We demonstrate direct three-dimensional (3-D) microfabrication inside a volume of silica glass. The whole fabrication process was carried out in two steps: (i) writing of the preprogrammed 3-D pattern inside silica glass by focused femtosecond (fs) laser pulses and (ii) etching of the written structure in a 5% aqueous solution of HF acid. This technique allows fabrication of 3-D channels as small as 10 μm in diameter inside the volume with any angle of interconnection and a high aspect ratio (10‐μm-diameter channels in a 100‐μm-thick silica slab).

https://researchbank.swinburne.edu.au/file/42ab4800-28c9-4d55-a2f8-cb94ba900230/1/PDF (Accepted manuscript).pdf

Femtosecond laser-assisted three-dimensional microfabrication in silica.

We study the femtosecond laser ablation properties of borosilicate glass using atomic force microscopy and laser pulses of 200 fs duration, centered at 780 nm wavelength. We show that both single-shot and multishot ablation threshold fluences can be determined by studying the diameter and the depth of single-shot ablated craters. The linear relationship between the square of the crater diameter and the logarithm of the laser fluence in the form of D2=2w02ln(F0∕FthN=1) provides the single-shot ablation threshold, FthN=1, whereas the linear relationship between the ablation depth and the logarithm of laser fluence in the form of ha=αeff−1ln(F0∕FthN>1) provides the multishot ablation threshold, FthN>1. The results depict a multishot ablation threshold of ≈1.7J∕cm2 independent of the atmospheric conditions. The slopes of the linear fits also provide a precise estimate of the beam radius at the surface, w0≈5.9μm, and the “effective optical penetration depth,” αeff−1≈238nm in air. The method is systematic, prov...

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Femtosecond laser ablation properties of borosilicate glass

Femtosecond laser micromachining has excited vivid attention in various industrial fields and in medicine owing to the advantages of ultrashort laser pulses compared to long-pulse treatment. These are mainly the reduction of the laser fluence needed to induce ablation and the improvement of the contour sharpness of the laser-generated structures. Recently, special attention was paid to femtosecond laser experiments on nonabsorbing inorganic dielectrics. This is due to the fact that optical damage in dielectric optical elements limits the performance of high-power laser systems. Despite the fact that a large variety of organic polymers can be machined with excimer lasers successfully, the involvement of thermal processes can lead to an unsatisfactory quality of the structures. Ultrashort, fs-laser pulses might be an alternative for the treatment of polymers. Therefore, femtosecond laser machining investigations of dielectrics and polymers are reviewed in this paper. Similarities and differences of the ablation behavior of both material classes are discussed. The influence of the bandgap on the ablation threshold in dependence on the pulse duration, the enhancement of the machining precision with a shortening of the pulse duration, incubation phenomena, and morphological features appearing on the surface after femtosecond laser treatment are mentioned. Possible applications, e.g., in medicine and biosensors, are described.

Ultrashort pulse laser interaction with dielectrics and polymers

Advances in the generation of coherent lasers at wavelengths below 200 nm as well as the associated equipment and technologies have greatly spurred the development of nonlinear optical (NLO) materials that are capable of phase-matching in the deep-ultraviolet (deep-UV) spectral regions. However, few crystals can meet the technical demands, and studies to date have focused mainly on finding the next competitive candidates. Consequently, several crystals have emerged that hold great potential for the production of deep-UV harmonic coherent light, which benefit from newly developed systems with novel NLO-active units and chromophores. This Review provides a comprehensive overview of the developments of emergent candidates in the field of deep-UV NLO materials, discussing the recent efforts and active advances in the search for superior systems and in understanding their structure-property relationships. The intention is to provide a clear perspective on the current emergent deep-UV NLO candidates, and to accelerate the discovery of next candidates with high performances to meet the urgent demands.

Emergent Deep-Ultraviolet Nonlinear Optical Candidates.

Precision glass machining, drilling and profile cutting by short pulse lasers

https://www.physics.utoronto.ca/~marj/references/Herman2000-9.pdf

Laser shaping of photonic materials: deep-ultraviolet and ultrafast lasers

Since the trend with many sectors of industry is toward miniaturisation (electronics, photonics, biomedical), laser micromachining is playing an increasingly important role in the manufacturing of high-tech and consumer products. Research in laser micromachining has to address many facets of the effort, including novel laser sources development, basic laser-matter interaction, and the exploration of new processes and devices. Photonics Research Ontario (PRO), a Centre of Excellence of the Government of Ontario, is tackling laser micromachining research on all of these fronts by funding basic research in Ontario universities, R&D projects with industry, and collaborative efforts bringing together both industry and academia. This paper presents the PRO/MMO state-of-the-art Laser Micromachining Facility and highlights some of the research conducted by PRO principal investigators.Since the trend with many sectors of industry is toward miniaturisation (electronics, photonics, biomedical), laser micromachining is playing an increasingly important role in the manufacturing of high-tech and consumer products. Research in laser micromachining has to address many facets of the effort, including novel laser sources development, basic laser-matter interaction, and the exploration of new processes and devices. Photonics Research Ontario (PRO), a Centre of Excellence of the Government of Ontario, is tackling laser micromachining research on all of these fronts by funding basic research in Ontario universities, R&D projects with industry, and collaborative efforts bringing together both industry and academia. This paper presents the PRO/MMO state-of-the-art Laser Micromachining Facility and highlights some of the research conducted by PRO principal investigators.

I. Konovalov

Papers

Laser shaping of photonic materials: deep-ultraviolet and ultrafast lasers

Laser microprocessing at photonics research Ontario