Christian Gaida

High-power nonlinear compression stage delivering sub-50 fs, 0.25 mJ pulses, 15 W at 2 µm wavelength for HHG

We present the nonlinear compression of ultrashort pulses at 2 µm wavelength to sub-50 fs, >3 GW at 15.4 W of average power. This source was used for HHG in an argon gas jet.

Nonlinear pulse compression stage delivering 43-W few-cycle pulses with GW peak-power at 2-µm wavelength

In this contribution we demonstrate the nonlinear pulse compression of an ultrafast thulium-doped fiber laser down to 14 fs FWHM duration (sub-3 optical cycles) at a record average power of 43 W and 34.5 μJ pulse energy. To the best of our knowledge, we present the highest average power few-cycle laser source at 2 μm wavelength. This performance level in combination with GW-class peak power makes our laser source extremely interesting for driving high-harmonic generation or for generating mid-infrared frequency combs via intra-pulse frequency down-conversion at an unprecedented average power. The experiments were enabled by an ultrafast thulium-doped fiber laser delivering 110 fs pulses at high repetition rates, and an argon gas-filled antiresonant hollow-core fiber (ARHCF) with excellent transmission and weak anomalous dispersion, leading to the self-compression of the pulses. We have shown that ARHCFs are well-suited for nonlinear pulse compression around 2 μm wavelength and that this concept features excellent power handling capabilities. Based on this result, we discuss the next steps for energy and average power scaling including upscaling the fiber dimensions in order to fully exploit the capabilities of our laser system, which can deliver several GW of peak power. This way, a 100 W-class laser source with mJ-level few-cycle pulses at 2 μm wavelength is feasible in the near future.

Temperature-based wavelength tuning of non-solitonic radiation in liquid-core fibers

Nonlinear light generation in optical fibers is an indispensible tool to generate light to access wavelengths offside of the fundamental laser lines broadening the field of applications in biophotonics, metrology, and communications. However, most multi-wavelength sources rely on glass fibers which are static in their material properties after fabrication. Recently, gas-filled fibers were demonstrated to provide impressive wavelength tunability of non-solitonic radiation in the ultraviolet by adjusting the gas pressure [1], however, they require high pump power and sophisticated micro-structured cross-sections. Alternatively, also liquid-core fibers offer tunability due to the large thermo-optical coefficient (TOC) and miscibility of the core liquid, and promise to be an ideal nonlinear platform due to their large nonlinearity and wide transmission windows.

Nonlinear compression of ultrashort pulses from a high repetition rate Tm-doped fiber laser to sub-5 cycle duration

We present nonlinear pulse compression in the wavelength region around 2 µm using two different approaches. Pulse-shortening to sub-30 fs at 26.5 W of average power or 200 MW peak power is presented, respectively.

Tm-Doped Fiber CPA System with 152 W Average Power and Sub-700fs Pulse Duration

Thulium-doped photonic crystal fibers exhibit cross relaxation with slope efficiencies of up to 55% and enabled a high power fiber CPA system emitting a record compressed average output power of 152 W and 4 MW peak power.

Sub-200 fs, nJ-level stretched-pulse thulium-doped fiber oscillator at 23MHz repetition rate

We report on an ultrafast thulium fiber oscillator delivering pulses with 0.7 nJ pulse energy at 22.9 MHz repetition rate. The oscillator output could be externally compressed to sub-200 fs pulse duration.

Trans-wafer processing of semiconductors with nanosecond mid-IR laser radiation

In recent years, a major push was made for the use of novel laser sources in the processing of semiconductors and other materials used in photovoltaic and IC applications. In addition to a large number of highly automated laser processes already adopted by the industry, more laser-based processing approaches are being developed to improve performance and reduce manufacturing costs. Common semiconductors are transparent in the infrared spectral region. Therefore laser sources operating at mid-IR wavelengths can be successfully utilized to induce material modifications in semiconductor wafers even beyond the laser-incident surface. We present our initial studies of this processing regime utilizing a self-developed nanosecond-pulsed thulium fiber laser emitting at the wavelength 2u2005µm. Our experimental approach confirmed that morphology changes could be induced not only at the front (laser-incident) surface of the wafer, but also independently at the back surface. We investigated the influence of process parameters, such as the incident pulse energy, duration and focusing conditions, on the induced surface morphology. In addition, we studied experimental routes to a number of potential applications of this processing regime, such as the PV cell edge isolation and the wafer scribing.In recent years, a major push was made for the use of novel laser sources in the processing of semiconductors and other materials used in photovoltaic and IC applications. In addition to a large number of highly automated laser processes already adopted by the industry, more laser-based processing approaches are being developed to improve performance and reduce manufacturing costs. Common semiconductors are transparent in the infrared spectral region. Therefore laser sources operating at mid-IR wavelengths can be successfully utilized to induce material modifications in semiconductor wafers even beyond the laser-incident surface. We present our initial studies of this processing regime utilizing a self-developed nanosecond-pulsed thulium fiber laser emitting at the wavelength 2u2005µm. Our experimental approach confirmed that morphology changes could be induced not only at the front (laser-incident) surface of the wafer, but also independently at the back surface. We investigated the influence of process para...