Optical Sculpting in glass using ultrafast lasers

Problem Definition:

Femtosecond laser irradiation followed by chemical etching (F.L.I.C.E) is an emerging technique for the fabrication of micro-optical components such as micro-lenses, 45° micro-mirrors, micro- attenuators, beam splitters and directly buried three-dimensional microfluidic channels in transparent dielectrics. The selectivity comes from the fact that the chemical etch rate of the transparent dielectric such as fused silica enhances by 2 orders of magnitude on the laser treated areas as compared to unexposed areas. The simplicity and flexibility offered by F.L.I.C.E makes it a niche technology for fabricating well-aligned 3D micro-optical structures and 3D microfluidic channels in the same glass substrate.

 

The fabrication procedure consists of two steps: first a photo-modification in the glass is executed by irradiating a focused femtosecond laser beam into the material (Fig 1). Second the irradiated material is immersed in an etching media for a specified period of time at an elevated temperature. To reduce the roughness of the features further annealing steps (laser based or thermal) are employed to have a smooth profile of the finished components (e.g. Fig 2). 

Objectives:

The primary goal of the project will be to develop the technology of femtosecond laser irradiation followed by chemical etching (F.L.I.C.E) for glasses (fused silica for example). The project will focus on the following aspects:

 

1)      Optimization of laser writing parameters for photo-modification in bulk glasses without ablating/damaging the surface. These will include-laser energy, repetition rate, beam polarization, writing speed.

2)      Optimization of the selective etching of the laser treated regions. Different etchant solutions will be used for this task.  The key parameters to be optimized are- etch time, concentration of the etchant, temperature of the etchant, etch rate.

3)      Fabrication of specific micro-optical components such as micro lenses, prisms and micro-mirrors.  

4)      Optical characterization of the fabricated components.

 

The student will use recently installed state-of-the-art ultrafast laser system for realizing laser-induced photo-modification in glasses.  He/she will work in a cleanroom environment for all the experiments related to laser and wet chemical etching. Proper training will be given to work in a cleanroom and to use all the other tools needed for characterization involved in this work.



Keywords:

femtosecond laser, chemical etching, micro optics, microfluidics, glass.

Location:

Ardoyen CMST + technicum + at home.

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Kamalpreet Kaur,
Mar 6, 2015, 3:25 PM