Greifswald 2024 – scientific programme

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K: Fachverband Kurzzeit- und angewandte Laserphysik

K 2: Gas dynamics – Laser Systems and Laser Applications

K 2.3: Talk

Monday, February 26, 2024, 14:40–15:00, ELP 6: HS 1

17 GHz monolithic self-starting Kerr-lens mode-locked Titanium-Sapphire laser — •Torben Fiehler and Ulrich Wittrock — Photonics Laboratory, FH Münster, Stegerwaldstraße 39, 48565 Steinfurt, Germany

Ultrafast lasers with pulse repetition rates in the multi-GHz regime are of interest for applications in frequency metrology, dual-comb spectroscopy, calibration of astronomical spectrographs, microwave generation, and telecommunication.

We present a monolithic self-starting soft-aperture Kerr-lens mode-locked Titanium-Sapphire (Ti:Sa) laser that generates 204 fs pulses at 812 nm with 900 mW average power and a pulse repetition rate of 16.9 GHz. This is the highest repetition rate for a fundamentally mode-locked Ti:Sa laser. Moreover, our laser is the first monolithic mode-locked Ti:Sa laser. It consists of a 5 mm thick plane-parallel Ti:Sa disk where both surfaces bear dispersive mirror coatings. This plane-plane resonator is stabilized by the thermal lens that is generated by the pump power. Reliable self-starting soft-aperture Kerr-lens mode-locking sets in at an absorbed pump power of 1.8 W which corresponds to 700 mW of average mode-locked laser power. At 900 mW, the frequency comb has a spectral bandwidth of 4 nm and about 300 modes resulting in about 5 mW per mode in average. Mode locking is maintained up to an absorbed pump power of 2.6 W and 1100 mW average laser power. Above this power, mode locking becomes unstable.

Keywords: Ti:Sa; Frequency comb; Kerr-lens mode locking; High repetition rate; New laser design