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Invited Lecture

Ultrafast-laser-enabled Polishing, Micro-bonding and Waveguide Writing for Photonics Fabrication and Integration

Tuesday (23.06.2020)
15:00 - 15:40 Room 2
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We investigate femtosecond laser-based 3D writing, polishing and micro-bonding techniques for the fabrication and integration of photonics devices and/or micro optics.

A two-temperature model and scanning strategy were established to perform femtosecond laser polishing which enabled precise material removal with controllable depth while achieving sub-nanometer surface roughness [1]. We have demonstrated, for the first time to our knowledge, precision polishing of Germanium using a femtosecond laser. The figuring capability and resulting optical surface quality demonstrate the viability of femtosecond laser polishing as a novel pathway towards precision finishing of optics and photonic devices.

For ultrafast-laser-based waveguide micro-bonding, we study the underlying physics behind nonlinear optical dynamics during the femtosecond laser processing of crystalline materials. Unidirectional pulse propagation equation simulation is carried out to study the evolution of energy, fluence, plasma generation, and beam waist of a femtosecond pulse along the propagation direction under different energy and focusing conditions. Waveguides having a loss of 0.21 ± 0.06 dB/cm are obtained [2]. A Nd:YAG based waveguide laser with lasing threshold of 50 mw was demonstrated. It is foreseeable to generate other wavelengths such as mid-infrared via difference frequency generation, using the similar ultrafast-laser enabled waveguide platform.

For optimizing the ultrafast-laser-based micro-bonding process, it is essential to evaluate temperature distribution and dimension of the internal modification by fs-laser. The evolution of free electron density and temperature under the influence of femtosecond laser pulse propagation having intensity are numerically evaluated. This modelling capability facilitates to focus the laser beam at desired location at the interface of the two substrates to be welded, eliminating the need for approximating the size of heat source by fitting the experimental data [3]. The welding demonstration based on the modeling results will be presented.

 

 

Speaker:
Prof. Jie Qiao
Rochester Institute of Technology
Additional Authors:
  • Gong Chen
    Rochester Institute of Technology
  • Dr. Pankaj Sahoo
    Rochester Institute of Technology
  • Dr. Tao Feng
    Rochester Institue of Technology

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