2023/08/29 by Sean E. Sullivan, Sullivan, Sean E., Jonghoon Ahn +13 · 1 citation
Engineering · Materials Science · #Applied Physics (physics.app-ph) #FOS: Physical sciences #Photonic and Optical Devices #Quantum Physics (quant-ph) #Semiconductor Lasers and Optical Devices #Silicon Nanostructures and Photoluminescence
paper · pdf · doi:10.48550/arxiv.2308.14999
openalex publication_date 2023/08/29 · openalex created_date 2023/08/31 · openalex updated_date 2026/08/01
With their shielded 4f orbitals, rare-earth ions (REIs) offer optical and electron spin transitions with good coherence properties even when embedded in a host crystal matrix, highlighting their utility as promising quantum emitters and memories for quantum information processing. Among REIs, trivalent erbium (Er3+) uniquely has an optical transition in the telecom C-band, ideal for transmission over optical fibers, and making it well-suited for applications in quantum communication. The deployment of Er3+ emitters into a thin film TiO2 platform has been a promising step towards scalable integration; however, like many solid-state systems, the deterministic spatial placement of quantum emitters remains an open challenge. We investigate laser annealing as a means to locally tune the optical resonance of Er3+ emitters in TiO2 thin films on Si. Using both nanoscale X-ray diffraction measurements and cryogenic photoluminescence spectroscopy, we show that tightly focused below-gap laser annealing can induce anatase to rutile phase transitions in a nearly diffraction-limited area of the films and improve local crystallinity through grain growth. As a percentage of the Er:TiO2 is converted to rutile, the Er3+ optical transition blueshifts by 13 nm. We explore the effects of changing laser annealing time and show that the amount of optically active Er:rutile increases linearly with laser power. We additionally demonstrate local phase conversion on microfabricated Si structures, which holds significance for quantum photonics.