Abstract: The use of microresonators with sharp corners (rectangular and square-shaped) can be limited by severe energy loss at the corners. The effect of incorporating fillet design at sharp corners (rounding of corners) of such single mode optical microresonators is described. The effect on quality factor, free spectral range (“FSR”), and energy loss for varying values of fillet radii are quantified and compared with standard circular microring resonator. It is shown that the selection of optimum fillet radius for sharp-cornered microresonators provide higher quality factor than that of the conventional circular resonators.