Three Calculation Methods of the WGM Cylindrical Cavity Diameter

WGM mode in cylindrical cavity can be rapidly calibrated with analytical approximate formulas based on cylindrical micro-cavity WGM resonance peaks position. On this basis, the diameter of circular cavity can be calculated by applying the three methods, which are the first-order approximation method, the second-order approximation method and mode field radius. When comparing the results which are got from the three methods with the actual geometric diameter, we find that the deviation is within 3%, 2%, 1% respectively. As a result, the diameter of circular cavity can be correctly worked out by making use of these three ways mentioned.