ABSTRACT
Femtosecond laser engraving offers appealing advantages compared to regular laser engraving such as higher precision and versatility. In particular, the inscription of deep patterns exhibits an increasing interest in industry. In this work, an optimization protocol based on constraining overlap ratio and scan number is demonstrated. The proposed method allows changing overlap ratio while maintaining depth in the same range, which reduces the sampling number. This study WAS applied to stainless steel 316 L and sapphire for engravings deeper than 100 µm. Results exhibit overall depths higher than threshold values and allowed to determine optimized engraving quality, for instance, roughness in steel can be reduced while maintaining depth and taper angle by reducing overlap ratio. The optimized laser parameters such as roughness and taper angle factors for sapphire were also found to be as follows: 200 kHz, 86% overlap and 12 J/cm2. As a demonstration, a logo engraving is illustrated at the end.
ABSTRACT
We numerically and experimentally demonstrate ultra-broadband fiber optical parametric amplification in a microstructured fiber pumped by stretched short pulses. The chirped pump pulse induces a temporally spread spectral gain suitable for optical parametric chirped pulse amplification in fibers. Numerical simulation shows ~45 dB flat gain with more than 70 nm bandwidth, allowing sub-35 fs pulse amplification around 1 µm with reduced gain narrowing. This amplification principle is experimentally confirmed by measuring the instantaneous spectral gain band and related chirp.
ABSTRACT
We demonstrate with realistic numerical simulations that fiber optical parametric chirped pulse amplification is able to amplify ultra-short optical pulses. Such amplifiers driven by two-pump waves can amplify pulse bandwidth twice as large as the one of a single pump configuration. We show that pulses as short as 50 fs can be directly amplified. In addition, we take benefit from the saturation regime to achieve spectral broadening which makes possible to reduce pulse duration down to 15 fs.
