Microfabrication of optical elements with femtosecond Ti:sapphire laser oscillator

Bing Bai; Changhe Zhou; Xiaohui Sun; Huayi Ru

doi:10.1117/12.576130

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13 January 2005 Microfabrication of optical elements with femtosecond Ti:sapphire laser oscillator

Bing Bai, Changhe Zhou, Xiaohui Sun, Huayi Ru

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Proceedings Volume 5629, Lasers in Material Processing and Manufacturing II; (2005) https://doi.org/10.1117/12.576130
Event: Photonics Asia, 2004, Beijing, China

Abstract

We report the experimental fabrication of optical elements with femtosecond pulses. The laser source we adopted is a low power Ti: sapphire laser oscillator, with a central wavelength of 790 nm and pulse duration of 100 fs. Positive-photoresist-coated film acts as the sacrificial material. To obtain the optical elements, three microobjectives with high numerical aperture 0.25 and 0.1 were used to focus the light beam of femtosecond laser. Due to the extreme high intensity of the tightly focused femtosecond laser beam, nonlinear effect occurred between photoresist and the laser pulses, which enable the ablation of the photoresist. In the experiments, we use a translational stage that hold the sample by a pump through a ventage. Various gratings and phase plates are fabricated by this method. The obtained gratings patterns are checked with a conventional optical microscopy. The fabricating widths and depths are measured with the Taylor Hobson equipment. With the same method, photomask for microelectronics can also be fabricated. From the experimental results, we see that the fabrication of the different microobjectives can be achieved with this method. This technique can be applied to the fields of microoptics and microelectronics. The mechanism between femtosecond laser and photoresist is also investigated. The processing mechanics is considered as laser ablation. Fabrication of optical elements with femtosecond laser reflects a new trend for fabrication of microoptical elements.

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Bing Bai, Changhe Zhou, Xiaohui Sun, and Huayi Ru "Microfabrication of optical elements with femtosecond Ti:sapphire laser oscillator", Proc. SPIE 5629, Lasers in Material Processing and Manufacturing II, (13 January 2005); https://doi.org/10.1117/12.576130

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