Novel ultrasound detector based on small slot micro-ring resonator with ultrahigh Q factor

An ultrasound detector based on a novel slot micro-ring resonator (SMRR) with ultrahigh Q factor and small size is proposed in this study. The theoretical Q factor of SMRR can be approximately 8.34×108 with bending radius of merely 12 µm. The ultrahigh Q factor leads to an enhanced sensitivity that is approximately two orders of that of state-of-the-art ultrasound detector based on polymer micro-ring resonator. Moreover, the 3 dB bandwidth of the ultrasound detector is approximately 540 MHz, thereby leading to an ultrahigh axial resolution of 1.2 µm. The proposed detector is also CMOS compatible and can be easily and extensively integrated to be maximized in photoacoustic microscopy.