Nonlinear System Identification Scheme for Efficient Compensators Design

Opto-electronic transmitters such as vertical-cavity surface-emitting lasers (VCSELs) may include nonlinear dis-tortions combined with memory effect. Using a system model identification scheme based on Volterra series, enables distortions root cause identification and design of efficient compensators to mitigate these effects. Extraction of the memory depth of the linear and nonlinear effects enables low cost and efficient digital pre-distortion (DPD) design, based on the combination of a “long” linear finite impulse response (FIR) filter and a “short” look-up-table (LUT) that mitigates the nonlinear distortion part. VCSEL-based lab experiments are performed, which demonstrate an efficient DPD of X-taps FIR followed by a LUT which pre-distorts only the most significant nonlinear terms associated with memory depth of 3.