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We demonstrate, for the first time, the direct writing of curved optical waveguides in monocrystalline silicon with curve radii from 2 mm to 6 cm. The bending loss of the curved waveguides is measured and a good agreement with theoretical values is found. Raman spectroscopy measurements suggest the formation of inhomogeneous amorphous and polycrystalline phases in the laser-modified region. This direct laser-writing method may advance fabrication capabilities for integrated 3D silicon photonic devices.
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Transmission Electron Microscopy Characterizations of Local Amorphization of Single Crystal Silicon by Nanosecond Pulsed Laser Direct Writing
The concept for fabrication of waveguides by an in‐volume laser direct writing in single‐crystal silicon is explored using a nanosecond pulse laser. The key innovation of this technology relies on the generation of amorphous silicon, which has a higher refractive index than that of crystalline silicon. Herein, transmission electron microscopy (TEM) together with selected area electron diffraction (SAED) and high‐resolution TEM (HRTEM) characterizations are used to better understand the microstructural evolutions. TEM images reveal the core‐shell structures, while SAED patterns and HRTEM directly observe the presence of amorphous silicon in the core surrounded by a crystalline silicon shell. With a lower laser scanning speed, a higher density of defects yet less amorphous silicon is formed by laser direct writing.
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- PAR ID:
- 10479362
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Engineering Materials
- Volume:
- 26
- Issue:
- 2
- ISSN:
- 1438-1656
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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