Nanosecond Yb-Doped Monolithic Dual-Cavity Laser Oscillator With Large Core Fiber
TL;DR: In this paper, a high pulse energy Yb-doped all-fiber dual-cavity laser oscillator is reported, based on the pulse generation mechanism of passive $Q$ -switch with large core fiber saturable absorber.
Abstract: A high pulse energy Yb-doped all-fiber dual-cavity laser oscillator is reported, based on the pulse generation mechanism of passive $Q$ -switch with large core fiber saturable absorber. Sequential pulses with 49-ns pulse duration and 21-W average power operating at 1080 nm can be achieved in the scheme using the Yb-doped fiber with the core-diameter of 10 $\mu \text{m}$ . The repetition rate varies from $\sim 1$ to 113.6 kHz, while the incident pump power increases. The monolithic all-fiber dual-cavity oscillator can achieve the highest pulse energy of $187~\mu \text{J}$ . Moreover, using the all-fiber scheme with the core-diameter of uniform 20 $\mu \text{m}$ , the single-pulse energy can be further scaled up to 484 $\mu \text{J}$ , which is directly the output from the all-fiber oscillator without additional amplifiers.
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TL;DR: In this paper, a pulsed ytterbium all-fiber laser passively switches with excited-state absorption of thulium fiber and a mode-field-area mismatch.
Abstract: We demonstrated a pulsed ytterbium all-fiber laser passively $Q$Q-switched using excited-state absorption of thulium fiber and a mode-field-area mismatch. The absorption cross section of the excited state $^3{F_4} $3F4 was measured and determined to be the key factor inducing pulsing, and it was much higher than that of the ground state $^3{H_6} $3H6 over 0.95–1.15 µm. By successfully realizing the pulsed laser at 1030 nm, which is the most critical wavelength for $Q$Q-switching, we verified that the excite state $^3{F_4} $3F4 of ${{\rm Tm}^{3 + }}$Tm3+ could be a full-range saturable-absorber $Q$Q-switch for a Yb fiber laser over 1.0–1.15 µm.
6 citations
TL;DR: In this article, a theoretical model for stable Q-switching of a pulsed Yb-Tm fiber laser was derived with both excited state absorption processes and mode field area mismatch taken into account.
Abstract: Taking a comprehensive consideration of related excited state absorption, upconversion emission, and cross relaxation processes, a theoretical model concerning a pulsed Yb-Tm fiber laser is established. The criterion for stable Q-switching is derived with both excited state absorption processes and mode field area mismatch taken into account. And, detailed population transitions of major energy levels are illustrated. Impacts of pump power, mode field area ratio and saturable absorber length on the output characteristics of the pulsed laser system are investigated and analyzed. Simulations show that the excited state absorption transition 3F4→3F2,3 is the predominant factor supporting the passive Q-switching of Yb-Tm fiber lasers. Besides the pump power, the mode field area ratio and the length of the saturable absorber are also important factors affecting the output characteristics of the pulsed laser system. Proper choice of these parameters not only brings significant improvements to the pulse performance, with regards to both the pulse energy and the pulse duration, but also expands the stable operation range of the laser system. And, in practice, an effective mode field area ratio bigger than 1.65 should be exploited for the stable Q-switching operation of a pulsed Yb-Tm fiber laser.
2 citations
15 Apr 2019
TL;DR: In this article, an efficient method to improve the efficiency of mode-field adaptation between two mismatched fibers with arcs and hydrogen-loading is proposed and demonstrated for the first time, where the transmission loss was reduced from −3.71 to −0.24 dB by an arc duration of approximately 10 seconds.
Abstract: An efficient method to improve the efficiency of mode-field adaptation between two mismatched fibers with arcs and hydrogen-loading is proposed and demonstrated for the first time. By hydrogen-loading the fiber of a relatively smaller core, the dopant diffusion rate and the mode transition region length were significantly increased. These enhancements contributed to an abrupt diffusion rate difference at the intersection of the fibers and an adiabatic mode transition. For the mode-field adaptation of the two fibers that have a mode-field area ratio of 7.25, the transmission loss was reduced from −3.71 to −0.24 dB by an arc duration of approximately 10 seconds.
2 citations
TL;DR: In this article, the authors reported the simulation and modeling of a passively Q-switched dual-cavity fiber-laser-doped Yb-Yb and showed that the density of the saturable absorber (SA) is a crucial parameter for the optimization of the two laser signals.
Abstract: We report the simulation and modeling of a passively Q-switched dual-cavity fiber-laser-doped Yb–Yb. To the best of our knowledge, this is the first time that the traveling-wave model has been applied to the study of the dynamics and to the optimization of the two laser signals produced by the two-cavity laser. An excellent agreement between our simulation results and the experimental measurements published by other researchers is obtained. In addition, we show that the density of the saturable absorber (SA) is a crucial parameter for the optimization of the two laser signals. An increase in the peak power of the two laser signals by an order of magnitude is obtained by increasing the density of the SA.
1 citations
Cites background from "Nanosecond Yb-Doped Monolithic Dual..."
...Equations (3) and (4) are the propagation equations of the pump and laser emission in the gain fiber, respectively....
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...(3) represents the absorption of the pump and the second one characterizes its optical loss....
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...EQ-TARGET;temp:intralink-;e003;116;369− ∂Ppðx; tÞ ∂x þ 1 Vgp ∂Ppðx; tÞ ∂t 1⁄4 Γp1⁄2−σap N1ðx; tÞ þ σep N2ðx; tÞ Ppðx; tÞ − αpPpðx; tÞ; (3)...
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References
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TL;DR: This paper reviews the current state of the art in terms of continuous-wave and pulsed performance of ytterbium-doped fiber lasers, the current fiber gain medium of choice, and by far the most developed in Terms of high-power performance.
Abstract: The rise in output power from rare-earth-doped fiber sources over the past decade, via the use of cladding-pumped fiber architectures, has been dramatic, leading to a range of fiber-based devices with outstanding performance in terms of output power, beam quality, overall efficiency, and flexibility with regard to operating wavelength and radiation format. This success in the high-power arena is largely due to the fiber’s geometry, which provides considerable resilience to the effects of heat generation in the core, and facilitates efficient conversion from relatively low-brightness diode pump radiation to high-brightness laser output. In this paper we review the current state of the art in terms of continuous-wave and pulsed performance of ytterbium-doped fiber lasers, the current fiber gain medium of choice, and by far the most developed in terms of high-power performance. We then review the current status and challenges of extending the technology to other rare-earth dopants and associated wavelengths of operation. Throughout we identify the key factors currently limiting fiber laser performance in different operating regimes—in particular thermal management, optical nonlinearity, and damage. Finally, we speculate as to the likely developments in pump laser technology, fiber design and fabrication, architectural approaches, and functionality that lie ahead in the coming decade and the implications they have on fiber laser performance and industrial/scientific adoption.
1,689 citations
TL;DR: An overview of the state of the art in the field can be found in this paper, where the authors discuss present challenges and the future outlook of high-power fiber laser applications.
Abstract: High-power fibre lasers are in demand for industrial, defence and scientific applications. This review provides an overview of the present state of the art in the field and discusses present challenges and the future outlook.
781 citations
TL;DR: In this article, the authors presented a model for passively Q-switched microchip lasers and derived simple equations for the pulse width, repetition rate, and pulse energy, which can be varied in large ranges by adoption of the parameters of the semiconductor saturable-absorber mirror and choice of the appropriate gain medium.
Abstract: We present a model for passively Q-switched microchip lasers and derive simple equations for the pulse width, repetition rate, and pulse energy. We experimentally verified the validity of the model by systematically varying the relevant device parameters. We used the model to derive practical design guidelines for realizing operation parameters that can be varied in large ranges by adoption of the parameters of the semiconductor saturable-absorber mirror and choice of the appropriate gain medium. Applying these design guidelines, we obtained 37-ps pulses, which to our knowledge are the shortest pulses ever generated in a passively Q-switched solid-state laser.
326 citations
"Nanosecond Yb-Doped Monolithic Dual..." refers background in this paper
...DURING the last several decades, nanosecond fiber lasers are really desirable for a lot of applications due to their distinguished properties of good beam quality, simple construction and low cost [1]–[3], and the nanosecond pulse operation can be achieved by actively Q-switch or passively Q-switch using the bulk crystal, semiconductor saturable absorber mirror, grapheme, or other types of saturable absorbers (SAs) [4]–[7]....
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TL;DR: To the best of the knowledge, this is the first report for passively Q-switched sub-100-ns pulse operation of a graphene-based saturable absorber in a Yb-doped fiber laser.
Abstract: We demonstrate stable 70 ns pulse generation from a Yb-doped fiber laser passively Q-switched by a graphene-based saturable absorber mirror in a short linear cavity. The maximum output power was 12 mW and the highest single pulse energy was 46 nJ. The repetition rate of the fiber laser can be widely tuned from 140 to 257 kHz along with the increase of the pump power. To the best of our knowledge, this is the first report for passively Q-switched sub-100-ns pulse operation of a graphene-based saturable absorber in a Yb-doped fiber laser.
210 citations
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.
181 citations
"Nanosecond Yb-Doped Monolithic Dual..." refers background in this paper
...DURING the last several decades, nanosecond fiber lasers are really desirable for a lot of applications due to their distinguished properties of good beam quality, simple construction and low cost [1]–[3], and the nanosecond pulse operation can be achieved by actively Q-switch or passively Q-switch using the bulk crystal, semiconductor saturable absorber mirror, grapheme, or other types of saturable absorbers (SAs) [4]–[7]....
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