Moritz Emons

Passively mode-locked Yb:KLu(WO 4 ) 2 thin-disk oscillator operated in the positive and negative dispersion regime

We demonstrate a passively mode-locked femtosecond Yb:KLu(WO(4))(2) thin-disk laser oscillator. Chirped-pulse operation in the positive dispersion regime as well as solitary operation have been realized, and the laser performance of both configurations are compared. In the solitary mode-locking regime the output power exceeds 25 W in a diffraction-limited beam, and pulse durations as short as 440 fs at a 34.7 MHz repetition rate have been generated. For the first time we present a chirped-pulse operation of a thin-disk oscillator that yields a maximum average output power of 9.5 W with a Fourier limit of 450 fs.

Two-photon polymerization technique with sub-50 nm resolution by sub-10 fs laser pulses

Nanofabrication of structures with a feature size of sub-50 nm with ultrashort-laser based two-photon polymerization (2PP) technique is presented. The spatial resolution of the 2PP structures depends on the characteristics of the polymer material and the laser system used for fabrication. Here we compare the successful creation of sub-100 nm structures with two different few-cycle laser systems and chemically modified zirconium-based sol-gel composite material using cross-linker for resolution enhancement.

Passively mode-locked and cavity-dumped Yb:KY(WO4)2 oscillator with positive dispersion

We demonstrate, what is to our knowledge the first passively mode-locked Ytterbium based solid state high energy laser oscillator operated in the positive dispersion regime. Compared to solitary mode-locking the pulse energy can be increased with even broader spectral bandwidth. With high speed cavity dumping the laser generates 2 µJ-pulses at a 1 MHz repetition rate. The chirped output pulses are compressible down to 420 fs.

Development of functional sub-100 nm structures with 3D two-photon polymerization technique and optical methods for characterization

Investigations of two-photon polymerization (TPP) with sub-100 nm in the structuring resolution are presented by using photosensitive sol-gel material. The high photosensitivity of this material allows for TPP using a large variety in laser pulse durations covering a range between sub-10 fs and ≈140 fs. In this study, the authors demonstrate TPP structuring to obtain sub-100 nm in resolution by different approaches, namely, by adding a cross-linker to the material and polymerization with sub-10 fs short pulses. Additionally, a simulation and model based characterization method for periodic sub-100 nm structures was implemented and applied in an experimental white light interference Fourier-Scatterometry setup.

Double waveguide couplers produced by simultaneous femtosecond writing

We report on a novel method to create waveguide coupler devices in fused silica by combining the technique of beam shaping with femtosecond laser writing. The method is based on a programmable phase modulator and a dynamic variation of the phase-pattern during the writing process. The major advantage is the possibility to create complex devices in a single sweep by simultaneously writing two or more waveguides with changing separation. The guiding properties and the coupling behavior between the waveguides are investigated.

Multi-μJ, CEP-stabilized, two-cycle pulses from an OPCPA system with up to 500 kHz repetition rate

We present a two-stage OPCPA system based on a Ti:sapphire seed and a thin-disk regenerative amplifier producing compressed pulse energies of more than 3 μJ and durations of less than 6 fs at a high repetition rate of 143 kHz. In combination with the obtained CEP stability and the repetition rate scalability between 100 and 500 kHz the system forms an ideal tool for high field and phase sensitive spectroscopic experiments.

Few-cycle OPCPA system at 143 kHz with more than 1 μJ of pulse energy

We present an OPCPA system delivering 8.8 fs (3.3 optical cycles) pulses with 1.3 microJ of energy at 143 kHz repetition rate. Pump and seed for the parametric amplification are simultaneously generated by a broadband Ti:sapphire oscillator. The spectral components beyond 1000 nm are separated and amplified in an Yb:YAG thin-disk regenerative amplifier. The pulses are characterized using autocorrelation and SPIDER apparatus. With a pulse peak power of nearly 130 MW, the system is well-suited for future table top strong field experiments.

Sub-10-fs pulses from a MHz-NOPA with pulse energies of 0.4 μJ

We present a non-collinear optical parametric amplifier (NOPA) delivering sub-10-fs pulses with 420 nJ of pulse energy. The system is driven by microjoule pulses from an Yb:KYW oscillator with cavity-dumping and a subsequent single-stage rod-type fiber amplifier at 1-MHz repetition rate. The ultrabroadband seed is based on stable white-light generation from 420 fs long pulses in a YAG plate.

High power ultra-widely tuneable femtosecond pulses from a non-collinear optical parametric oscillator (NOPO)

We present an ultra-widely tunable non-collinear optical parametric oscillator with an average output power of more than 3 W and a repetition frequency of 34 MHz. The system is pumped by the second harmonic of a femtosecond Yb:KLu(WO4)2 thin-disk laser oscillator. The wavelength of the signal pulse can be rapidly tuned over a wide range from the visible to the NIR just by scanning the resonator length.

12 MW peak power from a two-crystal Yb:KYW chirped-pulse oscillator with cavity-dumping

We report on substantial pulse energy increase in Yb:KYW femtosecond laser oscillators by utilizing multiple laser crystals for an enhanced net-gain at higher pump power. The two-crystal oscillator generates pulse energies of 7 µJ at 1 MHz repetition rate which is, to our knowledge the highest energy ever reported from an Yb-doped tungstate fs-laser oscillator. The external pulse compression yields a pulse duration of 416 fs with a peak power of 12 MW being enough for stable white light generation in YAG.