an imaging guidewire can include one or more optical fibers communicating light along the guidewire . at or near its distal end , one or more blazed or other fiber bragg gratings can direct light to a photoacoustic transducer material that provides ultrasonic imaging energy . returned ultrasound can be sensed by an fbg sensor . a responsive signal can be optically communicated to the proximal end of the guidewire , and processed such as to develop a 2d or 3d image . in an example , the guidewire outer diameter can be small enough such that an intravascular catheter can be passed over the guidewire . to minimize the size of the guidewire , an ultrasound - to - acoustic transducer that is relatively insensitive to the polarization of the optical sensing signal can be used . the ultrasound - to - optical transducer can be manufactured so that it is relatively insensitive to the polarization of the optical sensing signal .