Partial response schemes like duobinary trade bandwidth for controlled interference between neighboring symbols, rather than eliminating it entirely. The student first works through the underlying theory and builds a simulation to verify it. Building on that, the student applies the concept to a realistic optical fiber link, where chromatic dispersion limits the usable bandwidth. Finally, the filter coefficients are optimized so that transmission reaches further than with the standard, fixed duobinary target.

Voraussetzungen

Photodetectors in optical communication systems measure only field intensity, the phase is lost. Phase retrieval methods aim to recover the full complex field from intensity-only measurements, avoiding the need for a local oscillator laser. This assignment covers two such approaches: the Kramers–Kronig (KK) receiver, which uses a single detector with a specially prepared transmit signal, and the Gerchberg–Saxton (GS) algorithm with a dispersive element, which requires two intensity measurements.

The student's task is to understand the working principles of both methods and summarize them in a report.

Possible literature

• Recent Advances in Coherent Optical Communications for Short-Reach: Phase Retrieval Methods, Karar et al. Photonics 2023
• Gerchberg–Saxton Algorithm Based Phase Correction in Optical Wireless Communication, Li et al. Phyiscal Comm 2017

Voraussetzungen

Optical Signal-to-Noise Ratio (OSNR) is a key metric for assessing the performance of optical communication systems. Although different measurement instruments may employ distinct methods, they are expected to yield consistent OSNR values under comparable conditions. This work focuses on evaluating OSNR measurements obtained from two industry-leading devices, with the objective of identifying their limitations, quantifying discrepancies, and defining the conditions under which their results can be considered equivalent.