All-optical probing of a semiconductor photodiode

We investigate the possibility of probing the electrical status of a p-i-n junction via an optical fiber, without the need for electrical contacts. A photonic crystal with a resonance in the near-infrared is etched in a thin membrane of III-V semiconductor with an embedded p-i-n junction and placed on the cleaved facet of a fiber. We measure the effect of photoexcited carriers on the built-in voltage of the diode through the Pockels effect. This may enable the all-optical read-out of electrical signals from sensors in a distant or inaccessible environment.