Comparative study on grating fabrication in transparent materials by TWIN-LIBWE and ultrashort pulsed ablation techniques

Two methods for micro-structuring of transparent dielectric were compared in this study: the two-beam interferometric laser-induced backside wet etching (TWIN-LIBWE) and the two beam in-terferometric ablation by ultrashort laser pulses. In TWIN-LIBWE we used the 4th harmonic of Nd:YAG laser (λ=266 nm, τFWHM=8 ns, fuence: 265-500 mJ/cm2), while a Ti:Sapphire-based femto-second system (λ=800 nm, τFWHM=30 fs, pulse energy: 600-900 μJ) was used for direct ablation. Fused silica, sapphire and glass were used as bulk targets, while Al2O3, Y2O3, HfO2 and ZrO2 thin films (thickness: 160-1000 nm) on fused silica substrates were used as transparent film targets. The incident angle of the interfering beams was adjusted to result in 1 μm period structures in both ar-rangements. The surface morphologies of gratings were studied by atomic force microscope (AFM). After the comparison of best quality gratings produced by both setup in each material, we cannot determined which is the universally optimal method. The grating quality depends on the target ma-terial, their thickness, and certainly on the laser parameter

Single-shot CEP drift measurement at arbitrary repetition rate based on dispersive Fourier transform

This paper presents a single-shot technique for measuring CEP. The Temporal dispersion based One-shot Ultrafast Carrier envelope phase Analysis method (TOUCAN) is an arbitrary repetition rate single-shot CEP drift measurement technique based on dispersive Fourier transformations and has been experimentally tested at 100 kHz. TOUCAN was validated by a direct comparison of decimated data with an independent traditional CEP drift measurement technique. The impact of a temporal jitter on the CEP drift measurement is investigated and a new mitigation technique is shown to produce high accuracy jitter-free CEP drift extraction. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen