We present a Brillouin–Raman random fiber laser(BRRFL)with full-open linear cavity structure to generate broadband Brillouin frequency comb(BFC)with double Brillouin-frequency-shift spacing.The incorporation of a reg...We present a Brillouin–Raman random fiber laser(BRRFL)with full-open linear cavity structure to generate broadband Brillouin frequency comb(BFC)with double Brillouin-frequency-shift spacing.The incorporation of a regeneration portion consisting of an erbium-doped fiber and a single-mode fiber enables the generation of broadband BFC.The dynamics of broadband BFC generation changing with the pump power(EDF and Raman)and Brillouin pump(BP)wavelength are investigated in detail,respectively.Under suitable conditions,the bidirectional BRRFL proposed can produce a flatamplitude BFC with 40.7-nm bandwidth ranging from 1531 nm to 1571.7 nm,and built-in 242-order Brillouin Stokes lines(BSLs)with double Brillouin-frequency-shift spacing.Moreover,the linewidth of single BSL is experimentally measured to be about 2.5 kHz.The broadband bidirectional narrow-linewidth BRRFL has great potential applications in optical communication,optical sensing,spectral measurement,and so on.展开更多
We report a single-frequency linearly polarized Q-switched fiber laser based on an Nb_(2)GeTe_(4)saturable absorber(SA).The Nb_(2)GeTe_(4)SA triggers passive Q-switching of the laser,and an un-pumped Yb-doped fiber to...We report a single-frequency linearly polarized Q-switched fiber laser based on an Nb_(2)GeTe_(4)saturable absorber(SA).The Nb_(2)GeTe_(4)SA triggers passive Q-switching of the laser,and an un-pumped Yb-doped fiber together with a 0.08-nmbandwidth polarization-maintaining fiber Bragg grating(FBG)acts as an ultra-narrow bandwidth filter to realize singlelongitudinal-mode(SLM)oscillation.The devices used in the laser are all kept polarized,so as to ensure linearly polarized laser output.Stable SLM linearly polarized Q-switching operation at 1064.6 nm is successfully achieved,producing a laser with a shortest pulse width of 1.36μs,a linewidth of 28.4 MHz,a repetition rate of 28.3 kHz-95.9 kHz,and a polarization extinction ratio of about 30 dB.It is believed that the single-frequency linearly polarized pulsed fiber laser studied in this paper has great application value in gravitational wave detection,beam combining,nonlinear frequency conversion,and other fields.展开更多
We present experimental observations of soliton pulsations in the net normal-dispersion fiber laser by using the dispersive Fourier transform(DFT) technique. According to the pulsating characteristics, the soliton pul...We present experimental observations of soliton pulsations in the net normal-dispersion fiber laser by using the dispersive Fourier transform(DFT) technique. According to the pulsating characteristics, the soliton pulsations are classified as visible and invisible soliton pulsations. The visible soliton pulsation is converted from single-into dual-soliton pulsation with the common characteristics of energy oscillation and bandwidth breathing. The invisible soliton pulsation undergoes periodic variation in the spectral profile and peak power but remains invariable in pulse energy. The reason for invisible soliton pulsation behavior is periodic oscillation of the pulse inside the soliton molecule. These results could be helpful in deepening our understanding of the soliton pulsation phenomena.展开更多
A multiwavelength tunable ring-cavity erbium-doped fiber laser(EDFL)based on a Lyot filter was presented.For the proposed Lyot filter,a comb filter consisting of an EDF-polarization-maintaining fiber(EDF-PMF),a polari...A multiwavelength tunable ring-cavity erbium-doped fiber laser(EDFL)based on a Lyot filter was presented.For the proposed Lyot filter,a comb filter consisting of an EDF-polarization-maintaining fiber(EDF-PMF),a polarization controller(PC),and a circulator with four ports was used to suppress the mode competition.The light transmission direction was guaranteed by the circulator.For the proposed fiber laser,tunable single,dual,triple,quadruple,quintuple,sextuple,and septuple wavelengths were realized.A single-wavelength laser output with an optical signal-to-noise ratio(SNR)of up to30.56 dB was realized,and a tuning range of 1590.54 nm to 1599.54 nm was achieved by tuning the PC.The stability of the single,dual,triple,and quadruple-wavelength center power fluctuations was less than 0.05 dB,0.98 dB,5.07 dB,and7.71 dB respectively.When the laser was operated in the multiwavelength condition,the SNR was more than 20.97 dB.The proposed erbium-doped fiber laser is suitable for fiber-sensing system applications.展开更多
The understanding of soliton dynamics promotes the development of ultrafast laser technology. High-energy purequartic solitons(PQSs) have gradually become a hotspot in recent years. Herein, we numerically study the in...The understanding of soliton dynamics promotes the development of ultrafast laser technology. High-energy purequartic solitons(PQSs) have gradually become a hotspot in recent years. Herein, we numerically study the influence of the gain bandwidth, saturation power, small-signal gain, and output coupler on PQS dynamics in passively mode-locked fiber lasers. The results show that the above four parameters can affect PQS dynamics. Pulsating PQSs occur as we alter the other three parameters when the gain bandwidth is 50 nm. Meanwhile, PQSs evolve from pulsating to erupting and then to splitting as the other three parameters are altered when the gain bandwidth is 10 nm, which can be attributed to the existence of the spectral filtering effect and intra-cavity fourth-order dispersion. These findings provide new insights into PQS dynamics in passively mode-locked fiber lasers.展开更多
Objective:The holmium:yttrium-aluminium-garnet laser(Ho:YAG)has been the gold standard for laser lithotripsy over the last three decades.After demonstrating good in vitro efficacy,the thulium fiber laser(TFL)has been ...Objective:The holmium:yttrium-aluminium-garnet laser(Ho:YAG)has been the gold standard for laser lithotripsy over the last three decades.After demonstrating good in vitro efficacy,the thulium fiber laser(TFL)has been recently released in the market and the initial clinical results are encouraging.This article aims to review the main technology differences between the Ho:YAG laser and the TFL,discuss the initial clinical results with the TFL as well as the optimal settings for TFL lithotripsy.Methods:We reviewed the literature focusing on the technological aspects of the Ho:YAG laser and TFL as well as the results of in vitro and in vivo studies comparing both technologies.Results:In vitro studies show a technical superiority of TFL compared to the Ho:YAG laser and encouraging results have been demonstrated in clinical practice.However,as TFL is a new technology,limited studies are currently available,and the optimal settings for lithotripsy are not yet established.Conclusion:TFL has the potential to be an alternative to the Ho:YAG laser,but more reports are still needed to determine the optimal laser for lithotripsy of urinary tract stones when considering all parameters including effectiveness,safety,and costs.展开更多
We demonstrate antimonene as a saturable absorber(SA) to generate an ultrafast mode-locked and Q-switched laser in the 2 μm wavelength region. The two antimonene-based SAs were prepared and inserted separately in a t...We demonstrate antimonene as a saturable absorber(SA) to generate an ultrafast mode-locked and Q-switched laser in the 2 μm wavelength region. The two antimonene-based SAs were prepared and inserted separately in a thulium–holmiumdoped fiber laser to produce the pulsed laser. Antimonene was coated onto a tapered fiber to generate soliton mode-locked pulses and used in thin-film form for the generation of Q-switched pulses. The mode-locking was stable within a pump power of 267 m W–511 m W, and the laser operated at a central wavelength of 1897.4 nm. The mode-locked laser had a pulse width of 1.3 ps and a repetition rate of 12.6 MHz, with a signal-to-noise ratio of 64 d B. Q-switched laser operation was stable at a wavelength of 1890.1 nm within a pump power of 312 m W–381 m W. With the increase in pump power from 312 m W to 381 m W, the repetition rate increased to a maximum of 56.63 k Hz and the pulse width decreased to a minimum value of 2.85 μs. Wide-range tunability of the Q-switched laser was also realized within the wavelength range of1882 nm–1936 nm.展开更多
We experimentally demonstrated a stable multi-wavelength bright-dark pulse pair in a mode-locked thulium-doped fiber laser(TDFL).The nonlinear polarization rotation(NPR)and nonlinear optical loop mirror(NOLM)were empl...We experimentally demonstrated a stable multi-wavelength bright-dark pulse pair in a mode-locked thulium-doped fiber laser(TDFL).The nonlinear polarization rotation(NPR)and nonlinear optical loop mirror(NOLM)were employed in a figure-eight cavity to allow for multi-wavelength mode-locking operation.By incorporating different lengths of high birefringence polarization-maintaining fiber(PMF),the fiber laser could operate stably in a multi-wavelength emission state.Compared with the absence of the PMF,the birefringence effect caused by PMF resulted in rich multi-wavelength optical spectra and better intensity symmetry and stability of the bright-dark pulse pair.展开更多
In this paper,the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber(TDF) laser is investigated.The analytical formulations of pump energy threshold,peak power extraction efficiency...In this paper,the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber(TDF) laser is investigated.The analytical formulations of pump energy threshold,peak power extraction efficiency,and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse.They are useful for understanding,designing,and optimizing the in-band pumped TDF lasers in a 1.9 μm-2.1 μm wavelength region.The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted,and our experimental results show good agreement with theoretical analysis.展开更多
The carboxyl-functionalized graphene oxide(GO-COOH) is a kind of unique two-dimensional(2 D) material and possesses excellent nonlinear saturable absorption property and high water-solubility. In this paper, we prepar...The carboxyl-functionalized graphene oxide(GO-COOH) is a kind of unique two-dimensional(2 D) material and possesses excellent nonlinear saturable absorption property and high water-solubility. In this paper, we prepare saturable absorber(SA) device by depositing GO-COOH nanosheets aqueous solution on a D-shaped fiber. The modulation depth(MD) and saturable intensity of the SA are measured to be 9.6% and 19 MW/cm^2, respectively. By inserting the SA into the erbium-doped fiber(EDF) laser, a passively mode-locked EDF laser has been achieved with the spectrum center wavelength of 1562.76 nm. The pulse duration, repetition rate, and the signal-to-noise ratio(SNR) are 500 fs, 14.79 MHz, and 80 dB,respectively. The maximum average output power is measured to be 3.85 mW. These results indicate that the GO-COOH nanosheets SA can be used as a promising mode locker for the generation of ultrashort pulses.展开更多
This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the...This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the power transfer between the core modes and the cladding modes during thermally-induced refractive index variations is established based on the mode coupling theory. The results of numerical simulations based on actual laser parameters are presented. Experimental measurements were also carried out, the results showed good agreement with the corresponding simulation results.展开更多
We report the generation of high energy 2μm picosecond pulses from a thulium-doped fiber master oscillator power amplifier system.The all-fiber configuration was realized by a flexible large-mode area photonic crysta...We report the generation of high energy 2μm picosecond pulses from a thulium-doped fiber master oscillator power amplifier system.The all-fiber configuration was realized by a flexible large-mode area photonic crystal fiber(LMA-PCF).The amplifier output is a linearly-polarized 1.5 ns,100 kHz pulse train with a pulse energy of up to 250μJ.Pulse compression was achieved with(2+2)-pass chirped volume Bragg grating(CVBG)to obtain a 2.8 ps pulse width with a total pulse energy of 46μJ.The overall system compactness was enabled by the all-fiber amplifier design and the multi-pass CVBG-based compressor.The laser output was then used to demonstrate high-speed direct-writing capability on a temperature-sensitive biomaterial to change its topography(i.e.fabricate microchannels,foams and pores).The topographical modifications of biomaterials are known to influence cell behavior and fate which is potentially useful in many cell and tissue engineering applications.展开更多
We propose and demonstrate a passively mode-locked erbium-doped fiber laser(EDFL)based on zinc-oxide/polydimethylsiloxane(ZnO/PDMS)saturable absorber(SA)that evanescently interacts with the light on a tapered fiber.Th...We propose and demonstrate a passively mode-locked erbium-doped fiber laser(EDFL)based on zinc-oxide/polydimethylsiloxane(ZnO/PDMS)saturable absorber(SA)that evanescently interacts with the light on a tapered fiber.The ZnO/PDMS composite is coated on the whole surface of the tapered fiber to guarantee the maximum efficiency of the SA device,with a measured insertion loss of 0.87 dB and a modulation depth of 6.4%.The proposed laser can generate soliton mode-locking operation at a threshold power of 33.07 mW.The generated output pulse yields a repetition rate and pulse width of 9.77 MHz and 1.03 ps,respectively.These results indicate that the proposed ZnO/PDMS-clad tapered fiber could be useful as an efficient,compatible,and low-cost SA device for ultrafast laser applications.展开更多
We demonstrate multiwavelength Brillouin fiber lasers(MWBFLs)with double-frequency spacing based on a small-core fiber(SCF)and a standard single-mode fiber(SMF),which have core diameters of 5 and 8.8μm,respectively.E...We demonstrate multiwavelength Brillouin fiber lasers(MWBFLs)with double-frequency spacing based on a small-core fiber(SCF)and a standard single-mode fiber(SMF),which have core diameters of 5 and 8.8μm,respectively.Experimental results show that the SCF-based MWBFL exhibits a higher laser output power and a lower pump threshold.The output powers of the SCF-based MWBFL are>1.4 times those of the SMF-based MWBFL.Moreover,the threshold power required to generate each channel of the SCF-based MWBFL is 59%that of the SMF-based MWBFL.When the same pump power of 180 mW is injected,the number of laser channels generated for the SCF-based MWBFL is 13,which is twice that generated for the SMF-based MWBFL.In addition,the SCF-based MWBFL exhibits good wavelength tunability from 1535 to 1565 nm and temporal stability over an hour.展开更多
A novel organized multipulse pattern and its birth dynamics under strong optomechanical effect in microfiber-assisted ultrafast fiber laser are investigated in this work.The background pulses are observed to obviously...A novel organized multipulse pattern and its birth dynamics under strong optomechanical effect in microfiber-assisted ultrafast fiber laser are investigated in this work.The background pulses are observed to obviously exhibit selectively amplifying self-organized process of evolving into quasi-stable equidistant clusters.The radio frequency spectrum of the multipulse pattern displays a harmonic mode-locking-like behavior with a repetition rate of 2.0138 GHz,corresponding to the frequency of torsional-radial(TR_(2m))acoustic mode in microfiber.The results show the evidence of optomechanical effect in dominating the birth dynamics and pattern of multipulse.展开更多
We demonstrate a Q-switched erbium-doped fiber laser(EDFL) using a newly developed zinc oxide-(ZnO) based saturable absorber(SA). The SA is fabricated by embedding a prepared ZnO powder into a poly(vinyl alcohol)film....We demonstrate a Q-switched erbium-doped fiber laser(EDFL) using a newly developed zinc oxide-(ZnO) based saturable absorber(SA). The SA is fabricated by embedding a prepared ZnO powder into a poly(vinyl alcohol)film. A small piece of the film is then sandwiched between two fiber ferrules and is incorporated in an EDFL cavity for generating a stable Q-switching pulse train. The EDFL operates at 1560.4 nm with a pump power threshold of 11.8 mW, a pulse repetition rate tunable from 22.79 to 61.43 kHz, and the smallest pulse width of 7.00 μs. The Q-switching pulse shows no spectral modulation with a peak-to-pedestal ratio of 62 dB indicating the high stability of the laser. These results show that the ZnO powder has a great potential to be used for pulsed laser applications.展开更多
A 135 mW single-frequency distributed Bragg reflector fiber laser at 1.95μm was obtained based on a Tm:YAG ceramic-derived all-glass fiber.The fiber laser achieved an optical signal-to-noise ratio of~77 d B.Moreover,...A 135 mW single-frequency distributed Bragg reflector fiber laser at 1.95μm was obtained based on a Tm:YAG ceramic-derived all-glass fiber.The fiber laser achieved an optical signal-to-noise ratio of~77 d B.Moreover,the threshold and linewidth of the single-frequency laser were measured to be 15.4 mW and 4.5 kHz,respectively.In addition,the measured relative intensity noise was less than-140 d B·Hz^(-1)at frequencies of over 10 MHz.The results show that the as-drawn Tm:YAG ceramic-derived all-glass fiber is highly promising for~2μm single-frequency fiber laser applications.展开更多
Multi-wavelength square pulses are generated in the dissipative soliton resonance(DSR) regime by a Yb-doped fiber laser(YDFL) with a long cavity configuration. The spectral filter effect provided by a passive fiber wi...Multi-wavelength square pulses are generated in the dissipative soliton resonance(DSR) regime by a Yb-doped fiber laser(YDFL) with a long cavity configuration. The spectral filter effect provided by a passive fiber with low-stress birefringence facilitates the establishment of multi-wavelength operation. Through appropriate control of the cavity parameters,a multi-wavelength DSR pulse can be generated in single-and dual-waveband regions. When the multi-wavelength DSR works in the 1038 nm waveband, the pulse duration can broaden from 2 ns to 37.7 ns. The maximum intra-cavity pulse energy is 152.7 nJ. When the DSR works in the 1038 nm and 1080 nm wavebands, the pulse duration can be tuned from2.3 ns to 10.5 ns with rising pump power. The emergence of the 1080 nm waveband is attributed to the stimulated Raman scattering(SRS) effect. Our work might help a deeper insight to be gained into DSR pulses in all-normal-dispersion YDFLs.展开更多
Fiber laser technology has experienced a rapid growth over the past decade owing to increased applications in precision measurement and optical testing,medical care,and industrial applications,including laser welding,...Fiber laser technology has experienced a rapid growth over the past decade owing to increased applications in precision measurement and optical testing,medical care,and industrial applications,including laser welding,cleaning,and manufacturing.A fiber laser can output laser pulses with high energy,a high repetition rate,a controllable wavelength,low noise,and good beam quality,making it applicable in photoacoustic imaging.Herein,recent developments in fiber-laser-based photoacoustic microscopy(PAM)are reviewed.Multispectral PAM can be used to image oxygen saturation or lipid-rich biological tissues by applying a Q-switched fiber laser,a stimulated Raman scattering-based laser source,or a fiber-based supercontinuum source for photoacoustic excitation.PAM can also incorporate a single-mode fiber laser cavity as a high-sensitivity ultrasound sensor by measuring the acoustically induced lasing-frequency shift.Because of their small size and high flexibility,compact head-mounted,wearable,or hand-held imaging modalities and better photoacoustic endoscopes can be enabled using fiber-laser-based PAM.展开更多
An all-fiber dumbbell-shaped dual-amplifier mode-locked Er-doped laser that can function in dissipative soliton resonance(DSR)regime is demonstrated.A nonlinear optical loop mirror(NOLM)and a nonlinear amplifying loop...An all-fiber dumbbell-shaped dual-amplifier mode-locked Er-doped laser that can function in dissipative soliton resonance(DSR)regime is demonstrated.A nonlinear optical loop mirror(NOLM)and a nonlinear amplifying loop mirror(NALM)are employed to initiate the mode-locking pulses.Unlike conventional single-amplifier structure,the output peak power of which remains unchanged when pump power is varied,the proposed structure allows its output peak power to be tuned by changing the pump power of the two amplifiers while the pulse duration is directly determined by the amplifier of nonlinear amplifying loop mirror.The entire distribution maps of peak power and pulse duration clearly demonstrate that the two amplifiers are related to each other,and they supply directly a guideline for designing tunable peak power DSR fiber laser.Pulse width can change from 800 ps to 2.6 ns and peak power varies from 13 W to 27 W.To the best of our knowledge,the peak power tunable DSR pulse is observed for the first time in dumbbell-shaped Er-doped all-fiber mode-locked lasers.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 62175116 and 91950105)the 1311 Talent Plan of Nanjing University of Posts and Telecommunications, Chinathe Postgraduate Research & Practice Innovation Program, Jiangsu Province, China (Grant No. SJCX21_0276)
文摘We present a Brillouin–Raman random fiber laser(BRRFL)with full-open linear cavity structure to generate broadband Brillouin frequency comb(BFC)with double Brillouin-frequency-shift spacing.The incorporation of a regeneration portion consisting of an erbium-doped fiber and a single-mode fiber enables the generation of broadband BFC.The dynamics of broadband BFC generation changing with the pump power(EDF and Raman)and Brillouin pump(BP)wavelength are investigated in detail,respectively.Under suitable conditions,the bidirectional BRRFL proposed can produce a flatamplitude BFC with 40.7-nm bandwidth ranging from 1531 nm to 1571.7 nm,and built-in 242-order Brillouin Stokes lines(BSLs)with double Brillouin-frequency-shift spacing.Moreover,the linewidth of single BSL is experimentally measured to be about 2.5 kHz.The broadband bidirectional narrow-linewidth BRRFL has great potential applications in optical communication,optical sensing,spectral measurement,and so on.
基金Project supported by the National Natural Science Foundation of China(Grant No.62275272)the Training Program for Excellent Young Innovators of Changsha,China(Grant No.KQ2206003).
文摘We report a single-frequency linearly polarized Q-switched fiber laser based on an Nb_(2)GeTe_(4)saturable absorber(SA).The Nb_(2)GeTe_(4)SA triggers passive Q-switching of the laser,and an un-pumped Yb-doped fiber together with a 0.08-nmbandwidth polarization-maintaining fiber Bragg grating(FBG)acts as an ultra-narrow bandwidth filter to realize singlelongitudinal-mode(SLM)oscillation.The devices used in the laser are all kept polarized,so as to ensure linearly polarized laser output.Stable SLM linearly polarized Q-switching operation at 1064.6 nm is successfully achieved,producing a laser with a shortest pulse width of 1.36μs,a linewidth of 28.4 MHz,a repetition rate of 28.3 kHz-95.9 kHz,and a polarization extinction ratio of about 30 dB.It is believed that the single-frequency linearly polarized pulsed fiber laser studied in this paper has great application value in gravitational wave detection,beam combining,nonlinear frequency conversion,and other fields.
基金supported by the National Natural Science Foundation of China (Grant No. 41875040)the Natural Science Foundation of Anhui Province, China (Grant No. 2008085MF211)+1 种基金the Foundation for Young Talents in College of Anhui Province, China (Grant No. gxyqZD2019034)the Innovation Fund for Postgraduates of Huaibei Normal University, China (Grant No. CX2022035)。
文摘We present experimental observations of soliton pulsations in the net normal-dispersion fiber laser by using the dispersive Fourier transform(DFT) technique. According to the pulsating characteristics, the soliton pulsations are classified as visible and invisible soliton pulsations. The visible soliton pulsation is converted from single-into dual-soliton pulsation with the common characteristics of energy oscillation and bandwidth breathing. The invisible soliton pulsation undergoes periodic variation in the spectral profile and peak power but remains invariable in pulse energy. The reason for invisible soliton pulsation behavior is periodic oscillation of the pulse inside the soliton molecule. These results could be helpful in deepening our understanding of the soliton pulsation phenomena.
基金Beijing Great Wall Scholars Program(Grant No.CIT&TCD20190323)Beijing Youth Talent Support Program(Grant No.Z2019042)the National Natural Science Foundation of China(Grant No.61875237).
文摘A multiwavelength tunable ring-cavity erbium-doped fiber laser(EDFL)based on a Lyot filter was presented.For the proposed Lyot filter,a comb filter consisting of an EDF-polarization-maintaining fiber(EDF-PMF),a polarization controller(PC),and a circulator with four ports was used to suppress the mode competition.The light transmission direction was guaranteed by the circulator.For the proposed fiber laser,tunable single,dual,triple,quadruple,quintuple,sextuple,and septuple wavelengths were realized.A single-wavelength laser output with an optical signal-to-noise ratio(SNR)of up to30.56 dB was realized,and a tuning range of 1590.54 nm to 1599.54 nm was achieved by tuning the PC.The stability of the single,dual,triple,and quadruple-wavelength center power fluctuations was less than 0.05 dB,0.98 dB,5.07 dB,and7.71 dB respectively.When the laser was operated in the multiwavelength condition,the SNR was more than 20.97 dB.The proposed erbium-doped fiber laser is suitable for fiber-sensing system applications.
基金the financial support from Science and Technology Project of the Jilin Provincial Department of Education (Grant No. JJKH20231171KJ)。
文摘The understanding of soliton dynamics promotes the development of ultrafast laser technology. High-energy purequartic solitons(PQSs) have gradually become a hotspot in recent years. Herein, we numerically study the influence of the gain bandwidth, saturation power, small-signal gain, and output coupler on PQS dynamics in passively mode-locked fiber lasers. The results show that the above four parameters can affect PQS dynamics. Pulsating PQSs occur as we alter the other three parameters when the gain bandwidth is 50 nm. Meanwhile, PQSs evolve from pulsating to erupting and then to splitting as the other three parameters are altered when the gain bandwidth is 10 nm, which can be attributed to the existence of the spectral filtering effect and intra-cavity fourth-order dispersion. These findings provide new insights into PQS dynamics in passively mode-locked fiber lasers.
文摘Objective:The holmium:yttrium-aluminium-garnet laser(Ho:YAG)has been the gold standard for laser lithotripsy over the last three decades.After demonstrating good in vitro efficacy,the thulium fiber laser(TFL)has been recently released in the market and the initial clinical results are encouraging.This article aims to review the main technology differences between the Ho:YAG laser and the TFL,discuss the initial clinical results with the TFL as well as the optimal settings for TFL lithotripsy.Methods:We reviewed the literature focusing on the technological aspects of the Ho:YAG laser and TFL as well as the results of in vitro and in vivo studies comparing both technologies.Results:In vitro studies show a technical superiority of TFL compared to the Ho:YAG laser and encouraging results have been demonstrated in clinical practice.However,as TFL is a new technology,limited studies are currently available,and the optimal settings for lithotripsy are not yet established.Conclusion:TFL has the potential to be an alternative to the Ho:YAG laser,but more reports are still needed to determine the optimal laser for lithotripsy of urinary tract stones when considering all parameters including effectiveness,safety,and costs.
基金support for this work through Grant, HiCoE (PRC-2022)the Universiti Malaya for the funding of this work through Grant Nos. RU005-2021 and MGO23-2022。
文摘We demonstrate antimonene as a saturable absorber(SA) to generate an ultrafast mode-locked and Q-switched laser in the 2 μm wavelength region. The two antimonene-based SAs were prepared and inserted separately in a thulium–holmiumdoped fiber laser to produce the pulsed laser. Antimonene was coated onto a tapered fiber to generate soliton mode-locked pulses and used in thin-film form for the generation of Q-switched pulses. The mode-locking was stable within a pump power of 267 m W–511 m W, and the laser operated at a central wavelength of 1897.4 nm. The mode-locked laser had a pulse width of 1.3 ps and a repetition rate of 12.6 MHz, with a signal-to-noise ratio of 64 d B. Q-switched laser operation was stable at a wavelength of 1890.1 nm within a pump power of 312 m W–381 m W. With the increase in pump power from 312 m W to 381 m W, the repetition rate increased to a maximum of 56.63 k Hz and the pulse width decreased to a minimum value of 2.85 μs. Wide-range tunability of the Q-switched laser was also realized within the wavelength range of1882 nm–1936 nm.
基金the National Natural Science Foundation of China(Grant No.6170031626)the Natural Science Foundation of Chongqing City,China(Grant Nos.cstc2018jcyjAX0585 and cstc2017zdzxX0011).
文摘We experimentally demonstrated a stable multi-wavelength bright-dark pulse pair in a mode-locked thulium-doped fiber laser(TDFL).The nonlinear polarization rotation(NPR)and nonlinear optical loop mirror(NOLM)were employed in a figure-eight cavity to allow for multi-wavelength mode-locking operation.By incorporating different lengths of high birefringence polarization-maintaining fiber(PMF),the fiber laser could operate stably in a multi-wavelength emission state.Compared with the absence of the PMF,the birefringence effect caused by PMF resulted in rich multi-wavelength optical spectra and better intensity symmetry and stability of the bright-dark pulse pair.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60878011 and 61078008)the Program for New Century ExcellentTalents in University,China (Grant No. NCET-10-0067)
文摘In this paper,the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber(TDF) laser is investigated.The analytical formulations of pump energy threshold,peak power extraction efficiency,and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse.They are useful for understanding,designing,and optimizing the in-band pumped TDF lasers in a 1.9 μm-2.1 μm wavelength region.The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted,and our experimental results show good agreement with theoretical analysis.
基金Project supported by the Central University Special Fund Basic Research and Operating Expenses,China(Grant No.GK201702005)the Natural Science Foundation of Shaanxi Province,China(Grant No.2017JM6091)+1 种基金the National Natural Science Foundation of China(Grant No.61705183)the Fundamental Research Funds for the Central Universities,China(Grant No.2017TS011)
文摘The carboxyl-functionalized graphene oxide(GO-COOH) is a kind of unique two-dimensional(2 D) material and possesses excellent nonlinear saturable absorption property and high water-solubility. In this paper, we prepare saturable absorber(SA) device by depositing GO-COOH nanosheets aqueous solution on a D-shaped fiber. The modulation depth(MD) and saturable intensity of the SA are measured to be 9.6% and 19 MW/cm^2, respectively. By inserting the SA into the erbium-doped fiber(EDF) laser, a passively mode-locked EDF laser has been achieved with the spectrum center wavelength of 1562.76 nm. The pulse duration, repetition rate, and the signal-to-noise ratio(SNR) are 500 fs, 14.79 MHz, and 80 dB,respectively. The maximum average output power is measured to be 3.85 mW. These results indicate that the GO-COOH nanosheets SA can be used as a promising mode locker for the generation of ultrashort pulses.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61307057 and 61675114)
文摘This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the power transfer between the core modes and the cladding modes during thermally-induced refractive index variations is established based on the mode coupling theory. The results of numerical simulations based on actual laser parameters are presented. Experimental measurements were also carried out, the results showed good agreement with the corresponding simulation results.
基金Agency for Science,Technology and Research(A^*STAR)Singapore through the X-ray Photonics Programme(1426500052)A^*STAR Graduate Academy through the A^*STAR Graduate Scholarship.
文摘We report the generation of high energy 2μm picosecond pulses from a thulium-doped fiber master oscillator power amplifier system.The all-fiber configuration was realized by a flexible large-mode area photonic crystal fiber(LMA-PCF).The amplifier output is a linearly-polarized 1.5 ns,100 kHz pulse train with a pulse energy of up to 250μJ.Pulse compression was achieved with(2+2)-pass chirped volume Bragg grating(CVBG)to obtain a 2.8 ps pulse width with a total pulse energy of 46μJ.The overall system compactness was enabled by the all-fiber amplifier design and the multi-pass CVBG-based compressor.The laser output was then used to demonstrate high-speed direct-writing capability on a temperature-sensitive biomaterial to change its topography(i.e.fabricate microchannels,foams and pores).The topographical modifications of biomaterials are known to influence cell behavior and fate which is potentially useful in many cell and tissue engineering applications.
基金the Ministry of Higher Education of Malaysia(MOHE)(Grant No.FRGS/1/2019/STG02/UPM/02/4).
文摘We propose and demonstrate a passively mode-locked erbium-doped fiber laser(EDFL)based on zinc-oxide/polydimethylsiloxane(ZnO/PDMS)saturable absorber(SA)that evanescently interacts with the light on a tapered fiber.The ZnO/PDMS composite is coated on the whole surface of the tapered fiber to guarantee the maximum efficiency of the SA device,with a measured insertion loss of 0.87 dB and a modulation depth of 6.4%.The proposed laser can generate soliton mode-locking operation at a threshold power of 33.07 mW.The generated output pulse yields a repetition rate and pulse width of 9.77 MHz and 1.03 ps,respectively.These results indicate that the proposed ZnO/PDMS-clad tapered fiber could be useful as an efficient,compatible,and low-cost SA device for ultrafast laser applications.
基金Project supported by the National Natural Science Foundation of China (Grant No. 61875094)China Postdoctoral Science Foundation (Grant No. 2018M642386)K. C. Wong Magna Fund in Ningbo University
文摘We demonstrate multiwavelength Brillouin fiber lasers(MWBFLs)with double-frequency spacing based on a small-core fiber(SCF)and a standard single-mode fiber(SMF),which have core diameters of 5 and 8.8μm,respectively.Experimental results show that the SCF-based MWBFL exhibits a higher laser output power and a lower pump threshold.The output powers of the SCF-based MWBFL are>1.4 times those of the SMF-based MWBFL.Moreover,the threshold power required to generate each channel of the SCF-based MWBFL is 59%that of the SMF-based MWBFL.When the same pump power of 180 mW is injected,the number of laser channels generated for the SCF-based MWBFL is 13,which is twice that generated for the SMF-based MWBFL.In addition,the SCF-based MWBFL exhibits good wavelength tunability from 1535 to 1565 nm and temporal stability over an hour.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61525505,11774310,and 62035010)the Postdoctoral Science Foundation of China(Grant No.2019M652076).
文摘A novel organized multipulse pattern and its birth dynamics under strong optomechanical effect in microfiber-assisted ultrafast fiber laser are investigated in this work.The background pulses are observed to obviously exhibit selectively amplifying self-organized process of evolving into quasi-stable equidistant clusters.The radio frequency spectrum of the multipulse pattern displays a harmonic mode-locking-like behavior with a repetition rate of 2.0138 GHz,corresponding to the frequency of torsional-radial(TR_(2m))acoustic mode in microfiber.The results show the evidence of optomechanical effect in dominating the birth dynamics and pattern of multipulse.
基金Supported by the University of Malaya under Grant No PG173-2015B
文摘We demonstrate a Q-switched erbium-doped fiber laser(EDFL) using a newly developed zinc oxide-(ZnO) based saturable absorber(SA). The SA is fabricated by embedding a prepared ZnO powder into a poly(vinyl alcohol)film. A small piece of the film is then sandwiched between two fiber ferrules and is incorporated in an EDFL cavity for generating a stable Q-switching pulse train. The EDFL operates at 1560.4 nm with a pump power threshold of 11.8 mW, a pulse repetition rate tunable from 22.79 to 61.43 kHz, and the smallest pulse width of 7.00 μs. The Q-switching pulse shows no spectral modulation with a peak-to-pedestal ratio of 62 dB indicating the high stability of the laser. These results show that the ZnO powder has a great potential to be used for pulsed laser applications.
基金Project supported by the Yunnan Fundamental Research Projects(Grant No.202201AU070065)Natural Science Foundation of China for Young Scholars(Grant No.52002131)+1 种基金Open Fund of the Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques(Grant No.2021-04)the Scientific Research Fund Project of Yunnan Provincial Department of Education(Grant No.2022J0591)
文摘A 135 mW single-frequency distributed Bragg reflector fiber laser at 1.95μm was obtained based on a Tm:YAG ceramic-derived all-glass fiber.The fiber laser achieved an optical signal-to-noise ratio of~77 d B.Moreover,the threshold and linewidth of the single-frequency laser were measured to be 15.4 mW and 4.5 kHz,respectively.In addition,the measured relative intensity noise was less than-140 d B·Hz^(-1)at frequencies of over 10 MHz.The results show that the as-drawn Tm:YAG ceramic-derived all-glass fiber is highly promising for~2μm single-frequency fiber laser applications.
基金supported by the National Natural Science Foundation of China (Grant No. 41875040)the Natural Science Foundation of Anhui Province,China (Grant No. 2008085MF211)+1 种基金the Foundation for Young Talents in College of Anhui Province (Grant No. gxyqZD2019034)the Key Natural Science Research Project for Colleges and Universities of Anhui Province,China (Grant No. KJ2020A0027)。
文摘Multi-wavelength square pulses are generated in the dissipative soliton resonance(DSR) regime by a Yb-doped fiber laser(YDFL) with a long cavity configuration. The spectral filter effect provided by a passive fiber with low-stress birefringence facilitates the establishment of multi-wavelength operation. Through appropriate control of the cavity parameters,a multi-wavelength DSR pulse can be generated in single-and dual-waveband regions. When the multi-wavelength DSR works in the 1038 nm waveband, the pulse duration can broaden from 2 ns to 37.7 ns. The maximum intra-cavity pulse energy is 152.7 nJ. When the DSR works in the 1038 nm and 1080 nm wavebands, the pulse duration can be tuned from2.3 ns to 10.5 ns with rising pump power. The emergence of the 1080 nm waveband is attributed to the stimulated Raman scattering(SRS) effect. Our work might help a deeper insight to be gained into DSR pulses in all-normal-dispersion YDFLs.
基金This work was supported by the National Natural Science Foundation of China,Nos.61775083 and 61805102.
文摘Fiber laser technology has experienced a rapid growth over the past decade owing to increased applications in precision measurement and optical testing,medical care,and industrial applications,including laser welding,cleaning,and manufacturing.A fiber laser can output laser pulses with high energy,a high repetition rate,a controllable wavelength,low noise,and good beam quality,making it applicable in photoacoustic imaging.Herein,recent developments in fiber-laser-based photoacoustic microscopy(PAM)are reviewed.Multispectral PAM can be used to image oxygen saturation or lipid-rich biological tissues by applying a Q-switched fiber laser,a stimulated Raman scattering-based laser source,or a fiber-based supercontinuum source for photoacoustic excitation.PAM can also incorporate a single-mode fiber laser cavity as a high-sensitivity ultrasound sensor by measuring the acoustically induced lasing-frequency shift.Because of their small size and high flexibility,compact head-mounted,wearable,or hand-held imaging modalities and better photoacoustic endoscopes can be enabled using fiber-laser-based PAM.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61435009,61235008,and 61405254).
文摘An all-fiber dumbbell-shaped dual-amplifier mode-locked Er-doped laser that can function in dissipative soliton resonance(DSR)regime is demonstrated.A nonlinear optical loop mirror(NOLM)and a nonlinear amplifying loop mirror(NALM)are employed to initiate the mode-locking pulses.Unlike conventional single-amplifier structure,the output peak power of which remains unchanged when pump power is varied,the proposed structure allows its output peak power to be tuned by changing the pump power of the two amplifiers while the pulse duration is directly determined by the amplifier of nonlinear amplifying loop mirror.The entire distribution maps of peak power and pulse duration clearly demonstrate that the two amplifiers are related to each other,and they supply directly a guideline for designing tunable peak power DSR fiber laser.Pulse width can change from 800 ps to 2.6 ns and peak power varies from 13 W to 27 W.To the best of our knowledge,the peak power tunable DSR pulse is observed for the first time in dumbbell-shaped Er-doped all-fiber mode-locked lasers.