We report an ultrafast laser mode-locked with a graphene saturable absorber.The linear dispersions of the Dirac electrons in graphene enable wideband tunability.We get-1 ps pulses,tunable between 1525 and 1559 nm,with...We report an ultrafast laser mode-locked with a graphene saturable absorber.The linear dispersions of the Dirac electrons in graphene enable wideband tunability.We get-1 ps pulses,tunable between 1525 and 1559 nm,with stable mode-locking,insensitive to environmental perturbations.展开更多
With MoS2 as saturable absorber, passive Q-switching and Q-switched mode-locking operations of a Tm-doped calcium lithium niobium gallium garnet（Tm:CLNGG） laser were experimentally demonstrated. The Q-switched laser...With MoS2 as saturable absorber, passive Q-switching and Q-switched mode-locking operations of a Tm-doped calcium lithium niobium gallium garnet（Tm:CLNGG） laser were experimentally demonstrated. The Q-switched laser emitted a maximum average output power of 62 mW and highest pulse energy of 0.72 μJ. Q-switched mode locking was also obtained in the experiment. The research results will open up applications of MoS2 at the mid-infrared wavelength.展开更多
The mode-locked fluoride fiber laser(MLFFL)is an exciting platform for directly generating ultrashort pulses in the mid-infrared(mid-IR).However,owing to difficulty in managing the dispersion in fluoride fiber lasers,...The mode-locked fluoride fiber laser(MLFFL)is an exciting platform for directly generating ultrashort pulses in the mid-infrared(mid-IR).However,owing to difficulty in managing the dispersion in fluoride fiber lasers,MLFFLs are restricted to the soliton regime,hindering pulse-energy scaling.We overcame the problem of dispersion management by utilizing the huge normal dispersion generated near the absorption edge of an infrared-bandgap semiconductor and promoted MLFFL from soliton to breathing-pulse mode-locking.In the breathing-pulse regime,the accumulated nonlinear phase shift can be significantly reduced in the cavity,and the pulse-energy-limitation effect is mitigated.The breathing-pulse MLFFL directly produced a pulse energy of 9.3 nJ and pulse duration of 215 fs,with a record peak power of 43.3 kW at 2.8μm.Our work paves the way for the pulse-energy and peak-power scaling of mid-IR fluoride fiber lasers,enabling a wide range of applications.展开更多
Real-time spectroscopy based on an emerging time-stretch technique can map the spectral information of optical waves into the time domain,opening several fascinating explorations of nonlinear dynamics in mode-locked l...Real-time spectroscopy based on an emerging time-stretch technique can map the spectral information of optical waves into the time domain,opening several fascinating explorations of nonlinear dynamics in mode-locked lasers.However,the self-starting process of mode-locked lasers is quite sensitive to environmental perturbation,which causes the transient behaviors of lasers to deviate from the true buildup process of solitons.We optimize the laser system to improve its stability,which suppresses the Q-switched lasing induced by environmental perturbation.We,therefore,demonstrate the first observation of the entire buildup process of solitons in a mode-locked laser,revealing two possible pathways to generate the temporal solitons.One pathway includes the dynamics of raised relaxation oscillation,quasimode-locking stage,spectral beating behavior,and finally the stable single-soliton mode-locking.The other pathway contains,however,an extra transient bound-state stage before the final single-pulse modelocking operation.Moreover,we propose a theoretical model to predict the buildup time of solitons,which agrees well with the experimental results.Our findings can bring real-time insights into ultrafast fiber laser design and optimization,as well as promote the application of fiber laser.展开更多
The paper summarizes the recent achievements in the area of ultrafast fiber lasers mode-locked with so-called lowdimensional nanomaterials: graphene, topological insulators（Bi2Te3, Bi2Se3, Sb2Te3）, and transition me...The paper summarizes the recent achievements in the area of ultrafast fiber lasers mode-locked with so-called lowdimensional nanomaterials: graphene, topological insulators（Bi2Te3, Bi2Se3, Sb2Te3）, and transition metal sulfide semiconductors, like molybdenum disulfide（MoS2）. The most important experimental achievements are described and compared. Additionally, new original results on ultrashort pulse generation at 1.94 μm wavelength using graphene are presented. The designed Tm-doped fiber laser utilizes multilayer graphene as a saturable absorber and generates 654 fs pulses at 1940 nm wavelength, which are currently the shortest pulses generated from a Tm-doped fiber laser with a graphene-based saturable absorber.展开更多
By reducing the effects of frequency dependent mode size and intracavity gain saturation of a KLM Ti: sapphire laser, the pulse bandwidth broadening is enhanced significantly. 8.5 fs pulses with the bandwidth of 92 nm...By reducing the effects of frequency dependent mode size and intracavity gain saturation of a KLM Ti: sapphire laser, the pulse bandwidth broadening is enhanced significantly. 8.5 fs pulses with the bandwidth of 92 nm at wavelength of 710 nm have been generated directly from this laser and measured with an extracavity group velocity dispersion compensation system.展开更多
An optoelectronic oscillator(OEO)is a microwave photonic system that produces microwave signals with ultralow phase noise using a high-quality-factor optical energy storage element.This type of oscillator is desired i...An optoelectronic oscillator(OEO)is a microwave photonic system that produces microwave signals with ultralow phase noise using a high-quality-factor optical energy storage element.This type of oscillator is desired in various practical applications,such as communication links,signal processing,radar,metrology,radio astronomy,and reference clock distribution.Recently,new mode control and selection methods based on Fourier domain mode-locking and parity-time symmetry have been proposed and experimentally demonstrated in OEOs,which overcomes the long-existing mode building time and mode selection problems in a traditional OEO.Due to these mode control and selection methods,continuously chirped microwave waveforms can be generated directly from the OEO cavity and single-mode operation can be achieved without the need of ultranarrowband filters,which are not possible in a traditional OEO.Integrated OEOs with a compact size and low power consumption have also been demonstrated,which are key steps toward a new generation of compact and versatile OEOs for demanding applications.We review recent progress in the field of OEOs,with particular attention to new mode control and selection methods,as well as chip-scale integration of OEOs.展开更多
Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor sat-urable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The aver...Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor sat-urable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.展开更多
基金We acknowledge funding from a Royal Society Brian Mercer Award for Innovation,the European Research Council(ERC)grant NANOPOTS,Engineering and Physical Sciences Research Council(EPSRC)grants(Nos.EP/GO30480/1 and EP/G042357/1),King’s College and Imperial College.
文摘We report an ultrafast laser mode-locked with a graphene saturable absorber.The linear dispersions of the Dirac electrons in graphene enable wideband tunability.We get-1 ps pulses,tunable between 1525 and 1559 nm,with stable mode-locking,insensitive to environmental perturbations.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61008018 and 11421064)the National Basic Research Program of China (Grant No. 2013CBA01505)
文摘With MoS2 as saturable absorber, passive Q-switching and Q-switched mode-locking operations of a Tm-doped calcium lithium niobium gallium garnet（Tm:CLNGG） laser were experimentally demonstrated. The Q-switched laser emitted a maximum average output power of 62 mW and highest pulse energy of 0.72 μJ. Q-switched mode locking was also obtained in the experiment. The research results will open up applications of MoS2 at the mid-infrared wavelength.
基金the National Natural Science Foundation of China(Grant Nos.61675130,91850203,and 11721091)the National Postdoctoral Program for Innovative Talents(Grant No.BX20170149).
文摘The mode-locked fluoride fiber laser(MLFFL)is an exciting platform for directly generating ultrashort pulses in the mid-infrared(mid-IR).However,owing to difficulty in managing the dispersion in fluoride fiber lasers,MLFFLs are restricted to the soliton regime,hindering pulse-energy scaling.We overcame the problem of dispersion management by utilizing the huge normal dispersion generated near the absorption edge of an infrared-bandgap semiconductor and promoted MLFFL from soliton to breathing-pulse mode-locking.In the breathing-pulse regime,the accumulated nonlinear phase shift can be significantly reduced in the cavity,and the pulse-energy-limitation effect is mitigated.The breathing-pulse MLFFL directly produced a pulse energy of 9.3 nJ and pulse duration of 215 fs,with a record peak power of 43.3 kW at 2.8μm.Our work paves the way for the pulse-energy and peak-power scaling of mid-IR fluoride fiber lasers,enabling a wide range of applications.
基金We thank X.Yao,X.Han,G.Chen,W.Li,G.Wang,and Y.Zhang for fruitful discussions.The work was supported by the National Natural Science Foundation of China under Grant Nos.61525505,11774310, 61705193by the Key Scientific and Technological Innovation Team Project in Shaanxi Province(2015KCT-06)and by China Postdoctoral Science Foundation(2017M610367).
文摘Real-time spectroscopy based on an emerging time-stretch technique can map the spectral information of optical waves into the time domain,opening several fascinating explorations of nonlinear dynamics in mode-locked lasers.However,the self-starting process of mode-locked lasers is quite sensitive to environmental perturbation,which causes the transient behaviors of lasers to deviate from the true buildup process of solitons.We optimize the laser system to improve its stability,which suppresses the Q-switched lasing induced by environmental perturbation.We,therefore,demonstrate the first observation of the entire buildup process of solitons in a mode-locked laser,revealing two possible pathways to generate the temporal solitons.One pathway includes the dynamics of raised relaxation oscillation,quasimode-locking stage,spectral beating behavior,and finally the stable single-soliton mode-locking.The other pathway contains,however,an extra transient bound-state stage before the final single-pulse modelocking operation.Moreover,we propose a theoretical model to predict the buildup time of solitons,which agrees well with the experimental results.Our findings can bring real-time insights into ultrafast fiber laser design and optimization,as well as promote the application of fiber laser.
基金supported by the National Science Centre (NCN, Poland) under the research project entitled “Passive mode-locking in dispersion-managed ultrafast thulium-doped fiber lasers” (decision no. DEC-2013/11/D/ST7/03138)
文摘The paper summarizes the recent achievements in the area of ultrafast fiber lasers mode-locked with so-called lowdimensional nanomaterials: graphene, topological insulators（Bi2Te3, Bi2Se3, Sb2Te3）, and transition metal sulfide semiconductors, like molybdenum disulfide（MoS2）. The most important experimental achievements are described and compared. Additionally, new original results on ultrashort pulse generation at 1.94 μm wavelength using graphene are presented. The designed Tm-doped fiber laser utilizes multilayer graphene as a saturable absorber and generates 654 fs pulses at 1940 nm wavelength, which are currently the shortest pulses generated from a Tm-doped fiber laser with a graphene-based saturable absorber.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 19874082 and 60178020)Guangdong Provincial Natural Science Foundation (Grant No. 980368).
文摘By reducing the effects of frequency dependent mode size and intracavity gain saturation of a KLM Ti: sapphire laser, the pulse bandwidth broadening is enhanced significantly. 8.5 fs pulses with the bandwidth of 92 nm at wavelength of 710 nm have been generated directly from this laser and measured with an extracavity group velocity dispersion compensation system.
基金supported by the National Key Research and Development Program of China(2018YFB2201902,2018YFB2201901,2018YFB2201903)the National Natural Science Foundation of China(61925505,61535012,61705217)
文摘An optoelectronic oscillator(OEO)is a microwave photonic system that produces microwave signals with ultralow phase noise using a high-quality-factor optical energy storage element.This type of oscillator is desired in various practical applications,such as communication links,signal processing,radar,metrology,radio astronomy,and reference clock distribution.Recently,new mode control and selection methods based on Fourier domain mode-locking and parity-time symmetry have been proposed and experimentally demonstrated in OEOs,which overcomes the long-existing mode building time and mode selection problems in a traditional OEO.Due to these mode control and selection methods,continuously chirped microwave waveforms can be generated directly from the OEO cavity and single-mode operation can be achieved without the need of ultranarrowband filters,which are not possible in a traditional OEO.Integrated OEOs with a compact size and low power consumption have also been demonstrated,which are key steps toward a new generation of compact and versatile OEOs for demanding applications.We review recent progress in the field of OEOs,with particular attention to new mode control and selection methods,as well as chip-scale integration of OEOs.
基金This work was supported by the National Key Basic Research Special Foundation of China (No. G1999075201-2) the National Natural Science Foundation of China (No. 69978016, 60178008) the Foundation of the Optoelectronic United Center of Tianjin, the Na
文摘Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor sat-urable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.
基金国家自然科学基金(62022033,12074122,11704123,61775059,62022033,12074122)上海市市级科技重大专项子项目(2019SHZDZX01-ZX05)+3 种基金上海市青年科技启明星计划National Key Laboratory Foundation of China(6142411196307)Sustainedly Supported Foundation by National Key Laboratory of Science and Technology on Space Microwave under Grant(2022-WDKY-SYS-DN-04)上海市自然科学基金(23ZR1419000)。
