Spiral amplifiers in a-Al2O3:Er on a silicon chip with 20 dB internal net gain

Sergio Andrés Vázquez-Córdova, Edward Bernhardi, Kerstin Worhoff, Jennifer Lynn Herek, Sonia Maria García Blanco, Markus Pollnau

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademic

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Spiral-waveguide amplifiers in erbium-doped amorphous aluminum oxide are fabricated by RF reactive co-sputtering of 1-µm-thick layers onto a thermally-oxidized silicon wafer and chlorine-based reactive ion etching. The samples are overgrown by a SiO2 cladding. Spirals with several lengths ranging from 13 cm to 42 cm and four different erbium concentrations between 0.5-3.0×10^20 cm^-3 are experimentally characterized. A maximum internal net gain of 20 dB in the small-signal-gain regime is measured at the peak emission wavelength of 1532 nm for two sample configurations with waveguide lengths of 13 cm and 24 cm and erbium concentrations of 2×10^20 cm^-3 and 1×10^20 cm^-3, respectively. The obtained gain improves previous results by van den Hoven et al. in this host material by a factor of 9. Gain saturation as a result of increasing signal power is investigated. Positive net gain is measured in the saturated-gain regime up to ~100 µW of signal power, but extension to the mW regime seems feasible. The experimental results are compared to a rate-equation model that takes into account migration-accelerated energy-transfer upconversion (ETU) and a fast quenching process affecting a fraction of the erbium ions. Without these two detrimental processes, several tens of dB/cm of internal net gain per unit length would be achievable. Whereas ETU limits the gain per unit length to 8 dB/cm, the fast quenching process further reduces it to 2 dB/cm. The fast quenching process strongly deteriorates the amplifier performance of the Al2O3:Er3+ waveguide amplifiers. This effect is accentuated for concentrations higher than 2×10^20 cm^-3.
Original languageEnglish
Title of host publicationIntegrated Optics: Devices, Materials, and Technologies XIX
Place of PublicationBellingham, USA
PagesPaper 93650M
Number of pages6
ISBN (Print)978-1-62841-455-4
Publication statusPublished - Apr 2015
EventIntegrated Optics: Devices, Materials, and Technologies XIX - San Francisco, United States
Duration: 9 Feb 201511 Feb 2015
Conference number: 19

Publication series

NameProceedings of the SPIE


ConferenceIntegrated Optics: Devices, Materials, and Technologies XIX
Country/TerritoryUnited States
CitySan Francisco


  • spiral amplifier
  • rate-equation model
  • waveguide amplifier
  • EWI-25963
  • IR-95789
  • Amorphous aluminum oxide
  • Erbium
  • optical gain
  • METIS-312572
  • IOMS-APD: Active Photonic Devices


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