George H. Cadena, III

Mr. Cadena has a diverse electrical engineering background and his areas of expertise include optics, electromagnetic applications, and signal processing, with particular emphasis on telecommunications, holography, and imaging techniques. He is also interested in wireless communication, infrared and microwave technologies, and radar. He is currently involved in projects related to safety evaluation, risk assessment, and failure analysis for consumer products.

Prior to joining Exponent, Mr. Cadena held graduate fellowships at Bell Labs, Murray Hill, NJ, and AT&T Labs, Middletown, NJ. At Bell Labs, he developed imaging methods using phase-modulating micro-displays for the development of next generation television screens with lasers as a light source. Mr. Cadena has analyzed fiber-optic network performance and developed network monitoring techniques for AT&T Labs. These coherent performance-monitoring methods enabled fiber-optic network operators to perform optical signal-to-noise ratio measurement within the individual channel optical bandwidth. This technique is particularly useful in wavelength-routed networks and ROADMs, where growing signal bandwidth prevents reliable noise power measurements between the tightly packed WDM channels.

While at Georgia Tech, he designed and implemented an interferometric holographic stabilizer that was used to characterize storage media for holographic memory applications. He has software experience in Java and Matlab and has completed coursework in optical wave propagation, electromagnetic theory and application, fiber optics, laser theory and application, digital signal processing, random signals, and microelectronic circuits.

Momtahan O, Cadena G, Makhmalbaf A, Adibi A. Two-center holographic recording in highly doped LiNbO3 crystals. Appl Phys B 2008; 90(3–4):519–552.

Cadena G, Momtahan O, Adibi A. A simple and efficient software-based stabilized holographic recording system. Opt Eng 2006; 45(12).

Momtahan O, Cadena G, Adibi A. Sensitivity variation in two-center holographic recording. Opt Lett 2005; 30:2709–2711.

Published Abstracts

Oh J, Brodsky M, Nelson LE, Cadena G, Feuer MD. Coherent performance monitoring for telecom signals. Summer Optics and Photonics Congress, 2008.

Momtahan O, Cadena G, Adibi A. Stabilized two-center holographic recording in highly doped LiNbO3 crystals. CLEO/QELS & PhAST Conference, Baltimore, MD, May 2005.

• Research Assistant, Alcatel/Lucent Bell Labs, Summer 2007
• Research Assistant, AT&T Labs Research, Summer 2006
• Student Researcher, Georgia Institute of Technology, 2003–2004
• Student Researcher, California Institute of Technology, Summer 2003
• Student Assistant, Georgia Tech Research Institute, 2001–2003
  

Projected full-color movies by wave front generation using a phase-only modulating micro-display with HDTV resolution. Phase patterns were written in Matlab and outputted to the display in Java. Designed an optical setup that involved three lasers (red, green, blue) for image projection. Signal to noise ratio and speckle reduction were optimized to obtain the highest quality images.

Successfully demonstrated an interferometric, in-band, optical signal to noise ratio measurement technique with error ~< 1 dB for OSNR range 7-25 dB. This project was the first demonstration of how interferograms of modulated telecom signals can be used to monitor signal degradation in real networks. The results of this experiment are in-press in peer-reviewed scientific literature.

Created a stabilized holographic interferometer that could actively compensate for changes in the environment during a holographic recording session. Used this stabilizer to investigate the photosensitive properties of an optical storage medium (i.e., a photo-refractive crystal) that was used for holographic memory applications. Papers were published about the stabilization scheme and the characterization of the optical storage medium in peer-reviewed journals.

Demonstrated a chirped grating inside of an iron-doped lithium niobate crystal by way of a holographic recording method.