Abstract

We report on the first active surface Y-branch waveguide in the ∼2 μm spectral range. Depressed-cladding rectangular-cross-section surface waveguides with a splitting ratio of 1 × 2 are fabricated by femtosecond direct laser writing in a thulium (Tm³⁺) doped monoclinic double tungstate crystal. Confocal laser microscopy and μ-Raman spectroscopy reveal well preserved crystallinity of the waveguide core. Under high-brightness laser pumping at 0.8 μm, a simultaneous continuous-wave laser operation in both arms is achieved resulting in a total output power of 0.46 W at ∼1.84 μm with a slope efficiency of 40.6% and a laser threshold of 0.28 W. The laser output is linearly polarized and spatially multimode (TE₁₂/TE₂₂) with a power splitting ratio between arms of 52.1/47.9%). The waveguide propagation losses at 1.84 μm are ∼1.6 dB/cm and the loss from the Y-junction is 0.1 dB. The fabricated waveguides represent a route towards advanced photonic micro-structures such as a Mach–Zehnder interferometer for bio-sensing at ∼2 μm.

Femtosecond-laser-written Ho:KGd(WO₄)₂ waveguide laser at 2.1  μm

Esrom Kifle, Pavel Loiko, Carolina Romero, Javier Rodríguez Vázquez de Aldana, Airán Ródenas, Viktor Zakharov, Andrey Veniaminov, Magdalena Aguiló, Francesc Díaz, Uwe Griebner, Valentin Petrov, and Xavier Mateos
Opt. Lett. 44(7) 1738-1741 (2019)

Diamond saw dicing of thulium channel waveguide lasers in monoclinic crystalline films

Esrom Kifle, Pavel Loiko, Uwe Griebner, Valentin Petrov, Patrice Camy, Alain Braud, Magdalena Aguiló, Francesc Díaz, and Xavier Mateos
Opt. Lett. 44(7) 1596-1599 (2019)

Refined orientation of the optical axes as a function of wavelength in three monoclinic double tungstate crystals KRE(WO₄)₂ (RE = Gd, Y or Lu)

P. Loiko, P. Segonds, P.L. Inácio, A. Peña, J. Debray, D. Rytz, V. Filippov, K. Yumashev, M. C. Pujol, X. Mateos, M. Aguiló, F. Díaz, M. Eichhorn, and B. Boulanger
Opt. Mater. Express 6(9) 2984-2990 (2016)

Monoclinic Tm³⁺:MgWO₄: a promising crystal for continuous-wave and passively Q-switched lasers at ∼2  μm

Pavel Loiko, Josep Maria Serres, Xavier Mateos, Magdalena Aguiló, Francesc Díaz, Lizhen Zhang, Zhoubin Lin, Haifeng Lin, Ge Zhang, Konstantin Yumashev, Valentin Petrov, Uwe Griebner, Yicheng Wang, Sun Yung Choi, Fabian Rotermund, and Weidong Chen
Opt. Lett. 42(6) 1177-1180 (2017)

Low-loss fs-laser-written surface waveguide lasers at >2  µm in monoclinic Tm³⁺:MgWO₄

Esrom Kifle, Pavel Loiko, Javier Rodríguez Vázquez de Aldana, Carolina Romero, Víctor Llamas, Josep Maria Serres, Magdalena Aguiló, Francesc Díaz, Lizhen Zhang, Zhoubin Lin, Haifeng Lin, Ge Zhang, Viktor Zakharov, Andrey Veniaminov, Valentin Petrov, Uwe Griebner, Xavier Mateos, Li Wang, and Weidong Chen
Opt. Lett. 45(14) 4060-4063 (2020)