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Microwave Photonics Research at KRISS

Kolloquium der Abteilung 2

The Center for Electromagnetic Wave at KRISS (Korea Research Institute of Standards and

Science)  has  conducted  research  in  microwave  photonics  for  the  last  eight  years.  The

capability  to  measure  microwave  can  be  significantly  enhanced  when  it  is  assisted  with

photonic  technology.  We,  KRISS,  have  employed  optical  crystals  -  associated  with  laser

systems - to overcome several challenges in relation to electromagnetic measurements. The

crystals  were  utilized  to  build  EO/MO  (electrooptic/magnetooptic)  probes  to  measure

challenging  electric/magnetic  fields. The  following  topics  will be  presented:

 

1.  Minimally  invasive  field  probe:  The  transparent  nature  of  EO/MO  probes  for  both

electromagnetic  and  optical  bands  allows  the  realization  of  minimally  invasive  microwave

field  measurements.  Field  distribution  images  radiated  within  a  wavelength  region  from

electrical devices are presented.

 

2.  High-intensity  field  measurements:  The  all-dielectric  embodiment  of  optical  probes

enables us to sense very intense electric fields up to the MV/m scale. Our EO probes show a

dynamic  range  which  exceeds  100  dB  with  good  linearity.  The  capability  of  intense  field

measurements using a high-power gyrotron, a plasma source, an MRI system, and a 50 kV

AC voltage supply is presented.  

 

3.  Millimeter-wave  measurements:  A  photonic-based  sensing  scheme  is  also  a  clear

advantage given that it enhances the sensing bandwidth by extending it to the mm-wave band.

We devised sub-mm scale EO probes for mm-wave sensing to minimize invasiveness. The

stability of the EO probe system was also improved by compensating any system drift with

multiple probes. Stabilized sensing results for various W-band devices are presented.

 

4. Fast pulse scoping system: Rapid electrical pulses can be measured using an ultrafast laser.

We have built a pump-probe time-domain sensing scheme to sample 100 GHz pulses from a

laser-driven  photodiode.  The  detailed  sensing  technique  is  presented  and  the  results  are

discussed.

 

5. Highly sensitive field probes: The sensitivity of the EO probes can be greatly improved

when the electrodes are assisted. We have fabricated a folded Mach-Zehnder type of optical

waveguide on an EO wafer. With free-space electrodes which serve as a dipole antenna along

the  waveguide,  the  EO  wafer  works  as  an  effective  field  probe  at  the  bandwidth  of  the

electrodes. The enhanced performance of such integrated optic probes is presented.