EventsAhmet Turnalı

Three-dimensional photonic devices and microstructures deep inside silicon fabricated by nonlinear laser lithography

Subsurface processing of materials have widely been used for various applications in diverse fields from photonics to microfluidics, especially in glass and polymers. It has already been demonstrated that optical elements such as waveguides, resonators, filters etc. can be fabricated in silica with laser writing. So far conventional lithography and etching techniques worked successfully in fabricating such elements only top layers of silicon and fail to fabricate anything inside Si without damaging the surface. Even relatively simple curved geometries cannot be realized with techniques like reactive ion etching. Creation of photonic structures similar to those embedded in glasses remains elusive. This is particularly important limitation since Si is an excellent material for microelectronics and integrated photonics with untapped potential for mid-IR optics.

Recently, we reported a technique, which accomplishes single-step, maskless laser writing deep inside Si, and can be used to create highly-controllable modification, without damaging the surface. The laser-modified Si has a different optical index than unmodified parts, which enables numerous photonic devices. Optionally, these parts are chemically etched to produce desired 3D shapes. We exemplify a plethora of subsurface, i.e., “in-chip” microstructures for microfluidic cooling of chips, vias, MEMS, photovoltaic applications and photonic devices that match or surpass the corresponding state-of-the-art device performances.

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About The Speaker

Ahmet Turnalı received his B.Sc and M.Sc degrees in electrical and electronics engineering from Bilkent University. Currently, he is a PhD candidate at the same department. His main research interest is laser-material interaction. Specifically, he focuses on understanding nonlinear dynamics for materials processing and exploring high performance photonic devices based on novel mechanisms.