Photo-stability of pulsed laser deposited Ge(x)As(y)Se(100-x-y) amorphous thin films.

Quest for photo-stable amorphous thin films in ternary Ge(x)As(y)Se(100-x-y) chalcogenide system is reported. Studied layers were fabricated using pulsed laser deposition technique. Scanning electron microscope with energy dispersive X-ray analyzer, Raman scattering spectroscopy, transmittance measurements, variable angle spectroscopic ellipsometry, and non-linear imaging technique with phase object inside the 4f imaging system were employed to characterize prepared thin films. Their photo-stability/photo-induced phenomena in as-deposited and relaxed states were also investigated, respectively. In linear regime, we found intrinsically photo-stable relaxed layers within Ge(20)As(20)Se(60) composition. This composition presents also the highest optical damage threshold under non-linear optical conditions.

Light trimming of a narrow bandpass filter based on a photosensitive chalcogenide spacer.

We present an experimental study of the photosensitive properties of a narrow bandpass filter based on a Ge(15)Sb(20)S(65) spacer fabricated by electron beam deposition. For a single layer, near the optical bandgap of this chalcogenide material, the efficiency of the photo-bleaching increases as the central wavelength of the light source for exposure decreases. The maximum relative photo-induced change of the optical thickness reaches about 1%. By using controlled light exposure around 480 nm of a photosensitive narrow bandpass filter centered at 1550 nm, we obtained a spatially localized shift of its peak wavelength up to 5.4 nm. This property is used to perform, for the first time at our knowledge, the post trimming of a narrow bandpass filter with a light beam. A 5 x 5 mm(2) ultra uniform area in which the relative spatial variation of its peak wavelength remains below 0.004% is demonstrated.

Light emission from sources located within metallodielectric planar microcavities.

A simple, rigorous electromagnetic formula is derived for predicting the electromagnetic power provided by sources located in transparent or dissipative planar microcavities. With this simple approach, we compare numerically and experimentally the electromagnetic power that escapes the microcavity when the source is located in a metallodielectric or in an all-dielectric resonant planar structure. Although a strong light-extraction coefficient might be expected for metallodielectric microcavities, we show that these attractive structures suffer from metal absorption even when thin metallic layers are used. Experiments implemented with europium chelates located in metallodielectric or in all-dielectric microcavities confirm this result.