Center for VLSI and Embedded System Technologies

Optics and RF

Research Supervisor - Dr. Azeemuddin Syed

Optics and Photonics: Photonics is a field concerned with the science of light and developing applications for it. It includes all aspects related to the generation, processing, transmission and detection of light and its interaction with matter. Recent advances in photonics for communications, imaging, health care & medicine, defence, optics and electronics have all contributed to spectacular new applications in every corner of our lives.The emphasis on the study and application of Photonics is at rise and will keep expanding in harmony with electronics.
Photonics is an active and growing area of research within CVEST. The main research themes in this area are:

Electromagnetic Theory
Laser Technology
Optical Technology and Imaging

Specific areas presently under investigation include High Energy Lasers, Optical Detection and Characterization, Semiconductor photonics, Optical gait analysis etc.

The research area includes different techniques of laser beam combination, detailed study, design and development of simulation models for incoherent beam combination in free space, control system model for coarse pointing and fine pointing systems.

We work on the development of the mathematical model for beam directing optical channel, multiple beam source position optimization model, atmospheric turbulence model etc. The different Beam Combination techniques are applied for the development of a High Energy Directed Energy System. It includes the design of different architectures for beam combiners, mathematical modeling and performance analysis of the same.

Optical spectroscopy is defined as the study of how matter interacts with electromagnetic radiation. The technique has been used as a tool to characterize various samples in a variety of industries.One of the application cases being explored is to calculate nutrients value of fodder without using spectrophotometer which is an expensive device. The underlying principle is to calculate important optical wavelengths which are responsible for the change in the nutrients value in fodder.

Another research in this area focuses on the development of new experimental approaches for low cost optical diagnostic devices for water quality measurements. More specifically, it involves applying Machine Learning techniques to identify characteristic wavelengths from spectral absorption data. These wavelengths are used to decide the right LD-PD pairs in the design. The research finally aims at a viable low cost solution which can work as a handy replacement for expensive benchtop lab instruments.

The research area includes analysis of Gait, as a walking pattern, walking speed and pattern of footfall. Gait characteristics have been linked with a variety of medical conditions in clinical research . We aim to utilize Guided-Path Tomography (GPT) to develop an inexpensive, easy to use mechanism for gait measurement.
Plastic Optical fiber (POF) are proposed to be used as sensing element due to their higher sensitivity to bending compared to glass fibers and low cost.The goal is to reduce cost, while improving reliability, ruggedness, and accuracy. We aim to recognize the medical condition from the analysis of gait measurement.

Ring laser gyroscopes (RLG) are optical inertial rotation sensors used to measure the rate and direction of rotation. With the help of accelerometers, they provide accurate information about the position and orientation of an object. Semiconductor RLG is a compact, low cost and low power inertial rotation sensor working on the principle of Sagnac effect. We are working on the mathematical modeling of SRLG using rate equations of counter-traveling electric fields inside the gain medium and the resonant cavity. We have been working on increasing the sensitivity, which is found to be limited by locking of the counter-traveling fields, by proposing few novel designs and biasing techniques.

Our research aims to be adventurous and curiosity-driven but relevant to the wider photonics and photonics user communities. We welcome interaction with industry and try to ensure that our research priorities are informed by our industrial partners as well as by the academic community.

Optics is a vast research area which finds its application in various disciplines. One amongst is calculation of nutrients value of fodder without using spectrophotometer. Spectrophotometer is an expensive device, hence is not affordable for everyone. To circumvent the cost factor, research is in progress to design a device which can estimate the nutrient value of the fodder. The approach used involves calculation of important wavelengths which are responsible for the change in the nutrients value in fodder.

RFIC: Radio Frequency Integrated Circuit (RFIC) research at CVEST focuses on the modeling, design, fabrication and characterization of on-chip RF components. The aim is to provide low-cost, low-power and high yield designs of various RF components used extensively in communication devices. New analytical and modeling techniques are also developed to improve the understanding of RF circuits and the underlying principles.
Main areas of research in this group are:

On Chip RF Inductor
RF sensor design for detection of biological liquids
RF sensor design for detection of amino-acids and proteins
RF sensor design for distinguishing between specific and non-specific binding

Inductors are used in RFICs for impedance matching, as a tuned load, series feedback element etc. They play a limiting role in RFICs because of the large area they occupy, lower Q-factor, associated noise and parasitic coupling. Our group has demonstrated improvement in the inductor Q-factor and frequency response by incorporating domain-patterned Permalloy of various thicknesses on top of inductors. The fabricated inductor is shown in figure. Varying the shape, size and thickness of the Permalloy gives about 200% peak improvement in inductance and 700% peak improvement in Q-factor.

The above setup shows a VNA(vector network analyser) and RF sensor connected using SMA probes.

RF and microwaves is an emerging field for its application in Biomedical. One such application is for detection of various liquids in our body. The basic principle behind a RF sensor is that it detects a change on the basis of change in dielectric constant of the material. RF sensor is designed to detect the change in permittivity as well as change in the concentration of the bio-liquid. Also RF sensor is designed to detect a change in permeability of sample. Using RF sensor, we are able to detect the ferritin concentration in blood, which helps in detection of anaemia.

The above picture shows the RF sensor for detection of ferritin.

Fractal capacitor based RF sensor

RF sensor for simultaneous detection of permittivity and permeability

Highly sensitive RF sensor is designed using commercially available tools like CST and fabricated for detection of amino-acids and proteins, which are an important part of our blood and fluid system. This can be used as a way for diagnosis of certain diseases.

Specific binding is the binding of the ligand to its designated receptor. Whereas, Non-specific binding is the binding of ligands to receptors other than its designated receptor. So RF sensor is designed to differentiate between the two.