An Optical Fiber Tip Micrograting Thermometer

An ~ 12-μm-long Bragg grating was engraved in an ~ 5-μm-diameter optical fiber tip by focused ion beam (FIB) milling. An ~ 10-dB extinction was achieved at 1570 nm with only 11 indentations. The grating was used for temperature sensing, and it exhibited a temperature sensitivity of ~ 22 pm°C.