Abstract

Passive integrated-optical (IO) devices may be important in future telecommunication, e.g., as cheap power splitters, combiners, and demultiplexers, as well as in optic and fiber-optic sensors.^1-2 In numerous applications of single-mode sensors, the state of polarization is a crucial physical parameter (e.g., in Faraday sensors). Therefore, the polarization properties of the IO components are, in addition to the price, of utmost importance in sensor design. In our work we focus on IO linear waveguides and Y-couplers. The birefringence in buried IO waveguides is at least an order of magnitude smaller than in surface waveguides made by a K⁺ ion exchange in BK7 (n ≤ 10^–4).^2,3 However, the exact value of the birefringence and its variation with temperature is not known. We measured the temperature dependence of the birefringence at 1300 nm and compared it with the theoretical value. For the measurements, we set up an ellipsometer with a rotating analyzer. With this arrangement an absolute accuracy of ~ ±0.5° phase difference between the TE and TM modes was achieved over the complete temperature range of –35°C to +80°C provided that the phase differences were not too small(≥5°).

© 1990 Optical Society of America