Name: BRUNO PEREIRA DE SOUZA ROCHA
Publication date: 14/08/2026
Examining board:
Name |
Role |
|---|---|
| CARLOS EDUARDO SCHMIDT CASTELLANI | Examinador Interno |
| MARCELO EDUARDO VIEIRA SEGATTO | Presidente |
| PABLO RAFAEL NEVES MARCIANO | Coorientador |
| ULYSSES ROBERTO CHAVES VITOR | Examinador Externo |
Summary: Chromatic dispersion is a primary linear impairment that limits the reach and the
data rate of optical fiber communication systems. This dissertation studies a passive
photonic Finite Impulse Response (FIR) filter, a programmable optical delay-line
structure, for the optical-domain compensation of chromatic dispersion in intensitymodulation/direct-detection links. A frequency-domain simulation framework is developed to evaluate the link scenarios. The tap-delay spacing rule = Ts/2
and the associated tap-count requirement N 1 4|D|L(2/c)R2s are derived.
Coefficient-determination methods are implemented and studied on a common
pipeline: an analytical weighted-least-squares design, intensity-domain L-BFGS-B
optimization, two data-aided adaptive algorithms (NLMS and RLS), and a genetic
algorithm (GA). At the 50 km, 25 Gbaud, 16-tap reference point, all methods
reached Q between 6.35 and 6.54: the closed-form least-squares design, which needs
only a model of the channel, achieved Q = 6.54, matching the field-domain RLS
and NLMS methods (Q = 6.49 and 6.45), which assume access to samples of
the received complex optical field, while L-BFGS-B reached Q = 6.36 and gave
the longest reach at the forward-error-correction threshold. At this point the GA
did not improve on its least-squares starting point, and it required about thirty
times the design time of L-BFGS-B. The effect of the photonic-circuit insertion
loss is analyzed, separating a negligible penalty on the equalization shape from
an insertion-loss power penalty that scales with the tap count. At 25 Gbaud, a
16-tap filter restores a closed dispersed eye to near back-to-back quality over 50 km,
raising Q above the hard-decision forward-error-correction threshold. Finally, three
silicon-on-insulator chip designs implementing the equalizer and submitted for
fabrication are presented.
