arXiv subjects

Tino Lang

Publications and source records attributed to Tino Lang.

6 recordsLinked to original sources

arXiv2026

Optical parametric multi-pass cell amplifier

Ultrafast lasers with simultaneously high average and peak power have become indispensable for driving a multitude of applications, including high-harmonic generation, strong-field physics, and particle source applications. Both parametric amplifiers and post-compressed Ytterbium lasers have emerged as prime platforms to meet these demands. While multi-pass cell (MPC) based post-compression offers broadband output with high beam quality, it provides limited wavelength tunability and suffers from temporal contrast degradation. Conversely, optical parametric amplifiers (OPAs) provide spectral tunability and high temporal contrast but they are limited by low pump-to-signal conversion efficiency and spatial beam inhomogeneities. Here, we introduce the Optical Parametric Multi-Pass Cell Amplifier (OPMPC), a hybrid architecture that overcomes the limitations of both schemes. Our approach utilizes two non-collinearly intersecting MPCs providing broadband parametric amplification of the seed pulses and complete idler removal after each pass through the crystal, thereby suppressing back-conversion. We experimentally demonstrate a record pump-to-signal power conversion efficiency of 43% using a 1030 nm pump at a 1 kHz repetition rate with a pulse energy of 174 $\mu$J. The amplified signal at 1500 nm exhibits excellent beam quality, power and spectral stability and is compressed to 48 fs, demonstrating a new platform for ultrafast pulse generation.

physics.optics↗

arXiv2025

Post-compression of a Q-switched laser in a glass-rod multi-pass cell

Q-switched lasers are compact, cost-effective, and highly pulse energy-scalable sources for nanosecond-scale laser pulses. The technology has been developed for many decades and is widely used in scientific, industrial and medical applications. However, their inherently narrow bandwidth imposes a lower limit on pulse duration - typically in the few-hundred-picosecond range - limiting the applicability of Q-switched technology in fields that require ultrafast laser pulses in the few-picosecond or femtosecond regime. In contrast, mode-locked lasers can produce broad-band, ultrafast (< 1 ps) pulses, but are complex, expensive, and typically require a large footprint. To bridge the parameter gap between these two laser platforms - in terms of pulse duration and achievable peak power - we here propose a Herriott-type multi-pass cell (MPC) based post-compression scheme for shortening the pulse durations of Q-switched lasers down to the ultrafast, picosecond regime. We experimentally demonstrate post-compression of 0.5 ns, 1 mJ pulses from a Q-switched laser to 24 ps using a compact glass-rod MPC for spectral broadening. We verify this result numerically and show that compression down to a few picoseconds is possible using the nanosecond MPC (nMPC).

physics.optics↗

arXiv2025

Redirection and Reshaping of Intense Extreme-Ultraviolet Radiation

The goal to control short-wavelength radiation for the investigation and manipulation of ultrafast dynamics in quantum systems coevolves with the growing availability of extreme-ultraviolet (XUV) and x-ray sources from high-harmonic generation and free-electron lasers. Here, we present an XUV spatio-spectral phase modulator based on an intense XUV laser beam propagating through an optically thick resonant target, introducing dispersion profile variations around the resonance both perpendicular to and along the laser propagation direction. The resulting dipole radiation gets spectrally reshaped and becomes more divergent as compared to the original beam in the far field. As an experimental demonstration, the intense-XUV-induced double-peak off-axis structure in the far-field spectrum obtained at the Free-Electron Laser in Hamburg (FLASH) shows indications of the underlying XUV-driven Rabi dynamics and resonant pulse propagation effects. The presented work highlights a ubiquitous phenomenon occurring when an intense laser beam passes through a resonant medium.

physics.atom-ph↗

arXiv2023

Acousto-Optic Modulation in Ambient Air

Control over intensity, shape, direction, and phase of coherent light is essential in numerous fields, reaching from gravitational wave astronomy over quantum metrology and ultrafast sciences to semi-conductor fabrication. Modern laser optics, however, frequently demands parameter regimes where either the wavelength or the optical power restricts control due to linear absorption, light-induced damage or optical nonlinearity. The properties of solid media, upon which most photonic control schemes rely, impose these limitations. We propose to circumvent these constraints using gaseous media tailored by high-intensity ultrasound waves. We demonstrate a first implementation of this approach by deflecting ultrashort laser pulses using ultrasound waves in ambient air, entirely omitting transmissive solid media. At optical peak powers of 20 GW exceeding previous limits of solid-based acousto-optic modulation by about three orders of magnitude, we reach a deflection efficiency greater than 50% while preserving excellent beam quality. Our approach is not limited to laser pulse deflection via acousto-optic modulation: gas-phase photonic schemes controlled by sonic waves can prospectively be translated to various optical methods, e.g., lenses or waveguides, rendering them effectively invulnerable against damage and opening up new spectral regions.

physics.optics↗

arXiv2020

Post-compression of picosecond pulses into the few-cycle regime

In this work, we demonstrate post-compression of 1.2 picosecond laser pulses to 13 fs via gas-based multi-pass spectral broadening. Our results yield a single-stage compression factor of about 40 at 200 W in-burst average power and a total compression factor >90 at reduced power. The employed scheme represents a route towards compact few-cycle sources driven by industrial-grade Yb:YAG lasers at high average power.

physics.optics↗

arXiv2019

Multi-microjoule GaSe-based mid-infrared optical parametric amplifier with an ultra-broad idler spectrum covering 4.2-16 μm

We report a multi-microjoule, ultra-broadband mid-infrared optical parametric amplifier based on a GaSe nonlinear crystal pumped at ~2 μm. The generated idler pulse has a flat spectrum spanning from 4.5 to 13.3 μm at -3 dB and 4.2 to 16 μm in the full spectral range, with a central wavelength of 8.8 μm. The proposed scheme supports a sub-cycle Fourier-transform-limited pulse width. A (2+1)-dimensional numerical simulation is employed to reproduce the obtained idler spectrum. To our best knowledge, this is the broadest -3 dB spectrum ever obtained by optical parametric amplifiers in this spectral region. The idler pulse energy is ~3.4 μJ with a conversion efficiency of ~2% from the ~2 μm pump to the idler pulse.

physics.optics↗