Optoelectronic chromatic dispersion in germanium PN photodiodes: Wavelength monitoring and FBG interrogation

Optoelectronic chromatic dispersion (OED) has recently been shown to be a significant source of chromatic dispersion in photodiodes. We characterize the OED in a commercial germanium PN-type photodiode and determine the optimum conditions for maximum OED sensitivity and wavelength monitoring. A peak OED sensitivity of 1 deg/nm is measured in a spectral range of 1550-1558 nm with 4 MHz modulation. We also demonstrate an application of OED in fiber Bragg grating (FBG) interrogation. Quasi-static and vibration strains are monitored, with a spectral and strain sensitivity of 1.25 pm/^√Hz and 1.08 µε/^√Hz, respectively. Photodiode OED can form the basis of inexpensive chip-scale grating-less spectral analysis.