NUMERICAL STUDY ON TIP SHAPE OF NEAR-FIELD OPTICAL FIBER PROBE FOR DETECTING ELECTRIC FIELD INTENSITY OF WHISPERING GALLERY MODE RESONANCE

For the measurement of micron-sized components, there are many methods widely used, such as by using CMM, and the size of the probe sphere of CMM - is essential for measuring. In order to accurately measure the size of the probe sphere, a method by using Whispering Gallery Mode (WGM) resonance has been proposed. To measure the diameter of the microsphere with this method, the resonance wavelength and the angular mode number of WGM need to be known. The resonance wavelength can be measured by a wavelength meter and the angular mode number can be obtained by using the near-field optical fiber probe to measure the electric field intensity distribution on the surface of the microsphere. The detecting sensitivity of probe on electric field intensity is quite important for angular mode number measuring, which is deeply related to the accuracy of microsphere diameter measurement. In the process of electric field intensity detecting, the sensitivity of the probe can be affected by its shape. Therefore, the effect of probe tip shape on measurement was studied to optimize it. In this study, the effect of probe tip diameter, angle and shape on the measuring of electric field intensity on microsphere surface was investigated.