Fabıan Rotermund

Abstract Single‐walled carbon‐nanotube absorbers are experimentally demonstrated for laser mode‐locking. A saturable absorber device is used to mode‐lock three different bulk solid‐state lasers in a 500 nm‐wide wavelength interval. The devices exhibit a low saturation fluence of <10 µJ cm −2 , low scattering losses, and an exceptionally rapid relaxation, with time constants reaching <100 fs. The latter two properties are explained by a decreased curling tendency and increased tube‐to‐tube

We present the first sub-100 fs bulk solid-state laser in the 2-μm spectral range employing the monoclinic Tm³⁺-dopedMgWO₄ crystal as an active medium. By applying a graphene-based saturable absorber and chirped mirrors for dispersion management, stable self-starting mode-locked operation at 2017 nm was achieved. Nearly Fourier-limited pulses as short as 86 fs featuring a bandwidth of 53 nm were generated at a repetition rate of 76 MHz. A pulse energy of 1.1 nJ was achieved

Efficient and power-scalable laser operation of a vibronic Tm3+:KLu(WO4)2 microchip laser at ∼2.13 μm is demonstrated. In the continuous-wave mode under diode pumping at ∼805 nm, this laser generated 1.17 W at 2109–2133 nm with a slope efficiency of 39%. This emission is related to the coupling of the electronic transitions of Tm3+ ions with the stretching vibrations of the WOW oxygen bonds in the monoclinic KLu(WO4)2 crystal host appearing at ∼379, 406, and 450 cm−1. The achieved emission wavel

Depressed-index channel waveguides with a circular and photonic crystal cladding structures are prepared in a bulk monoclinic Tm:KLu(WO₄)₂ crystal by 3D direct femtosecond laser writing. The channel waveguide structures are characterized and laser operation is achieved using external mirrors. In the continuous-wave mode, the maximum output power of 46 mW is achieved at 1912 nm corresponding to a slope efficiency of 15.2% and a laser threshold of only 21 mW. Passive Q-switch