A 23-watt single-frequency vertical-external-cavity surface-emitting laser.

We report on a single-frequency semiconductor disk laser which generates 23.6 W output power in continuous wave operation, at a wavelength of 1013 nm. The high output power is a result of optimizing the chip design, thermal management and the cavity configuration.

Evolution of multi-mode operation in vertical-external-cavity surface-emitting lasers.

The longitudinal multi-mode emission in a vertical-external-cavity surface-emitting laser is investigated using both single shot streak camera measurements and interferometric measurement techniques. For this, the laser is operated in the single- and two-color emission regime using both an etalon and a free-running configuration without etalon, respectively. The laser emission is analyzed with respect to pump power and output coupling losses for a long and for a short resonator.

4.35 kW peak power femtosecond pulse mode-locked VECSEL for supercontinuum generation.

We report a passively mode-locked vertical external cavity surface emitting laser (VECSEL) producing 400 fs pulses with 4.35 kW peak power. The average output power was 3.

Terahertz radiation at 0.380 THz and 2.520 THz does not lead to DNA damage in skin cells in vitro.

The question whether nonionizing electromagnetic radiation of low intensity can cause functional effects in biological systems has been a subject of debate for a long time. Whereas the majority of the studies have not demonstrated these effects, some aspects still remain unclear, e.g.

Efficient terahertz en-face imaging.

In this work, we develop a pulsed terahertz imaging system in reflection geometry, where due to scanning of the terahertz beam neither the sample nor the emitter and detector have to be moved. We use a two mirror galvanoscanner for deflecting the beam, in combination with a single rotationally symmetric focusing lens. In order to efficiently image planar structures, we develop an advanced scanning routine that resolves all bending effects of the imaging plane already during measurement.