Optical characterization of mechanically tunable microwire based resonators by changing ring radius and wire diameter

Three tunable microring resonators were assembled using 3.5, 2.5, and 2 μm diameter of poly(trimethylene terephthalate) (PTT) wires, respectively. Their free spectral ranges (FSRs) and quality (Q) factors were measured by reducing ring radius of the microrings. For specific wire diameter and operating wavelength, the FSR increases continuously while the Q increases to a maximum value firstly and then decreases with a reduction of the ring radius. For specific ring radius and operating wavelength, the FSR increases a little and the Q decreases with a decrease of the wire diameter.