CHARACTERIZATION AND THEORETICAL-ANALYSIS OF 2ND-ORDER INTERMODULATION DISTORTION OF INGAAS INP P-I-N PHOTODIODE MODULES FOR FIBEROPTIC CATV/

InGaAs/InP p-i-n photodiode (PD) modules for fiber-optic analog CATV h ave been developed. The optical configuration was optimized by making use of a spherical lens aberration. Responsivity and second-order inte rmodulation distortion (IMD2) were 0.95 A/W and -85 dBc at V-r = 12 V, P-in = 0 dBm, and m = 40%, respectively. The improvement of IMD2 by d efocusing was explained by the decrease of incident optical power dens ity calculated by ray tracing. IMD2 was quantitatively explained throu gh the reverse voltage dependence of responsivity which originates fro m the variation of the p(+)-InGaAs depletion layer thickness.