In-Band Pumping of Tm:LiYF4 Channel Waveguide: A Power Scaling Strategy for ∼2 μm Waveguide Lasers

Waveguide (WG) lasers emitting in the eye-safe spectral range of ~2 μm are of interest for spectroscopy, optical communications and sensing applications. Such emission is typically achieved using Thulium (Tm
³⁺
) ions (the
³
F
₄
→
³
H
₆
transition). In the traditional pumping scheme, Tm
³⁺
ions are excited at ~0.8 μm (to the
³
H
₄
state) and high laser efficiency can be reached due to the cross-relaxation process,
³
H
₄
+
³
H
₆
→
³
F
₄
+
³
F
₄
[1]. In the present work, we aimed to demonstrate a power-scaling strategy for Tm WG lasers utilizing in-band pumping scheme.