Polarization Difference Probing
Polarization Difference Probing (PDP) utilizes the interaction of infra-red light with active regions of a device under stimulation. A static phase shift is introduced between two orthogonally polarized laser beams, which are directed at the region-of-interest. A fluctuating signal on the node-of-interest introduces a modulated phase-shift in the light returned, which may be displayed as a timing waveform. Waveforms are easily obtained and are reproducible. | 
