Showing papers on "Fiber laser published in 2005"
TL;DR: In this paper, the authors provide an overview of beam combining and highlight some of the tradeoffs among beam-combining techniques, including wavelength (spectral) and coherent (phased array) techniques.
Abstract: Beam combining of laser arrays with high efficiency and good beam quality for power and radiance (brightness) scaling is a long-standing problem in laser technology. Recently, significant progress has been made using wavelength (spectral) techniques and coherent (phased array) techniques, which has led to the demonstration of beam combining of a large semiconductor diode laser array (100 array elements) with near-diffraction-limited output (M/sup 2//spl sim/1.3) at significant power (35 W). This paper provides an overview of progress in beam combining and highlights some of the tradeoffs among beam-combining techniques.
973 citations
06 Mar 2005
TL;DR: In this paper, a distributed sensor system for detecting and locating intruders based on the phase-sensitive optical-time-domain reflectometer (/spl phi/-OTDR) is described.
Abstract: A distributed sensor system for detecting and locating intruders based on the phase-sensitive optical-time-domain reflectometer (/spl phi/-OTDR) is described. The sensing element is a cabled single-mode telecommunications fiber buried along the monitored perimeter. Light pulses from a continuous-wave Er:fiber Fabry-Pe/spl acute/rot laser with a narrow (/spl ap/3 kHz) instantaneous linewidth and low (few kilohertz per second) frequency drift are injected into one end of the fiber, and the backscattered light is monitored with a photodetector. The effect of phase changes resulting from the pressure of the intruder on the ground immediately above the buried fiber are sensed by subtracting a /spl phi/-OTDR trace from an earlier stored trace. In laboratory tests with fiber on reels, the effects of localized phase perturbations induced by a piezoelectric fiber stretcher on /spl phi/-OTDR traces were observed. In field tests, people walking on the ground above a buried fiber cable induced phase shifts of several-/spl pi/ radians.
652 citations
TL;DR: In this paper, a high-speed, frequency swept, 1300 nm laser source for frequency domain reflectometry and OCT with Fourier domain/swept source detection is presented, which uses a fiber coupled, semiconductor amplifier and a tunable fiber Fabry-Perot filter.
Abstract: We demonstrate a high-speed, frequency swept, 1300 nm laser source for frequency domain reflectometry and OCT with Fourier domain/swept-source detection. The laser uses a fiber coupled, semiconductor amplifier and a tunable fiber Fabry-Perot filter. We present scaling principles which predict the maximum frequency sweep speed and trade offs in output power, noise and instantaneous linewidth performance. The use of an amplification stage for increasing output power and for spectral shaping is discussed in detail. The laser generates ~45 mW instantaneous peak power at 20 kHz sweep rates with a tuning range of ~120 nm full width. In frequency domain reflectometry and OCT applications the frequency swept laser achieves 108 dB sensitivity and ~10 mum axial resolution in tissue. We also present a fast algorithm for real time calibration of the fringe signal to equally spaced sampling in frequency for high speed OCT image preview.
634 citations
TL;DR: In this article, numerical simulations on multiple-soliton generation and soliton energy quantization in a soliton fiber ring laser passively mode locked by using the nonlinear polarization rotation technique were conducted.
Abstract: We report results of numerical simulations on multiple-soliton generation and soliton energy quantization in a soliton fiber ring laser passively mode locked by using the nonlinear polarization rotation technique. We found numerically that the formation of multiple solitons in the laser is caused by a peak-power-limiting effect of the laser cavity. It is also the same effect that suppresses the soliton pulse collapse, an intrinsic feature of solitons propagating in gain media, and makes the solitons stable in the laser. Furthermore, we show that the soliton energy quantization observed in the lasers is a natural consequence of the gain competition between the multiple solitons. Enlightened by the numerical result we speculate that multisoliton formation and soliton energy quantization observed in other types of soliton fiber lasers could have a similar mechanism.
551 citations
TL;DR: A bound state of temporal solitons in optical fibers is predicted numerically and demonstrated experimentally and appropriately described as a pair of brightsolitons, bound together by a dark soliton.
Abstract: A bound state of temporal solitons in optical fibers is predicted numerically and demonstrated experimentally. It is appropriately described as a pair of bright solitons, bound together by a dark soliton. This structure exists only in dispersion-managed fiber and is different from bound solitons in fiber lasers.
393 citations
TL;DR: The thulium fiber laser has several potential advantages over the holmium:YAG laser, including smaller size, more efficient operation, more precise incision of tissues, and operation in either the pulsed or the continuous-wave mode.
Abstract: Purpose: This paper describes the preliminary testing of a new laser, the thulium fiber laser, as a potential replacement for the holmium:YAG laser for multiple applications in urology Materials and Methods: A 40 W thulium fiber laser operating at a wavelength of 194 µm delivered radiation in a continuous-wave or pulsed mode (10 msec) through either 300-µm- or 600-µm-core low-OH silica fibers for vaporization of canine prostate and incision of animal ureter and bladder-neck tissues Results: The thulium fiber laser vaporized prostate tissue at a rate of 021 ± 002 g/min The thermal-coagulation zone measured 500 to 2000 µm, demonstrating the potential for hemostasis Laser incisions were also made in bladder tissue and ureter, with coagulation zones of 400 to 600 µm Conclusions: The thulium fiber laser has several potential advantages over the holmium laser, including smaller size, more efficient operation, more precise incision of tissues, and operation in either the pulsed or the continuous-wave mod
372 citations
TL;DR: In this paper, a new fiber laser based on a bismuth-doped aluminosilicate glass fiber is proposed and fabricated and obtained in the spectral region between 1150 and 1300 nm.
Abstract: A new fibre laser based on a bismuth-doped aluminosilicate glass fibre is proposed and fabricated. CW lasing is obtained in the spectral region between 1150 and 1300 nm. The fibres are fabricated by the method of modified chemical vapour deposition.
315 citations
TL;DR: In this article, the authors considered the practical case of the ytterbium-doped fiber laser operating in the normal dispersion regime and derived an iterative equation for the optical Kerr nonlinearity, the phase plates and the polarizer.
Abstract: A passively mode-locked fiber laser is theoretically investigated. The mode locking is achieved using the nonlinear polarization technique. We consider the practical case of the ytterbium-doped fiber laser operating in the normal dispersion regime. The effect of the phase plates is explicitly taken into account. The resulting model reduces to one iterative equation for the optical Kerr nonlinearity, the phase plates and the polarizer, and one partial differential equation for the gain and the dispersion. Numerical simulations allow us to describe several features observed in passively mode-locked fiber lasers such as bistability between the mode lock and the continuous regime, multiple pulse behavior, hysteresis phenomena. The dynamics of the number of pulses as a function of the pumping power is also reported. Pump power hysteresis is demonstrated.
299 citations
TL;DR: A novel ytterbium-doped fiber design that combines the advantages of rod and fiber gain media is reported that has significantly reduced nonlinearity, which allows for scalability in the performance of a high-peak-power fiber laser and amplifier system.
Abstract: We report on a novel ytterbium-doped fiber design that combines the advantages of rod and fiber gain media. The fiber design has outer dimensions of a rod laser, meaning a diameter in the range of a few millimeters and a length of just a few tens of centimeters, and includes two important waveguide structures, one for pump radiation and one for laser radiation. We obtained 120-W output power in single-mode beam quality from a 48-cm-long fiber cane that corresponds to an extracted power of 250 W/m. The fiber has significantly reduced nonlinearity, which therefore allows for scalability in the performance of a high-peak-power fiber laser and amplifier system.
294 citations
06 Mar 2005
TL;DR: These results were obtained with (nearly) diffraction-limited beam quality, which determines the ability to focus to a tight spot, and this, rather than the power itself, determines the power density achievable on a target.
Abstract: Over 1 kW of output power has now been reached with nearly diffraction-limited ytterbium-doped fiber lasers. Amplifiers can reach comparable powers, even with single-frequency beams. We review these and other recent results and discuss the possibilities for further progress.
277 citations
TL;DR: A miniature hydrogen sensor that consists of a subwavelength diameter tapered optical fiber coated with an ultra thin palladium film suitable for detecting low concentrations of hydrogen at normal conditions is reported.
Abstract: We report a miniature hydrogen sensor that consists of a sub-wavelength diameter tapered optical fiber coated with an ultra thin palladium film. The optical properties of the palladium layer changes when the device is exposed to hydrogen. Consequently, the absorption of the evanescent waves also changes. The sensor was tested in a simple light transmission measurement setup that consisted of a 1550 nm laser diode and a photodetector. Our sensor is much smaller and faster than other optical hydrogen sensors reported so far. The sensor proposed here is suitable for detecting low concentrations of hydrogen at normal conditions.
TL;DR: Based on the fiber Bragg gratings and high nonlinear photonic crystal fiber, a novel dual-wavelength erbium-doped fiber (EDF) laser is proposed and demonstrated and can selectively realize one wavelength lasing.
Abstract: Based on fiber Bragg gratings (FBGs) and high nonlinear photonic crystal fiber (HN-PCF), a novel dual-wavelength erbium-doped fiber (EDF) laser is proposed and demonstrated. Experimental results show that, owing to the contributions of two degenerate four-wave mixings in the HN-PCF, the proposed fiber laser is quite stable and two output signals are uniform at room temperature. With adjustment of the attenuator, our fiber laser can selectively realize one wavelength lasing.
TL;DR: In this article, the authors demonstrate passive mode locking of solid-state lasers by saturable absorbers based on carbon nanotubes (CNTs), which are fabricated by spin-coating a polymer doped with CNTs onto commercial dielectric laser-mirrors.
Abstract: We demonstrate passive mode locking of solid-state lasers by saturable absorbers based on carbon nanotubes (CNT). These novel absorbers are fabricated by spin-coating a polymer doped with CNTs onto commercial dielectric laser-mirrors. We obtain broadband artificial saturable absorber mirrors with ultrafast recovery times without the use of epitaxial growth techniques and the well-established spin-coating process allows the fabrication of devices based on a large variety of substrate materials. First results on passive mode locking of Nd:glass and Er/Yb:glass lasers are discussed. In the case of Er/Yb:glass we report the to our knowledge shortest pulse generated in a self-starting configuration based on Er/Yb:bulk-glass: 68 fs (45 fs Fourier-limit) at 1570 nm wavelength at a pulse-repetition rate of 85 MHz.
TL;DR: In this article, the authors investigated the soliton interaction in a passively mode-locked fiber ring laser and revealed the existence of three types of strong soliton interactions: a global type of solitons interaction caused by the presence of unstable cw components, a local type of Soliton interaction mediated through the radiative dispersive waves, and the direct soliton interaction.
Abstract: We have experimentally investigated the soliton interaction in a passively mode-locked fiber ring laser and revealed the existence of three types of strong soliton interaction: a global type of soliton interaction caused by the existence of unstable cw components, a local type of soliton interaction mediated through the radiative dispersive waves, and the direct soliton interaction. We found that the appearance of the various soliton operation modes observed in the passively mode-locked fiber soliton lasers are the direct consequences of these three types of soliton interactions. The soliton interaction in the laser is further numerically simulated based on a pulse tracing technique. The numerical simulations confirmed the existence of the dispersive-wave-mediated soliton interaction and the direct soliton interaction. Furthermore, it was shown that the resonant dispersive-wave-mediated soliton interaction in the laser always has the consequence of causing random irregular relative soliton movement and the experimentally observed states of bound solitons are caused by the direct soliton interaction. In particular, as the solitons generated in the laser could have a profile with long tails, the direct soliton interaction could extend to a soliton separation that is larger than 5 times the soliton pulse width.
TL;DR: Numerical simulations showed that the laser emission was caused by the combined effect of soliton collapse and positive cavity feedback in the laser.
Abstract: A passively mode-locked soliton fiber ring laser with dispersion managed cavity is reported. The laser emits intense bunched noise-like pulses including the transform limited pulses. The optical spectrum of the laser emission has a bandwidth as broad as 32.10 nm. It was found that purely depending on the linear cavity phase delay the laser could be switched between the soliton operation and the noise-like pulse emission. Numerical simulations showed that the laser emission was caused by the combined effect of soliton collapse and positive cavity feedback in the laser.
TL;DR: An ytterbium-doped photonic-crystal-fiber-based chirped-pulse amplification system delivering 131 W average power 220 fs pulses at 1040 nm center wavelength in a diffraction-limited beam is reported on.
Abstract: We report on an ytterbium-doped photonic-crystal-fiber–based chirped-pulse amplification system delivering 131?W average power 220?fs pulses at 1040?nm center wavelength in a diffraction-limited beam. The pulse repetition rate is 73?MHz, corresponding to a pulse energy of 1.8??J and a peak power as high as 8.2?MW.
TL;DR: A series of experiments aimed at determining the maximum pulse energy that can be produced by a femtosecond fiber laser is reported, exploiting modes of pulse propagation that avoid wave breaking in a Yb fiber laser.
Abstract: A series of experiments aimed at determining the maximum pulse energy that can be produced by a femtosecond fiber laser is reported. Exploiting modes of pulse propagation that avoid wave breaking in a Yb fiber laser allows pulse energies up to 14?nJ to be achieved. The pulses can be dechirped to sub-100-fs duration to produce peak powers that reach 100?kW. The limitations to the maximum pulse energy are discussed.
TL;DR: Waveguide writing in fused silica with a novel commercial femtosecond fiber laser system (IMRA America, FCPA microJewel) and the influence of a range of laser parameters were investigated, finding that it was not possible to produce low-loss waveguides when writing with the fundamental wavelength of 1045 nm, but it was possible to fabricate telecom-compatible waveguide at the second harmonic wavelength of 522 nm.
Abstract: We report on waveguide writing in fused silica with a novel commercial femtosecond fiber laser system (IMRA America, FCPA microJewel) The influence of a range of laser parameters were investigated in these initial experiments, including repetition rate, focal area, pulse energy, scan speed, and wavelength Notably, it was not possible to produce low-loss waveguides when writing with the fundamental wavelength of 1045 nm However, it was possible to fabricate telecom-compatible waveguides at the second harmonic wavelength of 522 nm High quality waveguides with propagation losses below 1 dB/cm at 1550 nm were produced with 115 nJ/pulse at 1 MHz and 522 nm
TL;DR: Contrary to the FBG inscription in silica microstructured fiber, where high-energy laser pulses are a prerequisite, a low-power cw laser source operating at 325 nm is used to produce 1 cm long gratings with a reflection peak at 1570 nm.
Abstract: We report observations and measurements of the inscription of fiber Bragg gratings (FBGs) in two different types of microstructured polymer optical fiber: few-mode and an endlessly single mode. Contrary to the FBG inscription in silica microstructured fiber, where high-energy laser pulses are a prerequisite, we have successfully used a low-power cw laser source operating at 325 nm to produce 1 cm long gratings with a reflection peak at 1570 nm. Peak reflectivities of more than 10% have been observed.
TL;DR: In this article, a coherent phase-locked laser array was demonstrated by combining the outputs of seven individual fiber lasers together in a self-Fourier cavity, and the total output power of this laser array when operated as a coherent ensemble was 0.4watts.
Abstract: A coherent phase-locked laser array has been experimentally demonstrated by combining the outputs of seven individual fiber lasers together in a self-Fourier cavity. By analyzing the interference fringes of the laser output in the far field of the array, a fringe visibility was measured of V=0.87, indicating a coherence of 0.73. The total output power of this laser array when operated as a coherent ensemble was 0.4watts.
TL;DR: In this paper, the authors present a review of eyesafe erbium lasers that are resonantly pumped by both fiber and diode lasers, and show that high brightness pumping with a 1.53-/spl mu/m Erbium fiber laser has yielded 60 W of continuous wave (CW) output, 10 W of repetitively Q-switched output, and as much as 16 mJ of pulse energy.
Abstract: The viability of high-power and high-energy, direct eyesafe emission from bulk erbium lasers has recently been demonstrated. In this paper, we present a review of eyesafe erbium lasers that are resonantly pumped by both fiber and diode lasers. High brightness pumping with a 1.53-/spl mu/m erbium fiber laser has yielded 60 W of continuous wave (CW) output, 10 W of repetitively Q-switched output, and as much as 16 mJ of pulse energy. Diode laser pumping has yielded 38 W of quasi-CW output and >40 mJ of Q-switched output.
TL;DR: A distributed sensor system for detecting and locating intruders based on a phase-sensitive optical time-domain reflectometer (phi-OTDR) that utilizes polarization discrimination is described.
Abstract: A distributed sensor system for detecting and locating intruders based on a phase-sensitive optical time-domain reflectometer (phi-OTDR) that utilizes polarization discrimination is described. The sensing element is a single-mode telecommunications fiber in a 3 mm diameter cable buried along a monitored perimeter in a 20-46 cm deep, 10 cm wide trench in clay soil. Light pulses from a continuous-wave Er fiber Fabry-Perot laser with a narrow (< 3 kHz) instantaneous linewidth and low (a few Kilohertz per second) frequency drift are injected into one end of the fiber, and the orthogonal polarizations of the backscattered light are monitored with separate receivers. Localized phase changes in the optical carrier are sensed by subtraction of a phi-OTDR trace from an earlier stored trace. In field tests with a monitored length of 12 km, detection of intruders on foot as far as 4.5 m from the cable line was consistently achieved.
TL;DR: A single-mode, linearly polarized, 1118 nm ytterbium fiber laser was applied to pumping of a short fiber length, polarization-maintaining Raman cavity, resulting in a 0.4 nm linewidth, 23 W CW source at 1179 nm.
Abstract: A single-mode, linearly polarized, 1118 nm ytterbium fiber laser was applied to pumping of a short fiber length, polarization-maintaining Raman cavity, resulting in a 0.4 nm linewidth, 23 W CW source at 1179 nm. Efficient, single-pass frequency doubling of the Raman source in MgO doped PPLN to 589 nm was demonstrated with CW power levels in excess of 3 W. No beam quality degradation was observed due to photorefraction at pump power densities up to 2 MW/cm2. The proposed approach can be readily extended to Watt-level generation of any desired wavelength in the 560 to 770 nm range.
TL;DR: In this paper, a multiwavelength switchable-tunable erbium-doped fiber laser with excellent stability and uniformity based on four-wave mixing (FWM) was proposed.
Abstract: We propose and report on a novel multiwavelength-switchable-tunable erbium-doped fiber laser with excellent stability and uniformity based on four-wave mixing (FWM) in a highly nonlinear photonic crystal fiber. By adjusting the attenuators, the single, dual, or triple wavelengths can be lasing simultaneously. Under the influence of the FWM, the spectrum is stabilized and the uniformity is less than 0.6 dB.
TL;DR: An all-fiber laser system that generates tunable Watt-level femtosecond pulses at around 2 microm without an external pulse compressor is reported for the first time.
Abstract: We report for the first time an all-fiber laser system that generates tunable Watt-level femtosecond pulses at around 2 μm without an external pulse compressor. The system is based on amplification of a Raman shifted Er-doped fiber laser in a Tm-doped 25-μm-core fiber. We obtain 108-fs pulses at 1980 nm with an average power of 3.1 W and a pulse energy of 31 nJ. The peak power at the output of the amplifier is estimated as ~230 kW, which to the best of our knowledge is the highest peak power obtained from a femtosecond or a few-picosecond amplifier based on any doped fiber. The amplified output is frequency-doubled to produce 78-fs pulses at 990 nm with an average power of 1.5 W and a pulse energy of 15 nJ. We demonstrate broad wavelength tunability around 2 μm as well as around 1 μm.
TL;DR: In this article, a diode-pumped single-frequency piezoelectrically tuned fiber laser with narrow spectral linewidth has been used as a light source in applications for long-range coherent frequency-domain reflectometry.
Abstract: A diode-pumped single-frequency piezoelectrically tuned fiber laser with narrow spectral linewidth has been used as a light source in applications for long-range coherent frequency-domain reflectometry. Frequency-modulated continuous-wave (FMCW) measurements of Rayleigh back-scattering and Fresnel reflection from a 95-km-long fiber have been demonstrated without the use of an optical amplifier. This is, to our knowledge, the longest distance measurement with FMCW. The high sensitivity and dynamic range of the long-range backscattering measurements benefit from the extremely long coherence length of the narrow linewidth fiber laser, which has been estimated to be 210 km in air.
TL;DR: The dynamics of a fiber ring laser mode locked by nonlinear polarization rotation is reduced to a quintic complex Ginzburg-Landau (CGLQ) equation and the coefficients of the equation are explicitly given as functions of the physical parameters of the laser, especially the orientation of the phase plates.
Abstract: The dynamics of a fiber ring laser mode locked by nonlinear polarization rotation is reduced to a quintic complex Ginzburg-Landau (CGLQ) equation. The coefficients of the equation are explicitly given as functions of the physical parameters of the laser, especially the orientation of the phase plates. Then known results about analytic solutions, stability of pulse-like solutions, and bound states of the CGLQ equation are examined from the point of view of their dependence with regard to the physical parameters.
TL;DR: This work explored high-energy and high-peak-power pulse generation in large-core multimode fiber amplifiers, achieving what is to the authors' knowledge the highest reported energies and output-beam quality.
Abstract: We explored high-energy and high-peak-power pulse generation in large-core multimode fiber amplifiers, achieving what is to our knowledge the highest reported energies, up to 82 mJ for 500-ns pulses, 27 mJ for 50-ns pulses, and 2.4-MW peak power for 4-ns pulses at 1064 nm, using 200?µm-diameter and 0.062-N.A. core Yb-doped double-clad fiber amplifiers. The highly multimode nature of the fiber core was mitigated by use of a coiling-induced mode-filtering effect to yield a significant improvement in output-beam quality from M2=25 from an uncoiled fiber to M2=6.5 from a properly coiled fiber, with the corresponding reduction in number of propagating transverse modes from ?200 to ?20.
TL;DR: Large signal-to-noise ratios demonstrate the ability of the optimally engineered optical hardware to reject beam steering and vibration noise and demonstrates the utility of a scanned wavelength modulation strategy in such situations.
Abstract: Tunable diode laser absorption measurements of gas temperature and water concentration were made at the exit of a model scramjet combustor fueled on JP-7. Multiplexed, fiber-coupled, near-infrared distributed feedback lasers were used to probe three water vapor absorption features in the 1.34–1.47 μm spectral region (2v1 and v1 + v3 overtone bands). Ratio thermometry was performed using direct-absorption wavelength scans of isolated features at a 4-kHz repetition rate, as well as 2f wavelength modulation scans at a 2-kHz scan rate. Large signal-to-noise ratios demonstrate the ability of the optimally engineered optical hardware to reject beam steering and vibration noise. Successful measurements were made at full combustion conditions for a variety of fuel/air equivalence ratios and at eight vertical positions in the duct to investigate spatial uniformity. The use of three water vapor absorption features allowed for preliminary estimates of temperature distributions along the line of sight. The improved signal quality afforded by 2f measurements, in the case of weak absorption, demonstrates the utility of a scanned wavelength modulation strategy in such situations.
TL;DR: The high‐power Thulium fiber laser is shown to rapidly vaporize and coagulate soft urinary tissues (e.g., prostate) and cause fragmentation of urinary stones.
Abstract: Background and Objectives
The high-power Thulium fiber laser has previously been shown to rapidly vaporize and coagulate soft urinary tissues (e.g., prostate). This is the first preliminary study of a high-power Thulium fiber laser for fragmentation of urinary stones.
Study Design/Materials and Methods
A continuous-wave, high-power Thulium fiber laser operating at a wavelength of 1.94 µm, was modulated to operate in pulsed mode with an output pulse energy of 1 J through a 300-µm-core silica fiber at a 20 milliseconds pulse length and repetition rate of 10 Hz. The fragmentation time to reduce uric acid (UA) (n = 13) and calcium oxalate monohydrate (COM) (n = 6) stones into particles < 2 mm was measured.
Results
Mean initial mass of the UA and COM stones measured 860±211 and 763 ± 204 mg. Fragmentation rates measured 388 ± 49 and 25 ± 2 mg/minute. Average time needed to fragment the UA and COM stones into particles < 2 mm was 2.25 ± 0.63 and 30.7 ± 8.4 minutes, respectively.
Conclusions
The high-power Thulium fiber laser, when operated in pulsed mode, is capable of fragmenting both soft (UA) and hard (COM) urinary stones. The Thulium fiber laser may be useful as a single laser system for use in multiple soft and hard tissue laser ablation applications in urology. Lasers Surg. Med. © 2005 Wiley-Liss, Inc.