30 W-average-power femtosecond NIR laser operating in a flexible GHz-burst-regime

Abstract

Laser sources which produce GHz bursts of ultrashort pulses attract a lot of attention by demonstrating superior performance in material processing. Flexibility of the laser source in a selection of parameters for custom application is highly preferable. In this work, we demonstrate a very versatile method for burst formation using the active fiber loop (AFL). It allows forming GHz bursts containing from 2 up to approximately 2200 pulses in a burst (1000 ns burst width) with identical pulse separation and any predefined intra-burst pulse repetition rate (PRR). The burst pre-shaping by the amplification conditions in the AFL and by the modulation of transmission of the acousto-optic modulator was demonstrated. Industrial-grade ultrafast laser system was able to operate in the single-pulse and GHz-burst regimes. The laser system delivered high-quality 368 fs duration (FWHM) pulses of 15.3 µJ pulse energy and 30.6 W average output power at 2 MHz PRR in the single-pulse regime. In the GHz-burst operation regime, bursts of 2.2 GHz intra-burst repetition rate were formed and amplified to more than 30 W average output power with a burst energy up to 135 µJ at a burst repetition rate of 200 kHz. The sub-picosecond duration of pulses was obtained in the GHz-burst regime at different burst widths.

Versatile ultrashort pulse laser tunable up to nanosecond range

“…The AFL is a versatile technology suitable to form GHz bursts of ultrashort laser pulses and to tune pulse duration even up to the nanosecond range. The main concept of GHz burst formation, its flexibility and advantages over other fiberbased techniques are presented in subsection 2.1 and our previous works more in detail [11][12][13]. Furthermore, in this work, we introduce patent-pending [14,15] modifications of the AFL technology which allow to tune the pulse duration from femtoseconds to nanoseconds and to shape the pulse spectrum (subsections 2.2 and 2.3).…”

“…A detailed description of a pulse multiplication technique and the demonstration of its versatility in industrial-grade high-power laser is provided in ref. 13.…”

“…In this work, we present a versatile technology based on the use of an active fiber loop (AFL) for GHz burst formation [11][12][13] and its modification which allowed to tune pulse duration from a few hundred femtoseconds to picoseconds and even up to the nanosecond pulse duration range. A patent-pending technology enabled new operation *t.bartulevicius@ekspla.com; phone +370 5 264 96 29 Fax; +370 5 264 18 09; ekspla.com regimes and a unique set of features in the industrial-grade 30 W-level average power femtosecond hybrid laser.…”

Where flexibility meets precision

“…A patent-pending solution for the formation of short and long GHz bursts is realized in an all-in-fiber design [7][8][9]. The developed method is based on an active fiber loop (AFL) (Fig.…”

Novel dual-wavelength front-end with active fiber loop for high intensity laser systems

“…The AFL is designed as an all-in-fiber system and consists of three key components that enable burst formation: the acousto-optic modulators for temporal control of the pulses/bursts, a ytterbium-doped fiber (YDF) amplifier for pulse amplification, and a chirped fiber Bragg grating (CFBG) for dispersion compensation. [2] Figure 3. The principle of the AFL operation for GHz-burst formation.…”