光电子技术新进展Lecture6.ppt
光电子技术新进展Lecture6 Four short words sum up what has lifted most successful Four short words sum up what has lifted most successful individuals above the crowd: a little bit more. individuals above the crowd: a little bit more. -author -author -date-date1. What is THz radiation An example of THz system3. ApplicationTHz RADIATION WAVE1THz=1012Hz, radiation in the terahertz range, looselydefined as o.1-10THz, spans the relatively undevelopedgap between electronics, on the low end of the spectrum,and optics on the high frequency end .ELECTROMAGNETIC WAVETHz time-domain spectroscopy system based on the optical rectification pumped by femtosecond lasers0.20.40.60.81.01.21.41.61.82.02.2024681.101631.378211.42041.490721.532911.607921.673541.720421.762611.800121.88451.9221.992322.025132.067322.104822.14701bacillus subtilis, 0-50ps 32768 point03/27/2003 data BAbsorbanceFrequency (Thz)01020304050-0.00025-0.00020-0.00015-0.00010-0.000050.000000.000050.000100.000150.0002003/27/2003 data D ETera signal (V)Time delay (ps)THz signal of bacillus subtilis in time domain (left) and Fourier transform (right)Time-domain SpectrumTime-Resolved THz SpectroscopyOptical Phonon Dynamics of GaAsImagingCharacter of THz Frequency: 0.110 THz Coherent radiation with very low power Gated detection: insensitive to thermal background; very high sensitivity with dynamic range up to 106 in E-field E-field measurement: amplitude and phase non-destructive to living tissue
