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T-RAYSTECHNOLOGY INFUTURE SCANNERS By:- Amit Ranjan
INTRODUCTIONTerahertz radiation refers to electromagneticwaves propagating at frequencies in theterahertz range.Terahertz waves lie at the far end of theinfrared band, just before the start of themicrowave band.The T-ray band lies between 0.1 and 10terahertz (THz).
T-rays, bridge the gap between electronics and photonics, havenovel properties and interact uniquely with many materials.
BACKGROUND Terahertz radiation is emitted as part of the black body radiation from anything with temperatures greater than about 10 kelvin. mid-2007:- scientists at the U.S. Argonne National Laboratory announced the creation of 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 was generated 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 SINGAPORE have shown off a tera hertz antenna that is just 100 nanometers across- about
High-temperaturesuperconducting crystal Schematic of the terahertz- source, which was fabricated on the top of an atomically layered super conducting crystal (Credit: Argonne National Laboratory) Its enough to apply a voltage of 2 millivolts per junction to the crystals to induce electromagnet fields of frequencies in the terahertz range.
T-RAYS SCANNERSPresent T-rays scanners used at airports
Drawbacks of old scanners: BULKY EXPENSIVE NOT PORTABLE COMPUTING IS COMPLEX Not familier with room temprature LARGE IN SIZE
High-performance terahertzsources based on plasmonicphotoconductors
EMISSION of TERAHERTZ RAYSthrough NANO-ANTENNAThe tip-to-tip nanogap electrode structure provides strong terahertz fieldenhancement and acts as a nano-antenna to radiate the terahertz wavegeneratedin the active region of the photomixer.
Structure of Nano-Antenna highly efficient continuous-wave terahertz emission using nanogapelectrodes in a photoconductive antenna-based photomixer.
Advantages of nano-antenna Operates at room temprature sense molecules such as those present in cancerous tumours and living DNA, Portable Smaller in size lower RC time constant Allow 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.201 1.322.html 2. Imperial college ,london NEWS and EVENTS, jan 2012 http://www3.imperial.ac.uk/newsandeventspggrp/imperialcolle ge/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 117602 H. 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