Research

Terahertz

The Terahertz (THz) region exists between the electrical (< 300 GHz) and photonic (> 10 THz) regions of the electromagnetic spectrum. This region is commonly called the THz Gap because few room-temperature sources exist.

Terahertz Engineering

My research focuses on THz engineering. The idea is to extend known millimeter wave and photonic engineering methods into the THz gap. Key difficulties arise from the limited selection of transmitters, receivers, and transmission mediums.

Transmitters and Receivers

In my lab we generally use photoconductive switches as transmitters and receivers. This technology has been selected for its low-cost, and ability to function into the 5-10 THz region.

Transmission mediums

Transmission mediums are used to transfer energy between two locations. Common examples in the electrical region are cables and circuit board traces. In the photonic region optical fibers are used. In the THz region significant loss and dispersion limits the viability of cables and optical fiber over large distances; however, for relatively short distances (< 30 mm) conductive transmission lines can be utilized in numerous applications.

Applications

THz Spectroscopy

THz spectroscopy is used for chemical sensing. Molecules have unique absorption characteristics which act as finger prints which are then used for classification. The following Figure illustrates the absorption spectra for H2O, CO, NH3, and H2S.

Photonic Spectroscopy

Greenhouse gases (GHGs) are a major contributor to climate change and there is a need for effective and low-cost emission quantification methods. Our lab develops technologies that can achieve these goals using a novel combination of lasers and sensitive detectors.

Equipment

  • Large assortment of optics, fiber, and optomechanics
  • Femtosecond laser (Calmar Carmel 780/1550)
  • Agilent External Cavity Tunable Lasers (C and L band)
  • Dozens of laser current and temperatures controllers
  • Voltage/signal sources
  • Oscilloscopes
  • Spectrum analyzers
  • Optical spectrum analyzers
  • High speed balanced photo detectors (43 GHz)
  • Lock-in amplifiers
  • Many more…

Lots of shared equipment (with Prof. Gordon and Prof. Bornemann):

  • Optical tables
  • Anechoic chamber
  • RF/optical probe station
  • Streak camera
  • 65 GHz vector network analyzer
  • Optical tweezers
  • Many more…

 

List of Publications