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Título
Passively Q-switched femtosecond-laser-written thulium waveguide laser based on evanescent field interaction with carbon nanotubes
Autor(es)
Fecha de publicación
2018-10
Citación
Esrom Kifle, Pavel Loiko, Javier Rodríguez Vázquez de Aldana, Carolina Romero, Airán Ródenas, Sun Yung Choi, Ji Eun Bae, Fabian Rotermund, Viktor Zakharov, Andrey Veniaminov, Magdalena Aguiló, Francesc Díaz, Uwe Griebner, Valentin Petrov, and Xavier Mateos, "Passively Q-switched femtosecond-laser-written thulium waveguide laser based on evanescent field interaction with carbon nanotubes," Photon. Res. 6, 971-980 (2018)
Resumen
Surface channel waveguides (WGs) were fabricated in a monoclinic Tm3+:KLu(WO4)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 was 0.7±0.3 dB/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 PQS 60 μm diameter WG laser generated a record output power of 150 mW 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.
URI
DOI
10.1364/PRJ.6.000971
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- ALF. Artículos [297]
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