In recent times, there has been extensive research on fiber-optic imaging devices in order to enable imaging/sensing at a size scale inaccessible to other modalities. The design for fabrication of a highly sensitive fiber-optic ultrasound detector is proposed. The transducer employs a polymer Fabry-Pérot resonator for ultrasound detection. To enhance acoustic sensitivity, a method is proposed for fabricating a self-aligned polymer waveguide within the cavity to improve the resonator quality factor (Q-factor). Simulation studies were conducted to evaluate feasibility and quantify the improvement in Q-factor for different transducer configurations. Results show that with dielectric mirrors and a waveguide, Q-factor can approach the order of 10,000. Additional simulation studies are presented to analyze the effect of cavity shape on the device performance, drawing out the importance of a flat mirror for waveguided devices. Subsequently, results from optical testing of the first iteration of fabricated devices are presented, highlighting the main drawback of this method - the nonideal shape of the waveguiding pillar. Finally, initial results from the second iteration of devices that overcome this drawback are presented, demonstrating the feasibility of creating straight self-aligned polymer waveguides on gold-coated fibers, followed by a discussion on the implications of this work and future steps.
Bibliographical noteFunding Information:
The authors would like to acknowledge the funding received from the NSF and Institute for Engineering in Medicine (IEM) at the University of Minnesota. Portions of this work were conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure Network (NNCI) under Award Number ECCS-1542202. We would like to thank Dr. Amin Tadayon for very useful technical discussions and Cameron Motameni for assistance in the lab.
© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE).
- intravascular imaging
- optical ultrasound detection