We demonstrate a Q-switched ytterbium-doped fiber laser （YDFL） using a newly developed multi-layer black phosphorous （BP） saturable absorber （SA）. The BP SA is prepared by mechanically exfoliating a BP crystal a...We demonstrate a Q-switched ytterbium-doped fiber laser （YDFL） using a newly developed multi-layer black phosphorous （BP） saturable absorber （SA）. The BP SA is prepared by mechanically exfoliating a BP crystal and sticking the acquired BP flakes onto a scotch tape. A small piece of the tape is then placed between two ferrules and incorporated in a YDFL cavity to achieve a stable Q-switched operation in a 1.0 μm region. The laser has a pump threshold of 55.1 mW, a pulse repetition rate that is tunable from 8.2 to 32.9 kHz, and the narrowest pulse width of 10.8 μs. The highest pulse energy of 328 nJ is achieved at the pump power of 97.6 mW. Our results show that multi-layer BP is a promising SA for Q-switching laser operation.展开更多
By using a loop mirror filter, a novel wavelength-tunable single-frequency ytterbium-doped fiber laser is developed to select single longitudinal modes in a linear cavity. The output wavelength could be tuned 2.4 nm i...By using a loop mirror filter, a novel wavelength-tunable single-frequency ytterbium-doped fiber laser is developed to select single longitudinal modes in a linear cavity. The output wavelength could be tuned 2.4 nm intervals range from 1063.3 to 1065.Tnrn with the temperature change of the fiber Bragg grating. The maximum output power could reach 32 m W while the pump power increases to 120 m W. The corresponding optical-to-optical conversion efficiency is 26.7% and the slope efficiency is 33.9%, respectively. The output power fluctuation is below 2%, and its highest signal-to-noise ratio is 60 dB.展开更多
We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-...We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-NPs into a polyvinyl alcohol （PVA） as a host polymer, and then inserted between two fiber ferrules to act as a saturable absorber （SA）. By incorporating the Al2O3-PVA SA into the laser cavity, a stable dual-wavelength pulse output centered at 1050 and 1060.7nm is observed at threshold pump power of 80mW. As the pump power is gradually increased from 80 to 300mW, the repetition rate of the generated pulse increases from 16.23 to 59 kHz, while the pulse width decreases from 19 to 6μs. To the best of our knowledge, this is the first demonstration for this type of SA operating in the 1 μm region.展开更多
We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intens...We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of -- 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.展开更多
The potential of bulk-like WTe2 particles for the realization of a passive Q-switch operating at the 1 μm wavelength was investigated. The WTe2 particles were prepared using a simple mechanical exfoliation method tog...The potential of bulk-like WTe2 particles for the realization of a passive Q-switch operating at the 1 μm wavelength was investigated. The WTe2 particles were prepared using a simple mechanical exfoliation method together with Scotch tape. By attaching bulk-like WTe2 particles, which remained on the top of the sticky surface of a small segment of the Scotch tape, to the flat side of a side-polished fiber, a saturable absorber（SA） was readily implemented. A strong saturable absorption was then readily obtained through an evanescent field interaction with the WTe2 particles. The modulation depth of the prepared SA was measured as ~2.18% at 1.03 μm. By incorporating the proposed SA into an all-fiberized ytterbium-doped fiber ring cavity, stable Qswitched pulses were readily achieved.展开更多
A tunable passively Q-switched ytterbium-doped fiber laser using few-layer gallium selenide（GaSe） as a saturable absorber（SA） is demonstrated.The few-layer GaSe SA,which is fabricated by the mechanical exfoliation...A tunable passively Q-switched ytterbium-doped fiber laser using few-layer gallium selenide（GaSe） as a saturable absorber（SA） is demonstrated.The few-layer GaSe SA,which is fabricated by the mechanical exfoliation method,is able to generate a Q-switched fiber laser that has a maximum repetition rate of 92.6 kHz and a minimum pulsed width of 2.3 μs.The highest pulse energy exhibited by the generated pulse is 18.8 nJ with a signal to noise ratio of ~40 dB.The tunability of the proposed laser covers from 1042 to 1082 nm,giving a tuning range of 40 nm.展开更多
A wavelength-interval switchable Brillouin–Raman random fiber laser(BRRFL) based on Brillouin pump(BP) manipulation is proposed in this paper. The proposed wavelength-interval switchable BRRFL has a full-open cavity ...A wavelength-interval switchable Brillouin–Raman random fiber laser(BRRFL) based on Brillouin pump(BP) manipulation is proposed in this paper. The proposed wavelength-interval switchable BRRFL has a full-open cavity configuration, featuring multiwavelength output with wavelength interval of double Brillouin frequency shifts. Through simultaneously injecting the BP light and its first-order stimulated Brillouin-scattered light into the cavity, the laser output exhibits a wavelength interval of single Brillouin frequency shift. The wavelength-interval switching effect can be manipulated by controlling the power of the first-order stimulated Brillouin scattering light. The experimental results show the multiwavelength output can be switched between double Brillouin frequency shift multiwavelength emission with a broad bandwidth of approximately 60 nm and single Brillouin frequency shift multiwavelength emission of 44 nm. The flexible optically controlled random fiber laser with switchable wavelength interval makes it useful for a wide range of applications and holds significant potential in the field of wavelength-division multiplexing optical communication.展开更多
Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers r...Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive.We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations.We find that net dispersion,linear loss,gain and filter shaping can affect the quality of Nyquist pulses significantly.We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium.Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers.展开更多
Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback ...Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback structure should be established to realize phase-locking. In this paper, an innovative internal active phase control CBC fiber laser array based on photodetector array is proposed. The dynamic phase noises of the laser amplifiers are compensated before being emitted into free space. And the static phase difference compensation of emitting laser array is realized by interference measurement based on photodetector array. The principle of the technique is illustrated and corresponding simulations are carried out, and a CBC system with four laser channels is built to verify the technique. When the phase controllers are turned on, the phase deviation of the laser array is less than λ/20, and ~ 95% fringe contrast of the irradiation distribution is obtained. The technique proposed in this paper could provide a reference for the system design of a massive high-power CBC system.展开更多
In this work,we theoretically unlock the potential of Ho^(3+)-doped InF3 fiber for efficient~3.2μm laser generation(from the ^(5)F_(4),^(5)S_(2)→^(5)F_(5) transition),by employing a novel dual-wavelength pumping sch...In this work,we theoretically unlock the potential of Ho^(3+)-doped InF3 fiber for efficient~3.2μm laser generation(from the ^(5)F_(4),^(5)S_(2)→^(5)F_(5) transition),by employing a novel dual-wavelength pumping scheme at 1150 nm and 980 nm,for the first time.Under clad-coupled 1150 nm pumping of 5 W,~3.2μm power of 3.6 W has been predicted with the optical-to-optical efficiency of 14.4%.Further efficient power scaling,however,is blocked by the output saturation with 980 nm pumping.To alleviate this behavior,the cascaded ^(5)I_(5)→^(5)I_(6) transition,targeting~3.9μm,has been activated simultaneously,therefore accelerating the population circulation between the laser upper level ^(5)F_(4),^(5)S_(2) and long-lived ^(5)I_(6) level under 980 nm pumping.As a result,enhanced~3.2μm power of 4.68 W has been obtained with optical-to-optical efficiency of 15.6%.Meanwhile the~3.9μm laser,yielding power of 2.76 W with optical-to-optical efficiency of 9.2%,is theoretically achievable as well with a moderate heat load,of which the performance is even better than the prior experimentally and theoretically reported Ho^(3+)-doped InF3 fiber lasers emitting at~3.9μm alone.This work demonstrates a versatile platform for laser generation at~3.2μm and~3.9μm,thus providing the new opportunities for many potential applications,e.g.,polymer processing,infrared countermeasures,and free-space communications.展开更多
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
A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetr...A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.展开更多
Optical memory effect-based speckle-correlated technology has been developed for reconstructing hidden objectsfrom disordered speckle patterns,achieving imaging through scattering layers.However,the lighting efficienc...Optical memory effect-based speckle-correlated technology has been developed for reconstructing hidden objectsfrom disordered speckle patterns,achieving imaging through scattering layers.However,the lighting efficiency and fieldof view of existing speckle-correlated imaging systems are limited.Here,a near-infrared low spatial coherence fiberrandom laser illumination method is proposed to address the above limitations.Through the utilization of random Rayleighscattering within dispersion-shifted fibers to provide feedback,coupled with stimulated Raman scattering for amplification,a near-infrared fiber random laser exhibiting a high spectral density and extremely low spatial coherence is generated.Based on the designed fiber random laser,speckle-correlated imaging through scattering layers is achieved,with highlighting efficiency and a large imaging field of view.This work improves the performance of speckle-correlated imagingand enriches the research on imaging through scattering medium.展开更多
A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine(ZnPc)thin film as passive saturable absorber(SA)in ytterbium-doped fiber laser(YDFL).The ZnPc thin film was obtained using a cast...A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine(ZnPc)thin film as passive saturable absorber(SA)in ytterbium-doped fiber laser(YDFL).The ZnPc thin film was obtained using a casting method and then inserted between the two fiber ferrules of a YDFL ring cavity to generate mode-locked pulses.The resulting pulsed laser operated at a wavelength of 1034.5 nm having a repetition rate of 3.3 MHz.At pump power of 277 mW,the maximum output power and pulse energy are achieved at 4.92 mW and 1.36 nJ,respectively.ZnPc has a high chemical and photochemical stability,and its significance for use as a potential SA in a mode-locked laser is reported in this work.展开更多
We demonstrate a kW continuous-wave ytterbium-doped all-fiber laser oscillator with M1 domestic fiber compo- nents： a 7× I fused fiber bundle combiner, a fiber Bragg grating and a double-clad gain fiber. The osc...We demonstrate a kW continuous-wave ytterbium-doped all-fiber laser oscillator with M1 domestic fiber compo- nents： a 7× I fused fiber bundle combiner, a fiber Bragg grating and a double-clad gain fiber. The oscillator operates at 1079.48nrn with 80.94% slope efficiency and shows no limit of temperature and nonlinear effects. These indicate that the passive fiber components and the gain fiber are all qualified for the high power environ- ment. No evidence of the signal power roll-over shows that this oscillator possesses the capacity to higher output with available pump power.展开更多
A diode-pumped, acousto-optic Q-switched fiber laser is presented based on multimode ytterbium-doped fiber. The fiber with core diameter of 30 μm is used to increase the laser gain volume and the pulse energy efficie...A diode-pumped, acousto-optic Q-switched fiber laser is presented based on multimode ytterbium-doped fiber. The fiber with core diameter of 30 μm is used to increase the laser gain volume and the pulse energy efficiently. The average power in excess of 9 W is obtained at the repetition rate of 20 kHz with 66% slope efficiency. The pulse width is 198 ns with no evident amplified spontaneous emission between pulses, thus the pulse energy and peak power are 465 μJ and 2.36 kW, respectively.展开更多
With the rapid development of ytterbium-doped fiber lasers, some obtrusive limitations on power scaling appeared. In order to avoid these problems, a scheme called tandem pumping is introduced into the fiber laser fie...With the rapid development of ytterbium-doped fiber lasers, some obtrusive limitations on power scaling appeared. In order to avoid these problems, a scheme called tandem pumping is introduced into the fiber laser field. In this paper, the optical properties of an ytterbium-doped tandem-pumped fiber oscillator are presented. According to the oscillator profile, the proper gain fiber type and pump wavelength range are picked out, under the comprehensive consideration of laser conversion efficiency and beam quality. In addition, the photodarkening performances of tandem pumping lasers and conventional ones are compared based on practical application, with all possible impact parameters taken into account. Moreover, an all-fibered tandem-pumped oscillator centered at 1079.5 nm is built, in the way of clad pumping by a 1030-nm fiber laser. The laser power of the oscillator reaches 7 W, with an opto-optic efficiency of 82.4%.展开更多
The third paragraph in Sec.IV REGENERATIVE AMPLIFICATION erroneously states“In other words,the distribution of spectral components is time-dependent,and the spectral distortion in the amplification process will not c...The third paragraph in Sec.IV REGENERATIVE AMPLIFICATION erroneously states“In other words,the distribution of spectral components is time-dependent,and the spectral distortion in the amplification process will not change the time-domain shape.”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
Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target produc...Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target products were characterized by thermogravimetric analyzer,X-ray diffrotometer,fourier transform infrared spectrometer,scanning electron microscope,spectrophotometer and infrared emissivity tester,and the effects of Er^(3+)doping on its infrared and laser emissivity were studied.At the same time,the Sn_(1−x)Er_(x)O_(2)(x=0%,16%)doping models were constructed based on the first principles of density functional theory,and the related optoelectronic properties such as their energy band structure,density of states,reflectivity and dielectric constant were analyzed,and further explained the mechanism of Er^(3+)doping on SnO_(2)infrared emissivity and laser absorption from the point of electronic structure.The results showed that after calcination at 600℃,single rutile type SnO_(2)was formed,and the crystal structure was not changed by doping Er^(3+).The calcined products showed good fiber morphology,and the average fiber diameter was 402 nm.The infrared emissivity and resistivity of the samples both decreased first and then increased with the increase of Er^(3+)doping amount.When x=16%,the infrared emis-sivity of the sample was at least 0.71;and Er^(3+)doping can effectively reduce the reflectivity of SnO_(2)at 1.06μm and 1.55μm,when x=16%,its reflectivity at 1.06μm and 1.55μm are 50.5%and 40%,respectively,when x=24%,the reflectivity at 1.06μm and 1.55μm wavelengths are 47.3%and 42.1%,respectively.At the same time,the change of carrier concentration and electron transition before and after Er^(3+)doping were described by first-principle calculation,and the regulation mechanism of infrared emissivity and laser reflectivity was explained.This study provides a certain experimental and theoretical basis for the development of a single-type,light-weight and easily prepared infrared and laser compatible-stealth material.展开更多
基金Supported by the University of Malaya under Grant No PG100-2014B
文摘We demonstrate a Q-switched ytterbium-doped fiber laser （YDFL） using a newly developed multi-layer black phosphorous （BP） saturable absorber （SA）. The BP SA is prepared by mechanically exfoliating a BP crystal and sticking the acquired BP flakes onto a scotch tape. A small piece of the tape is then placed between two ferrules and incorporated in a YDFL cavity to achieve a stable Q-switched operation in a 1.0 μm region. The laser has a pump threshold of 55.1 mW, a pulse repetition rate that is tunable from 8.2 to 32.9 kHz, and the narrowest pulse width of 10.8 μs. The highest pulse energy of 328 nJ is achieved at the pump power of 97.6 mW. Our results show that multi-layer BP is a promising SA for Q-switching laser operation.
基金Supported by the International Cooperation Projects of Ministry of Science and Technology under Grant No 2012DFB10120the National Natural Science Foundation of China under Grant No 61177059
文摘By using a loop mirror filter, a novel wavelength-tunable single-frequency ytterbium-doped fiber laser is developed to select single longitudinal modes in a linear cavity. The output wavelength could be tuned 2.4 nm intervals range from 1063.3 to 1065.Tnrn with the temperature change of the fiber Bragg grating. The maximum output power could reach 32 m W while the pump power increases to 120 m W. The corresponding optical-to-optical conversion efficiency is 26.7% and the slope efficiency is 33.9%, respectively. The output power fluctuation is below 2%, and its highest signal-to-noise ratio is 60 dB.
基金Supported by the Iraqi Ministry of Higher Education and Scientific Research and University of Baghdad
文摘We report on generation of a dual-wavelength, all-fiber, passively Q-switched ytterbium-doped fiber laser using aluminum oxide nanoparticle （Al2O3-NP） thin film. A thin film of Al2O3 was prepared by embedding Al2O3-NPs into a polyvinyl alcohol （PVA） as a host polymer, and then inserted between two fiber ferrules to act as a saturable absorber （SA）. By incorporating the Al2O3-PVA SA into the laser cavity, a stable dual-wavelength pulse output centered at 1050 and 1060.7nm is observed at threshold pump power of 80mW. As the pump power is gradually increased from 80 to 300mW, the repetition rate of the generated pulse increases from 16.23 to 59 kHz, while the pulse width decreases from 19 to 6μs. To the best of our knowledge, this is the first demonstration for this type of SA operating in the 1 μm region.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274115 and 10990101)the National Key Project for Basic Research of China(Grant No.2011CB808105)+2 种基金the National Key Scientific Instrument Project,China(Grant No.2012YQ150092)the Natural Science Foundation of Shanghai,China(Grant No.11ZR1410900)the Innovation Program of Shanghai Municipal Education Commission,China(Grant No.2014Z10269011)
文摘We report on controllable pulse shaping in a Yb-doped stretched-pulse fiber laser followed by a high-power chirped pulse amplifier. We demonstrate that the pulses after an extra-cavity grating pair change their intensity profile from Lorentz to Gaussian and then to sech2 shapes by adjusting the intra-cavity polarization through a quarter-wave plate inside the fiber laser cavity. The laser pulses with different pulse shapes exhibit pulse-to-pulse amplitude fluctuation of -- 1.02%, while the sech2-shaped pulse train is provided with a more stable free-running repetition rate as a result of the stronger self-phase modulation in the fiber laser cavity than Lorentz- and Gaussian-shaped pulse trains.
基金supported by the National Research Foundation of Korea funded by the Korean Government(MSIT),South Korea(Grant Nos.NRF-2015R1A2A2A11000907 and NRF-2015R1A2A2A04006979)Ministry of Science and ICT(MSIT),Korea,under the Information Technology Research Center(ITRC)support program(IITP-2017-2015-0-00385),supervised by the Institute for Information and Communications Technology Promotion(IITP)
文摘The potential of bulk-like WTe2 particles for the realization of a passive Q-switch operating at the 1 μm wavelength was investigated. The WTe2 particles were prepared using a simple mechanical exfoliation method together with Scotch tape. By attaching bulk-like WTe2 particles, which remained on the top of the sticky surface of a small segment of the Scotch tape, to the flat side of a side-polished fiber, a saturable absorber（SA） was readily implemented. A strong saturable absorption was then readily obtained through an evanescent field interaction with the WTe2 particles. The modulation depth of the prepared SA was measured as ~2.18% at 1.03 μm. By incorporating the proposed SA into an all-fiberized ytterbium-doped fiber ring cavity, stable Qswitched pulses were readily achieved.
基金the Ministry of Higher Education,MOHE,for funding this work under Grant LRGS(2015) NGOD/UM/KPTthe University of Malaya,UM,for funding this work under Grant RU 001–2017
文摘A tunable passively Q-switched ytterbium-doped fiber laser using few-layer gallium selenide（GaSe） as a saturable absorber（SA） is demonstrated.The few-layer GaSe SA,which is fabricated by the mechanical exfoliation method,is able to generate a Q-switched fiber laser that has a maximum repetition rate of 92.6 kHz and a minimum pulsed width of 2.3 μs.The highest pulse energy exhibited by the generated pulse is 18.8 nJ with a signal to noise ratio of ~40 dB.The tunability of the proposed laser covers from 1042 to 1082 nm,giving a tuning range of 40 nm.
基金Poject supported by the National Natural Science Foundation of China(Grant Nos.62175116 and 62311530343)the Postgraduate Research Innovation Program of Jiangsu Province,China(Grant No.KYCX22_0913)。
文摘A wavelength-interval switchable Brillouin–Raman random fiber laser(BRRFL) based on Brillouin pump(BP) manipulation is proposed in this paper. The proposed wavelength-interval switchable BRRFL has a full-open cavity configuration, featuring multiwavelength output with wavelength interval of double Brillouin frequency shifts. Through simultaneously injecting the BP light and its first-order stimulated Brillouin-scattered light into the cavity, the laser output exhibits a wavelength interval of single Brillouin frequency shift. The wavelength-interval switching effect can be manipulated by controlling the power of the first-order stimulated Brillouin scattering light. The experimental results show the multiwavelength output can be switched between double Brillouin frequency shift multiwavelength emission with a broad bandwidth of approximately 60 nm and single Brillouin frequency shift multiwavelength emission of 44 nm. The flexible optically controlled random fiber laser with switchable wavelength interval makes it useful for a wide range of applications and holds significant potential in the field of wavelength-division multiplexing optical communication.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11621404,11561121003,11727812,61775059,12074122,62022033,and 11704123)Shanghai Rising-Star Program,the Sustainedly Supported Foundation by the National Key Laboratory of Science and Technology on Space Microwave(Grant No.HTKT2022KL504008)+1 种基金Shanghai Natural Science Foundation(Grant No.23ZR1419000)the National Key Laboratory Foundation of China(Grant No.6142411196307).
文摘Nyquist pulses have wide applications in many areas,from electronics to optics.Mode-locked lasers are ideal platforms to generate such pulses.However,how to generate high-quality Nyquist pulses in mode-locked lasers remains elusive.We address this problem by managing different physical effects in mode-locked fiber lasers through extensive numerical simulations.We find that net dispersion,linear loss,gain and filter shaping can affect the quality of Nyquist pulses significantly.We also demonstrate that Nyquist pulses experience similariton shaping due to the nonlinear attractor effect in the gain medium.Our work may contribute to the design of Nyquist pulse sources and enrich the understanding of pulse shaping dynamics in mode-locked lasers.
基金Project supported by the National Natural Science Foundation of China(Grant No.62275272)the Training Program for Excellent Young Innovators of Changsha(Grant No.KQ2305025)。
文摘Coherent beam combining(CBC) of fiber laser array is a promising technique to realize high output power while maintaining near diffraction-limited beam quality. To implement CBC, an appropriate phase control feedback structure should be established to realize phase-locking. In this paper, an innovative internal active phase control CBC fiber laser array based on photodetector array is proposed. The dynamic phase noises of the laser amplifiers are compensated before being emitted into free space. And the static phase difference compensation of emitting laser array is realized by interference measurement based on photodetector array. The principle of the technique is illustrated and corresponding simulations are carried out, and a CBC system with four laser channels is built to verify the technique. When the phase controllers are turned on, the phase deviation of the laser array is less than λ/20, and ~ 95% fringe contrast of the irradiation distribution is obtained. The technique proposed in this paper could provide a reference for the system design of a massive high-power CBC system.
基金supported in parts by the National Natural Science Foundation of China under Grants No.62005040 and No.U20A20210.
文摘In this work,we theoretically unlock the potential of Ho^(3+)-doped InF3 fiber for efficient~3.2μm laser generation(from the ^(5)F_(4),^(5)S_(2)→^(5)F_(5) transition),by employing a novel dual-wavelength pumping scheme at 1150 nm and 980 nm,for the first time.Under clad-coupled 1150 nm pumping of 5 W,~3.2μm power of 3.6 W has been predicted with the optical-to-optical efficiency of 14.4%.Further efficient power scaling,however,is blocked by the output saturation with 980 nm pumping.To alleviate this behavior,the cascaded ^(5)I_(5)→^(5)I_(6) transition,targeting~3.9μm,has been activated simultaneously,therefore accelerating the population circulation between the laser upper level ^(5)F_(4),^(5)S_(2) and long-lived ^(5)I_(6) level under 980 nm pumping.As a result,enhanced~3.2μm power of 4.68 W has been obtained with optical-to-optical efficiency of 15.6%.Meanwhile the~3.9μm laser,yielding power of 2.76 W with optical-to-optical efficiency of 9.2%,is theoretically achievable as well with a moderate heat load,of which the performance is even better than the prior experimentally and theoretically reported Ho^(3+)-doped InF3 fiber lasers emitting at~3.9μm alone.This work demonstrates a versatile platform for laser generation at~3.2μm and~3.9μm,thus providing the new opportunities for many potential applications,e.g.,polymer processing,infrared countermeasures,and free-space communications.
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.
文摘A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.
基金supported by the National Natural Science Foundation of China(Grant Nos.62375040 and 11974071)the Sichuan Science and Technology Program(Grant Nos.2022ZYD0108 and 2023JDRC0030).
文摘Optical memory effect-based speckle-correlated technology has been developed for reconstructing hidden objectsfrom disordered speckle patterns,achieving imaging through scattering layers.However,the lighting efficiency and fieldof view of existing speckle-correlated imaging systems are limited.Here,a near-infrared low spatial coherence fiberrandom laser illumination method is proposed to address the above limitations.Through the utilization of random Rayleighscattering within dispersion-shifted fibers to provide feedback,coupled with stimulated Raman scattering for amplification,a near-infrared fiber random laser exhibiting a high spectral density and extremely low spatial coherence is generated.Based on the designed fiber random laser,speckle-correlated imaging through scattering layers is achieved,with highlighting efficiency and a large imaging field of view.This work improves the performance of speckle-correlated imagingand enriches the research on imaging through scattering medium.
基金This work was supported in part by the Airlangga University(Grant No.804/UN3.15/PT/2021)the University of Malaya(Grant No.ML001-2017).
文摘A stable mode-locked laser was demonstrated using a newly developed zinc phthalocyanine(ZnPc)thin film as passive saturable absorber(SA)in ytterbium-doped fiber laser(YDFL).The ZnPc thin film was obtained using a casting method and then inserted between the two fiber ferrules of a YDFL ring cavity to generate mode-locked pulses.The resulting pulsed laser operated at a wavelength of 1034.5 nm having a repetition rate of 3.3 MHz.At pump power of 277 mW,the maximum output power and pulse energy are achieved at 4.92 mW and 1.36 nJ,respectively.ZnPc has a high chemical and photochemical stability,and its significance for use as a potential SA in a mode-locked laser is reported in this work.
基金Supported by the National High-Technology Research and Development Program of China under Grant No 2013AA031501the Fundamental Research Funds for the Central Universities under Grant No 2014TS017
文摘We demonstrate a kW continuous-wave ytterbium-doped all-fiber laser oscillator with M1 domestic fiber compo- nents： a 7× I fused fiber bundle combiner, a fiber Bragg grating and a double-clad gain fiber. The oscillator operates at 1079.48nrn with 80.94% slope efficiency and shows no limit of temperature and nonlinear effects. These indicate that the passive fiber components and the gain fiber are all qualified for the high power environ- ment. No evidence of the signal power roll-over shows that this oscillator possesses the capacity to higher output with available pump power.
基金This work was supported by the State Key Lab of All Optical Network & Advanced Telecommunication Network under Grant No.0501.
文摘A diode-pumped, acousto-optic Q-switched fiber laser is presented based on multimode ytterbium-doped fiber. The fiber with core diameter of 30 μm is used to increase the laser gain volume and the pulse energy efficiently. The average power in excess of 9 W is obtained at the repetition rate of 20 kHz with 66% slope efficiency. The pulse width is 198 ns with no evident amplified spontaneous emission between pulses, thus the pulse energy and peak power are 465 μJ and 2.36 kW, respectively.
文摘With the rapid development of ytterbium-doped fiber lasers, some obtrusive limitations on power scaling appeared. In order to avoid these problems, a scheme called tandem pumping is introduced into the fiber laser field. In this paper, the optical properties of an ytterbium-doped tandem-pumped fiber oscillator are presented. According to the oscillator profile, the proper gain fiber type and pump wavelength range are picked out, under the comprehensive consideration of laser conversion efficiency and beam quality. In addition, the photodarkening performances of tandem pumping lasers and conventional ones are compared based on practical application, with all possible impact parameters taken into account. Moreover, an all-fibered tandem-pumped oscillator centered at 1079.5 nm is built, in the way of clad pumping by a 1030-nm fiber laser. The laser power of the oscillator reaches 7 W, with an opto-optic efficiency of 82.4%.
文摘The third paragraph in Sec.IV REGENERATIVE AMPLIFICATION erroneously states“In other words,the distribution of spectral components is time-dependent,and the spectral distortion in the amplification process will not change the time-domain shape.”
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.
基金supported by the Key Research and Development Program of Hebei Province(No.21351501D)A Provincial and Ministerial Scientific Research Project(LJ20212C031165)Basic Frontier Science and Technology Innovation Project of Army Engineering University of PLA(KYSZJQZL2210)。
文摘Sn_(1−x)Er_(x)O_(2)(x=0%,8%,16%,24%)micro/nanofibers were prepared by electrospinning combined with heat treatment using erbium nitrate,stannous chloride and polyvinylpyrrolidone(PVP)as raw materials.The target products were characterized by thermogravimetric analyzer,X-ray diffrotometer,fourier transform infrared spectrometer,scanning electron microscope,spectrophotometer and infrared emissivity tester,and the effects of Er^(3+)doping on its infrared and laser emissivity were studied.At the same time,the Sn_(1−x)Er_(x)O_(2)(x=0%,16%)doping models were constructed based on the first principles of density functional theory,and the related optoelectronic properties such as their energy band structure,density of states,reflectivity and dielectric constant were analyzed,and further explained the mechanism of Er^(3+)doping on SnO_(2)infrared emissivity and laser absorption from the point of electronic structure.The results showed that after calcination at 600℃,single rutile type SnO_(2)was formed,and the crystal structure was not changed by doping Er^(3+).The calcined products showed good fiber morphology,and the average fiber diameter was 402 nm.The infrared emissivity and resistivity of the samples both decreased first and then increased with the increase of Er^(3+)doping amount.When x=16%,the infrared emis-sivity of the sample was at least 0.71;and Er^(3+)doping can effectively reduce the reflectivity of SnO_(2)at 1.06μm and 1.55μm,when x=16%,its reflectivity at 1.06μm and 1.55μm are 50.5%and 40%,respectively,when x=24%,the reflectivity at 1.06μm and 1.55μm wavelengths are 47.3%and 42.1%,respectively.At the same time,the change of carrier concentration and electron transition before and after Er^(3+)doping were described by first-principle calculation,and the regulation mechanism of infrared emissivity and laser reflectivity was explained.This study provides a certain experimental and theoretical basis for the development of a single-type,light-weight and easily prepared infrared and laser compatible-stealth material.
