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298 results on '"Saraceno C"'

1. Diode-pumped 88-fs SESAM mode-locked Tm,Ho:CLNGG laser at 2090 nm

Author

Suzuki, A., Wang, Y., Tomilov, S., Pan, Z., and Saraceno, C. J.

Subjects
Physics - Optics
Abstract

We report on a passively mode-locked Tm, Ho:CLNGG laser operating at 2090 nm, pumped by a multimode fiber-coupled 793 nm laser diode, representing the first demonstration of an affordable diode-pumped sub-100-fs mode-locked laser in the 2.1-\mum wavelength range. Due to the disordered nature of the gain material that exhibits a broad and smooth gain profile, pulses as short as 88 fs were achieved with an average output power of 120 mW at a repetition rate of 70.3 MHz. The stable self-starting mode-locked operation was obtained using a semiconductor saturable absorber mirror based on GaSb material system.

Published
2023

6. Terahertz radiation from a large-area photoconductive emitter via high average power Yb-oscillator

Author

Khalili, M., Vogel, T., Mansourzadeh, S., (0000-0002-8090-9198) Winnerl, S., Saraceno, C., Khalili, M., Vogel, T., Mansourzadeh, S., (0000-0002-8090-9198) Winnerl, S., and Saraceno, C.

Abstract

Photoconductive emitters excited by fs-lasers are the most commonly used emitters in THz-TDS systems, enabling record high dynamic range and wide bandwidths [1,2]. So far, these emitters have mostly optimized for operation with low average power, low-cost fs-laser systems and have a typical dimension of a few µm^2 for the photoconductive gap [3]. In parallel, large-area emitters with mm^2 size have been explored for scaling fluence and obtaining high fields [4]. However, so far, no attempts have been made of using high average power laser systems as excitation sources, as a possible path to increase the THz source average power and reach even higher dynamic range than current reported records. In this work, we present our first results in this direction and show THz emission from a large area photoconductive emitter (LAE) based on SI-GaAs with a 1×1 cm^2 active area, excited by a frequency-doubled home-built high average power ultrafast oscillator, capable of 92 fs at a centre frequency 515 nm with 90 MHz repetition rate and 17 W of average power. We show here preliminary results exciting the LAE with 1 W from this laser system, which is to the best of our knowledge the highest average power applied to such an emitter, without any apparent sign of thermal saturation. 1. R. B. Kohlhaas, S. Breuer, L. Liebermeister, S. Nellen, M. Deumer, M. Schell, M. P. Semtsiv, W. T. Masselink, and B. Globisch, Appl. Phys. Lett. 117, 131105 (2020). 2. U. Nandi, K. Dutzi, A. Deninger, H. Lu, J. Norman, A. C. Gossard, N. Vieweg, and S. Preu, Opt. Lett. 45, 2812 (2020). 3. S. Winnerl, J Infrared Milli Terahz Waves 33, 431 (2012). 4. M. Beck, H. Schäfer, G. Klatt, J. Demsar, S. Winnerl, M. Helm, and T. Dekorsy, Opt. Express 18, 9251 (2010).

Published
2023

12. 400 kHz repetition rate THz-TDS with 24 mW of average power driven by a compact industrial Yb-laser

Author

Millon, C., Houver, S., and Saraceno, C. J.

Subjects
FOS: Physical sciences, Atomic and Molecular Physics, and Optics, Optics (physics.optics), Physics - Optics
Abstract

We demonstrate a high average power terahertz time-domain spectroscopy (THZ-TDS) set-up based on optical rectification in the tilted-pulse front geometry in lithium niobate at room temperature, driven by a commercial, industrial femtosecond-laser operating with flexible repetition rate between 40 kHz – 400 kHz. The driving laser provides a pulse energy of 41 µJ for all repetition rates, at a pulse duration of 310 fs, allowing us to explore repetition rate dependent effects in our TDS. At the maximum repetition rate of 400 kHz, up to 16.5 W of average power are available to drive our THz source, resulting in a maximum of 24 mW of THz average power with a conversion efficiency of ∼ 0.15% and electric field strength of several tens of kV/cm. At the other available lower repetition rates, we show that the pulse strength and bandwidth of our TDS is unchanged, showing that the THz generation is not affected by thermal effects in this average power region of several tens of watts. The resulting combination of high electric field strength with flexible and high repetition rate is very attractive for spectroscopy, in particular since the system is driven by an industrial and compact laser without the need for external compressors or other specialized pulse manipulation.

Published
2023
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23. Poverty in Italy : Features and Drivers in a European Perspective

Author

Saraceno, C, Benassi, D, Morlicchio, E, Saraceno, C, Benassi, D, and Morlicchio, E

Abstract

Italy is one of the EU countries that was hardest hit by the 2008 financial crisis and is also slowest in recovering, even compared to other Mediterranean countries that share some of its societal features. Poverty has steadily increased throughout the period following 2008, and no clear indication of a trend reversal is yet visible. Working poor, the young, children and migrant foreign households are the main victims of the situation. Also the territorial divide has deepened, with the Southern regions bearing the brunt of the crisis much more, and for a longer time, than the Centre-North ones. According to the authors, the duration and depth of the crisis in Italy, and its impact on poverty, were largely a consequence of long-term structural features of the Italian economy, of its weak and fragmented social safety net, with its high expectations concerning family solidarity and the gender division of labour on the one hand, of its sluggish growth since the 1990s on the other. Governments’ austerity choices in reaction to the crisis (and under pressure from the EU) have further strengthened these features, although the recent introduction of a minimum income provision has marked an important change in the policy approach to poverty.

Published
2020

36. Sub-100 femtosecond pulses from a SESAM modelocked thin disk laser

Author

Saraceno, C., Heckl, O., Baer, C., Schriber, C., Golling, M., Beil, K., Kränkel, C., Südmeyer, T., Huber, G., Keller, U., Saraceno, C., Heckl, O., Baer, C., Schriber, C., Golling, M., Beil, K., Kränkel, C., Südmeyer, T., Huber, G., and Keller, U.

Abstract

We present the first passively modelocked thin disk laser (TDL) with sub-100-fs pulse duration using the broadband sesquioxide gain material Yb:LuScO3 and an optimized SEmiconductor Saturable Absorber Mirror (SESAM). In this proof-of-principle experiment, we obtained 5.1W of average power at a repetition rate of 77.5MHz and a pulse duration of 96fs. We carefully explored and optimized the different parameters on the soliton pulse formation process for the generation of short pulses. In particular, SESAMs combining fast recovery time, high modulation depth and low nonsaturable losses proved crucial to achieve this result even though they are expected to only play a minor role in soliton modelocking. To our knowledge, these are the shortest pulses ever obtained with a modelocked TDL, reaching for the first time the sub-100-fs milestone. This result opens the door to sub-100-fs oscillators with substantially higher power levels in the near future

Published
2018

38. The role of rho-gtpases in the aetiology of Alzheimer's disease

Author

Saraceno, C., Pontelli, Valeria, Catania, M., Paterlini, A., Borin, Mirta, Lorenzetto, Erika, Fostinelli, S., Di Fede, G., Buffelli, Mario Rosario, Benussi, L., Binetti, G., Ghidoni, R., and Bolognin, Silvia

Subjects
Alzheimer’s disease, Rho-GTPases, biomarkers
Published
2017

43. Extreme Ultraviolet Light Source by High-Harmonic Generation Inside an Ultrafast Thin-Disk Laser

Author

Labaye, F., primary, Gaponenko, M., additional, Wittwer, V. J., additional, Diebold, A., additional, Paradis, C., additional, Modsching, N., additional, Merceron, L., additional, Emaury, F., additional, Graumann, I. J., additional, Phillips, C. R., additional, Saraceno, C. J., additional, Kränkel, C., additional, Keller, U., additional, and Südmeyer, T., additional

Published
2018
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46. Dual-beam multipass cell compression for time-resolved femtosecond spectroscopy setups

Author

Omar Alan, Kassai Boldizsar, Hoffmann Martin, and Saraceno Clara J.

Subjects
Physics, QC1-999
Abstract

We present a dual-beam single multi-pass cell compressor designed for applications in time-resolved pump-probe spectroscopy. A single MPC simultaneously compresses two beams with different pulse energies to the same pulse duration, allowing for independent modulation of the input beams. The two beams have different, high pulse energies (82 µJ and 296 µJ) and are compressed to the same pulse duration of 50 fs with high efficiency.

Published
2024
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47. Broadband regenerative amplifier based on Ho:CALGO at 2.1 μm

Author

Suzuki Anna, Ahmed Shahwar, Wang Yicheng, Tomilov Sergei, and Saraceno Clara J.

Subjects
Physics, QC1-999
Abstract

We present a broadband Ho:CALGO regenerative amplifier operating at 2.1 μm, delivering a pulse energy of 342 μJ at 1 kHz with a spectral bandwidth of 5 nm, supporting sub-ps pulse duration.

Published
2024
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48. High-power, µJ-class Kerr-lens mode-locked thin-disk oscillators at 2.1 µm

Author

Tomilov Sergei, Redkin Mykyta, Wang Yicheng, Yao Weichao, Suzuki Anna, Hoffmann Martin, and Saraceno Clara J.

Subjects
Physics, QC1-999
Abstract

We report on the development of 2.1-µm high-power Kerr-lens mode-locked thin-disk oscillator configurations based on Ho:YAG, reaching up to 29 W of output power and 1.74 µJ of pulse energy.

Published
2024
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49. Efficient Resonant Waveguide Grating for High-Power Lasers in the 2-µm Wavelength Range

Author

Boubekraoui Ayoub, Tomilov Sergei, Redkin Mykyta, Bashir Danish, Mourkioti Georgia, Mackenzie Jacob, Saraceno Clara J., Graf Thomas, and Ahmed Marwan Abdou

Subjects
Physics, QC1-999
Abstract

We present resonant waveguide-grating (RWG) tailored for lasers operating at the 2-µm wavelength range. Utilizing the RWG as a cavity mirror, generation of tunable narrow-bandwidth and linearly-polarized radiation from a Ho:YAG thin-disk laser was demonstrated.

Published
2024
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50. Optimized SESAMs for kilowatt-level ultrafast lasers

Author

Diebold A., Zengerle T., Alfieri C. G. E., Schriber C., Emaury F., Mangold M., Hoffmann M., Saraceno C. J., Golling M., Follman D., Cole G. D., Aspelmeyer M., Südmeyer T., and Keller U.

Abstract

We present a thorough investigation of surface deformation and thermal properties of high-damage threshold large-area semiconductor saturable absorber mirrors (SESAMs) designed for kilowatt average power laser oscillators. We compare temperature rise, thermal lensing, and surface deformation of standard SESAM samples and substrate-removed SESAMs contacted using different techniques. We demonstrate that for all cases the thermal effects scale linearly with the absorbed power, but the contacting technique critically affects the strength of the temperature rise and the thermal lens of the SESAMs (i.e. the slope of the linear change). Our best SESAMs are fabricated using a novel substrate-transfer direct bonding technique and show excellent surface flatness (with non-measureable radii of curvature (ROC), compared to astigmatic ROCs of up to 10 m for standard SESAMs), order-of-magnitude improved heat removal, and negligible deformation with absorbed power. This is achieved without altering the saturation behavior or the recovery parameters of the samples. These SESAMs will be a key enabling component for the next generation of kilowatt-level ultrafast oscillators.

Published
2016

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