Watt-level ultrafast laser inscribed thulium waveguide lasers

Abstract

We report on the first watt-level ultrafast laser inscribed Thulium waveguide (WG) lasers. Depressed-index buried channel WGs with a circular cladding (type III) are produced in monoclinic Tm 3þ :KLu(WO 4 ) 2 crystals. Laser operation is achieved under conventional ( 3 H 6 → 3 H 4 ) and in-band ( 3 H 6 → 3 F 4 ) pumping. In the former case, employing a Raman fiber laser emitting at 1679 nm as pump, the continuous-wave Tm channel WG laser generated 1.37 W at 1915-1923 nm with a record-high slope efficiency of 82.7% (with respect to the absorbed pump power), a threshold of only 17 mW and a spatially single-mode output with linear polarization. The WG propagation losses were 0.2 AE 0.3 dB/cm. Passive Q-switching of Tm channel WG lasers is achieved using Cr 2þ :ZnS and Cr 2þ :ZnSe saturable absorbers. With Cr 2þ :ZnS, record-short pulses of 2.6 ns/6.9 μJ at a repetition rate of 8.0 kHz were generated. The developed WGs are promising for compact GHz mode-locked lasers at~2 μm.

Optimization mechanism and applications of ultrafast laser machining towards highly designable 3D micro/nano structuring

“…3(a) ). 56 Metzner and co-workers reported a solid-state pulsed mode amplification laser source with an intraburst pulse repetition rate of 65 MHz and 2.5 GHz. 57 …”

Femtosecond laser-inscribed optical waveguides in dielectric crystals: a concise review and recent advances

“…Recently, MIR (∼2 μm) waveguide lasers, typically obtained from Tm 3þ -and Ho 3þ -doped materials, have attracted much attention from researchers. For a gain medium of Tm∶ KLuðWO 4 Þ 2 , efficient waveguide lasers at ∼1.8 μm operating both in the CW and Q-switched regimes have been reported by Kifle et al in various laser-written waveguide structures, such as Y-branch splitters, 208 surface cladding, 205 buried circular cladding, 166,206 and photonic-lattice-like cladding prototypes. 207 In addition, their group has demonstrated a low-loss (<0.1 dB∕cm) waveguide laser in a Tm 3þ ∶MgWO 4 crystal at ∼2.02 μm with a slope efficiency of 64.4%.…”