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SUMMARY:Development of Terahertz Time Resolved Spectroscopy
DTSTART:20170824T103000
DTEND:20170824T113000
DTSTAMP:20260511T085402Z
UID:990c3442f720620e3cebb38a6cc2c947cfc7765583f95736debcecd8
CATEGORIES:Conferences - Seminars
DESCRIPTION:Saood Nazir - Department of Physics\, Indian Institute of Tech
 nology\, Kharagpur\, West Bengal\, India\nTerahertz frequencies are betwee
 n optical and electronic frequencies. There are certain unique specificati
 ons of Terahertz waves that make the scientific community to continue work
 ing in this field and there has been an extensive advancement in the past 
 two decades. Terahertz waves have vast applications in fields of medical i
 maging\, security screening\, pharmaceutical industry\, industrial quality
  control\, just to name a few. Scientists are continuously working towards
  improving the available mechanisms to generate Terahertz.\nMy work focuss
 es on generating Terahertz radiation through the process of optical rectif
 ication in a non-linear crystal such as Zinc Telluride (ZnTe). A femtoseco
 nd laser is incident on the crystal creating a time varying polarisation w
 hich leads to the emission of radiation in the Terahertz regime. This radi
 ation is then detected using a process called electro-optic sampling in a 
 second ZnTe crystal. Inside the crystal\, we try to achieve a spatial and 
 temporal overlap between the generated Terahertz and a femtosecond pulse k
 nown as the probe pulse and observe the change in polarisation of the prob
 e as it senses the field of the Terahertz pulse inside the crystal. The ma
 in idea behind this detection mechanism is that\, in absence of the Terahe
 rtz pulse\, the probe passes through the crystal unaffected and then passe
 s through a quarter wave plate becoming circularly polarised and the ortho
 gonal components of this circularly polarised pulse are separated by a Wol
 laston prism. The two components impinge on two photodiodes which detect e
 qual intensity. However\, in presence of a Terahertz pulse\, the output af
 ter the quarter wave plate is elliptically polarised and thus the two orth
 ogonal components are unequal giving different intensities on the photodio
 des.
LOCATION:PPB019
STATUS:CONFIRMED
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