Temperature insensitive packaging of FBG based on a flat diaphragm and an L-shaped lever

A fiber Bragg grating (FBG) temperature insensitive packaging scheme based on a flat diaphragm and an L shaped lever is presented. The curve where the L shaped lever contacts the diaphragm is a segment of an Archimedes spiral, which is used to reduce the temperature responsivity. Because the thermal expansion coefficient of the quartz-glass L shaped lever and the steel sensor shell is different, the temperature effect is compensated for by optimizing the dimension parameters. Theoretical analysis is presented, and the experimental results show that a low temperature responsivity of 2.8pm/°C are achieved.