Characteristics of Ceramic Microheater for Fiber Coupler Fabrication

Abstract

Properties of a microheater have been greatly improved for use in fused-tapered fiber coupler fabrication by employing a ceramic heat source. Lanthanum chromite was adopted as a heat source because it has the highest melting point for the use in air and can be used without cooling equipment. The usual susceptibility to heat shock exhibited by ceramic heaters was essentially overcome by miniaturizing the structure so that it could handle quick temperature changes during fiber coupler fabrication. The microheater was typically only 22 mm long which helps shorten the fiber coupler length. The lifetime of the microheater was about 1500 h at 1530°C. This is more than 100 times that of the previously developed precious metal microheater. There was only a slight change in the temperature distribution along the heater with heating time. 1.31/1.55-µm wavelength-division-multiplexing (WDM) couplers were fabricated during the lifetime test and it was confirmed that the coupling properties could be very well controlled even after the test.