Mode-locked 2 μm laser with highly thulium-doped silicate fiber
TL;DR: This is the first demonstration of mode-locked 2 mum fiber laser using shorter than 1-m-long active fiber, which paves the way for the demonstration ofmode-locked fiber laser at 2 mum with gigahertz fundamental repetition rate.
Abstract: We report self-starting passively mode-locked fiber lasers with a saturable absorber mirror using a piece of 30-cm-long newly developed highly thulium (Tm)-doped silicate glass fibers. The mode-locked pulses operate at 1980 nm with duration of 1.5 ps and energy of 0.76 nJ. This newly developed Tm-doped silicate fiber exhibits a slope efficiency of 68.3%, an amplified spontaneous emission spectrum bandwidth (FWHM) of 92 nm, and a gain per unit length of greater than 2 dB/cm. To the best of our knowledge, it is the first demonstration of mode-locked 2 μm fiber laser using shorter than 1-m-long active fiber, which paves the way for the demonstration of mode-locked fiber laser at 2 μm with gigahertz fundamental repetition rate.
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TL;DR: In this paper , the authors present an experimental investigation of the generation of high-energy pulses by a thulium-doped fiber Mamyshev oscillator, enabled by a tailored redshifted gain spectrum in a highly doped doubleclad fiber.
Abstract: Mamyshev oscillators have pushed the frontiers in output parameters of ytterbium- and erbium-based ultrafast fiber oscillators in the spectral region around 1 µm and 1.5 µm within the last few years tremendously. In order to expand the superior performance toward the 2 µm spectral region, we present in this Letter an experimental investigation of the generation of high-energy pulses by a thulium-doped fiber Mamyshev oscillator. Generating highly energetic pulses is enabled by a tailored redshifted gain spectrum in a highly doped double-clad fiber. The oscillator emits pulses with an energy of up to 15 nJ, which can be compressed to 140 fs.
1 citations
Posted Content•
TL;DR: In this paper, the authors proposed that gain fiber should be condensed to short length in order to achieve high energy ultrafast laser pulses from anomalous dispersion gain media at 2.5 µm.
Abstract: While dissipative soliton operation has successfully improved the pulse energy of 1 {\mu}m and 1.5 {\mu}m fiber lasers to tens of nanojoules, it is still hard to scale the pulse energy of dissipative solitons at 2 {\mu}m due to the anomalous dispersion of the gain fiber. Based on theoretical simulation, we analyze intracavity dynamics of dissipative solitons (DSs) and propose that gain fiber should be condensed to short length in order to scale the pulse energy of 2 {\mu}m DSs. The simulation predicts pulse energy of over 10 nJ for 2 {\mu}m dissipative solitons, comparable to that achieved in the 1 {\mu}m and 1.5 {\mu}m regimes. Experimental operation generates stable 2 {\mu}m DSs from a linear cavity with pulse energy of 4.9 nJ and dechirped pulse duration of 579 fs. These results advance our understanding of mode-locked fiber laser at different wavelengths and lay an important step in achieving high energy ultrafast laser pulses from anomalous dispersion gain media at 2 {\mu}m.
15 Oct 2015
TL;DR: Parallelizable and bidirectional (PB) algorithm simulates the light waves matching in time domain instead of space domain, does not need iteration, and permits efficient parallelization on multiple processors to simulate power amplification of fiber lasers.
Abstract: The simulation of light waves propagating in fibers oppositely has to handle the extremely huge volume of data when employing sequential and unidirectional methods, where the simulation is in a coordinate system that moves along with the light waves. Therefore, alternative simulation algorithm should be used when calculating counter propagating light waves. Parallelizable and bidirectional (PB) algorithm simulates the light waves matching in time domain instead of space domain, does not need iteration, and permits efficient parallelization on multiple processors. The PB method is proposed to calculate the propagation of dispersing Gaussian pulse and a bit stream in fibers. However, PB method also has apparent advantages when simulating pulses in fiber laser amplifiers, which has not been investigated detailed yet. In this paper, we perform the simulation of pulses in a rare-earth-ions doped fiber amplifier. The influence of pump power, signal power, repetition rate, pulse width and fiber length on the amplifier’s output average power, peak power, pulse energy and pulse shape are investigated. The results indicate that the PB method is effective when simulating high power amplification of pulses in fiber amplifier. Furthermore, nonlinear effects can be added into the simulation conveniently. The work in this paper will provide a more economic and efficient method to simulate power amplification of fiber lasers.
Dissertation•
01 Sep 2017
TL;DR: In this paper, a thermally-guided fiber-rod (TGFR) is proposed as a novel power scalable concept for solid-state and fiber lasers, and the authors derive the refractive index profile that ensues as a result of end-pumping the TGFR with a fiber-coupled diode laser.
Abstract: This thesis focuses on developing power scaling architectures for solid-state and fiber lasers. The thermally-guided fiber-rod (TGFR) laser is suggested as a novel power scalable concept. This device lies in a domain between bulk rod lasers and traditional fiber lasers. The motivation is to benefit from the excellent thermal management properties of fibers, whilst negating deleterious nonlinear effects owing to the tight beam confinement and long interaction lengths that plague high power fiber lasers. An elegant thermal guiding technique is proposed to provide mode control with the TGFR. We derive the refractive index profile that ensues as a result of end-pumping the TGFR with a fiber-coupled diode laser. Furthermore, we construct a model that predicts the resulting impact on Gaussian beam propagation through the TGFR for various pump configurations. A model describing the gain within the device is derived from the laser rate equations. These two models allow us to predict amplifier and laser performance of the TGFR device. We initially suggest soft glass as a host material for the TGFR, owing to the ability to dope this material with rare-earth ions in significantly higher concentrations than silica which is the traditional material of choice for fiber lasers, thus allowing the realisation of shorter devices. The requirements of a soft glass host are discussed in terms of both device fabrication and laser operation. Three potential sources are identified, including an in-house manufactured neodymium-doped and undoped phosphate glass, a commercial neodymium-doped and undoped silicate glass, and a neodymium-doped and undoped phosphate glass obtained through collaboration. The fabrication of potential TGFR devices with these three sources is described. This is followed by a laser investigation of these devices, where the issues of glass homogeneity and transmission loss become apparent, which are largely attributed to poor glass quality and unsuitable compatibility between the doped and undoped glasses. The neodymium-doped phosphate obtained through collaboration performed best, with a maximum output power around 1054nm of 2.5W, with a slope efficiency with respect to launched pump power of 28.5%. However, the poor glass quality prevented the thermal guiding investigation, and thus the beam quality was dictated by the highly multimode guide, resulting in a beam propagation factor of M2 = 60. Additionally, although this device had the lowest loss of the three sources, a significant loss of 5.7dB/m was measured using the Findlay-Clay analysis. In light of these glass quality issues, the TGFR concept was fully tested using an extra-large mode area silica fiber. A mode guiding investigation revealed that an in-built non-uniform refractive index profile was responsible for providing a degree of guiding, even in the absence of pumping. This guiding was well predicted by assuming a parabolic refractive index profile and utilising the mode guiding model. Furthermore, the thermal guiding model gave excellent agreement with measured data across a range of launched pump powers up to 30W. The device was operated as an amplifier for seed beams at 976nm and 1030nm, and good agreement with the gain model was observed. At 976nm a maximum gain of 4.1dB was achieved for a 60mW seed resulting in an output power of 155mW, and 2.2dB for a 450mW seed resulting in an output power of 750mW. For 1030nm a maximum gain of 5.0dB was achieved for a 50mW seed resulting in an output power of 160mW, and 3.9dB for a 1.1W seed resulting in an output power of 2.7W. Excellent beam quality was maintained throughout amplification with M2 An Yb:YAG thin-slab architecture is suggested as a power scalable architecture for cylindrical vector (CV) beams, which have promising applications within materials processing. A seed source is constructed for operation at 1030nm, which exploits thermally-induced bi-focusing to produce a radially polarised output beam with a maximum output power of 6.9W, with a conversion efficiency of 41% with respect to absorbed pump power. The beam quality was measured as M2 = 2.3, whilst the radial polarisation extinction ratio (RPER) was > 15dB. It was demonstrated that the seed source could be amplified in a highly asymmetric thin-slab gain medium whilst maintaining radial polarisation purity. The implications of the Gouy phase shift owing to astigmatic focusing within the slab are discussed. Amplifier experiments yielded a gain of 7.5dB for a 25mW seed input power, and 4.4dB for a 1.45W seed input power, resulting in a maximum output power of 4W.The beam propagation factor at the maximum gain level was maintained at the lowest seed input power at M2 = 2.3, and was only slightly degraded to M2 = 2.4 at the highest seed input powers. Crucially, the RPER was maintained at >15dB for both cases.
Cites background from "Mode-locked 2 μm laser with highly ..."
...The gain bandwidth of SBS in silica, ~10MHz [8], is considerably narrower than SRS, ~40THz [9]....
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...These unique beams can form doughnut-shaped intensity distributions owing to a polarisation discontinuity at the centre, and have been shown to have promising applications with particle trapping [8], high-resolution imaging [9], and materials processing where they have demonstrated higher cutting and drilling efficiencies when compared to traditional polarisation states [10, 11]....
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03 Jul 2015
TL;DR: In this article, a nonlinear polarization rotation based all-fiber passively mode-locked Tm3+-doped fiber laser is demonstrated by using a 45° tilted fiber grating (TFG) as an in-line polarizer.
Abstract: A nonlinear polarization rotation based all-fiber passively mode-locked Tm3+-doped fiber laser is demonstrated by using a 45° tilted fiber grating (TFG) as an in-line polarizer. Stable soliton pulses centered at 1992.7 nm with 2.02 nm FWHM bandwidth were produced at a repetition rate of 1.902 MHz with pulse duration of 2.2 ps and pulse energy of 74.6 pJ. With the increased pump power, the laser also can operate at noise-like regime with 18.1 nm FWHM bandwidth and pulse energy of up to 250.1 nJ. Using the same 45° TFG, both stable soliton and noise-like mode-locking centered at ∼1970 nm and ∼2050 nm, were also achieved by shortening and extending the length of Tm3+-doped fiber, respectively, exhibiting advantages of broadband and low insertion loss at 2 µm band.
Cites background from "Mode-locked 2 μm laser with highly ..."
...Keywords: Tilted fiber grating, Mode-locked, Tm3+-doped fiber laser...
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References
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TL;DR: In this article, a ring-cavity thulium fiber laser with a single-wall carbon nanotube absorber was used in transmission, achieving an average output power of 3.4 mW.
Abstract: We report a ring-cavity thulium fiber laser mode locked with a single-wall carbon nanotube absorber used in transmission. A carboxymethyl cellulose polymer film with incorporated carbon nanotubes synthesized by the arc discharge method has an absorption coinciding with in the amplification bandwidth of a Tm-doped fiber. This laser is pumped by an erbium fiber laser at 1.57 μm wavelength and produces a 37 MHz train of mode-locked 1.32 ps pulses at 1.93 μm wavelength with an average output power of 3.4 mW.
377 citations
TL;DR: In this article, an additive-pulse mode-locked (APM) thulium-doped fiber ring laser was presented, which produces 350-500 fs pulses tunable from 1798 to 1902 nm.
Abstract: We report an additive‐pulse mode‐locked (APM) thulium‐doped fiber ring laser producing 350–500 fs pulses tunable from 1798 to 1902 nm. The laser operates in the soliton regime, where periodic perturbations cause predictable sidebands and modulation in the optical spectrum.
245 citations
02 Jun 1996
TL;DR: A self-starting passively mode-locked thulium-doped silica fiber laser capable of 190-fs pulses is reported, achieved with a band-gap-engineered saturable absorber fabricated monolithically along with the output coupler of the laser by MOCVD.
Abstract: Summary form only given. We report a self-starting passively mode-locked thulium-doped silica fiber laser capable of 190-fs pulses. Mode-locking of the fiber laser was achieved with a band-gap-engineered saturable absorber fabricated monolithically along with the output coupler of the laser by MOCVD. Stable, single-pulse-in-the-cavity mode-locking was observed for a 2-m-long fiber laser utilizing a nanosecond response strained InGaAs detector.
203 citations
TL;DR: Stabilization of a thulium-holmium codoped fiber soliton laser with a saturable absorber based on carbon nanotubes with transform-limited 750-fs pulses with 0.5-nJ energy is reported.
Abstract: We report stabilization of a thulium-holmium codoped fiber soliton laser with a saturable absorber based on carbon nanotubes. The laser generates transform-limited 750-fs pulses with 0.5-nJ energy.
195 citations
TL;DR: A chain of four Tm-doped fibers amplified a single-frequency, 2040 nm diode laser to 608 W with M(2)=1.05+/-0.03, to be known as the highest power obtained from any single- frequencies, single-mode fiber laser.
Abstract: A chain of four Tm-doped fibers amplified a single-frequency, 2040 nm diode laser to 608 W with M2=1.05±0.03, limited by available pump power. Stimulated Brillouin scattering limits were investigated by splicing different lengths of passive fiber to the output of the final amplifier stage. Integrated rms phase noise above 1 kHz was less than λ/30, suggesting the possibility of further scaling via coherent beam combining. To our knowledge, this is the highest power obtained from any single-frequency, single-mode fiber laser.
192 citations