Search

The effect of doping level (0.1-10 at.%) on mid-infrared laser performance of Er:CaF2 crystals was investigated. The Er:CaF2 laser delivered 1.17 W at 2798 nm with 35.8% slope efficiency and was tuned across 2690-2830 nm.

A Tm:LiYF4 laser operating on the 3H4→3H5 transition with upconversion pumping at 1.45 µm generates 831 mW at 2313 nm with 34.0% slope efficiency. Mode-locked by a GaSb- based SESAM, it delivers 855-fs pulses at 104.4-MHz.

We demonstrate the generation of broadband tunable and synchronized pulses exceeding the microjoule level using the new concept of Fiber Optical Parametric Chirped-Pulse Oscillation (FOPCPO). The oscillator is based on a collapsed-ends photonic crystal fiber pumped in the normal dispersion regime by an ytterbium fiber laser delivering highly-chirped pulses. The experimental results are compared with the results of numerical simulations and highlight that the feedback ratio appears as a key parameter for optimizing the system’s efficiency and dynamics.

We demonstrate the generation of broadband tunable and synchronized pulses exceeding the microjoule level using the new concept of fiber optical parametric chirped-pulse oscillation (FOPCPO). The oscillator is based on a collapsed-ends photonic crystal fiber pumped in the normal dispersion regime by a fiber laser.

We report on a polarization-resolved study of mid-infrared emission properties of Er3+ ions in the orthorhombic YAlO3 crystal. For the 4I11/2 → 4I13/2 transition, σSE reaches 0.20×10-20 cm2 at 2919 nm (for light polarization E || c). Pump-induced polarization switching between the E || b and E || c eigen-states is observed in an 10 at.% Er:YAlO3 laser. Pumped by an Yb-fiber laser at 976 nm, this laser delivers 0.77 W at 2919 nm with a slope efficiency of 31.4% being close to the Stokes limit and a laser threshold of 33 mW.

We report on a high energy ultrafast fibre laser architecture designed for high harmonics generation in solids. The laser delivering 50 fs pulses with 2.12 µJ at 1550 nm has enabled the generation of harmonics up to harmonic H5 from a magnesium oxide (MgO) bulk sample. To the best of our knowledge this is the first solid-state HHG source driven by a µJ-class few-cycle fiber laser in the mid-IR region.

Fluorite-type 5 at.% Er3+:(M1,M2)F2 (M1 = Ca, Ba; M2 = Sr) crystals were grown by the conventional Bridgman technique and a comparative study of their spectroscopic properties was performed. The vibronic properties of the fluorite-type crystals were studied by Raman spectroscopy. The Er:(M1,M2)F2 crystals exhibited a slightly inhomogeneous broadening of mid-infrared luminescence spectra as compared to the ‘parent’ compound, Er:SrF2. The luminescence lifetimes of the 4I11/2 and 4I13/2 manifolds were measured, e.g., for the Er:(Ca,Sr)F2 crystal, the luminescence lifetimes were estimated to be 8.64 ms and 5.64 ms, respectively, representing a favorable ratio for mid-IR laser operation.

We demonstrate a versatile and user-friendly ultrafast single-shot imaging technique based on a simple and flexible acousto-optics spectro-temporal shaping stage combined with digital in-line holography.

The need to measure high repetition rate ultrafast processes cuts across multiple areas of science. The last decade has seen tremendous advances in the development and application of new techniques in this field, as well as many breakthrough achievements analyzing non-repetitive optical phenomena. Several approaches now provide convenient access to single-shot optical waveform characterization, including the dispersive Fourier transform (DFT) and time-lens techniques, which yield real-time ultrafast characterization in the spectral and temporal domains, respectively. These complementary approaches have already proven to be highly successful to gain insight into numerous optical phenomena including the emergence of extreme events and characterizing the complexity of laser evolution dynamics. However, beyond the study of these fundamental processes, real-time measurements have also been driven by particular applications ranging from spectroscopy to velocimetry, while shedding new light in areas spanning ultrafast imaging, metrology or even quantum science. Here, we review a number of landmark results obtained using DFT-based technologies, including several recent advances and key selected applications.

The generation of terahertz radiation via laser-induced plasma from two-color femtosecond pulses in air has been extensively studied due to its broad emission spectrum and significant pulse energy. However, precise control over the temporal properties of these ultra-broadband terahertz pulses, as well as the measurement of their polarization state, remain challenging. In this study, we review our latest findings on these topics and present additional results not previously reported in our earlier works. First, we investigate the impact of chirping on the fundamental wave and the effect of manipulating the phase difference between the fundamental wave and the second-harmonic wave on the properties of generated terahertz pulses. We demonstrate that we can tune the time shape of terahertz pulses, causing them to reverse polarity or become bipolar by carefully selecting the correct combination of chirp and phase. Additionally, we introduce a novel technique for polarization characterization, termed terahertz unipolar polarimetry, which utilizes a weak probe beam and avoids the systematic errors associated with traditional methods. This technique is effective for detecting polarization-structured terahertz beams and the longitudinal component of focused terahertz beams. Our findings contribute to the improved control and characterization of terahertz radiation, enhancing its application in fields such as nonlinear optics, spectroscopy, and microscopy. [ABSTRACT FROM AUTHOR]

We report on a passively mode-locked oscillator based on an erbium-doped dual concentric core fiber combining high normal dispersion and large mode area. This large normal dispersion laser generates long pulses with 30 ps duration and 0.17 nm spectral width at 1530 nm wavelength. The source delivers an average power of 64 mW at a repetition rate of 16 MHz, corresponding to 4 nJ energy. This concept opens up new degrees of freedom in the design of mode-locked fiber lasers.