arXiv subjects

Oleg Pronin

Publications and source records attributed to Oleg Pronin.

14 recordsLinked to original sources

arXiv2026

Low peak-power pulse compression in gas-filled Herriott cells in the 2 {\mu}m wavelength range

At laser wavelengths longer than the prominent 1 {\mu}m range of high-power ytterbium-doped lasers, nonlinear phase shifts produced in nonlinear media for spectral broadening and subsequent pulse compression decrease drastically. Consequently, at the 2 {\mu}m wavelength range, the threshold of the applicable peak power for pulse compression in gas-filled multipass cells increases. The common approach of choosing a Herriott multipass cell configuration close to the concentric resonator does not necessarily lead to the highest total nonlinear phase shift, due to a restriction of the total number of reflections on the cell mirrors of a given size. Therefore, an analytical approach is presented here to maximize the nonlinear phase shift for a given set of mirrors, considering lossless and dispersionless propagation. Furthermore, to achieve pulse compression with gas-filled multipass cells for relatively low peak powers at wavelengths around 2 {\mu}m, we developed a high-pressure gas cell and demonstrated experimentally pulse compression in the negative- and positive dispersion regimes, with achieved pulse durations of around 40 fs and 55 fs respectively.

physics.optics↗

arXiv2026

Free-space quasi-phase matched second harmonic generation in crystalline quartz

We report experimental results on second-harmonic generation in a z-cut quartz crystal under conditions of free-space quasi-phase matching in a multi-pass cell. In a 62-pass configuration, an efficiency of 0.027% or 1.4x10-4 %/MW/cm2 was achieved, delivering 1 uJ of the second harmonic at 3.7 mJ pump pulse. This corresponds to an enhancement factor of more than 1000 in conversion efficiency as compared to a single pass. The generated second-harmonic beam demonstrates high beam quality M2=1.1 and linear polarization. The scaling of the output power with the number of passes is in good agreement with the calculated values. Further increasing the pump intensity, number of passes, and amount of plates opens the way to scaling the conversion efficiency to values on the order of tens of percent.

physics.optics↗

arXiv2026

Carrier-Envelope-Offset Frequency Stabilization of a High Peak and Average Power Thin-Disk Oscillator

In this work, we demonstrate carrier-envelope-offset (CEO) frequency stabilization of a Kerr-lens mode-locked thin-disk oscillator delivering 180 W average power, 80 MW output peak power, and >500 MW intra-cavity peak power, the highest peak power achieved in any stabilized thin-disk oscillator system. The CEO frequency detection is performed with an f-2f interferometer based on supercontinuum generation in a YAG crystal. Intra-cavity loss modulation using an acousto-optic modulator, that simultaneously provides the Kerr lens, yields 50 mrad of residual phase noise with a 250 kHz control bandwidth. After pulse compression to 0.9 GW peak power in a dual-stage multipass cell, the system directly enables high harmonic generation in noble gases. These results represent a significant step in realizing a compact and robust high-repetition-rate driver system suitable for vacuum ultraviolet and extreme ultraviolet frequency comb generation.

physics.optics↗

arXiv2025

Supercontinuum Generation in the Low-Peak-Power Regime Using a Single-Stage Multipass Cell

We demonstrate a single-stage multipass cell (MPC) compressor driven directly by a 500 nJ, 5 W, 120 fs, 10 MHz oscillator that delivers efficient spectral broadening from 800 to 1200 nm with >75% transmission. The compressed pulses approach the Fourier limit (FTL) of 8.1 fs, representing, to the best of our knowledge, the first realization of supercontinuum (SC) generation and compression in a single-stage MPC at such low, MW-level, input peak power. This compact, high-repetition-rate source holds strong potential for multiphoton microscopy and coherent Raman imaging.

physics.optics↗

arXiv2024

Quasi-waveguide amplifiers based on bulk laser gain media in Herriott-type multipass cells

We present here a new geometry for laser amplifiers based on bulk gain media. The overlapped seed and pump beams are repetitively refocused into the gain medium with a Herriott-type multipass cell. Similar to a waveguide, this configuration allows for a confined propagation inside the gain medium over much longer lengths than in ordinary single pass bulk amplifiers. Inside the gain medium, the foci appear at separate locations. A proof-of-principle demonstration with Ti:sapphire indicates that this could lead to higher amplification due to a distribution of the thermal load.

physics.optics↗

arXiv2024

Amplification-free GW-level, 150 W, 14 MHz, and 8 fs, thin-disk laser oscillator

We report an amplification-free thin-disk laser oscillatory system delivering 0.9 GW peak power. The 120 fs pulses at 14 MHz containing 12.8 $μ$J delivered by thin-disk oscillator were compressed by factor 15 down to 8.0 fs with 148 W average output power and 82 % overall efficiency. Additionally, we showed that even a sub-two-cycle operation with 6.2 fs can be reached with this technology. The system will be a crucial part of the XUV frequency comb being developed and a unique high-repetition rate driver for attosecond pulse generation.

physics.optics↗

arXiv2023

Multipass Faraday rotators and isolators

Faraday isolators are usually limited to Faraday materials with strong Verdet constants. We present a method to reach the 45° polarization rotation angle needed for optical isolators with materials exhibiting a weak Faraday effect. The Faraday effect is enhanced by passing the incident radiation multiple times through the Faraday medium while the rotation angle accumulates after each pass. Materials having excellent thermos-optical properties in the ultraviolet and mid-infrared range become available for optical isolators. Herriott-type multipass cells offer a simple and compact way to realize the desired propagation length in usual optical materials of standard sizes. A proof-of-principle experiment was carried out, demonstrating polarization rotation of a 532 nm laser beam by an angle of 45° in anti-reflection-coated fused silica surrounded by a standard neodymium ring magnet.

physics.optics↗

arXiv2022

Spectral broadening in convex-concave multipass cells

Since its first demonstration in 2016, the multi-pass spectral broadening technique has covered impressive ranges of pulse energy (3 $μ$J - 100 mJ) and peak power (4 MW - 100 GW). Energy scaling of this technique into the joule-level is currently limited by phenomena such as optical damage, gas ionization and spatio-spectral beam inhomogeneity. These limitations can be overcome by the novel multi-pass convex-concave arrangement, which exhibits crucial properties such as large mode size and compactness. In a proof-of-principle experiment, 260 fs, 15 $μ$J and 200 $μ$J pulses are broadened and subsequently compressed to approximately 50 fs with 90 % efficiency and excellent spatio-spectral homogeneity across the beam profile.

physics.optics↗

arXiv2022

White Light Generation and Few Cycle Pulse Compression in Cascaded Multipass Cells

We report supercontinuum generation and pulse compression in two stacked multipass cells based on dielectric mirrors. The 230 fs pulses at 1 MHz containing 12 $μ$J were compressed by factor 33 down to 7 fs, corresponding to 1.0 GW peak power and overall transmission of 84 %. The source is particularly interesting for such applications as time-resolved ARPES, photoemission electron microscopy, and nonlinear spectroscopy.

physics.optics↗

arXiv2022

Free-space quasi-phase matching

We report a new approach to phase matching of nonlinear materials based on the free space multipass cells. This concept quasi-phase matches crystalline quartz and increases the second harmonic generation efficiency by a factor 40.

physics.optics↗

arXiv2022

110 MW Thin-Disk Oscillator

A compact Kerr-lens mode-locked thin-disk oscillator delivering 110 MW output peak power, the highest among all oscillators, is reported. A pulse train with a repetition rate of 14 MHz carries 115 fs long, 14.4 uJ pulses resulting in 202 W of average power. This compact, simple, and stable oscillator is a suitable driver and an important milestone for further high harmonics generation and the development of extreme ultraviolet transportable frequency comb sources.

physics.optics↗

arXiv2020

Dual-comb thin-disk oscillator

For the first time to our knowledge, a dual-comb laser based on thin-disk technology and its application to direct frequency comb spectroscopy are presented. The peak power (0.6 MW) and the average power (12 W) of our Yb:YAG thin-disk dual-comb system are more than one-order-of-magnitude higher than in any previous systems. The scheme allows easy adjustment of the repetition frequency difference during operation. A time-domain signal recorded over 10 μs without any active stabilization was sufficient to resolve individual comb lines after Fourier transformation. The demonstration should enable a wider adoption of dual-comb systems towards practical applications in research laboratories. Its simplicity and compactness especially for the realization of tri- and multi-comb systems and conversion into the still poorly covered UV and VUV ranges makes it a promising next-generation technology.

physics.optics↗

arXiv2019

Directly diode-pumped, Kerr-lens mode-locked, few-cycle Cr:ZnSe oscillator

Lasers based on Cr$^{2+}$-doped II-VI material, often known as the Ti:Sapphire of the mid-infrared, can directly provide few-cycle pulses with super-octave-spanning spectra, and serve as efficient drivers for generating broadband mid-infrared radiation. It is expected that the wider adoption of this technology benefits from more compact and cost-effective embodiments. Here, we report the first directly diode-pumped, Kerr-lens mode-locked Cr$^{2+}$-doped II-VI oscillator pumped by a single InP diode, providing average powers of over 500 mW and pulse durations of 45 fs - shorter than six optical cycles at 2.4 $μ$m. These correspond to a sixty-fold increase in peak power compared to the previous diode-pumped record, and are at similar levels with respect to more mature fiber-pumped oscillators. The diode-pumped femtosecond oscillator presented here constitutes a key step towards a more accessible alternative to synchrotron-like infrared radiation, and is expected to accelerate research in laser spectroscopy and ultrafast infrared optics.

physics.optics↗

arXiv2014

High photon flux table-top coherent extreme ultraviolet source

High harmonic generation (HHG) enables extreme ultraviolet radiation with table-top setups. Its exceptional properties, such as coherence and (sub)-femtosecond pulse durations, have led to a diversity of applications. Some of these require a high photon flux and megahertz repetition rates, e.g. to avoid space charge effects in photoelectron spectroscopy. To date this has only been achieved with enhancement cavities. Here, we establish a novel route towards powerful HHG sources. By achieving phase-matched HHG of a megahertz fibre laser we generate a broad plateau (25 eV - 40 eV) of strong harmonics, each containing more than $10^{12}$ photons/s, which constitutes an increase by more than one order of magnitude in that wavelength range. The strongest harmonic (H25, 30 eV) has an average power of 143 $μ$W ($3\cdot10^{13}$ photons/s). This concept will greatly advance and facilitate applications in photoelectron or coincidence spectroscopy, coherent diffractive imaging or (multidimensional) surface science.

physics.optics↗