Direct laser writing of graded-index SiGe waveguides via phase segregation

Ozan Aktas; Yuji Yamamoto; Mehmet Kaynak; Anna C. Peacock

doi:10.1117/12.2575437

5 March 2021 Direct laser writing of graded-index SiGe waveguides via phase segregation

Ozan Aktas, Yuji Yamamoto, Mehmet Kaynak, Anna C. Peacock

Proceedings Volume 11673, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXVI; 1167317 (2021) https://doi.org/10.1117/12.2575437
Event: SPIE LASE, 2021, Online Only

Abstract

We report direct laser writing of graded-index optical waveguides via phase segregation in initially homogenous silicongermanium (SiGe) thin films epitaxially-grown on silicon substrates. We used a continuous wave (CW) laser operating at a wavelength of 532 nm. The laser beam was focused to a 5 μm diameter spot on the surface of SiGe films with a thickness of 575 nm and a Ge concentration of %50. Compositional separation of a SiGe film was induced by melting the surface, and the composition profile was tailored by controlling the scan speed of the laser-induced molten zone in a range of 0.1-200 mm/s. At high scan speeds, scanning the laser beam produces a travelling Ge-rich molten zone, where a build-up of Ge content occurs at the trailing edge because of insufficient diffusion-limited Ge transport. Material characterizations have revealed that the laser-processed SiGe microstripes consist of Ge-rich strip cores (> 70% Ge) surrounded by Si-rich under-claddings (<30% Ge). Scan-speed dependent phase segregation allows for fabrication of graded-index SiGe waveguides with tunable compositional profiles, which were characterized by optical transmission measurements, and modal analysis using simulations. Our method could also be applied to pseudo-binary alloys of ternary semiconductors (AlGaAs), which have equilibrium phase diagrams similar to that of SiGe alloys.

Conference Presentation

Citation Download Citation

Ozan Aktas, Yuji Yamamoto, Mehmet Kaynak, and Anna C. Peacock "Direct laser writing of graded-index SiGe waveguides via phase segregation", Proc. SPIE 11673, Laser Applications in Microelectronic and Optoelectronic Manufacturing (LAMOM) XXVI, 1167317 (5 March 2021); https://doi.org/10.1117/12.2575437

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