DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Hoven, van den, G.N.; Snoeks, E.; Polman, A.; Dam, van, C.; Uffelen, van, J.W.M.; Smit, M.K. Published in:Journal of Applied Physics Published: 01/01/1996 Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication Citation for published version (APA):Hoven, van den, G. N., Snoeks, E., Polman, A., Dam, van, C., Uffelen, van, J. W. M., & Smit, M. K. (1996). Upconversion in Er-implanted Al2O3 waveguides. Journal of Applied Physics, 79(3), 1258-1266. General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. When pumped with a 1.48 m laser diode, Er-implanted Al 2 O 3 ridge waveguides emit a broad spectrum consisting of several distinct peaks having wavelengths ranging from the midinfrared ͑1.53 m͒ to the visible ͑520 nm͒. In order to explain these observations, three different upconversion mechanisms are considered: cooperative upconversion, excited state absorption, and pair-induced quenching. It is found that for samples with a high Er concentration ͑1.4 at. %͒, cooperative upconversion completely dominates the deexcitation of the Er 3ϩ ions. For a much lower concentration ͑0.12 at. %͒, the influence of cooperative upconversion is strongly reduced, and another upconversion effect becomes apparent: excited state absorption. These conclusions are based on measurements of the luminescence emission versus pump intensity, and also on measured luminescence decay curves. The upconversion coefficient is found to be ͑4Ϯ1͒ϫ10 Ϫ18 cm 3 /s; the excited state absorption cross section is ͑0.9Ϯ0.3͒ϫ10 Ϫ21 cm 2 . It is shown that in spite of these upconversion effects, a high fraction of the Er 3ϩ can be excite...

Hoven, van den, G.N.; Elsken, van der, J.A.; Polman, A.; Dam, van, C.; Uffelen, van, K.W.M.; Smit, M.K. Published in: Applied OpticsPublished: 01/01/1997 Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication Citation for published version (APA):Hoven, van den, G. N., Elsken, van der, J. A., Polman, A., Dam, van, C., Uffelen, van, K. W. M., & Smit, M. K. (1997). Absorption and emission cross sections of Er3+ in Al2O3 waveguides. Applied Optics, 36(15), 3338-3341. General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. with a maximum at 1.530 m of 8 dB͞cm. The Er 3ϩ absorption cross section is determined as a function of wavelength. We used the McCumber theory to derive the emission cross section spectrum from the absorption results, which we then compared with the Er 3ϩ photoluminescence spectrum. The peak absorption and emission cross sections are found to be 6 ϫ 10 Ϫ21 cm Ϫ2. The results are used to predict the optical gain performance of an Er-doped Al 2 O 3 optical amplifier that operates around 1.5 m.

No abstract