Further results on the optical properties of oxidised porous silicon as a f
unction of porosity and oxidation conditions are presented in this paper. T
he refractive index varies logarithmically with the oxidation time irrespec
tive of the porosity of the sample and the oxidation temperature. Burried w
aveguides have been realised from as-prepared and oxidised porous silicon.
Optical losses of 18 dB cm(-1) at lambda = 1.3 mu m have been obtained afte
r oxidation at 800 degrees C for 35 min.