Large and tunable optoelectronic chromatic dispersion in PIN-type photodiodes

It is known that PN-type photodiodes possess high optoelectronic chromatic dispersion (OED). Here we present a theoretical and experimental study of OED in PIN-type photodiodes. Applying the modulation phase-shift technique, a Ge PIN photodiode exhibits ∼0.5 deg/nm phase-shift sensitivity at 10 MHz modulation, corresponding to a dispersion of 1.4 ×10⁹ps/(n m ×k m), many orders of magnitude larger than high-dispersion optical materials such as chalcogenide glass. A striking feature of the PIN device is the ability to tune the amount and sign of the OED through the bias voltage. Electronic tuning between -0.8 deg/nm and +0.5 deg/nm is shown. The PIN photodiode is an on-chip device possessing significant tunable dispersion for applications in optical sensing and spectroscopy.