INFLUENCE OF HUMIDITY ON REFRACTIVE-INDEX OF POLYMERS FOR OPTICAL WAVE-GUIDE AND ITS TEMPERATURE-DEPENDENCE

Humidity dependence of the refractive index of deuterated polymethylme thacylate (d-PMMA) is examined at a wavelength of 1.3 mu m using the r eturn loss method. The refractive index of d-PMMA increases as humidit y increases at room temperature, while it decreases as humidity increa ses at temperatures higher than 60 degrees C. This humidity dependence was ascribed to the counterbalance between moisture sorption and swel ling, Some hydrophobic polymers, such as silicone resin and fluorinate d epoxy resin were affected by humidity to a lesser degree than d-PMMA . (C) 1998 American Institute of Physics.