Professor Federici has several active research programs in

Terahertz Spectroscopy and Imaging    Terahertz Wireless Communications  Flexible Electronic Devices and Sensors and Electrospinning

Older Areas of Research include:  Biophotonics     Photoinduced Superconductivity    Photonics Education and Others

A full listing of Professor Federici's publications can be found on Google Scholar:  http://scholar.google.com/citations?user=N0tH-6AAAAAJ&hl=en&oi=ao

Terahertz Technology and Spectroscopy

    My research in THz Technology and Imaging covers a wide area of topics including:  THz Wireless Communication, THz Technology for Agriculture, Viticulture and Enology, THz Metamaterials, Synthetic Aperture Imaging, Detection of concealed weapons and explosives,THz Technology, THz Sources/ Detectors/ Near-field Microscopy, solid state physics (nanotubes and other materials).

   THz Wireless Communications

We have an upcoming book chapter on THz wireless communications:
      J. F. Federici, L. Moeller, and K. Su, "Terahertz Wireless Communications" to appear in Handbook of Terahertz Technology for Imaging, Sensing, and Communications, Woodhead Publishers (expected publication January 2013).

K. Su, L. Moeller, R. B. Barat, J. F. Federici, "Experimental comparison of terahertz and infrared data signal attenuation in dust clouds",  Journal of the Optical Society of America A: Optics and Image Science, and Vision 29 (11) , pp. 2360-2366 (2012). http://dx.doi.org/10.1364/JOSAA.29.002360

Ke Su, Lothar Moeller, Robert B. Barat, and John F. Federici, 'Experimental Comparison of Performance Degradation from Terahertz and Infrared Wireless Links in Fog', J. Opt. Soc. Am. A 29, 179-184 (2012). http://www.opticsinfobase.org/josaa/abstract.cfm?uri=josaa-29-2-179

      L. Moeller, J. Federici, and K. Su, '2.5Gbit/s duobinary signalling with narrow bandwidth 0.625 terahertz source', Electronics Letters 47, 856-858 (2011). 
Featured paper in IEE letters. Click here for Inside View article from IEE Letters. http://dx.doi.org/10.1049/el.2011.1451

J. F. Federici and L. Moeller, ‘Review of terahertz and sub-terahertz wireless communications’, J. Appl. Phys. 107 (11), 111101 (2010). (Invited Review Paper). http://link.aip.org/link/?JAPIAU/107/111101/1

L. Möller, J. Federici, A. Sinyukov, C. Xie, H. C. Lim, and R. C. Giles, ‘Data Encoding on THz Signals for Communication and Sensing’, Opt. Lett.  33, 393-395 (2008).

THz Metamaterials

Y. Li Hor, Z. Szabó, H. C. Lim, J. F. Federici, and E. P. Li, ‘Terahertz response of microfluidic-jetted three-dimensional flexible metamaterials’ Applied Optics 49 (8), 1179-1184 (2010). http://www.opticsinfobase.org/abstract.cfm?URI=ao-49-8-1179 

 O. Sternberg, K. P. Stewart, Y. Hor, A. Bandyopadhyay, J. F. Federici, M. Bornefeld, Y.-L. Mathis, D. Sliwinski, K. D. Moeller, and H. Grebel, 'Square-shaped metal screens in the infrared to terahertz spectral region: Resonance frequency, band gap, and bandpass filter characteristics', J. Appl. Phys 105. 023103 (2008).

B. Schulkin, L. Sztancsik, J. F. Federici, "Analytic Solution for 1 Dimension Photonic Band Gap Crystals", Amer. J. Phys. 72, 1051-1054 (2004).

 THz Technology for Agriculture, Viticulture, and Enology

In this area, we have explored various applications of THz imaging and spectroscopy to Viticulture and Enology in particular. Our current research focuses on developing THz 2-D and 3-D THz tomography imaging for non-destructive evaluation of wine corks. THz imaging allows one to detect the internal defects, voids, and lenticular channels in corks.

Our most recent effort is a review article on the use of THz imaging and sensing for moisture detection:
      J. F. Federici, 'Review of Moisture and Liquid Detection and Mapping using Terahertz Imaging',  J. Infrared Millimeter and THz Waves Waves 33 (2), 97-126 (2012). http://www.springerlink.com/content/l754153827rxggm5/

    A. J. Teti, D. E. Rodriguez, J. F. Federici, C. Brisson, 'Non-destructive measurement of water diffusion in natural cork enclosures using terahertz spectroscopy and imaging' J. of Infrared, Millimeter, and Terahertz Waves 32, 513-527 (2011).  http://www.springerlink.com/content/07h822l68024k313

Y. L. Hor, J. F. Federici, and R. L. Wample, ‘Non-destructive evaluation of cork enclosures using terahertz/ millimeter wave spectroscopy and imaging’, Appl. Optics 47, 72-78 (2008). Featured article on cover of Jan 1, 2008 issue. Also in Virtual Journal for Biomedical Optics (VJBO).  http://vjbo.osa.org/virtual_issue.cfm

Below, are images acquired through a 4mm thick cork sample. Figures (a) and (b) show the front and reversed back visible image of the sample. The THz images (c) and (d) show evidence of the various cracks, voids, and grain in the cork sample. THz image (d) is taken with 100 micron resolution. For pixels in the image that do NOT correspond to a void or a defect, the THz absorbance spectra is well-represented by weak Mie-scattering theory.

Initially, we had thought that THz spectroscopy could be used to detect the presence of 2,4,6-Trichloroanisole in corks. TCA is one of the chemicals that is thought to be the primary cause of "cork taint" in wine. TCA can inject a mushroomy, wet cardboard taste to wine. Wine that is spoiled is commonly called "corked wine". The paper below describes the THz spectroscopy of TCA. Unfortunately, the absorption coefficient of TCA in the THz range is not strong enough to detect TCA with sufficient sensitivity.

Y. L. Hor, H. C. Lim, J. F. Federici, E. Moore, J. W. Bozzelli, ‘Terahertz study of trichloroanisole by time-domain spectroscopy’, Chem. Phys. 353, Issues 1-3, Pages 185-188 (2008), http://dx.doi.org/10.1016/j.chemphys.2008.08.011

We have demonstrated the use of THz and Millimeter wave Imaging and Spectroscopy as a method to estimate fruit crop yield. More specifically, as a method to estimate the number and size of grapes during the growing season. The following paper details our studies:

    J F. Federici, D Rodriguez, S Mukherjee, and R L. Wample, ‘Application of terahertz Gouy phase shift from curved surfaces for estimation of crop yield', Applied Optics Vol. 48, Iss. 7, pp. 1382–1388 (2009)

Synthetic Aperture Imaging, Detection of Concealed Weapons, Explosives, Homeland Security Applications

Since 2001, NJIT has been developing a synthetic aperture imaging method, more specifically interferometric imaging, and adapting the technique to stand-off detection of explosives. Rather than using each detector in an imaging array for one pixel in the THz image, each PAIR of detectors generates a spatial Fourier component in the THz image. By adding multiple Fourier components from all possible combinations of detector pairs, one can reconstruct the THz image by an inverse Fourier transform.

Z.-H. Michalopoulou, S. Mukherjee, Y. L. Hor, K. Su, Z. Liu, R. B. Barat, D. E. Gary, J. F. Federici, 'RDX detection with THz spectroscopy', Journal of Infrared, Millimeter, and Terahertz Waves 31, 1171-1181 (2010). 

In our most recent work, we have demonstrated a hybrid THz synthetic aperture imaging system which using a microwave source for the generation of THz while a CW photomixing detector array is used to detect the image.

K. Su, Z. Liu, R. B.Barat, D. E.Gary, J. F.Federici and Z.-H. Michalopoulou, ‘Two-dimensional interferometric and synthetic aperture imaging with a hybrid terahertz/ millimeter wave system’, Applied Optics 49 (19), pp.E13-E19 (2010). http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-49-19-E13

Top figure is schematic of the hybrid system. Bottom left figure is a simulation imaged of object shaped as a cross. Bottom right is the Terahertz image reconstructed through the experimental data. The object is a cross-shaped object covered with aluminum foil.

We have demonstrated the potential of THz video-rate imaging using this method. The paper below shows video-rate imaging of a THz source.

Z. Liu, K. Su, D. E. Gary, J. F. Federici, R. B. Barat, and Z.-H. Michalopoulou, ‘Video-rate terahertz interferometric and synthetic aperture imaging’, Appl. Optics 48, 3788-95 (2009).

   

Figure on Left is experimental setup for video rate imaging including rapid phase modulation of the source which enables the measurement of the THz amplitude and phase at each THz detector. Figure on right is our array of four photoconductive antenna detectors.

The above figure shows the reconstructed and cleaned image of a THz source moving source along a 20x20 mm square. CLICK on the figure to open a movie. REAL TIME THZ IMAGING!

A M Sinyukov, Z Liu, Y L Hor, K Su, R B Barat, D E Gary, Z-H Michalopoulou, I Zorych, J F Federici, and D Zimdars, ‘Rapid Phase Modulation of THz Radiation for High Speed THz Imaging and Spectroscopy’, Optics Letters 33, pp. 1593-1595 (2008).

J. Federici, R. Barat, D. Gary, Z-H. Michalopoulou, ‘Detection of Explosives by Terahertz Synthetic Aperture Imaging - Focusing and Spectral Classification', (Invited Paper) Comptes rendus – Physique  9, 248-261 (2008).  http://dx.doi.org/10.1016/j.crhy.2007.09.013

J. F. Federici, D. Gary, R. Barat, Z.-H. Michalopoulou, ‘Detection of Explosives by Terahertz Imaging’, in Counter-Terrorism Detection Techniques of Explosives Jehuda Yinon Ed. (Elsevier 2007).

    J. F. Federici, D. Gary, R. Barat, and Z.-H. Michalopoulou, “T-Rays vs. Terrorists”, IEEE Spectrum, July 2007.

A. M Sinyukov, A. Bandyopadhyay, A. Sengupta, R. B Barat, D. E Gary, Z. H. Michalopoulou, D. Zimdars, and J. F Federici, ‘Terahertz interferometric and synthetic aperture imaging, Inter. J. High Speed Electron. Systems, 17, 431-443 (2007).

A. Sengupta, A. Bandyopadhyay, J. F Federici, R. B Barat, D. E Gary, M. Chen, and D B Tanner, ‘Effects of scattering on THz spectra of granular solids’, Int. J. Infrared and Millimeter Waves, Int J Infrared Milli Waves (2007) 28:969978

A. Bandyopadhyay, A. Sengupta, A.M. Sinyukov, R.B. Barat, D.E. Gary, Z.H. Michalopoulou and J.F. Federici, ‘’Artificial neural network analysis in interferometric THz imaging for detection of lethal agents,’’ Int. J. Infrared and Millimeter Waves, 27, 1145-1158, 2006.

 A. Bandyopadhyay, , A. Stepanov, A. Sengupta, D. E. Gary, M. D. Federici, B. Schulkin, R. B. Barat, E. Michalopoulou, D. Zimdars, and J. F. Federici, 'Terahertz interferometric and synthetic aperture imaging', J. Opt. Soc. Amer. A 23, 1168 (2006).

J. Federici, R. Barat, D. Gary, Z-H. Michalopoulou, and D. Zimdars, 'Stand-Off Sensing of Explosives Using Terahertz Radiation',  American Laboratory 38, 28-33 (2006).

        A. Sengupta, A. Bandyopadhyay, J. F. Federici, D. E. Gary, and R. B. Barat, “THz reflection spectroscopy of Composition C-4 and its detection through interferometric imaging,” Proc. SPIE 6120, 61200A (2006).        

    

    A. Bandyopadhyay, A. Sengupta, R. B. Barat, D. E. Gary, and  J.F. Federici, “Grain size dependant scattering studies of common materials using THz time-domain techniques,” Proc. SPIE 6120, 61200H(2006).    

A. Bandyopadhyay, A. Sengupta, V. Johnson, J. A. Harrington, and J. F. Federici, “Characterization of hollow polycarbonate waveguides using THz time-domain spectroscopy,” Proc. SPIE 6120, 61200B (2006).

A. Sinyukov, A. Bandyopadhyay, A. Sengupta, D. E. Gary, R. B. Barat, E. Michalopoulou, D. Zimdars, and J. F. Federici, 'Terahertz interferometric and synthetic aperture imaging', Proc. SPIE 6120, 62120Z (2006)

    J. F. Federici, F. Huang, A. Bandyopadhyay, A. Sengupta, D. Gary. R. Barat, and D. Zimdars, 'THz Standoff Detection and Imaging of Explosives and Weapons', (INVITED PAPER), Proc. SPIE 5781, 75 (2005).

    J. F. Federici, F. Huang, D. Gary, R. Barat, D.Zimdars, 'THz Imaging using an Interferometric Array', Proc. SPIE 5790, 11 (2005).

    J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, 'THz Imaging and Sensing for Security Applications - Explosives, Weapons, and Drugs',  Semicond. Sci. Technol. 20 S266-S280 (2005).

    F. Huang, B. Schulkin, H. Altan, J. Federici, D. Gary, R. Barat, D. Zimdars, M. Chen and D. Tanner, 'Terahertz Study of 1,3,5-Trinitro-s-triazine (RDX) by Time Domain Spectroscopy and FTIR', Appl. Phys. Lett., 85 5535 (2004).

    K. P. Walsh, B. Schulkin, D. Gary, J. F. Federici, R. Barat, D. Zimdars, 'Terahertz near-field interferometric and synthetic aperture imaging,' Proc. SPIE 5411, 9 (2004).

    F. Oliveira, R. Barat, B. Schulkin, F. Huang, J. Federici, D. Gary, and D. Zimdars, 'Analysis of THz Spectral Images of Explosives and Bio-Agents using Trained Neural Networks', Proc. SPIE 5411, 45 (2004).

    F. Huang, J. F. Federici, R. Barat, D.Gary, 'Detection of the agent inside or behind a barrier material', Proc. SPIE Vol. 5584, p. 32-41, 2004

    J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. Altan, R. Barat, and D. Zimdars, "Terahertz imaging using an interferometric array", Appl. Phys. Lett. 83, 2477 (2003).

    F. Oliveira, R. Barat, B. Schulkin, J. F. Federici, D. Gary, and D. A. Zimdars, 'Neural network analysis of terahertz spectra of explosives and bio-agents', Proc SPIE 5070, 60 (2003).

THz Technology - Filter screen, THz optical Materials (Olefin), Detection of Defects in High K dielectrics, THz waveguides, etc.

This area includes a wide variety of material. We have used THz spectroscopy for examining the THz transmission through filter screens (also known as photonic crystals and metamaterials). Olefin polymer is a very transparent optical material in the THz range. We have characterized the THz optical constants of this polymer. Using visible pump/ THz probe techniques, we have demonstrated that THz spectroscopy can be used to identify the relative quantity of defects in high K dielectric layers. The figure below shows the change in normalized THz electrical field transmission for three types of dielectric coated samples: HfO2, SiO2 and Control samples.

Left Figure. DE/E (THz normalized change in electric field transmission) for a set of dielectric coated wafers under a visible pump power of 450 mW/cm2 from a CW Ar+-Ion laser. Clear differences emerge between HfO2, SiO2 and Control samples.

 

 

A. Sengupta, A. Bandyopadhyay, B. F. Bowden, J.A. Harrington, and J.F. Federici, ‘Characterization of olefin copolymers using terahertz spectroscopy’, Electron. Lett. 42, pp 1477-1479 (2006).

H. Altan, A. Sengupta, D. Pham, H. Grebel and J.F. Federici, “Characteristics of HfO2 and SiO2 on p-type Silicon wafers using THz spectroscopy,” Semicond. Sci. Tech., 22, 457-463, 2007.  

F. Huang, J. F. Federici, and D. Gary, 'Determining thickness independently from optical constants by use of ultrafast light', Opt. Lett. 29, 2435 (2004).

   Solid State Physics (nanotubes and other)   

    The application of THz spectroscopy and Imaging to solid state systems such as carbon nanotubes, silicon nanoclusters, superconductors, and GaAs.

    H. Altan, F. Huang, J. F. Federici, A. Lan, H. Grebel, “Optical and Electronic Characteristics of Single Walled Carbon Nanotubes and Silicon Nanoclusters by THz Spectroscopy”, J. Appl. Phys. 96, 6685 (2004)

    H. Altan, F. Huang, J. F. Federici, A. Lan, and H. Grebel, 'Characteristics of Nano-scale Composite Materials using THz spectroscopy', Proc. SPIE 5268, p53-60, (2004).

    H. Altan, F. Huang, J. F. Federici, A. Lan, and H. Grebel, 'Characteristics of nanoscale composites by terahertz spectroscopy', Proc SPIE 5070, 53 (2003).

    J. Federici and H. Grebel, “Characterization of nanoscale composites at Thz and IR spectral regions”, Int. J. of High Speed Elec. and Sys., 13, 969-993 (2003)

    J. F. Federici and H. Grebel, "Characteristics of Nano-Scale Composites at THz and IR Spectral Regions", in Sensing Science and Technology at THz Frequencies, Volume II. Emerging Scientific Applications & Novel Device Concepts, ed. D. Woodard, M. Shur, W. Loerop.

    S. Vijayalakshmi, M. George, J. F. Federici, Z. Iqbal and H. Grebel, "Non-linear optical properties of silicon nanoclusters", Thin Solid Films 339, 102-108 (1999).

    J.F. Federici, B.I. Greene, D.R. Dykaar, F. Sharifi, and R.C. Dynes, `Direct picosecond measurement of photoinduced Cooper pair breaking in lead', Phys. Rev. B 46, 11153, (1992).

    P. Saeta, J.F. Federici, B.I. Greene, and D.R. Dykaar, `Intervalley scattering in GaAs and InP probed by far infrared absorption spectroscopy', Appl. Phys. Lett. 60, 1477, (1992).

    B. I. Greene, J. F. Federici, D. R. Dykaar, A. F. J. Levi and L. Pfeiffer, `Picosecond Pump and Probe Spectroscopy Utilizing Freely Propagating Terahertz Radiation', Opt. Lett. 16, 48 (1991).

    Near-field Microscopy, THz sources and Detectors

    These papers describe some of my earlier work in the area of Near-Field THz Imaging and the development of THz photoconductive antennas.

     J. F. Federici and O. Mitrofanov, "Near Field THz Microscopy", Physics in Medicine & Biology, 47 3727-3734 (2002).

    O. Mitrofanov, M. Lee, J. W. P. Hsu, I. Brener, R. Harel, J. Federici, J. D. Wynn, L. N. Pfeiffer, and K. W. West, 'Collection mode near-field imaging with 0.5 THz pulses', IEEE Journal of Selected Topics in Quantum Electronics 7, 600 (2001)..

    O. Mitrofanov, M. Lee, J. W. P. Hsu, L. N. Pfeiffer, K. W. West, J. D. Wynn, J. F. Federici, 'Terahertz Pulse Propagation through Small Apertures', Appl. Phys. Lett. 79, 907 (2001).

    O. Mitrofanov, R. Harel, M. Lee, L. N. Pfeiffer, K. West, J. D. Wynn, J. Federici, "Study of the Single-Cycle Pulse Propagation inside the Near-Field Probe', Appl. Phys. Lett. 78, 252 (2001).

    O. Mitrofanov, I Brener, R. Harel, J. D. Wynn, M. Lee, J. Federici, "Far-Infared Near Field Microscopy based on a Collection Mode detector", Appl. Phys. Lett. 77, 3496 (2000).

    O. Mitrofanov, I. Brener, M. C. Wanke, R. R. Ruel, J. D. Wynn, A. J. Bruce, J. Federici, "Near-Field microscope probe for far infrared time domain measurements," Applied Physics Letters 77, 591 (2000).

    Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, J. B. Stark, Q. Wu, X. C. Zhang, and J. F. Federici, "Coherent Terahertz Radiation Detection: Direct Comparison Between Free-Space Electro-optic Sampling and Antenna Detection", Appl. Phys. Lett. 73, 444 (1998).

     Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer and J. Federici, `Singular Electric Field Terahertz Emitters and Detectors’ in Trends in Optics and Photonics Series 13, 237 (1997).

    Y. Cai, I. Brener, J. Lopata, J. Wynn, L. Pfeiffer, and J. Federici, `Design and performance of singular electric field terahertz photoconducting antennas,' Appl. Phys. Lett. 71, 2076 (1997).

    B.I. Greene, J.F. Federici, D.R. Dykaar, R.R. Jones, and P.H. Bucksbaum, `Interferometric characterization of 160 fs far-infrared light pulses', Appl. Phys. Lett. 59, 893, (1991).

    D. R. Dykaar, B. I. Greene, J. F. Federici, A. F. J. Levi, L. Pfeiffer and R. Kopf, `Log-Periodic Antennas for Pulsed Terahertz Radiation', Appl. Phys. Lett. 59, 262 (1991).

Flexible Electronic Devices and Sensors / Electrospinning

This work has focused mostly on characterization and device applications of large area electronic circuits which are fabricated on flexible substrates such as plastic. In our original work, the devices were fabricated in a Class 10 clean room at NJIT using silicon-based processing. Since 2007, we have focused exclusively on the design, fabrication and testing of Flexible Electronic Devices and Sensors using ink-jet printing technology.

A list of our publications in this area can be found HERE.