The BRADLEY DEPARTMENT of ELECTRICAL and COMPUTER ENGINEERING

Research Areas

Researchers in optics and photonics are using these technologies to overcome challenges in biological applications and high-risk systems. Applications include cancer research, disease diagnosis, and 3D imaging and pattern recognition.

Current Research

Smartphone-based Imaging

The low cost, compactness, and ever-improving quality of smartphones means that they have huge potential for mobile medicine. We are developing various smartphone-based, portable imaging systems to aid in diagnosing diseases.

In Vitro Fertilization

Approximately 10 percent of the population suffers from some type of infertility, and in vitro fertilization has become the dominant form of treatment. However, its success rate is low. To improve outcomes, we need methods for morphological assessment of gametes and embryos. We are developing novel optical microscopes for quantitative imaging of sperm cells, oocytes, and early embryos. These techniques offer deep sub-nanometer sensitivity and a high frame rate, capable of intensity, phase, and birefringence measurements in all dimensions. This allows us to quantify size, thickness, volume, and mass for quantitative quality assessment.

High-Speed Distributed Sensing

With an approach that may lead to the development of a distributed fiber-optic sensing technology with response speeds that are at least three orders of magnitude higher than traditional distributed sensing schemes, our researchers are developing technology that will have a response rate above kilohertz. We have already demonstrated speeds as high as 7 KHz, and the same method can be applied to interrogate more than 1000 serial Bragg grating sensors in one fiber. Each grating can be used to measure various physical parameters for structural health monitoring.

Efficient Models of Photonic Crystal Fibers

We have developed simple, fast, and efficient one-dimensional models for evaluating transmission characteristics of photonic crystal fibers. Using these models, we can predict the axial propagation constant, chromatic dispersion, effective area, and leakage loss with reasonable accuracy and in a much shorter time than by using two-dimensional analytical and numerical techniques, and with fewer computational resources. These models may serve as an effective tool for the design of photonic crystal fibers.

Holography

Working with Optical Scanning Holography (OSH), which is a form of Digital Holography (DH), we can electronically record 3-D objects using 2-D optical heterodyne scanning. A main research thrust is computer-generated holography, where we have developed novel algorithms to speed up the computation and encoding. Possible applications include 3-D pattern recognition, 3-D microscopy, holographic optical remote sensing, and 3-D holographic displays.

Imaging Tissue and Cells

ECE researchers are using fiber optics to study biological systems from the inside--they are looking at everything from the nervous system to muscle tissue, and even cells. One group is creating flexible multifunctional fibers for studying the nervous system and treating neurological disorders. Unlike conventional neural interface devices, which are based on hard materials such as silicon and metal wires, our fiber-based devices are compatible with the tissue compliance and are bio-compatible for chronic applications. These devices are capable of optical, electrical, chemical, and acoustic interactions with the nervous system.

Another group is studying how to use adaptive optics to construct an adaptive multimode fiber-optic network for sensing, communication, and imaging. Techniques such as these can be used to achieve high-resolution deep-tissue imaging in biomaterials.

Other researchers are using gold nanoparticles as therapeutic and contrast agents. By visualizing the movement of these nanoparticles inside cells, we can get a better understanding of the molecular and functional mechanisms of important processes. We are using quantitative measurements of nanoparticle scattering to determine their location in 3-D, with nanometer accuracy.

Distributed Sensing

Our goal is to develop an optical fiber sensor technology that will enable fully distributed simultaneous measurement of physical, chemical, and biological parameters in a single fiber. Our approach uses a traveling long-period grating, generated either acoustically or optically in a single-mode fiber, which allows for a variety of physical, chemical, and biological parameters--including temperature and strain--to be measured with a single fiber. Applications include structural health monitoring, pollution detection in rivers and lakes, and chemical- and bio-terrorism agent detection.

Measurements in Harsh Environments

The Center for Photonics Technology (CPT) is developing a fully distributed optical fiber high-temperature sensor that can be embedded into the refractory bricks or liner material in coal gasifiers to provide fully distributed temperature measurement.

Gasifiers operate under extreme conditions, including high temperatures, high pressure, and highly reducing, corrosive, and erosive conditions. Current temperature measurement in coal gasifiers is based on traditional high-temperature thermocouples, which have a limited lifespan and large size. Our fiber optic-sensing technology is small, immune to electromagnetic interference, and capable of distributed measurement.

Another project underway is to develop a distributed sensing system based on a first-of-a-kind low-mode-volume sapphire fiber. Through a precise masking and etching technique along the length of the fiber, a microstructure will be fabricated to lower its mode volume. This will lead to a major breakthrough that will benefit all current sapphire fiber-based high-temperature sensing technologies, including Fabry-Prot (F-P), Fiber Bragg Grating (FBG), and Long-Period Grating (LPG). We will then develop a novel Raman scattering-based distributed temperature sensing technology based on the low-mode-volume fiber, which is capable of operating reliably at temperatures above 1000 C.

When taking measurements for structural health in harsh environments, a low profile is often key. We are developing a first-of-a-kind remote fiber optic technology for detecting acoustic waves to monitor structural health. The technology requires no electric power supply at the monitoring site and can extract information about multiple material conditions including temperature, strain, corrosion, and cracking. The low physical profile of the optical fiber used guarantees a minimal intrusion on the integrity of the monitored material or structure, and can be operated at temperatures above 800 C.