Polarisation-independent ultrafast laser selective etching processing in fused silica. Issue 7 (14th February 2023)

• Record Type: Journal Article
• Authors: Ochoa, Mario; Roldán-Varona, Pablo; Algorri, José Francisco; López-Higuera, José Miguel; Rodríguez-Cobo, Luis
• Is Part Of: Lab on a chip. Volume 23:Issue 7(2023)
• Page Start: 1752
• Page End: 1757
• Publication Date: 2023-02-14
• Subjects: Miniature electronic equipment -- Periodicals; Combinatorial chemistry -- Periodicals; Biotechnology -- Periodicals; 543.0813
• DOI: 10.1039/d3lc00052d
• Languages: English
• ISSNs: 1473-0197

Abstract

Abstract : Few pulses and suitable low-energy femtosecond laser parameters achieve high etching rates (about 300 μm h −1 ) without the need to control the light polarisation, enabling the fabrication of 3D complex geometries within reasonable etching times. Abstract : In fused silica, ultrafast laser assisted etching enables high chemical etching rates (>300 μm h −1 ) by setting a light polarisation linear and perpendicular to the beam writing direction. However, for many non-planar surfaces and 3D structures, dynamic polarisation control is difficult or not yet possible to implement. In this contribution, we identify a laser inscription regime in which high etching rates are accomplished independently of the light polarisation. In this regime (<15 pulses per μm), we measure etching rates ∼300 μm h −1 (4 hours in NaOH) including femtosecond-pulse energies corresponding to type II modifications. Few pulse inscriptions show a low degree of anisotropy as compared to higher number of pulses, thus enabling the polarisation insensitivity whose mechanisms are discussed. To demonstrate the capabilities of the processing, we fabricate curved and square-wave microchannels together with a complex 3D geometrical structure (stellated octahedron) containing an inter-plane arrangement with challenging angles (45°), which are difficult to achieve even employing dynamic polarisation control.