Surface channel waveguides(WGs) were fabricated in a monoclinic Tm^(3+):KLu(WO_4)_2 crystal by femtosecond direct laser writing(fs-DLW). The WGs consisted of a half-ring cladding with diameters of 50 and 60 μm locate...Surface channel waveguides(WGs) were fabricated in a monoclinic Tm^(3+):KLu(WO_4)_2 crystal by femtosecond direct laser writing(fs-DLW). The WGs consisted of a half-ring cladding with diameters of 50 and 60 μm located just beneath the crystal surface. They were characterized by confocal laser microscopy and μ-Raman spectroscopy,indicating a reduced crystallinity and stress-induced birefringence of the WG cladding. In continuous-wave(CW)mode, under Ti:sapphire laser pumping at 802 nm, the maximum output power reached 171.1 mW at 1847.4 nm,corresponding to a slope efficiency η of 37.8% for the 60 μm diameter WG. The WG propagation loss was0.7 0.3 d B∕cm. The top surface of the WGs was spin-coated by a polymethyl methacrylate film containing randomly oriented(spaghetti-like) arc-discharge single-walled carbon nanotubes serving as a saturable absorber based on evanescent field coupling. Stable passively Q-switched(PQS) operation was achieved. The PQS60 μm diameter WG laser generated a record output power of 150 m W at 1846.8 nm with η = 34.6%. The conversion efficiency with respect to the CW mode was 87.6%. The best pulse characteristics(energy/duration)were 105.6 nJ/98 ns at a repetition rate of 1.42 MHz.展开更多
We demonstrate multi-gigahertz continuous-wave mode-locking of a Yb:KLuW waveguide laser. A femtosecondlaser-inscribed Yb:KLuW channel waveguide in an extended laser cavity delivers a fundamentally mode-locked laser n...We demonstrate multi-gigahertz continuous-wave mode-locking of a Yb:KLuW waveguide laser. A femtosecondlaser-inscribed Yb:KLuW channel waveguide in an extended laser cavity delivers a fundamentally mode-locked laser near 1030 nm. A tunable few-centimeter-long cavity containing a single-walled carbon nanotube saturable absorber as mode-locker generates self-starting femtosecond pulses with average output powers exceeding210 mW at repetition rates of 2.27, 2.69, and 3.55 GHz. The laser cavity, which includes a wedged waveguide,is extended by using a lens pair that controls the laser fluence on the saturable absorber for reliable mode-locked operation without instability. The presented laser performance, mode-locked up to 3.55 GHz, highly suggests the potential of crystalline Yb:KLuW waveguides for realizing high-power ultrafast lasers with higher GHz repetition rates in a quasi-monolithic cavity.展开更多
基金Ministerio de Economía y Competitividad(MINECO)(FIS2013-44174-P,FIS2015-71933-REDT,MAT2016-75716-C2-1-R(AEI/FEDER,UE),TEC2014-55948-R)Agència de Gestiód’Ajuts Universitaris i de Recerca(AGAUR)(2017SGR755)+1 种基金Consejería de Educación,Junta de Castilla y León(SA046U16,UIC016)Generalitat de Catalunya(2016FI_B00844,2017FI_B100158,2018FI_B2 00123)
文摘Surface channel waveguides(WGs) were fabricated in a monoclinic Tm^(3+):KLu(WO_4)_2 crystal by femtosecond direct laser writing(fs-DLW). The WGs consisted of a half-ring cladding with diameters of 50 and 60 μm located just beneath the crystal surface. They were characterized by confocal laser microscopy and μ-Raman spectroscopy,indicating a reduced crystallinity and stress-induced birefringence of the WG cladding. In continuous-wave(CW)mode, under Ti:sapphire laser pumping at 802 nm, the maximum output power reached 171.1 mW at 1847.4 nm,corresponding to a slope efficiency η of 37.8% for the 60 μm diameter WG. The WG propagation loss was0.7 0.3 d B∕cm. The top surface of the WGs was spin-coated by a polymethyl methacrylate film containing randomly oriented(spaghetti-like) arc-discharge single-walled carbon nanotubes serving as a saturable absorber based on evanescent field coupling. Stable passively Q-switched(PQS) operation was achieved. The PQS60 μm diameter WG laser generated a record output power of 150 m W at 1846.8 nm with η = 34.6%. The conversion efficiency with respect to the CW mode was 87.6%. The best pulse characteristics(energy/duration)were 105.6 nJ/98 ns at a repetition rate of 1.42 MHz.
基金National Research Foundation of Korea(2018H1A2A1061480,2019R1A2C3003504,2020R1A4A2002828)MCIN/Agencia Estatal de Investigación(PID2019-108543RB-I00,PID2020-119818GB-I00)Junta de Castilla y León(SA136P20)。
文摘We demonstrate multi-gigahertz continuous-wave mode-locking of a Yb:KLuW waveguide laser. A femtosecondlaser-inscribed Yb:KLuW channel waveguide in an extended laser cavity delivers a fundamentally mode-locked laser near 1030 nm. A tunable few-centimeter-long cavity containing a single-walled carbon nanotube saturable absorber as mode-locker generates self-starting femtosecond pulses with average output powers exceeding210 mW at repetition rates of 2.27, 2.69, and 3.55 GHz. The laser cavity, which includes a wedged waveguide,is extended by using a lens pair that controls the laser fluence on the saturable absorber for reliable mode-locked operation without instability. The presented laser performance, mode-locked up to 3.55 GHz, highly suggests the potential of crystalline Yb:KLuW waveguides for realizing high-power ultrafast lasers with higher GHz repetition rates in a quasi-monolithic cavity.
