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2015-07 ATTO conference

2015-03 UDIM conference

Attosecond transient absorption spectroscopy in two-dimensional functionalized transition metal carbide unveils ultrafast element, site, and carrier-specific electron-phonon relaxations on the few-femtosecond timescale and provides new insights towards engineering of electronic heat dissipation at atomic scale., Technical Digest Series, International Conference on Ultrafast Phenomena, ISBN:978-1-557528-20-9

2014-06 GRC Multiphoton Processes

We demonstrate a spatially-multiplexed dual-comb 250-MHz OPO from a single linear cavity. The adjustable repetition-rate difference is 4.1 kHz. Each idler comb has >200-mW average power at 3.5 μm with 30 nm bandwidth. The OPO is wavelength-tunable from 1.36 μm to 1.7 μm and 2.9 μm to 4.17 μm., EPJ Web of Conferences, 267, ISSN:2100-014X, ISSN:2101-6275, 10th EPS-QEOD Europhoton Conference on Solid-State, Fibre, and Waveguide Coherent Light Sources (EUROPHOTON 2022)

Ultrafast pump-probe measurements are used to characterize various samples, such as biological cells, bulk, and thin-film structures. However, typical implementations of the pump-probe apparatus are either slow or complex and costly hindering wide deployment. Here we combine a single-cavity dual-comb laser with a simple experimental setup to obtain pump-probe measurements with ultra-high sensitivity, fast acquisition, and high timing precision over long optical delay scan ranges of 12.5 ns that would correspond to a mechanical delay of about 3.75 m. We employ digital signal balancing to obtain shot-noise-limited detection compatible with pump-probe microscopy deployment. Here we demonstrate ultrafast photoacoustics for thin-film sample characterization. We measured a tungsten layer thickness of (700 ± 4) Å with shot-noise-limited detection. Such single-cavity dual-comb lasers can be used for any pump-probe measurements and are especially well-suited for ultrafast photoacoustic studies such as involving ultrasonic echoes, Brillouin oscillations, surface acoustic waves and thermal dynamics., Photoacoustics, 29, ISSN:2213-5979

Laser ranging (LIDAR) with dual optical frequency combs enables high-resolution distance measurements over long ranges with fast update rates. However, the high complexity of stabilized dual optical frequency comb systems makes it challenging to use this technique in industrial applications. To address this issue, here we demonstrate laser ranging directly from the output of both a free-running dual-comb diode-pumped semiconductor and solid-state laser oscillator. Dual-comb operation from a single cavity is achieved via polarization duplexing with intracavity birefringent crystals. We perform ranging experiments with two implementations of this scheme: A modelocked integrated external cavity surface-emitting laser (MIXSEL) and a Yb:CaF2 solid-state laser. For these proof of principle demonstrations, we measure the distance to a moving mirror mounted on a home-made shaker. The MIXSEL laser has a repetition rate of 2.736 GHz and a repetition rate difference of 52 kHz, and yields a measurement resolution of 1.36 μm. The Yb:CaF2 laser has a repetition rate of 137MHz and a repetition rate difference of 952 Hz, and yields a measurement resolution of 0.55 μm. In both cases the resolution is inferred by a parallel measurement with a HeNe interferometer. These results represent the first laser ranging with free-running dual-comb solid-state oscillators. With further optimization, resolution well below 1 μm and range well above 1 km are expected with this technique. ISSN:1094-4087

Dual optical frequency combs are an appealing solution to many optical measurement techniques due to their high spectral and temporal resolution, high scanning speed, and lack of moving parts. However, industrial and field-deployable applications of such systems are limited due to a high-cost factor and intricacy in the experimental setups, which typically require a pair of locked femtosecond lasers. Here, we demonstrate a single oscillator which produces two mode-locked output beams with a stable repetition rate difference. We achieve this via inserting two 45°-cut birefringent crystals into the laser cavity, which introduces a repetition rate difference between the two polarization states of the cavity. To mode-lock both combs simultaneously, we use a semiconductor saturable absorber mirror (SESAM). We achieve two simultaneously operating combs at 1050 nm with 175-fs duration, 3.2-nJ pulses and an average power of 440 mW in each beam. The average repetition rate is 137 MHz, and we set the repetition rate difference to 1 kHz. This laser system, which is the first SESAM mode-locked femtosecond solid-state dual-comb source based on birefringent multiplexing, paves the way for portable and high-power femtosecond dual-combs with flexible repetition rate. To demonstrate the utility of the laser for applications, we perform asynchronous optical sampling (ASOPS) on semiconductor thin-film structures with the free-running laser system, revealing temporal dynamics from femtosecond to nanosecond time scales. © 2020 Optical Society of America. ISSN:1094-4087

Gefördert durch den Publikationsfonds der Universität Kassel

Optica, 7 (5), ISSN:2334-2536

Who are the “gender experts” This conference explores the link between feminist knowledge production and how such knowledge travels and is translated into “gender expertise” in institutions and development policies. The debate is part of the controversy around gender mainstreaming: can it actually be a transformative strategy for rethinking the neo-liberal and patriarchal system, or has it simply become an integrationist model co-opting the feminist cause? Yet the conference wants to go beyo...

Depuis la quatrième Conférence mondiale sur les femmes à Beijing, on observe une forte augmentation du nombre de personnes expertes en genre. Celles-ci circulent, tout comme les pratiques, les idées, les théories et les textes féministes qui voyagent sont interprétés, resignifiés. Des inégalités existent dans les processus d’élaboration, la circulation et la traduction des savoirs. Le champ social constitué par les expertes en genre est ainsi traversé par des rapports de pouvoir. La notion de colonialité du pouvoir et des savoirs permet d’interroger l’hégémonie et l’autorité universelle des discours et des savoirs occidentaux. Les contributions des études féministes pour revisiter le développement sont soulignées dans cet ouvrage. Ces apports, énoncés depuis diverses perspectives, s’inscrivent dans des espaces de contestation de l’ordre mondial, sont nourris de la prise de conscience des multiples rapports de domination et de l’émergence de nouveaux mouvements sociaux. Ils participent d’un processus de décolonisation de la pensée féministe. Avec la collection « Genre et développement. Rencontres », nous poursuivons le dialogue de savoirs sur les questions féministes et de genre, la construction d’alliances et de ponts entre chercheur-es, organisations féministes et de recherche, ONG, organisations de coopération, expertes, aux Nords et aux Suds. Les textes, écrits par des chercheur-es ou personnes actives dans ces initiatives sont publiés dans leur langue originale.

Nova Acta Leopoldina. Neue Folge, 425, ISSN:0369-5034, Zeit in Natur und Kultur: Vorträge anlässlich der Jahresversammlung am 20. und 21. September 2019 in Halle (Saale), ISBN:978-3-8047-4107-2