatly improving its accuracy for the case of multimode fiber. Also presented are the results of bent fiber simulations using the beam propagation method (BPM), and experimental measurements of bend loss. Agreement among simulation, formula and measurement support the validity of both theoretical methods. BPM simulations showed that the lowest order modes of the bent fiber were reduced to their linearly polarized constituents prior to the onset of significant bend loss. This implies that certain LP mode orientations should propagate with much lower loss than previously expected, and should impact the mode stripping ability of bent large mode area fibers, as employed in fiber lasers and amplifiers.
327 citations
TL;DR: In this paper, a brief review of the development of high power fiber laser is presented, and initial data on welding of API 5L: X100 pipeline steel with an 8kW fiber laser.
300 citations
TL;DR: An embedded fiber-taper saturable absorber is proposed and demonstrated based on a fiber taper embedded in a carbon nanotube/polymer composite and an all-fiber mode-locked ring laser is built.
Abstract: We propose and demonstrate a new saturable absorber based on a fiber taper embedded in a carbon nanotube/polymer composite. Greater than a 10% reduction in absorption (due to saturation) is directly measured for our saturable absorber. Using an embedded fiber-taper saturable absorber, we built an all-fiber mode-locked ring laser, which produces 594 fs/1.7 nJ pulses with a repetition rate of 13.3 MHz.
286 citations
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TL;DR: A comparison with similar systems in bulk format shows that the random fiber laser presents an efficiency that is at least 2 orders of magnitude higher than the classical random laser system operating in the incoherent feedback regime.
Abstract: We investigate the effects of two-dimensional confinement on the lasing properties of a classical random laser system operating in the incoherent feedback (diffusive) regime. A suspension of 250 nm rutile (TiO2) particles in a rhodamine 6G solution was inserted into the hollow core of a photonic crystal fiber generating the first random fiber laser and a novel quasi-one-dimensional random laser geometry. A comparison with similar systems in bulk format shows that the random fiber laser presents an efficiency that is at least 2 orders of magnitude higher.
256 citations
TL;DR: A novel passive mode-locking scheme for pulsed lasers enhanced by the interaction of carbon nanotubes (CNTs) with the evanescent field of propagating light in a D-shaped optical fiber that ensures the preservation of the original morphology of the individual CNTs.
Abstract: We demonstrate a novel passive mode-locking scheme for pulsed lasers enhanced by the interaction of carbon nanotubes (CNTs) with the evanescent field of propagating light in a D-shaped optical fiber. The scheme features all-fiber operation as well as a long lateral interaction length, which guarantees a strong nonlinear effect from the nanotubes. Mode locking is achieved with less than 30% of the CNTs compared with the amount of nanotubes used for conventional schemes. Our method also ensures the preservation of the original morphology of the individual CNTs. The demonstrated pulsed laser with our CNT mode locker has a repetition rate of 5.88 MHz and a temporal pulse width of 470 fs.
239 citations
TL;DR: Single-walled carbon nanotubes have a fast saturable absorption over a broad wavelength range, and the demonstrated technique is an extremely simple and inexpensive method for making fiber-integrated, saturable absorbers for passive modelocking of fiber lasers.
Abstract: Optical radiation propagating in a fiber is used to deposit commercially available, single-walled carbon nanotubes on cleaved optical fiber end faces and fiber connectors. Thermophoresis caused by heating due to optical absorption is considered to be a likely candidate responsible for the deposition process. Single-walled carbon nanotubes have a fast saturable absorption over a broad wavelength range, and the demonstrated technique is an extremely simple and inexpensive method for making fiber-integrated, saturable absorbers for passive modelocking of fiber lasers. Pulse widths of 247 fs are demonstrated from an erbium-doped fiber laser operating at 1560 nm, and 137 fs pulses are demonstrated from an amplified Yb-doped fiber laser at 1070 nm.
231 citations
TL;DR: In this article, the challenges, achievements, and perspectives of high-power continuous-wave (CW) laser generation and amplification in fibers are reviewed, as well as their inherent compactness, monolithic architecture, and a power independent beam quality.
Abstract: The first rare-earth-doped fiber lasers were operated in the early 1960s, and produced a few milliwatts at a wavelength around 1 mum. Since the beginning of the decade, an enormous increase of fiber laser output power has been reported, the realm of kilowatt power has been entered, and power levels as high as 100 kW are envisaged. Apart from the power, fiber laser systems are renowned for their inherent compactness, monolithic architecture, and a power-independent beam quality. This paper reviews the challenges, achievements, and perspectives of high-power continuous-wave (CW) laser generation and amplification in fibers.
TL;DR: Values indicate that the tunable near-infrared input component is downconverted with a quantum efficiency that exceeds 30%.
Abstract: We report single-pass difference-frequency generation of mid-infrared femtosecond pulses tunable in the 3.2-4.8 μm range from a two-branch mode-locked erbium-doped fiber source. Average power levels of up to 1.1 mW at a repetition rate of 82 MHz are obtained in the mid infrared. This is achieved via nonlinear mixing of 170 mW, 65 fs pump pulses at a fixed wavelength of 1.58 μm, with 11.5 mW, 40 fs pulses tunable in the near-infrared range between 1.05 and 1.18 μm. These values indicate that the tunable near-infrared input component is downconverted with a quantum efficiency that exceeds 30%.
TL;DR: In this article, the authors demonstrate good beam quality from the combination of three fiber amplifiers, and discuss system scaling and design trades between laser linewidth, beam width, grating dispersion, and beam quality.
Abstract: Fiber lasers are well suited to scaling to high average power using beam-combining techniques. For coherent combining, optical phase-noise characterization of a ytterbium fiber amplifier is required to perform a critical evaluation of various approaches to coherent combining. For wavelength beam combining, we demonstrate good beam quality from the combination of three fiber amplifiers, and we discuss system scaling and design trades between laser linewidth, beam width, grating dispersion, and beam quality.
TL;DR: In this article, the authors present a self-consistent theory based on wave kinetic equations that describes the generation spectrum and output power of a Raman fiber laser (RFL), and show that the quasi-degenerate four-wave mixing between different longitudinal modes is the main broadening mechanism in the one-stage RFL at high powers.
Abstract: We present a detailed analytical self-consistent theory based on wave kinetic equations that describes generation spectrum and output power of a Raman fiber laser (RFL). It is shown both theoretically and experimentally that the quasi-degenerate four-wave mixing (FWM) between different longitudinal modes is the main broadening mechanism in the one-stage RFL at high powers. The shape and power dependence of the intracavity Stokes wave spectrum are in excellent quantitative agreement with predictions of the theory. FWM-induced stochasticity of the amplitude and the phase of each of the ∼106 longitudinal modes generated in the RFL cavity is an example of a light-wave turbulence in a fiber.
TL;DR: In this paper, the authors reported >9W transverse-fundamental-mode CW output near 3 μm from a 4m heavily erbium-doped ZBLAN double-clad fiber laser pumped by a collimated 100 W 975 nm laser diode array.
Abstract: We report on >9W transverse-fundamental-mode CW output near 3 μm from a 4m heavily erbium-doped ZBLAN double-clad fiber laser pumped by a collimated 100 W 975 nm laser diode array. The pump threshold of the fiber laser was about 1W, and the slope efficiency was 21.3%. The peak wavelength of free running was about 2708 nm at low pump power and moved to around 2785 nm at high pump power. Output of 9W was obtained when the launched pump power was 42.8W. The output, however, fluctuated intensively like a pulsed laser, and the operation broke down with optical damage of the pumping end facet when the pump was increased beyond 42.8 W. Therefore, alleviation of the operation fluctuation, heat management, and strengthening the pumping fiber are crucial considerations for the stable operation of 10-W-level mid-IR ZBLAN fiber lasers.
TL;DR: In this paper, a leakage channel fiber is designed to create large leakage loss for higher-order modes, while maintaining negligible transmission loss for the fundamental mode, which can be used for designing optical fibers with large effective area, which supports robust fundamental mode propagation.
Abstract: Leakage channel fibers, where few air holes form a core, can be precisely engineered to create large leakage loss for higher-order modes, while maintaining negligible transmission loss for the fundamental mode. This unique property can be used for designing optical fibers with large effective area, which supports robust fundamental mode propagation. The large air holes in the design also enable the optical fibers to be bend resistant. The principles of design and operation regime are outlined, demonstrating the potential of this approach for optical fibers that propagate a fundamental mode in core diameter exceeding 100 μm. Performance of a fabricated passive leakage channel fiber, an ytterbium-doped double-clad leakage channel fiber, and an ytterbium-doped polarization-maintaining double-clad leakage channel fiber are also discussed.
TL;DR: A 64 W fiber laser at 1.9 microm with a slope efficiency of 68% with respect to the launching pump power at 800 nm was demonstrated in a one-end pump configuration using a piece of 20 cm long newly developed thulium-doped germanate glass double-cladding single-mode fiber.
Abstract: A 64 W fiber laser at 1.9 μm with a slope efficiency of 68% with respect to the launching pump power at 800 nm was demonstrated in a one-end pump configuration using a piece of 20 cm long newly developed thulium-doped germanate glass double-cladding single-mode fiber. A quantum efficiency of 1.8 was achieved. An output laser power of 104 W at 1.9 μm was demonstrated from a piece of 40 cm long fiber with a dual-end pump configuration.
TL;DR: In this paper, a high power and high efficiency erbium:ytterbium (Er:Yb) codoped fiber laser was demonstrated, which produces 297 W of continuous-wave output at 1567 nm.
Abstract: We have demonstrated a high-power and high-efficiency erbium:ytterbium (Er:Yb) codoped fiber laser that produces 297 W of continuous-wave output at 1567 nm. The slope efficiency with respect to the launched pump power changed from 40% to 19% at higher output power due to the onset of Yb colasing at 1067 nm. However, the Yb colasing was essential for the suppression of catastrophic pulsation at high pump powers that otherwise results if the Yb-band gain is allowed to build up. Spectroscopic characteristics of the fiber and the impact of the Yb colasing on the 1567-nm slope efficiency are also discussed.
TL;DR: In this article, the authors proposed and demonstrated a new and efficient approach to generate a CW SC in optical fibers pumped by a CW ASE light, achieving a spectral bandwidth of over 1000nm.
Abstract: In this paper, we studied SC generation in fiber lasers and in optical fibers pumped by different
light sources which include fs and ps pulse sources, and continuous-wave (CW) amplified spontaneous
emission (ASE) light sources. First, we demonstrated SC generation with a 10dB spectral bandwidth of
430nm in a fiber ring laser with conventional nonlinear fiber. Second, we proposed and demonstrated a
new and efficient approach to generation of a CW SC in optical fibers pumped by a CW ASE light. A
bandwidth of 268nm (at -15dB level) with an average spectral density of 2.7mW/nm was
demonstrated. Various approaches to flattening the spectrum and increasing the spectral width were
also studied. The application of this SC source in WDM passive optical access networks (WDM-PONs)
was investigated. Third, the approach of SC generation in a fiber combination of standard SMF
and nonlinear DSF pumped by an all-fiber fs pulse Master Oscillator Power Amplifier (MOPA) system
was developed. A spectral bandwidth of over 1000nm was demonstrated. Finally, the generation of
broad comb-like-spectral light based on the pulse compression of 40GHz optical pulses in a new
nonlinear dispersion-decreasing fiber with high SBS threshold was studied. A continuum light source
with over 125 channels and a channel spacing of 40 GHz was achieved. The use of this continuum light
source as WDM source in WDM-PONs was investigated.
TL;DR: In this paper, an approach to generating and distributing ultrawideband (UWB) pulses based on optical spectral shaping and frequency-to-time conversion using all-fiber components is proposed and demonstrated.
Abstract: An approach to generating and distributing ultrawideband (UWB) pulses based on optical spectral shaping and frequency-to-time conversion using all-fiber components is proposed and demonstrated. In the system, the spectrum of an ultrashort pulse from a mode-locked fiber laser is spectrally shaped by an all-fiber spectrum shaper, to produce a monocycle- or a doublet-shaped power spectrum. Thanks to the frequency-to-time conversion in a dispersive fiber, time-domain optical pulses exhibiting the user-defined shape of the optical power spectrum are obtained. Experiments based on the proposed approach are carried out. UWB monocycle or doublet pulses are generated
Patent•
29 Jun 2007
TL;DR: In this article, rare earth doped glass compositions that may be used in optical fiber and rods having large core sizes are described, where the index of refraction of the glass may be substantially uniform and may be close to that of silica.
Abstract: Various embodiments described herein include rare earth doped glass compositions that may be used in optical fiber and rods having large core sizes. Such optical fibers and rods may be employed in fiber lasers and amplifiers. The index of refraction of the glass may be substantially uniform and may be close to that of silica in some embodiments. Possible advantages to such features include reduction of formation of additional waveguides within the core, which becomes increasingly a problem with larger core sizes.
TL;DR: Using a simple model, it is demonstrated that two- and three-photon absorption strongly limit the THz generation efficiency at high pump fluences in ZnTe and GaP.
Abstract: We demonstrate efficient generation of THz pulses by optical rectification of 1.03 um wavelength laser pulses in LiNbO3 using tilted pulse front excitation for velocity matching between the optical and THz fields. Pulse energies of 100 nJ with a spectral bandwidth of up to 2.5 THz were obtained at a pump energy of 400 uJ and 300 fs pulse duration. This conversion efficiency of 2.5×10-4 was an order of magnitude higher than that obtained with collinear optical recitification in GaP, and far higher still than that measured using ZnTe in an optimized geometry. Using a simple model we demonstrate that two- and three-photon absorption strongly limit the THz generation efficiency at high pump fluences in ZnTe and GaP respectively.
TL;DR: In this article, the authors consider the main factors determining the oscillation spectral range of cladding-pumped ytterbium-doped fiber lasers and the results obtained for lasers emitting at various wavelengths.
Abstract: In this brief review we consider the main factors determining the oscillation spectral range of cladding-pumped ytterbium-doped fiber lasers (YDFLs) and the results obtained for lasers emitting at various wavelengths. Like erbium-doped fiber amplifiers we suggest dividing the oscillation spectral range of YDFLs into three bands, namely: convenient (C-band), short (S-band), and long (L-band). Polymer-coated double-clad fibers with the inner cladding having a size of more than 100 μm allows one to get efficient operation in the convenient range (C-band): 1060 - 1130 nm. To get an oscillation within the S-band (976 - 980 nm and 1020 - 1060 nm) it is necessary to use active fibers with a small square of the inner cladding. Heating of the active fiber gives the possibility to get lasing within the L-band λ > 1130 nm). Another way to get an emission in this spectral range is by the application of long-wave pumping by a C-band YDFL. Also, we indicate some features that require further study.
TL;DR: In this paper, an all-fiber bismuth-doped laser with laser emission that can be chosen with corresponding fiber Bragg gratings between at least 1150 and 1225 nm is presented.
Abstract: In the present letter the authors report on the realization of an all-fiber bismuth-doped laser with laser emission that can be chosen with corresponding fiber Bragg gratings between at least 1150 and 1225 nm . In their experiments they achieved a slope efficiency of about 24% at 1200 nm , which is the highest reported for this kind of laser.
TL;DR: In this paper, a femtosecond pulse source that uses a mode-locked Tm-Ho oscillator and a self-frequency shift of Raman solitons in TmHo power amplifier is presented.
Abstract: We report a femtosecond pulse source that uses a mode-locked Tm-Ho oscillator and a self-frequency shift of Raman solitons in Tm-Ho power amplifier. The master oscillator mode-locked by an antimonide-based saturable absorber mirror produces 750-fs transform-limited soliton pulses over the tuning range from 1912 to 1972 nm. The soliton self-frequency shift in the amplifier resulted in transform-limited pulses with the wavelength adjusted by varying the amplifier pump power. We obtain ~150-fs soliton pulses at the wavelength of 2150 nm with average power up to 230 mW corresponding to the peak power of 27 kW. The efficiency of Raman conversion ranges from 47% to 62% over the tuning range
TL;DR: This work reports what it believes to be the first demonstration of stable short pulse (10 ns) generation from a gain-switched Tm-doped fiber laser in the 2 microm spectral region.
Abstract: We report what we believe to be the first demonstration of stable short pulse (10 ns) generation from a gain-switched Tm-doped fiber laser in the 2 μm spectral region. A modulated 1.55 μm pump laser was used for fast gain switching to regulate the conventionally chaotic spiking in the gain-switched fiber laser. From a 6.3 μm core all-fiber oscillator, over a kilowatt of peak power was obtained at the slope efficiency of 50% and freely varying repetition rate up to 500 kHz.
TL;DR: A model based on propagation-rate equations with consideration of transverse gain distribution is built up and individual transverse modes power distributions of output are simulated numerically for both fiber lasers and amplifiers under various conditions.
Abstract: A model based on propagation-rate equations with consideration of transverse gain distribution is built up to describe the transverse mode competition in strongly pumped multimode fiber lasers and amplifiers. An approximate practical numerical algorithm by multilayer method is presented. Based on the model and the numerical algorithm, the behaviors of multitransverse mode competition are demonstrated and individual transverse modes power distributions of output are simulated numerically for both fiber lasers and amplifiers under various conditions.
TL;DR: It is shown numerically that the noise-like pulse emission is caused by the peak power clamping effect of the laser cavity on the gain-guided soliton.
Abstract: We report on the operation of a passively mode-locked fiber ring laser made of purely positive dispersion fibers and mode-locked by using the nonlinear polarization rotation technique. It was experimentally found that apart from the gain-guided soliton operation the laser can also emit a kind of noise-like pulse. We show numerically that the noise-like pulse emission is caused by the peak power clamping effect of the laser cavity on the gain-guided soliton.
TL;DR: In this article, the authors present the recent results of their highly efficient directly diode-pumped Tm3+doped silica and Ho3+-doped fiber lasers.
Abstract: We review our recent work in high-power 2-mum fiber laser development, and present the recent results of our highly efficient directly diode-pumped Tm3+-doped silica and Ho3+-doped silica fiber lasers. We quantify the values of the dopant concentrations in the fibers used to construct the 2-mum fiber lasers, and present a more comprehensive assessment of fiber laser performance against dopant concentration.