We show spectral combination of pulsed fiber laser systems for the first time to our knowledge. In this proof of principle
experiment, two directly modulated wavelength-stabilized tunable external cavity diode lasers (ECDL) serve as
independent seed sources. Each signal is amplified in a two stage ytterbium-doped fiber amplifier. The spatial overlap is
created using a transmission grating with a combining efficiency as high as 92 %. No beam quality degradation has been
observed for the combined beam compared to a single emission. An electronic delay is used to adjust the temporal
overlap of the pulses from the spatially separated amplifier setups. The presented approach offers an enormous scaling
potential of pulsed fiber laser systems, which are generally limited by nonlinear effects or fiber damage. We show that
the huge gain bandwidth of Yb-doped fiber amplifiers and the high diffraction efficiency of dielectric reflection gratings
in this wavelength range yield potential for a combination of up to 50 channels. For state-of-the-art ns-amplifier systems
> 100 MW of peak power, > 100 mJ of pulse energy and average powers of > 10 kW seem feasible.
Here, we propose a new mirror architecture which is solely based upon a monolithic dielectric micro-structured surface. Hence, the mirror device, which consists of a possibly mono-crystalline bulk material, can in principle simultaneously provide perfect reflectivity and lowest mechanical loss. By specifically structuring the monolithic surface, resulting in T-shaped ridges of a subwavelength grating, a resonant behavior of light coupling can be realized, leading to theoretically 100% reflectivity.
A new approach for the realization of highly dispersive dielectric transmission gratings is presented. By covering
conventional transmission gratings with a plane substrate a complete suppression of any reflection losses and, thus,
100% diffraction efficiency can be achieved. Theoretical design considerations, a physical investigation of the
diffraction as well as very promising experimental results are shown.