Fig. 3
From: Highly sensitive ultrasound detection using nanofabricated polymer micro-ring resonators
(The reproduced with permission from [46])
a An image of the integrated polymer MRR with the SMF obtained by a CCD camera. b A top view SEM image of the MRR with IP-Dip polymer fabricated by MPL. c Close-up view of the gap between the ring and the straight waveguide. d High-magnification view of the waveguide cross-section with a diameter of 4 μm. e The resonance spectrum of the polymer MRR. f Spectral response profiles of ultrasound transducer (UT) and the MRR