MULTILAYER DIELECTRIC MATERIALS OF SIOX/TA2O5/SIO2 FOR TEMPERATURE-STABLE DIODE-LASERS

A novel athermal waveguide for temperature-stable diode lasers was investigated. The waveguide consisted of SiOX, Ta2O5 and SiO2 dielectric layers deposited on a Si substrate. A theoretical calculation shows that the optical path (defined by the product of the effective index of the waveguide and the waveguide length) of the waveguide can be independent of temperature if the thicknesses of Ta2O5 and SiOX layers are properly chosen. The Ta2O5 and SiOX layers were deposited using the magnetron sputtering technique. The indices of SiOX and Ta2O5 films are 1.5 and 2.12, respectively. The SiO2 layer was fabricated by flame hydrolysis deposition with a thickness of 4 mu m. Good surface morphology and thickness uniformity of the SiO2 layer were obtained. The index-temperature drift of SiO2 was measured to be 3 X 10(-5)/degrees C which is about 10 times less than that of a III-V semiconductor. A comparison of the temperature dependence of the SiOX/Ta2O5/SiO2 waveguide and Ta2O5/TiO2/SiO2 waveguide is also presented.