Evaluating system penalties in radio frequency photonic links due to photodiode nonlinearity

Meredith N Hutchinson,Nicholas J Frigo,Caitlin R S Williams

doi:10.1117/1.oe.56.10.100501

Abstract

We extend an earlier second-order characterization of photodiode nonlinearities to third order and present the data as a contour plot over the feasible photodiode operation points. Using this data, we calculate the additional penalty in a nonlinear (i.e., using a Mach–Zehnder modulator) optical link due to the photodiode nonlinearity and illustrate its utility in systems calculations.

Highlights

Radio frequency (RF)/microwave photonic links are superior to copper-based links, due to their low-loss and high-bandwidth characteristics.[1]
This survey technique concentrates on the nonlinear impairments created by the photodiode as a function of intermodulation distortion (IMD) output frequency, regardless of the input frequencies that contribute to that impairment
The third-order intercept[1] OIP3, the usual metric for discussing nonlinearities, is that output power for which the extrapolated IMD3 and fundamental powers are equal. This occurs at a normalized amplitude of φ 1⁄4 2 in our three-tone tests. [We performed three-tone tests to eliminate spurious effects of Mach–Zehnder modulators (MZMs) transmitter nonlinearity, a precaution that is generally unnecessary in RF and microwave tests.[9]

Summary

Introduction

Radio frequency (RF)/microwave photonic links are superior to copper-based links, due to their low-loss and high-bandwidth characteristics.[1]. Near each IMD output frequency there are either two or three combinations, as shown by the symbols This operation point (4 V, 9 mA) has an additional eight combinations of (f1; f2). The smaller inset (replicated from Ref. 5) shows that the second-order penalties (γ2) have distinctly different optimal operation points The implication of this is that it is not possible to simultaneously optimize the second- and third-order distortion performance for the photodiode: some sort of trade-off must be made at the system engineering level

Discussion

Conclusion