Self-assembled optical detectors for optical fiber sensors

Recent work in the fabrication of self assembled quantum dot (QD) detectors for optical fiber sensors is reported in this paper. The ability to develop the QD based devices and materials via the electrostatic self-assembly (ESA) process has been demonstrated. The QD precursor nanocluster materials involved in ESA have been designed and synthesized to proper size, stabilized in an aqueous-based solution, and functionalized to allow self-assembly. The optical fiber sensor instrumentation has been developed to monitor the reflected optical power with the buildup of the QD layers on the fiber endface during the ESA process. The results are confirmed by observing the effects of low-finesse QD Fabry-Perot interferometric cavities formed via such processes on the ends of optical fibers. The photocurrent-voltage characteristics show a diode-like behavior with linear photocurrent in the reverse bias and nonlinearity in the forward bias. It is suggested that fast response times can be achieved due to the high carrier mobilities that arise in part due to structure of the materials formed via the solution-based ESA process.