Abstract
Bulk $KY(WO_4)_2$ (hereafter KYW) laser crystals doped with rare-earth ions are recognized to be among the most promising host materials for obtaining novel solid-state lasers. The rare-earth ions $RE^{3+}$ are easily incorporated in the KYW structure by replacing the $Y{3+}$ ions, resulting in a stoichiometric active material with high absorption and emission cross-sections [1]. The realization of waveguiding structures with such materials is of great interest for future active integrated optics devices. In order to achieve highly confined single-mode propagation and low optical losses, we have developed a new KYW:Yb layer co-doped with $Lu{3+}$ and $Gd{3+}$ions. A special composition of $KLu_{0.253}Gd_{0.13}Yb_{0.017}Y_{0.6}W$ has provided reproducible crack-free layers with a refractive-index contrast as high as 7.5 x $10^{-3}$, which is the highest value reported for KYW:Yb / KYW composite structures. Rib waveguides obtained by reactive ion etching (RIE) are characterized by propagation losses below 1 dB/cm at the $Yb^{3+}$-fluorescence wavelength (λ ≈ 1020 nm) and by a high optical confinement. As a consequence, they offer a great potential for the realization of efficient nano-structured waveguides such as Bragg grating filters or even DBR/DFB (Distributed Bragg Reflection/ Distributed FeedBack) micro-lasers.
Here, the first promising results concerning the realization of Bragg filters on KYW by focused ion beam (FIB) etching are reported. This tool is very powerful for producing nano-structures in a large variety of materials. In this work, different thin conductive layers have been tested and a 20-nm-thick aluminum layer has been chosen to reduce charging effects. Then, FIB parameters have been optimised to etch periodical nano-scale patterns with a high aspect ratio at a high speed. The dimensions and the shape of the grating have been fixed by numerical simulations to obtain efficient rib-based Bragg filters at λ ≈ 1020 nm. Such gratings, with a periodicity as low as 250 nm and a high aspect ratio, have been milled on the KYW:Gd,Lu,Yb / KYW ribs. Current work concentrates on the optical characterization and optimization of these first Bragg filters produced in a double tungstate material.
Original language | English |
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Title of host publication | 15th International Laser Physics Workshop (LPHYS'06) |
Subtitle of host publication | Book of Abstracts |
Place of Publication | Lausanne, France |
Publisher | Ecole Polytechnique Fédérale de Lausanne |
Pages | 210-210 |
Number of pages | 1 |
Publication status | Published - 2006 |
Event | 15th International Laser Physics Workshop, LPHYS 2006 - École Polytechnique Fédérale De Lausanne, Lausanne, Switzerland Duration: 24 Jul 2006 → 28 Jul 2006 Conference number: 15 https://www.lasphys.com/workshops/2006 |
Workshop
Workshop | 15th International Laser Physics Workshop, LPHYS 2006 |
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Abbreviated title | LPHYS |
Country/Territory | Switzerland |
City | Lausanne |
Period | 24/07/06 → 28/07/06 |
Internet address |
Keywords
- EWI-12310
- IR-62257
- METIS-248241
- IOMS-APD: Active Photonic Devices