Temperature dynamics in silicon core fibers during CO₂ laser processing

Silicon core fibers are a promising candidate for optoelectronic and photonic applications. Fabrication and post-processing of those fibers is thus far done without precise knowledge of the processing temperatures. Here, a simple technique is presented that allows for in-situ temperature monitoring during thermal processing of silicon core fibers. The temperature was probed across the silicon melting point and cooling rates above 3500 °C s^-1 were measured. The silicon core was found to be molten at a temperature of 1281 °C, more than 100 °C below the bulk silicon melting point. This is attributed to stress inbuilt to silicon core fibers during the fabrication process.