光子学

SAMPLE AND SETUP Spectral dispersion of refractive index needs to be measured on microscopic core region in waveguides and optical fibers. The difference of refractive index between core and clad region may be as small as 0.001 at very low doping concentrations. Imaging ellipsometry with the nanofilm_ep4 offers highest lateral ellipsometric resolution down to 1 ?m. It combines the sensitivity for thickness and spectral refractive index measurements of ellipsometry with the benefits of magnification and lateral resolution of optical microscopy nanofilm_ep4 MEASUREMENT First identify, then measure: Angle of incidence, wavelength and polarizing angles are set to enhance the ellipsometric contrast in live view. This ECM mode (Ellipsometric Contrast enhanced Microscopy) enables a fast and easy identification of the core region, even with smallest doping concentrations. During the next step, two regions on core and clad are defined to run a spectroscopic measurement in a desired wavelength range between 190nm and 2700nm. All pixel within each region are averaged. As2S3 (fiber, core/clad) RESULTS - Core region easily identified - ECM mode helps to identify contaminations and to exclude them from measurements - Dispersive refractive index of core and clad region measured APPLICATIONS - efractive index of waveguides and fibers (190nm - 2700nm) - Thin layers on vertical waveguide facets - Integrated photonics

SAMPLE AND SETUP Thickness and composition of a multi layer film need to be mapped over larger samples with high speed. Imaging ellipsometry with the nanofilm_ep4 combines the sensitivity for thickness and spectral refractive index measurements of ellipsometry with the benefits of magnification and lateral resolution of optical microscopy

SAMPLE AND SETUP The dispersive refractive index needs to be measured on 8 μm wide waveguides of LiNbO3 . Additionally, the thickness of an SiO2 layer is to be determined on the waveguides and on clad region. Psi map at 250 nm (Courtesy of Samuel Margueron, FEMTO-ST) Imaging ellipsometry with the nanofilm_ep4 offers highest lateral ellipsometric resolution down to 1 μm. It combines the sub-nanometer sensitivity for thickness and precise spectral refractive index measurements of ellipsometry with the benefits of magnification and high lateral resolution of optical microscopy. MEASUREMEN Spectral micro mapping Spectral micro-maps of Delta and Psi were recorded from 200 nm to 400 nm. Spectral Delta and Psi data were extracted for multiple regions (average of 30 pixel) on the waveguides and beside them. Dispersive refractive index and thickness of top SiO2 layer are fitted, using the EP4 optical model sortware. RESULT - SiO2 thickness on Core: 3 nm / on Clad: 113 nm - Difference of dispersive refractive index of core and clad region clearly visible - Good reproducibility of results between different regions of the same kind APPLICATIONS - Spectral refractive index measurements on micron sized waveguides (wavelength 190-2700 nm) with a difference between clad and core of down to 0.001 - Thin layers on micron sized structures -Integrated photonics