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Proceedings Paper

Rare-earth-ion-doped ultra-narrow-linewidth lasers on a silicon chip and applications to intra-laser-cavity optical sensing
Author(s): E. H. Bernhardi; R. M. de Ridder; K. Wörhoff; M. Pollnau
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Paper Abstract

We report on diode-pumped distributed-feedback (DFB) and distributed-Bragg-reflector (DBR) channel waveguide lasers in Er-doped and Yb-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into the SiO2 top cladding. The maximum grating reflectivity exceeded 99%. Monolithic DFB and DBR cavities with Q-factors of up to 1.35×106 were realized. The Erdoped DFB laser delivered 3 mW of output power with a slope efficiency of 41% versus absorbed pump power. Singlelongitudinal- mode operation at a wavelength of 1545.2 nm was achieved with an emission line width of 1.70 0.58 kHz, corresponding to a laser Q-factor of 1.14×1011. Yb-doped DFB and DBR lasers were demonstrated at wavelengths near 1020 nm with output powers of 55 mW and a slope efficiency of 67% versus launched pump power. An Yb-doped dualwavelength laser was achieved based on the optical resonances induced by two local phase shifts in the DFB structure. A stable microwave signal at ~15 GHz with a –3-dB width of 9 kHz and a long-term frequency stability of ± 2.5 MHz was created via the heterodyne photo-detection of the two laser wavelengths. By measuring changes in the microwave beat signal as the intra-cavity evanescent laser field interacts with micro-particles on the waveguide surface, we achieved real-time detection and accurate size measurement of single micro-particles with diameters ranging between 1 μm and 20 μm, which represents the typical size of many fungal and bacterial pathogens. A limit of detection of ~500 nm was deduced.

Paper Details

Date Published: 6 March 2013
PDF: 5 pages
Proc. SPIE 8599, Solid State Lasers XXII: Technology and Devices, 859909 (6 March 2013); doi: 10.1117/12.2012520
Show Author Affiliations
E. H. Bernhardi, Univ. Twente (Netherlands)
R. M. de Ridder, Univ. Twente (Netherlands)
K. Wörhoff, Univ. Twente (Netherlands)
M. Pollnau, Univ. Twente (Netherlands)

Published in SPIE Proceedings Vol. 8599:
Solid State Lasers XXII: Technology and Devices
W. Andrew Clarkson; Ramesh Shori, Editor(s)

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