Photonic Information Processing Systems Laboratory
“Creating a Knowledge Base for Research and Teaching”
Riza Photonics group’s research and teaching activities use the physics of optics and the information manipulations of mathematics to invent, design, build and test innovative devices, sub-systems, and systems to solve current problems in science and engineering and to provide new approaches to study scientific fields. By nature, these efforts are multidisciplinary, requiring knowledge at both the optical device level and the system application level. In a sense, one plays with LEGO® style optical and electronic building blocks to realize inventions. So far, Riza group innovations have come in the following research areas.
Riza’s Defense Optics activities started from his Caltech Ph.D days in the mid-80’s where he showed for the first time how acousto-optics could be used to control transmit and receive mode phased array radars. Later work revolved around developing next generation highest phase stability acousto-optic signal processors such as convolvers, correlators, and spectrum analyzers for wideband Electronic Warfare (EW) applications. Additional innovations included powerful Range-Doppler and transversal filter optical implementations suited for extreme bandwidth and signal complexity radar signal processing. Another aspect of Riza group innovations includes a series of novel beamforming control systems for Phased Array Radars for both narrowband and wideband operations. The group has also pioneered optical security systems using multi-dimensional optical ID cards and a new Hybrid Photonic Signal Processing technique that combines the worlds of analog and digital signal processing..
Riza’s interest in medical optics goes back to his 1989 General Electric (GE) days with the development of simplest control liquid crystal electronic lens motivated by vision applications. Between 1995-1998, Riza’s group introduced the use of optics for phased array ultrasound controls including the concept of intracavity optical wavelength to one dimensional space mapping using an intracavity single fiber probe and spatial distribution via wavelength multiplexing. Since 1998, the group has also proposed and demonstrated several novel optical imaging systems such as the first acousto-optic design based Optical Coherence Tomography (OCT) system, Angstrom sensitivity high speed scanning interferometric imagers, fiber-based scanning imaging endoscopes, and confocal microscopes such as spectral microscopes and agile no-moving parts microscopes.
Riza and co-workers contributions in the field of communication have ranged from both the optical fiber domain to the laser communications wireless arena. In the fiber-optic signal attenuation arena, the group has pioneered the most diverse set of variable optical attenuator (VOA) modules using optical MEMS, acousto-optic, and liquid crystal (LC) technologies. The group for example proposed and demonstrated the world’s first fault-tolerant variable attenuators, all-digital fiber-optic switches, and wavelength sensitive add-drop filters. Riza also invented the Hybrid MEMS/LC design for fiber-optic applications including the hybrid analog-digital design for producing world record performance VOAs. In the free-space wireless domain, Riza invented Multiplexed Optical Scanner Technology, a new method for no-moving parts three dimensional steering of light beams. The group also developed the most advanced theoretical models for freespace-to-Single Mode Fiber (SMF) lens coupling that has realized amazing near zero loss SMF-to-SMF optical power transfer for short distances and expected low loss designs for long range optical wireless links.
-- Energy/Measurement Instrumentation
Generation and control of clean energy is an important research area for any society. Riza and co-workers are developing novel extreme environment optical sensors needed for Zero Emissions fossil fuel-based power generation systems. In addition, Riza and coworkers have developed a new class of laser beam profilers such as the world’s first all-digital and hybrid optical beam profiler instruments using MEMS and new minimally invasive and all-digital profilers using Liquid Crystal technology. These designs have been used for imaging using both coherent and incoherent light. New tools for optical surface metrology have also been invented and demonstrated using acousto-optics and liquid crystals that enable nano-scale measurements.