T-RAYS TECHNOLOGY IN FUTURE SCANNERS

By:-        Amit Ranjan

INTRODUCTIONTerahertz radiation refers to electromagnetic waves propagating at frequencies in the terahertz range.

 Terahertz waves lie at the far end of the infrared band, just before the start of the microwave band.

 The T-ray band lies between 0.1 and 10 terahertz (THz).

T-rays, bridge the gap between electronics and photonics, have  novel properties and interact uniquely with many materials.

BACKGROUND Terahertz radiation is emitted as part of the black body radiation from

anythingwith temperatures greater than about 10 kelvin.

mid-2007:- scientists at the U.S.  Argonne National Laboratory announced the creationof a compact device that can lead to portable battery-operated sources of  terahertz radiation which uses high-temperature superconducting crystals.

In 2008, engineers at Harvard University demonstrated that THz radiation wasgenerated by nonlinear mixing of two modes in a mid-infrared quantum cascade laser.

In 2009, T-waves are produced when unpeeling adhesive tape. The mechanism of  terahertz radiation is tribocharging of the adhesive tape and subsequent discharge.

In 2011, Japanese electronic parts maker Rohm and a research team at Osaka University produced a chip capable of transmitting 1.5 Gbps using terahertz radiation.

In 2012 scientists from IMPERIAL COLLEGE LONDON and A*STAR in SINGAPOREhave shown off a  tera hertz antenna that is just 100 nanometers across- about 30000times smaller then Rohm’s antenna.

High-temperature superconducting crystal

Schematic of the terahertz-source,which was fabricated on the topof an atomically layered super conducting crystal (Credit:     Argonne National Laboratory)

It's enough to apply a voltage of 2 millivolts per junction to the crystals to induce electromagneticfields of frequencies in the terahertz range.

T-RAYS SCANNERS

Present T-rays scanners used at airports

Drawbacks of old scanners:

BULKYEXPENSIVENOT PORTABLECOMPUTING IS COMPLEXNot familier with room

tempratureLARGE IN SIZE

High-performance terahertz sources based on plasmonic photoconductors

EMISSION of TERAHERTZ RAYS through NANO-ANTENNA

The tip-to-tip nanogap electrode structure provides strong terahertz field enhancement and acts as a nano-antenna to radiate the terahertz wave generated in the active region of the photomixer.

Structure of Nano-Antenna

highly efficient continuous-wave terahertz emission using nanogap electrodes in a photoconductive antenna-based photomixer.

Advantages of nano-antennaOperates at room tempraturesense molecules such as those

present in cancerous tumours and living DNA,  

PortableSmaller in sizelower RC time constantAllow efficient radiation at higher

part of the terahertz spectrum

Refrences: 1.Nature Photonics 6, 121–126 (2012),

http://www.nature.com/nphoton/journal/v6/n2/full/nphoton.2011.322.html

2. Imperial college ,london NEWS and EVENTS, jan 2012 http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_20-1-2012-15-50-15

3.http://www.extremetech.com/computing/114975-nano-scale-terahertz-antenna-created-hand-held-tricorders-incoming

4. Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), Singapore 117602H. Tanoto,J. H. Teng,Q. Y. Wu, B. Wang , C. C. Chum

5. terahertz radiation wilkkipidiahttp://en.wikipedia.org/wiki/Terahertz_radiation

6. Article in Nature 14 November 2002 (local copy from the Jefferson Lab)

7 photomixing wikipedia.http://en.wikipedia.org/wiki/Photomixing

Thank You