Research Objectives and Approaches: The objective of this research is to establish a versatile, designated light source in northern Alabama to support the area?s wide range of research activities encompassing optical frequency metrology, nanophotonics, plasmonics, micro-fabrication, and optical sensing. The approach is to create a service facility by acquiring an optical frequency synthesizer (OFS), along with compatible THz antennas, which will be accessible to the region?s academic, industrial and governmental research programs. Intellectual Merit: The distinctive capabilities of the OFS will greatly benefit a number of ongoing research programs, including the development of microfluidic catalytic reactors, fiber-based plasmonic sensors and microresonator-based frequency combs. Moreover, a diverse array of new research activities, such as frequency-comb-based atmospheric clock distribution, probing of ozone-layer activities, study of intraband dynamics of semiconductor nanocrystals, and multi-wavelength-range trace gas sensing, will also be enabled by this novel laser system. Broader Impacts: The new service facility is expected to become a catalyst that strengthens current partnerships between different sectors of the local research community and stimulates further collaborations across departments, research centers, institutions and disciplines. Meanwhile, the research activities enabled by the OFS will substantially enhance the quantity and quality of student research opportunities at both undergraduate and graduate levels. Furthermore, through developing stronger educational programs in science and engineering at UAH, this MRI acquisition will help build a knowledge dissemination ladder that bridges forefront research and K-12 education, and benefit a broad scope of the local community, including those from underrepresented groups.
The goal of this MRI project is to establish a versatile, broadband light source on the campus of the University of Alabama in Huntsville (UAH) to advance research in (1) optical frequency metrology, (2) nanophotonics and plasmonics, (3) micro fabrications, and (4) optical sensing, and to promote optics education and training in in the northern Alabama region. Here are some of the major scientific findings and achievements we have made through the project: (1) We have developed a new optical sampling technology called Optical Sampling by Cavity Tuning (OSCAT), which can potentially achieve a very fast tunable optical delay (up to 100 kHz) with a large scan depth (e.g., centimeters). It aims to address the ubiquitous need for a simple, low-cost means to scan optical delays with both fast rates and large depths. We developed a dynamic theory for OSCAT, and experimentally demonstrated its application in remote target tracking and ranging (Lidar), optical coherence tomography (OCT), and remote 3D surface profiling. This part of the activities has led to a couple of journal publications, a number of international and regional conference presentations, and a pending PhD dissertation. (2) We have studied the characteristics of the excess phase noise in remote distribution of precise clock signals based on a multi-frequency optical frequency reference (i.e. an optical frequency comb). Our work shows that optical frequency combs can be a feasible multi-frequency clock carrier for remote clock distribution. This work has led to a couple of journal publications. It also helped us develop international collaborations as two visiting scholars from China worked on this research in 2012-2013. (3) We have developed an experimental scheme based on an ultrastable laser referenced to an optical frequency comb to probe the fundamental thermal noise floor of optical fibers at very low frequencies (infrasonic region). This work could potentially lead to ultra-sensitive fiber-optic infrasound sensors, which find wide applications in defense and homeland security, oil and gas industry, civil engineering, and geophysics. It is also critical in understanding the fundamental physics regarding the ultimate limit of fiber-optic sensors. This part of the activities has led to one journal publication. (4) We have experimentally studied the energy transfer between semiconductor quantum dots (CdSe/ZnS) with the presence of metallic nanoparticles and discovered an enhancement of energy transfer. This research paved the way for our subsequent research on plasmonic enhancement of quantum dot emission, which opens up a new way to make quantum dots "brighter". This can lead to applications such as highly efficient light-harvesting structures, biologically/chemically triggered ultrafast nanoswitches, plasmon-controlled flourescent sensors, nanothermometers, energy nanogates, active nanostructures, etc. The work led to one journal publication. (5) This broadband light source also helped us develop a new micro-reactor technology using multiple diffusion bonded. The realization of a reusable chemical reactor featuring in-line fiber optic spectroscopy represents a major milestone in microfluidic technology. Once achieved, engineers will finally have the tools to manufacture picoliters of high purity chemicals using state of the art quality control in a hand held reactor that can reduce both the cost and waste required by today’s manufacturing techniques. Here are the major educational and infrastructural outcomes of the project: (1) Over the last 4 years, the Femtosecond Laser Frequency Comb Lab has become an educational and training center for UAH. A total of 6 graduate students, 4 undergraduate students and 2 visiting scholars have been directly involved in research activities related to the MRI instrument. Two of these students are female. Three of the undergraduate students completed their capstone research projects with their MRI-related activities and subsequently graduated. Two of the graduate students and the two visiting scholar have published or submitted journal papers based on their MRI research. (2) The data and the knowledge gained through the MRI project have been widely disseminated through publications and presentations. Pertinent work has been presented in international conferences such as the Conference of Laser and Electro- Optics (CLEO), regional conferences such as Alabama EPSCoR Annual Meeting and Von Braun Symposium, invited talks, and campus-wide seminars. In addition, many prospective students (both undergraduate and graduate) and K-12 students have visited the lab. (3) The FC1500 frequency comb laser is the first optical frequency synthesizer in the southeast region outside of Florida and one of the few within the US. It substantially enhances the competitiveness of UAH as well as the state of Alabama in attracting high-quality students, researchers and research funding in the relevant fields. The research activities revolving around this instrument has served as a magnet to draw additional collaborations from other regional research organizations, such as NASA Marshall Space Flight Center, Army AMRDEC and Optical Sciences Corporation.
