ADVANCED METHODS OF CHARACTERISATION OF THE THIN CHALCOGENIDE FILMS, PASSIVE AND ACTIVE OPTICAL WAVEGUIDES

In this paper we report a review concerning some experimental results using non-destructive optical methods for the characterization of the thin films of semiconductor chalcogenide glasses and Er super(3+) - doped Ti:LiNbO sub(3) waveguides, such as: light attenuation in planar, refractive index spatial distribution, dispersion of refractive index, absorption and emission spectra which is due to rare earth elements. Depending on the specific structure, resonator method or prism coupling method are favorable for the attenuation measurements in planar waveguides. A three prism method can be used for the characterisation of planar waveguides with low optical losses. The low loss planar waveguides can be realised using a multilayer structure of As sub(x)S sub(1-x) chalcogenide films with different compositions. The refractive index profile can be established from near field measurements, by using holographic technique or m-line spectroscopy. The refractive index anisotropy can reach the level of 0,02 in thin amorphous films. The measurements of the refractive index dispersion curve of the As sub(2)S sub(3) waveguides have found a maximum that occur for the wavelength range between 0.80/ mu m and 0.85/ mu m.Original Abstract: In acest articol prezentaam o recenzie privind cateva rezultate experimental in care se utilieazaa metode optice nedistructive pentru caracterizarea filmelor subtiri din sticle semiconductoare calcogenice si a ghidurilor optice de undaa de tip Er super(3+):Ti:LiNbO sub(3) ca: atenuarea luminii, distributia spatialaa a indicelui de refractie, dispersia indicelui de refractie, spectre de emisie si absorbtie care se datoreazaa elementelor paamaanturilor rare. Metoda rezonatorului optic si metoda cuplajului cu prismaa sunt potrivite pentru maasurarea atenuaarii in ghidurile planare intrucaat depind de structura specifieaa a acestora. Metoda celor trei prisme poate fi utilizataa pentru caracterizarea ghidurilor optice planare cu pierderi optice mici. Ghidurile optice planare cu pierderi optice mici pot fi realizate utilizand structuri calcogenice multistrat de tip As sub(x)S sub(1-x) cu diferite compozitii. Profilul indicelui de refractie poate fi determinat din maasuraatori de camp apropiat, sau cu tehnici holografice sau cu tehnici spectroscopice de tip "m-line". Anizotropia indicelui de refractie poate fi de ordinul 0.02 in filme amorfe subtiri. In cazul maasuraatorilor dispersiei indicelui de refractie in cazul ghidurilor de tip As sub(2)S