Showing papers on "Fiber laser published in 2012"
TL;DR: This result indicates that like the atomic layer graphene, the topological insulator Bi2Se3 could also operate as an effective saturable absorber for the passive mode locking of lasers at the telecommunication band.
Abstract: Based on the open-aperture Z-scan measurement, we firstly uncovered the saturable absorption property of the topological insulator (TI): Bi2Se3. A high absolute modulation depth up to 98% and a saturation intensity of 0.49 GWcm−2 were identified. By incorporating this novel saturable absorber material into an erbium-doped fiber laser, wavelength tunable soliton operation was experimentally demonstrated. Our result indicates that like the atomic layer graphene, the topological insulator Bi2Se3 could also operate as an effective saturable absorber for the passive mode locking of lasers at the telecommunication band.
406 citations
TL;DR: In this paper, the authors demonstrate comprehensive studies on graphene oxide and reduced graphene oxide (rGO) based saturable absorbers (SA) for mode-locking of Er-doped fiber lasers.
Abstract: In this work we demonstrate comprehensive studies on graphene oxide (GO) and reduced graphene oxide (rGO) based saturable absorbers (SA) for mode-locking of Er-doped fiber lasers. The paper describes the fabrication process of both saturable absorbers and detailed comparison of their parameters. Our results show, that there is no significant difference in the laser performance between the investigated SA. Both provided stable, mode-locked operation with sub-400 fs soliton pulses and more than 9 nm optical bandwidth at 1560 nm center wavelength. It has been shown that GO might be successfully used as an efficient SA without the need of its reduction to rGO. Taking into account simpler manufacturing technology and the possibility of mass production, GO seems to be a good candidate as a cost-effective material for saturable absorbers for Er-doped fiber lasers.
377 citations
TL;DR: It has been shown that GO might be successfully used as an efficient SA without the need of its reduction to rGO, and seems to be a good candidate as a cost-effective material for saturable absorbers for Er-doped fiber lasers.
Abstract: In this work we demonstrate comprehensive studies on graphene oxide (GO) and reduced graphene oxide (rGO) based saturable absorbers (SA) for mode-locking of Er-doped fiber lasers. The paper describes the fabrication process of both saturable absorbers and detailed comparison of their parameters. Our results show, that there is no significant difference in the laser performance between the investigated SA. Both provided stable, mode-locked operation with sub-400 fs soliton pulses and more than 9 nm optical bandwidth at 1560 nm center wavelength. It has been shown that GO might be successfully used as an efficient SA without the need of its reduction to rGO. Taking into account simpler manufacturing technology and the possibility of mass production, GO seems to be a good candidate as a cost-effective material for saturable absorbers for Er-doped fiber lasers.
359 citations
TL;DR: Rare events of extremely high optical intensity are experimentally recorded at the output of a mode-locked fiber laser that operates in a strongly dissipative regime of chaotic multiple-pulse generation.
Abstract: Rare events of extremely high optical intensity are experimentally recorded at the output of a mode-locked fiber laser that operates in a strongly dissipative regime of chaotic multiple-pulse generation. The probability distribution of these intensity fluctuations, which highly depend on the cavity parameters, features a long-tailed distribution. Recorded intensity fluctuations result from the ceaseless relative motion and nonlinear interaction of pulses within a temporally localized multisoliton phase.
359 citations
TL;DR: The extension of broadband degenerate OPO operation further into mid-infrared by synchronously pumps a 500-μm-long crystal of orientation patterned GaAs providing broadband gain centered at 4.1 µm is reported.
Abstract: We report the extension of broadband degenerate OPO operation further into mid-infrared. A femtosecond thulium fiber laser with output centered at 2050 nm synchronously pumps a 500-μm-long crystal of orientation patterned GaAs providing broadband gain centered at 4.1 µm. We observe a pump threshold of 17 mW and output bandwidth extending from 2.6 to 6.1 µm at the −30 dB level. Average output power was 37 mW. Appropriate resonator group dispersion is a key factor for achieving degenerate operation with instantaneously broad bandwidth. The output spectrum is very sensitive to absorption and dispersion introduced by molecular species inside the OPO cavity.
277 citations
TL;DR: Limpert et al. as mentioned in this paper used a large-pitch photonic-crystal fiber doped with ytterbium to provide gain and achieved state-of-the-art performance.
Abstract: Rare earth-doped fibres are a diode-pumped, solid-state laser architecture that is highly scalable in average power. The performance of pulsed fibre laser systems is restricted due to nonlinear effects. Hence, fibre designs that allow for very large mode areas at high average powers with diffraction-limited beam quality are of enormous interest. Ytterbium-doped, rod-type, large-pitch fibres (LPF) enable extreme fibre dimensions, i.e., effective single-mode fibres with mode sizes exceeding 100 times the wavelength of the guided radiation, by exploiting the novel concept of delocalisation of higher-order transverse modes. The non-resonant nature of the operating principle makes LPF suitable for high power extraction. This design allows for an unparalleled level of performance in pulsed fibre lasers. A new design of optical fibre could allow fibre lasers to reach unprecedented output powers while maintaining excellent beam quality. The design, developed by Jens Limpert and co-workers from Friedrich-Schiller Universitat, Helmholtz Institute Jena and Fraunhofer Institute for Applied Optics and Precision Engineering in Jena, Germany, uses a large-pitch photonic-crystal fibre doped with ytterbium to provide gain. The key to the fibre's performance is the delocalisation of higher order modes due to the transversal arrangement of air-holes. The concept ensures that the fibre operates with a large fundamental mode that has a high-quality beam profile and good power handling characteristics, while suppressing unwanted higher order modes. A pulsed fibre laser based on this design emitted diffraction-limited pulses containing 26 mJ of energy with an average power of 130 W.
275 citations
TL;DR: In this paper, the luminescent properties and light-emitting mechanisms of bismuth-doped fibres and the progress made towards constructing lasers and amplifiers from such fibers are reviewed.
Abstract: Optical fibers with the bismuth show promise for developing efficient fiber lasers and amplifiers in extended bands of near IR region, in particular, through a whole spectral range of 1150–1550 nm. Devices capable of operating in this region are required for applications in advanced optical communications, medicine and astrophysics, among others. In this paper, Evgeny Dianov from the Fiber Optics Research Center of the Russian Academy of Sciences in Moscow reviews the luminescent properties and light-emitting mechanisms of bismuth-doped fibres and the progress made towards constructing lasers and amplifiers from such fibers. In particular, the author describes a laser emitting at 1460 nm with a conversion efficiency of 50%, and an amplifier with a peak gain of 24 dB at 1427 nm, a 3 dB bandwidth of 36 nm and a noise figure of 6 dB.
271 citations
TL;DR: In this article, the authors demonstrate mode-locking of a thulium-doped fiber laser operating at 1.94 μm, using a graphene-polymer based saturable absorber.
Abstract: We demonstrate mode-locking of a thulium-doped fiber laser operating at 1.94 μm, using a graphene-polymer based saturable absorber. The laser outputs 3.6 ps pulses, with ~0.4 nJ energy and an amplitude fluctuation ~0.5%, at 6.46 MHz. This is a simple, low-cost, stable and convenient laser oscillator for applications where eye-safe and low-photon-energy light sources are required, such as sensing and biomedical diagnostics.
259 citations
TL;DR: In this paper, the relationship between the laser process conditions and the dimensions and quality of the seam was investigated by means of optical and phase-contrast microscopy, which revealed a tensile strength of greater than 80% of the bulk material strength.
Abstract: Absorber-free transmission and butt-welding of different polymers were performed using thulium fiber laser radiation at the wavelength 2 μm. The relations between the laser process conditions and the dimensions and quality of the seam were investigated by means of optical and phase-contrast microscopy. Mechanical properties of the weld joints were studied in tensile strength tests. Laser-welded polyethylene samples revealed a tensile strength of greater than 80% of the bulk material strength. Transmission welding of different polymer combinations featured the formation of different joint classes depending on the spectral properties. The experiments demonstrate new application areas of mid-IR fiber laser sources for materials processing.
256 citations
TL;DR: This work demonstrates mode-locking of a thulium-doped fiber laser operating at 1.94 μm, using a graphene-polymer based saturable absorber, which is a simple, low-cost, stable and convenient laser oscillator for applications where eye-safe and low-photon-energy light sources are required.
Abstract: We demonstrate mode-locking of a thulium-doped fiber laser operating at 1.94\mu m, using a graphene-based saturable absorber. The laser outputs 3.6ps pulses, with~0.4nJ energy and an amplitude fluctuation~0.5%, at 6.46MHz. This is a simple, low-cost, stable and convenient laser oscillator for applications where eye-safe and low-photon-energy light sources are required, such as sensing and biomedical diagnostics
250 citations
TL;DR: A fiber in-line Fabry-Perot interferometer cavity sensor for refractive index measurement is demonstrated, simple in configuration, easy for fabrication and reliable in operation due to extremely low temperature cross sensitivity.
Abstract: We demonstrate a fiber in-line Fabry-Perot interferometer cavity sensor for refractive index measurement. The interferometer cavity is formed by drilling a micro-hole at the cleaved fiber end facet, followed by fusion splicing. A micro-channel is inscribed by femtosecond laser micromachining to vertically cross the cavity to allow liquid to flow in. The refractive index sensitivity obtained is ~994 nm/RIU (refractive index unit). Such a device is simple in configuration, easy for fabrication and reliable in operation due to extremely low temperature cross sensitivity of ~4.8 × 10−6 RIU/°C.
TL;DR: Graphene is indeed a broadband saturable absorber that can operate at both microwave and optical band, report on the first experiments on saturable absorption in graphene at microwave frequency band.
Abstract: We report on the first experiments on saturable absorption in graphene at microwave frequency band. Almost independent of the incident frequency, microwave absorbance of graphene always decreases with increasing the power and reaches at a constant level for power larger than 80 µW, evidencing the microwave saturable absorption property of graphene. Optical saturable absorption of the same graphene sample was also experimentally confirmed by an open-aperture Z-scan technique by one laser at telecommunication band and another pico-second laser at 1053 nm, respectively. Herein, we are able to conclude that graphene is indeed a broadband saturable absorber that can operate at both microwave and optical band.
TL;DR: It is proposed that non-adiabatic waveguide changes play an important role in allowing energy transfer from the fundamental mode into the higher order mode, and this description of mode instabilities can explain many of the experimental observations reported to date.
Abstract: Mode instabilities, ie the rapid fluctuations of the output beam of an optical fiber that occur after a certain output power threshold is reached, have quickly become one of the most limiting effects for the further power scaling of fiber laser systems Even though much work has been done over the last year, the exact origin of the temporal dynamics of this phenomenon is not fully understood yet In this paper we show that the origin of mode instabilities can be explained by taking into account the interplay between the temporal evolution of the three-dimensional temperature profile inside of the active fiber and the related waveguide changes that it produces via the thermo-optical effect In particular it is proposed that non-adiabatic waveguide changes play an important role in allowing energy transfer from the fundamental mode into the higher order mode As it is discussed in the paper, this description of mode instabilities can explain many of the experimental observations reported to date
TL;DR: A study of laser mode pulling by the Brillouin optical gain spectrum is presented, and high-order, cascaded operation of the SBL is demonstrated, and potential application of these devices to microwave sources and phase-coherent communication is discussed.
Abstract: Recently, a high efficiency, narrow-linewidth, chip-based stimulated Brillouin laser (SBL) was demonstrated using an ultra-high-Q, silica-on-silicon resonator. In this work, this novel laser is more fully characterized. The Schawlow Townes linewidth formula for Brillouin laser operation is derived and compared to linewidth data, and the fitting is used to measure the mechanical thermal quanta contribution to the Brillouin laser linewidth. A study of laser mode pulling by the Brillouin optical gain spectrum is also presented, and high-order, cascaded operation of the SBL is demonstrated. Potential application of these devices to microwave sources and phase-coherent communication is discussed.
TL;DR: The femtosecond erbium-doped all-fiber lasers mode-locked with graphene oxide demonstrated are comparable with those of graphene saturable absorbers and the superiority of easy fabrication and hydrophilic property of graphene oxide will facilitate its potential applications for ultrafast photonics.
Abstract: We demonstrated the femtosecond erbium-doped all-fiber lasers mode-locked with graphene oxide, which can be conveniently obtained from natural graphite by simple oxidation and ultra-sonication process. With proper dispersion management in an all-fiber ring cavity, the laser directly generated 200 fs pulses at a repetition rate of 22.9 MHz and the average output power was 5.8 mW. With the variation of net cavity dispersion, output pulses with pulse width of 0.2~3 ps were obtained at a repetition rate of 22.9~0.93 MHz. These results are comparable with those of graphene saturable absorbers and the superiority of easy fabrication and hydrophilic property of graphene oxide will facilitate its potential applications for ultrafast photonics.
TL;DR: In this paper, a switchable dual-wavelength synchronously pulsed fiber laser Q-switched by graphene saturable absorber was demonstrated, and it was shown that the two pulses at each individual wavelength can be temporally synchronized with per-pulse energy up to ~ 70 nJ.
Abstract: We demonstrate a switchable dual-wavelength synchronously pulsed fiber laser Q-switched by graphene saturable absorber. Wavelength-resolved studies on the output Q-switched pulses show that despite of large wavelength spacing up to 26 nm, the two Q-switched pulses at each individual wavelength can be temporally synchronized with per-pulse energy up to ~ 70 nJ. Further experiments show that by adjusting the intracavity birefringence, dual-wavelength emission can be switched to another dual-wavelength operation regime with wavelength separation of 5.7 nm. Our experimental results are also qualitatively supported by the cavity linear transmission characteristics of the ring cavity.
TL;DR: It is demonstrated that the atomic-layer structure of graphene from CVD process may provide a reliable graphene based SA for stable soliton-like pulse formation of the MLFL.
Abstract: A stable mode-locked fiber laser (MLFL) employing multi-layer graphene as saturable absorber (SA) is presented. The multi-layer graphene were grown by chemical vapor deposition (CVD) on Ni close to A-A stacking. Linear absorbance spectrum of multi-layer graphene was observed without absorption peak from 400 to 2000 nm. Optical nonlinearities of different atomic-layers (7-, 11-, 14-, and 21- layers) graphene based SA are investigated and compared. The results found that the thicker 21-layer graphene based SA exhibited a smaller modulation depth (MD) value of 2.93% due to more available density of states in the band structure of multi-layer graphene and favored SA nonlinearity. A stable MLFL of 21-layer graphene based SA showed a pulsewidth of 432.47 fs, a bandwidth of 6.16 nm, and a time-bandwidth product (TBP) of 0.323 at fundamental soliton-like operation. This study demonstrates that the atomic-layer structure of graphene from CVD process may provide a reliable graphene based SA for stable soliton-like pulse formation of the MLFL.
TL;DR: It is demonstrated that high-energy pulses can be realized in anomalous-dispersion regime, and may be explained as dissipative soliton resonance.
Abstract: We have experimentally observed conventional solitons and rectangular pulses in an erbium-doped fiber laser operating at anomalous dispersion regime. The rectangular pulses exhibit broad quasi-Gaussian spectra (~40 nm) and triangular autocorrelation traces. With the enhancement of pump power, the duration and energy of the output rectangular pulses almost increase linearly up to 330 ps and 3.2 nJ, respectively. It is demonstrated that high-energy pulses can be realized in anomalous-dispersion regime, and may be explained as dissipative soliton resonance. Our results have confirmed that the formation of dissipative soliton resonance is not sensitive to the sign of cavity dispersion.
TL;DR: The novel concept of utilizing the RFL to achieve long-distance fiber-optic remote sensing, in which the R FL offers high-fidelity and long- distance transmission for the sensing signal, is proposed.
Abstract: We find that the random fiber laser (RFL) without point-reflectors is a temperature-insensitive distributed lasing system for the first time. Inspired by such thermal stability, we propose the novel concept of utilizing the RFL to achieve long-distance fiber-optic remote sensing, in which the RFL offers high-fidelity and long-distance transmission for the sensing signal. Two 100km fiber Bragg grating (FBG) point-sensing schemes based on RFLs are experimentally demonstrated using the first-order and the second-order random lasing, respectively, to verify the concept. Each sensing scheme can achieve >20dB optical signal-to-noise ratio (OSNR) over 100km distance. It is found that the second-order random lasing scheme has much better OSNR than that of the first-order random lasing scheme due to enhanced lasing efficiency, by incorporating a 1455nm FBG into the lasing cavity.
TL;DR: A robust laser design employing all normal dispersion polarisation maintaining fibres operating at 1 μm, mode-locked using a nonlinear amplifying fibre loop mirror that provides an additional degree of freedom allowing easy control over the pulse parameters.
Abstract: We report on a new design for a passively mode locked fibre laser employing all normal dispersion polarisation maintaining fibres operating at 1 μm The laser produces linearly polarized, linearly chirped pulses that can be recompressed down to 344 fs Compared to previous laser designs the cavity is mode-locked using a nonlinear amplifying fibre loop mirror that provides an additional degree of freedom allowing easy control over the pulse parameters This is a robust laser design with excellent reliability and lifetime
TL;DR: It is experimentally demonstrated a passively mode-locked femtosecond laser by using a graphene-based saturable absorber mirror (graphene SAM) in the spectral region of 2 μm.
Abstract: We experimentally demonstrated a passively mode-locked femtosecond laser by using a graphene-based saturable absorber mirror (graphene SAM) in the spectral region of 2 μm. The graphene SAM was fabricated by transferring chemical-vapor-deposited, high-quality, and large-area graphene on a highly reflective plane mirror. Stable mode-locked laser pulses as short as 729 fs were obtained with a repetition rate of 98.7 MHz and an average output power of 60.2 mW at 2018 nm.
TL;DR: A novel mode locked ultrafast laser, based on an integrated high-Q microring resonator, exhibits stable operation of two slightly shifted spectral optical comb replicas, and generates a highly monochromatic radiofrequency modulation on a 200GHz output pulse train.
Abstract: We demonstrate a novel mode locked ultrafast laser, based on an integrated high-Q microring resonator. Our scheme exhibits stable operation of two slightly shifted spectral optical comb replicas. It generates a highly monochromatic radiofrequency modulation of 65.8MHz with a linewidth < 10kHz, on a 200GHz output pulse train.
TL;DR: In this paper, an erbium-doped fiber laser with atomic multilayer graphene was used to operate at several harmonics (from 2nd to 21st) of the fundamental repetition frequency of the ring resonator.
Abstract: Passive harmonic-mode locking of erbium-doped fiber laser with atomic multilayer graphene is presented. The laser could operate at several harmonics (from 2nd to 21st) of the fundamental repetition frequency of the ring resonator (106 MHz). The highest achieved repetition rate was 2.22 GHz (which corresponds to the 21st harmonic) with sub-picosecond pulse durations and over 40 dB of the supermode noise suppression. The saturable absorber was formed by multilayer graphene, mechanically exfoliated from pure graphite block through Scotch-tape and deposited on the fiber ferrule.
TL;DR: The features that distinguish each new mode-locking state are described and how the interplay of basic processes in the fiber produces the balance of amplitude and phase evolutions needed for stable high-energy pulses is explained.
Abstract: Fiber lasers mode locked with large normal group-velocity dispersion have recently achieved femtosecond pulse durations with energies and peak powers at least an order of magnitude greater than those of prior approaches. Several new mode-locking regimes have been demonstrated, including self-similar pulse propagation in passive and active fibers, dissipative solitons, and a pulse evolution that avoids wave breaking at high peak power but has not been reproduced by theoretical treatment. Here, we illustrate the main features of these new pulse-shaping mechanisms through the results of numerical simulations that agree with experimental results. We describe the features that distinguish each new mode-locking state and explain how the interplay of basic processes in the fiber produces the balance of amplitude and phase evolutions needed for stable high-energy pulses. Dissipative processes such as spectral filtering play a major role in normal-dispersion mode locking. Understanding the different mechanisms allows us to compare and contrast them, as well as to categorize them to some extent.
TL;DR: A low-threshold single-wavelength all-fiber laser generating cylindrical vector beams using a few-mode fiber Bragg grating with very good modal symmetry and polarization purity higher than 94%.
Abstract: We propose and demonstrate a low-threshold single-wavelength all-fiber laser generating cylindrical vector beams using a few-mode fiber Bragg grating. Both radially and azimuthally polarized beams have been generated with very good modal symmetry and polarization purity higher than 94%. The radially and azimuthally polarized modes can be switched by simply adjusting the polarization controllers built in the fiber laser cavity. This fiber laser operates at a single wavelength of 1053 nm with a 3 dB linewidth of less than 0.02 nm, signal-to-background ratio of more than 55 dB, and a threshold as low as 16 mW. A new method for the polarization purity measurement is also proposed.
TL;DR: An electro-optic modulator that integrates single-layer graphene in a sub-wavelength thick, reflective modulator structure is reported on, offering solutions to a variety of high-speed amplitude modulation tasks that require optical amplitude modulation without phase distortions, a flat frequency response, or ultra-thin geometries.
Abstract: Graphene’s featureless optical absorption, ultrahigh carrier mobility, and variable optical absorption by an applied gate voltage enable a new breed of optical modulators with broad optical and electrical bandwidths. Here we report on an electro-optic modulator that integrates single-layer graphene in a sub-wavelength thick, reflective modulator structure. These modulators provide a large degree of design freedom, which allows tailoring of their optical properties to specific needs. Current devices feature an active aperture ~100 µm, and provide uniform modulation with flat frequency response from 1 Hz to >100 MHz. These novel, low insertion-loss graphene-based modulators offer solutions to a variety of high-speed amplitude modulation tasks that require optical amplitude modulation without phase distortions, a flat frequency response, or ultra-thin geometries, such as for controlling monolithic, high-repetition rate mode-locked lasers or active interferometers.
TL;DR: In this paper, optical fibres heavily doped with alumina are shown to exhibit an exceptionally low Brillouin gain coefficient and an athermal frequency response, which could prove useful for applications that employ fibre sensing or require high-power fibre laser systems.
Abstract: Optical fibres heavily doped with alumina are shown to exhibit an exceptionally low Brillouin gain coefficient and an athermal Brillouin frequency response. Such fibres could prove useful for applications that employ fibre sensing or require high-power fibre laser systems.
TL;DR: Synchronizing an 8.06 GHz microwave signal from a voltage-controlled oscillator with an optical pulse train from a 77.5 MHz mode-locked Er-fiber laser using a fiber-based optical-microwave phase detector has a potential to provide both subfemtosecond-level short-term phase noise and long- term phase stability in microwave extraction from mode-lock fiber lasers.
Abstract: We synchronize an 8.06 GHz microwave signal from a voltage-controlled oscillator with an optical pulse train from a 77.5 MHz mode-locked Er-fiber laser using a fiber-based optical-microwave phase detector. The residual phase noise between the optical pulse train and the synchronized microwave signal is -133 dBc/Hz (-154 dBc/Hz) at 1 Hz (5 kHz) offset frequency, which results in 838 as integrated rms timing jitter [1 Hz-1 MHz]. The long-term residual phase drift is 847 as (rms) measured over 2 h, which reaches 4×10(-19) fractional frequency instability at 1800 s averaging time. This method has a potential to provide both subfemtosecond-level short-term phase noise and long-term phase stability in microwave extraction from mode-locked fiber lasers.
TL;DR: In this paper, a wide-band tunable passively Q-switched fiber laser was demonstrated using a graphene-based saturable absorber (SA), which was prepared through the optically driven deposition method.
Abstract: We demonstrated a wide-band tunable passively Q-switched fiber laser by using a graphene-based saturable absorber (SA). The graphene SA was prepared through the optically driven deposition method. The Q-switched operation was initiated with a low pump threshold of about 33 mW. The wavelength tunable operation was obtained with a narrow bandwidth tunable filter. Experimentally, the stable Q-switched pulse with a tunable range from 1519.3 to 1569.9 nm was achieved, covering a wavelength range of over 50.6 nm.
TL;DR: It is shown experimentally and numerically new transient lasing regime between stable single-pulse generation and noise-like generation and spectral and temporal features of pulses produced in all three regimes as well as compressibility of such pulses.
Abstract: We show experimentally and numerically new transient lasing regime between stable single-pulse generation and noise-like generation. We characterize qualitatively all three regimes of single pulse generation per round-trip of all-normal-dispersion fiber lasers mode-locked due to effect of nonlinear polarization evolution. We study spectral and temporal features of pulses produced in all three regimes as well as compressibility of such pulses. Simple criteria are proposed to identify lasing regime in experiment.