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PUBDB-2025-05007

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Thulium-Doped Al 2 O 3 Waveguide Amplifiers Fabricated via Radio Frequency Reactive Co-Sputtering

Wang, K.Extern* ; Martinez, C. O. ; Lorenzen, J.CFEL*DESY* ; Dijkstra, M. ; Jongebloed, B. ; Singh, N.CFEL*DESY* ; Kärtner, F. X.CFEL*XFEL.EU*DESY* ; Garcia-Blanco, S. M.

2025
IEEE
ISBN: 979-8-3315-9778-8

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Please use a persistent id in citations: doi:10.1109/ICTON67126.2025.11125480

Abstract: Al2O3 is a promising material in integrated optics due to its extensive transparency window, spanning from ultraviolet (200 nm) to infrared (5500 nm), and its low optical propagation loss across this spectrum. Its high solubility for rare earth elements enables the incorporation of various dopants, making it a particularly suitable host material for integrated optical rare earth amplifiers and lasers. In this work, we report the deposition of thulium-doped Al2O3 films using radio frequency reactive co-sputtering, which is a cost-effective and scalable technique to produce thick and high quality films. These films are fabricated into optical waveguides and their spectral characteristics, including emission cross sections and lifetime, are measured. Thulium-doped Al2O3 waveguide amplifiers are successfully fabricated, demonstrating signal enhancements of 21 dB at 1818 nm using a 1609 nm pump in a 10 cm-long waveguide, and 27 dB at 1850 nm using a 790 nm pump in a 20 cm-long waveguide. Net on-chip gains of 9 dB in a 10 cm-long waveguide and 1.5 dB in a 3 cm-long waveguide are achieved with the 1609 nm and 790 nm pumps, respectively.

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Contributing Institute(s):

1. Ultrafast Lasers & X-rays Division (FS-CFEL-2)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)

Experiment(s):

1. Experiments at CFEL

Appears in the scientific report 2025

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