Measurement of propagation loss in rare-earth-ion-doped potassium yttrium double tungstate (KYW) waveguides by optical low coherence reflectometry
Luo, Y. and Gardillou, F. and Borca, C.N. and Coric, D. and Romanyuk, Y.E. and Pollnau, M. and Hoffmann, P. and Salathé, R.P. (2007) Measurement of propagation loss in rare-earth-ion-doped potassium yttrium double tungstate (KYW) waveguides by optical low coherence reflectometry. In: Proceedings of the European Materials Research Society Meeting 2007, Symposium C: Rare Earth ion doping for photonics: Materials, mechanisms and devices., 28 May - 1 June 2007, Strasbourg, France.
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|Abstract:||KYW is a promising candidate for diode-pumped solid-state lasers and Raman self converters. The optically active rare-earth ions can easily substitute the Y3+ ion with a high doping level. Because of its low laser thresholds, high efficiencies, and third-order nonlinear effects, rare-earth-ion-doped KYW is a promising laser material. By means of UV-photolithography and reactive-ion etching, micro-structured waveguides, either in the form of channels or Y-junctions have been realized from 2-10 micron thick (Lu,Gd)-codoped KYW:Yb thin films grown on a 1-mm thick (010) KYW substrate. The width of the waveguide channels ranges from 2 to 10 microns with a length of about half a centimeter.|
Given a refractive index contrast of 7.5x10-3 of the doped thin film with respect to the undoped substrate, monomode waveguiding has been successfully demonstrated at a wavelength of 980 nm. From the results obtained by optical low coherence reflectometry (OLCR) in reflection mode on those rare-earth-ion-doped KYW waveguides, we have been able to precisely evaluate their length, thickness, birefringence and propagation loss at different wavelengths. The relatively high propagation loss (~ 5 dB/cm @ 1550 nm) of these channels compared to unstructured, 17-micron-thick KYW:Yb planar waveguides (~ 0.1-0.2 dB/cm @ 1020 nm) shows that either the co-doping by Gd and Lu, or the tighter vertical confinement or the microstructuring currently adds additional losses which need to be improved. Generally, these co-doped KYW waveguides open up new possibilities for fabricating lasers and integrated optical devices in rare-earth-iondoped microstructures.
|Item Type:||Conference or Workshop Item|
Electrical Engineering, Mathematics and Computer Science (EEMCS)
|Link to this item:||http://purl.utwente.nl/publications/62075|
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