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We demonstrate passive mode-locking of a Tm,Ho-codoped crystalline laser operating on the Ho³⁺-ion transition ⁵I₇→⁵I₈ near 2 µm using a single-walled carbon nanotube saturable absorber. The Tm,Ho:KLu(WO₄)₂ laser emits nearly transform-limited pulses with duration of 2.8 ps at a repetition rate of 91 MHz. The output power amounts to 97 mW.

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Passive mode-locking of a Tm,Ho:KLu(WO(4))(2) laser operating at 2060 nm using different designs of InGaAsSb quantum-well based semiconductor saturable absorber mirrors (SESAMs) is demonstrated. The self-starting mode-locked laser delivers pulse durations between 4 and 8 ps at a repetition rate of 93 MHz with maximum average output power of 155 mW. Mode-locking performance of a Tm,Ho:KLu(WO(4))(2) laser is compared for usage of a SESAM to a single-walled carbon nanotube saturable absorber.

Following the completion of the installation and testing of the HPLS 2x10PW laser system at ELI-NP, prospective experiments related to spectral broadening in thin films for post-compression were performed at the HPLS 100TW output.

We demonstrate χ (2) -lens mode-locking of a diode pumped Nd:YVO 4 laser. The output power is 6 W, the pulse duration is 6 ps for repetition rates from 110 MHz up to 600 MHz. OCIS codes: (140.3530) Lasers, neodymium; (140.4050) Mode-locked lasersMode-locked diode-pumped lasers with high average power (>1 W) and high repetition rate (~1 GHz) have attracted significant attention because of their potential applications, especially in high-capacity telecommunication systems and time-resolved spectroscopy. Semiconductor saturable absorber mirror (SESAM) mode-locking technique has been used already to generate high repetition rate picosecond pulses with duration of 13.7 ps and 21 ps respectively [1,2]. A SESAM with low modulation depth is required in order to prevent Q-switching instabilities, because in fundamental mode-locking regime at certain intra-cavity power increasing the repetition rate leads to reducing the intra-cavity pulse energy [3]. However, utilizing a SESAM with low modulation depth prevents the pulse shortening and self-starting operation of the mode-locking regime. Moreover, the residual absorption of SESAMs can lead to heating or thermal damage of the absorber, especially for operation at high intra-cavity power and high repetition rate. As an alternative to SESAMs, χ (2) -lens mode-locking has been demonstrated with Nd:YVO 4 and Nd:GdVO 4 lasers emitting output power of several watts with transform-limited pulses [4,5]. In rhis technique two physical processes govern the mode-locking operation: resonator intensity dependent loses due to intra-cavity χ (2) -lens formation and soliton-like pulse shaping due to negative intra-cavity self-phase modulation introduced by phase mismatched SHG. Hence, χ (2) -lens mode-locking enables high power operation, because there is no residual absorption typical for saturable absorbers. Besides, soliton-like pulse shaping substantially reduces the tendency to Q-switching instabilities and supports generation of transform-limited pulses.In this work we report χ (2) -lens mode-locking of a diode-pumped Nd:YVO 4 laser. Stable and self-starting modelocking operation is achieved in the case of negative intra-cavity self-phase modulation. 6.1 ps transform-limited pulses have been generated with average output power of 6.1 W and repetition rate up to 600 MHz.The laser design is based on a linear cavity, whose length can vary from 1.5 m to 0.25 m ( fig. 1). The active medium is a 9 mm long, a-cut Nd:YVO 4 crystal with doping concentration of 0.27 at. % Nd 3+ . It is longitudinally pumped by the unpolarized radiation of a 808 nm laser diode bar coupled into a 400 µm optical fiber (NA=0.22). The output beam from the fiber is focused by a 1:1.5 reimaging unit (F1-F2) and delivered onto the active medium through the mirror M1, which transmits the pump radiation. The pump beam waist is measured to be ≈300 µm in radius and the absorbed pump power is ≈90% of the incident power. The SHG crystal is a periodically-poled 1 mol. % Mg-doped stoichiometric lithium tantalate (PPMgSLT) wit...

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Generation of high-power and high-reproducibility ultra-short laser pulses is demanded by a wide range of applications such as materials processing, medicine and optical spectroscopy. Passive mode-locking of CWpumped lasers is the conventional and most robust approach for obtaining steady-state laser operation but their single-pulse energy and average power are quite limited e.g. to ~100 W at 80-110 MHz repetition rate. Although the Yb 3+ -based thin-disk laser oscillators can operate with ~1-kW output power in CW mode, mode-locking is demonstrated up to ~275 W at repetition rate of 16 MHz [1]. In addition, this method for generation a train of ps-pulses requires a high degree of system complexity and development of passive mode-locking techniques applicable to oscillator with high average power. An alternative approach to meet the application requirements of ps-pulses with high-energy and average power is to generate a burst of picoseconds pulses with a kilohertz repetition rate and controllable duration and energy. Besides, such time structure is shown to be effective for a broad area of applications based on laser material interaction [2].In this work, we report an longitudinally pumped, double-pass Nd:YVO 4 preamplifier with two stage transversely diode-pumped Nd:YAG rod power amplifiers used for amplification of a 6 picosecond, 95 MHz burst of pulses with tunable macro-pulse (train) duration (10 μs -100 μs) at 0.5 kHz repetition rate. The pulses were derived from a near diffraction limited (M 2 < 1.3), CW pumped, passively mode-locked Nd:YVO 4 master oscillator [3]. The preamplifier is comprised by a 9-mm long Nd:YVO 4 crystal, longitudinally pumped via 600-um fiber with 65-W, 808-nm laser pulses from a QCW laser diode, with duration of 24 μs -120 μs (for the 10 μs and 100 μs macro-pulse duration), and 0.5-kHz repetition rate. The absorption is measured to be 90 % of the incident pump power. After a double pass through the preamplifier stage we were able to achieve macro-pulse energy of 0.17 mJ for the 10 μs and 1.9 mJ, for the 100 μs pulse duration. The delay between the seed pulse train and the pump, and the duration of the pump pulse itself are optimized in such way to achieve flat macro-pulse (all the pulses in the macro-pulse are amplified equally). The pulse train is further amplified in two-stage power amplifier. Double-pass amplification in both stages is realized by a polarizer and a 45 degree Faraday rotator for each stage. A telescope with the necessary magnification is placed in the input of each stage to form the required beam in the diode pumped module. After the first pass through Nd:YAG rod the beam is relay imaged onto itself by 1:1 telescope and a highly reflecting mirror through the Faraday rotator. With this setup we can assure that after the reflection the beam passes through the same trajectory as at the first pass. As a result nearly perfect compensation of depolarization of Nd:YAG rod is achieved. At the output of the system, the macro-pulse energy reached 15.