Night-time warming is vital for human production and daily life.Conventional methods like active heaters are energy-intensive,while passive insulating films possess restrictions regarding space consumption and the lac...Night-time warming is vital for human production and daily life.Conventional methods like active heaters are energy-intensive,while passive insulating films possess restrictions regarding space consumption and the lack of heat gain.In this work,a nanophotonic-based night-time warming strategy that passively inhibits thermal radiation of objects while actively harnessing that of atmosphere is proposed.By using a photonic-engineered thin film that exhibits high reflectivity(~0.91)in the atmospheric transparent band(8-14μm)and high absorptivity(~0.7)in the atmospheric radiative band(5-8 and 14-16μm),temperature rise of 2.1℃/4.4℃compared to typical low-e film and broadband absorber is achieved.Moreover,net heat loss as low as 9Wm-2 is experimentally observed,compared to 16 and 39Wm-2 for low-e film and broadband absorber,respectively.This strategy suggests an innovative way for sustainable warming,thus contributes to addressing the challenges of climate change and promoting global carbon neutrality.展开更多
MXene V_(2)CT_(x) has great practicability because it is not easy to degrade under ambient conditions.In this paper,a V_(2)CT_(x) saturable absorber(SA)was firstly applied to a passively Q-switched(PQS)laser,to the be...MXene V_(2)CT_(x) has great practicability because it is not easy to degrade under ambient conditions.In this paper,a V_(2)CT_(x) saturable absorber(SA)was firstly applied to a passively Q-switched(PQS)laser,to the best of our knowledge.The V_(2)CT_(x)-SA was prepared by the spin-coating method.The linear absorption of the V_(2)CT_(x)-SA in the 1000-2200 nm region and the nonlinear absorption near 2μm were studied.With the V_(2)CT_(x)-SA,a typical PQS operation at 1.94μm was realized in a Tm:YAlO3laser.The minimum pulse width produced by the PQS laser was 528 ns,and the peak power,repetition rate,and average output power were 10.06 W,65.9 kHz,and 350 mW,respectively.Meanwhile,the maximum pulse energy was 6.33μJ.This work demonstrates that the V_(2)CT_(x) can be used as an effective SA to obtain nanosecond pulses with high peak power and high repetition rate simultaneously.展开更多
We present the recent research progress of our group on mid-infrared pulsed fiber lasers at 3μm by passive switching. Three different kinds of saturable absorbers including semiconductor saturable absorber （SESAM）,...We present the recent research progress of our group on mid-infrared pulsed fiber lasers at 3μm by passive switching. Three different kinds of saturable absorbers including semiconductor saturable absorber （SESAM）, Fe2＋：ZnSe crystal, topological insulator （TI） were used to perform the pulse generation, respectively. The temporal regimes of mode locking, Q-switching and Q-switching induced gain switching were gained. Some relative discussions and prospective efforts are proposed at the end of this paper.展开更多
In this study,titanium disulfide(TiS_(2))polyvinyl alcohol(PVA)film-type saturable absorber(SA)is synthesized with a modulation depth of 5.08%and a saturable intensity of 10.62 MW/cm^(2) by liquid-phase exfoliation an...In this study,titanium disulfide(TiS_(2))polyvinyl alcohol(PVA)film-type saturable absorber(SA)is synthesized with a modulation depth of 5.08%and a saturable intensity of 10.62 MW/cm^(2) by liquid-phase exfoliation and spin-coating methods.Since TiS2-based SA has a strong nonlinear saturable absorption property,two types of optical soliton were observed in a mode-locked Er-doped fiber laser.When the pump power was raised to 67.3 mW,a conventional mode-locked pulse train with a repetition rate of 1.716 MHz and a pulse width of 6.57 ps was generated,and the output spectrum centered at 1556.98 nm and 0.466 nm spectral width with obvious Kelly sidebands was obtained.Another type of mode-locked pulse train with the maximum output power of 3.92 mW and pulse energy of 2.28 nJ at the pump power of 517.2 mW was achieved when the polarization controllers were adjusted.Since TiS2-based SA has excellent nonlinear saturable absorption characteristics,broad applications in ultrafast photonic are expected.展开更多
We demonstrate a Q-switched Raman fiber laser using molybdenum disulfide （MoS2） as a saturable absorber （SA）. The SA is assembled by depositing a mechanically exfoliated MoS2 onto a fiber ferrule facet before it i...We demonstrate a Q-switched Raman fiber laser using molybdenum disulfide （MoS2） as a saturable absorber （SA）. The SA is assembled by depositing a mechanically exfoliated MoS2 onto a fiber ferrule facet before it is matched with another clean ferrule via a connector. It is inserted in a Raman fiber laser cavity with a total cavity length of about 8kin to generate a Q-switching pulse train operating at 1560.2nm. A 7.7-kin-long dispersion compensating fiber with 584 ps.nm-i km-1 of dispersion is used as a nonlinear gain medium. As the pump power is increased from 395 m W to 422 m W, the repetition rate of the Q-switching pulses can be increased from 132.7 to 137.4 kHz while the pulse width is concurrently decreased from 3.35μs to 3.03μs. The maximum pulse energy of 54.3 nJ is obtained at the maximum pump power of 422 roW. These results show that the mechanically exfoliated MoS2 SA has a great potential to be used for pulse generation in Raman fiber laser systems.展开更多
A theoretical analysis of passive mode-locking in a thermal-stable ring cavity containing a Kerr medium and an aperture is presented.The analysis employing the beam propagation theory shows that the power dependence o...A theoretical analysis of passive mode-locking in a thermal-stable ring cavity containing a Kerr medium and an aperture is presented.The analysis employing the beam propagation theory shows that the power dependence of the cavity loss is extremely sensitive to the relative location of the Kerr medium and the aperture,and is different for the counterpropagating modes,so the unidirectional operation is expected.The combination of Kerr medium with an aperture acts as a p sition feedback,which is similar to the effect of a saturable absorber.展开更多
A highly stable Q-switched laser incorporating a mechanically exfoliated tungsten sulphoselenide （WSSe） thin sheet saturable absorber （SA） is proposed and demonstrated. The SA assembly, formed by sandwiching a thi...A highly stable Q-switched laser incorporating a mechanically exfoliated tungsten sulphoselenide （WSSe） thin sheet saturable absorber （SA） is proposed and demonstrated. The SA assembly, formed by sandwiching a thin WSSe sheet between two fiber ferrules within the erbium-doped fiber laser, is used to effectively modulate the laser cavity losses. The WSSe-based SA has a saturation intensity of ~0.006 MW∕cm^2 and a modulation depth of 7.8%, giving an optimum Q-switched laser output with a maximum repetition rate of 61.81 kHz and a minimum pulse width of 2.6 μs. The laser＇s highest output power of 0.45 mW and highest pulse energy of 7.31 nJ are achieved at the maximum pump power of 280.5 mW. The tunability of the cavity＇s output at the maximum pump power is analyzed with a C-band tunable bandpass filter, giving a broad tunable range of ~40 nm, from 1530 nm to 1570 nm. The output performance of the tunable Q-switched laser correlates well with the gain spectrum of erbium-doped fibers, with the shift in the gain profile as a result of the saturated SA.展开更多
基金supported by the National Natural Science Foundation of China(61975181).
文摘Night-time warming is vital for human production and daily life.Conventional methods like active heaters are energy-intensive,while passive insulating films possess restrictions regarding space consumption and the lack of heat gain.In this work,a nanophotonic-based night-time warming strategy that passively inhibits thermal radiation of objects while actively harnessing that of atmosphere is proposed.By using a photonic-engineered thin film that exhibits high reflectivity(~0.91)in the atmospheric transparent band(8-14μm)and high absorptivity(~0.7)in the atmospheric radiative band(5-8 and 14-16μm),temperature rise of 2.1℃/4.4℃compared to typical low-e film and broadband absorber is achieved.Moreover,net heat loss as low as 9Wm-2 is experimentally observed,compared to 16 and 39Wm-2 for low-e film and broadband absorber,respectively.This strategy suggests an innovative way for sustainable warming,thus contributes to addressing the challenges of climate change and promoting global carbon neutrality.
基金supported by the China Postdoctoral Science Foundation(No.2020M670937)the Basic Scientific Research Business Expenses of Colleges and Universities in Heilongjiang Province(No.2021-KYYWF-0020)。
文摘MXene V_(2)CT_(x) has great practicability because it is not easy to degrade under ambient conditions.In this paper,a V_(2)CT_(x) saturable absorber(SA)was firstly applied to a passively Q-switched(PQS)laser,to the best of our knowledge.The V_(2)CT_(x)-SA was prepared by the spin-coating method.The linear absorption of the V_(2)CT_(x)-SA in the 1000-2200 nm region and the nonlinear absorption near 2μm were studied.With the V_(2)CT_(x)-SA,a typical PQS operation at 1.94μm was realized in a Tm:YAlO3laser.The minimum pulse width produced by the PQS laser was 528 ns,and the peak power,repetition rate,and average output power were 10.06 W,65.9 kHz,and 350 mW,respectively.Meanwhile,the maximum pulse energy was 6.33μJ.This work demonstrates that the V_(2)CT_(x) can be used as an effective SA to obtain nanosecond pulses with high peak power and high repetition rate simultaneously.
基金supported by the National Natural Science Foundation of China under Grant No.61377042the Fundamental Research Funds for the Central Universities under Grant No.ZYGX2013J058the Program for New Century Excellent Talents in University of Ministry of Education of China under Grant No.NCET-13-0094
文摘We present the recent research progress of our group on mid-infrared pulsed fiber lasers at 3μm by passive switching. Three different kinds of saturable absorbers including semiconductor saturable absorber （SESAM）, Fe2＋：ZnSe crystal, topological insulator （TI） were used to perform the pulse generation, respectively. The temporal regimes of mode locking, Q-switching and Q-switching induced gain switching were gained. Some relative discussions and prospective efforts are proposed at the end of this paper.
基金Project supported by the National Natural Science Foundation of China(Nos.11904213 and 11747149)the Shandong Provincial Natural Science Foundation(Nos.ZR2018QF006 and ZR2019MF029)+1 种基金the China Postdoctoral Science Foundation(No.2016M602177)the Opening Foundation of Shandong Provincial Key Laboratory of Laser Technology and Application。
文摘In this study,titanium disulfide(TiS_(2))polyvinyl alcohol(PVA)film-type saturable absorber(SA)is synthesized with a modulation depth of 5.08%and a saturable intensity of 10.62 MW/cm^(2) by liquid-phase exfoliation and spin-coating methods.Since TiS2-based SA has a strong nonlinear saturable absorption property,two types of optical soliton were observed in a mode-locked Er-doped fiber laser.When the pump power was raised to 67.3 mW,a conventional mode-locked pulse train with a repetition rate of 1.716 MHz and a pulse width of 6.57 ps was generated,and the output spectrum centered at 1556.98 nm and 0.466 nm spectral width with obvious Kelly sidebands was obtained.Another type of mode-locked pulse train with the maximum output power of 3.92 mW and pulse energy of 2.28 nJ at the pump power of 517.2 mW was achieved when the polarization controllers were adjusted.Since TiS2-based SA has excellent nonlinear saturable absorption characteristics,broad applications in ultrafast photonic are expected.
文摘We demonstrate a Q-switched Raman fiber laser using molybdenum disulfide （MoS2） as a saturable absorber （SA）. The SA is assembled by depositing a mechanically exfoliated MoS2 onto a fiber ferrule facet before it is matched with another clean ferrule via a connector. It is inserted in a Raman fiber laser cavity with a total cavity length of about 8kin to generate a Q-switching pulse train operating at 1560.2nm. A 7.7-kin-long dispersion compensating fiber with 584 ps.nm-i km-1 of dispersion is used as a nonlinear gain medium. As the pump power is increased from 395 m W to 422 m W, the repetition rate of the Q-switching pulses can be increased from 132.7 to 137.4 kHz while the pulse width is concurrently decreased from 3.35μs to 3.03μs. The maximum pulse energy of 54.3 nJ is obtained at the maximum pump power of 422 roW. These results show that the mechanically exfoliated MoS2 SA has a great potential to be used for pulse generation in Raman fiber laser systems.
文摘A theoretical analysis of passive mode-locking in a thermal-stable ring cavity containing a Kerr medium and an aperture is presented.The analysis employing the beam propagation theory shows that the power dependence of the cavity loss is extremely sensitive to the relative location of the Kerr medium and the aperture,and is different for the counterpropagating modes,so the unidirectional operation is expected.The combination of Kerr medium with an aperture acts as a p sition feedback,which is similar to the effect of a saturable absorber.
基金supported by the Ministry of Higher Education,Malaysia(Grant No.LRGS(2015)NGOD/UM/KPT)the University of Malaya(Grant Nos.RU001-2017 and RP 029A–15 AFR)
文摘A highly stable Q-switched laser incorporating a mechanically exfoliated tungsten sulphoselenide （WSSe） thin sheet saturable absorber （SA） is proposed and demonstrated. The SA assembly, formed by sandwiching a thin WSSe sheet between two fiber ferrules within the erbium-doped fiber laser, is used to effectively modulate the laser cavity losses. The WSSe-based SA has a saturation intensity of ~0.006 MW∕cm^2 and a modulation depth of 7.8%, giving an optimum Q-switched laser output with a maximum repetition rate of 61.81 kHz and a minimum pulse width of 2.6 μs. The laser＇s highest output power of 0.45 mW and highest pulse energy of 7.31 nJ are achieved at the maximum pump power of 280.5 mW. The tunability of the cavity＇s output at the maximum pump power is analyzed with a C-band tunable bandpass filter, giving a broad tunable range of ~40 nm, from 1530 nm to 1570 nm. The output performance of the tunable Q-switched laser correlates well with the gain spectrum of erbium-doped fibers, with the shift in the gain profile as a result of the saturated SA.
