Multiscale roughness in optical multilayers: atomic force microscopy and light scattering.

We have previously shown that macroscopic roughness spectra measured with light scattering at visible wavelengths were perfectly extrapolated at high spatial frequencies by microscopic roughness spectra measured with atomic force microscopy [Europhys. Lett. 22, 717 (1993); Proc.

Single-mode couplers through end coatings on optical fibers.

For designing coatings on fiber ends, one should take into consideration the particular illumination conditions that are due to the propagation of light in the fibers. In a single-mode fiber, the guided wave is strongly polarized and the state of polarization greatly depends on the constraints applied to the fiber. In this research, we use Thelen's formalism to search for a law of index alternation of a layer stack to reduce the polarization rate for a given incidence.

Layer uniformity obtained by vacuum evaporation: application to Fabry-Perot filters.

We show how we can measure with accuracy the distribution law of thicknesses deposited inside a vacuum chamber. These measurement techniques are applied to the simultaneous production of high rejection narrowband multiple halfwave Fabry-Perot filters. To prevent any alteration of the filters' optical properties, we must control the variations vs time of the evaporant distribution.