Photoacoustic endoscopy using polymer microring resonators

We designed and fabricated a probe for endoscopic photoacoustic imaging with a structure that includes an optical fiber to deliver laser pulses and polymer microring resonators on transparent fused silica substrate. To calibrate the performance of the probe, a 6 mu m carbon fiber embedded in an agarose gel phantom was imaged. At a depth of 2.7 mm from the probe edge, radial resolution up to 21 mu m and transverse resolution of 750 mu m were obtained. Transverse resolution can be improved using fibers with small core sizes. Experimental results show that the devised probe has potential for high-resolution photoacoustic endoscopy.