High Average Power Femtosecond Laser Research Articles

Towards intense ultra-broadband high repetition rate terahertz sources based on organic crystals [Invited

Increasing the average power of broadband, few-cycle terahertz (THz) sources is currently a topic of intense investigation, fueled by recent immense progress in high average power femtosecond laser driving sources at 1030 nm. However, many crucial applications would benefit not only from an increase in average power, but also from ultra-broad bandwidth, while maintaining high dynamic range at these frequencies. This calls for the challenging combination of high repetition rates and high average power simultaneously. Here, we discuss the recent progress in the promising approach enabled by organic crystals for THz-generation. Specifically, this review article discusses advances with the most commonly used organic crystals BNA, DAST, DSTMS, OH1 and HMQ-TMS. We place special emphasis on nonlinear and thermal properties and discuss future directions for this field.

Pulse nonlinear compression generated 71.3 W femtosecond laser

<sec>The power of femtosecond lasers based on Ti: sapphire or Yb-doped gain media has reached a high level by using chirped pulse amplification. The dispersive elements are normally employed in CPA devices, thereby increasing the complexity and cost of the laser system. However, for the Nd-doped laser, its power can be amplified to hundreds of microjoules or even several millijoules directly without CPA technology. So compressing the picosecond pulse to obtain femtosecond laser pulses with hundreds of microjoules pulse energy by post-compression technology becomes meaningful. The pulsed post-compression technology is the combination of nonlinear spectral broadening and dispersion compensation. Currently, the most effective method of nonlinear spectral broadening is achieved through self-phase modulation. The multi-pass cell (MPC) device based on self-phase modulation for broadening spectral bandwidth has been extensively studied, since it was demonstrated. The MPC concept demonstrates significant practical benefits. Essentially, it requires only two curved mirrors and a Kerr medium in between, making it a cost-effective and easily implementable method. Moreover, the MPCs are robust, quite insensitive to beam pointing, and can evendeal with small mode mismatch without transmission losses. These favorable characteristics make MPCs very attractive not only for scientific applications, but also for commercial and facility laser systems where reliability is crucial. The striking progress of the technique in the past six years has made it possible to obtain high average power femtosecond laser.</sec><sec>In this work, we demonstrate the generation of a high average power femtosecond laser pulse by nonlinearly compressing the picosecond pulse in the Herriott multi-pass cell device, and the distribution of eigenmode is analyzed. With this efficient and robust scheme, the spectrum is broadened from 0.20 nm to 2.75 nm, with a broadening ratio of 13.75, and the pulse duration of a picosecond amplifier is compressed from 1.25 ps to 780 fs, with a compression factor of 16. The average power before and after pulse compression are 100 W and 71.3 W respectively, so the overall transmission reaches 71.3%. The present scheme offers a viable route to low-cost and simple-configuration high-power femtosecond lasers driven by Nd-doped picosecond amplifiers.</sec>

Generation of 56.5 W femtosecond laser radiation by the combination of an Nd-doped picosecond amplifier and multi-pass-cell device.

We demonstrate the generation of high average power femtosecond laser radiation by combination of an Nd-doped picosecond amplifier and a multi-pass cell device. With this efficient and robust scheme, the pulse duration of a picosecond amplifier is compressed from 9.13 ps to 477 fs, corresponding to a compression factor of 19.1. The average power before and after pulse compression is 77 W and 56.5 W respectively, so the overall transmission reaches 73.4%. The presented scheme offers a viable route toward low-cost and simple configuration high power femtosecond lasers driven by Nd-doped picosecond amplifiers.

КОМПЕНСАЦИЯ АСТИГМАТИЗМА В БЛОКЕ ВРЕМЕННОГО РАСШИРЕНИЯ ИМПУЛЬСА КАНАЛА НАКАЧКИ МОЩНОЙ ЛАЗЕРНОЙ СИСТЕМЫ

A high peak and high average power femtosecond laser system based on media doped with Yb3+ ions is being developed at the Institute of Laser Physics of the SB RAS. For efficient laser amplification and to avoid optical damage is actually to compensate wave front distortion caused by grating astigmatism in pump channel. Based on theory of propagation of gaussian beam in space and through optical elements the calculation of optimal parameters of two lenses telescope and comparison with experimental data has been performed. The obtained results can be used for decrease of astigmatic effect on beam profile quality in design of laser systems with elements involving astigmatism.

Ultra-stable high average power femtosecond laser system tunable from 1.33 to 20 μm.

A highly stable 350 fs laser system with a gap-free tunability from 1.33 to 2.0 μm and 2.13 to 20 μm is demonstrated. Nanojoule-level pulse energy is achieved in the mid-infrared at a 43 MHz repetition rate. The system utilizes a post-amplified fiber-feedback optical parametric oscillator followed by difference frequency generation between the signal and idler. No locking or synchronization electronics are required to achieve outstanding free-running output power and spectral stability of the whole system. Ultra-low intensity noise, close to the pump laser's noise figure, enables shot-noise limited measurements.

Extended femtosecond laser wavelength range to 330 nm in a high power LBO based optical parametric oscillator.

We experimentally demonstrate a compact tunable, high average power femtosecond laser source in the ultraviolet (UV) regime. The laser source is based on intra-cavity frequency doubling of a temperature-tuned lithium tribotate (LBO) optical parametric oscillator (OPO), synchronously pumped at 520 nm by a frequency-doubled, Yb-fiber femtosecond laser amplifier system. By adjusting crystal temperature, the OPO can provide tunable visible to near-infrared (NIR) signal pulse, which have a wide spectral tuning range from 660 to 884 nm. Using a β-barium borate (BBO) crystal for intra-cavity frequency doubling, tunable femtosecond UV pulse are generated across 330~442 nm with up to 364 mW at 402 nm.

Investigation of the thermally induced laser beam distortion associated with vacuum compressor gratings in high energy and high average power femtosecond laser systems

We report successful compensation of the thermally induced laser beam distortion associated with high energy 110 mJ and high average power femtosecond laser system of 11 Watts operated with vacuum compressor gratings. To enhance laser-based light source brightness requires development of laser systems with higher energy and higher average power. Managing the high thermal loading on vacuum optical components is a key issue in the implementation of this approach. To our knowledge this is the first time that such thermal induced distortions on the vacuum compressor gratings are characterized and compensated.