Characterization of integrated waveguides by atomic-force-microscopy-assisted mid-infrared imaging and spectroscopy

Year: 2020

Authors: Gallacher K., Millar RW., Paul DJ., Frigerio J., Ballabio A., Isella G., Rusconi F., Biagioni P., Giliberti V., Sorgi A., Baldassarre L., Ortolani M.

Autors Affiliation: ‎Univ Glasgow, James Watt Sch Engn, Rankine Bldg,Oakfield Ave, Glasgow G12 8LT, Lanark, Scotland; Politecn Milan, Dipartimento Fis, L NESS, Via Anzani 42, I-22100 Como, Italy; Politecn Milan, Dipartimento Fis, Piazza Leonardo Da Vinci 32, I-20133 Milan, Italy; Ist Italiano Tecnol, Ctr Life Nanosci, Viale Regina Elena 291, I-00161 Rome, Italy; Ist Nazl Ott INO CNR, Largo E Fermi 6, I-50125 Florence, Italy; European Lab Nonlinear Spect, LENS, Via N Carrara 1, I-50019 Sesto Fiorentino, Italy;‎ Univ Roma La Sapienza, Dipartimento Fis, Piazzale Aldo Moro 5, I-00185 Rome, Italy

Abstract: A novel spectroscopy technique to enable the rapid characterization of discrete mid-infrared integrated photonic waveguides is demonstrated. The technique utilizes lithography patterned polymer blocks that absorb light strongly within the molecular fingerprint region. These act as integrated waveguide detectors when combined with an atomic force microscope that measures the photothermal expansion when infrared light is guided to the block. As a proof of concept, the technique is used to experimentally characterize propagation loss and grating coupler response of Ge-on-Si waveguides at wavelengths from 6 to 10 ?m. In addition, when the microscope is operated in scanning mode at fixed wavelength, the guided mode exiting the output facet is imaged with a lateral resolution better than 500 nm i.e. below the diffraction limit. The characterization technique can be applied to any mid-infrared waveguide platform and can provide non-destructive in-situ testing of discrete waveguide components.

Journal/Review: OPTICS EXPRESS

Volume: 28 (15)      Pages from: 22186  to: 2219

More Information: Engineering and Physical Sciences Research Council (EP/N003225/1); Royal Academy of Engineering (RF-201819-18-187); Directorate-General for Research and Innovation (613055).
DOI: 10.1364/OE.393748

Citations: 8
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