Bidirectional UWB over fiber for WDM-PON system.

Area of Science:

• Optical Communications
• Fiber Optics
• Signal Processing

Background:

• Existing ultra-wideband over-fiber (UWBoF) systems face challenges in bidirectional transmission and wavelength compatibility.
• Wavelength-division multiplexing (WDM) is a standard architecture for increasing fiber capacity.
• Rayleigh scattering can induce noise in bidirectional fiber optic systems.

Purpose of the Study:

• To present a novel bidirectional UWBoF system compatible with WDM architecture.
• To enable simultaneous upstream and downstream data transmission over a single fiber.
• To investigate wavelength reuse for efficient spectral utilization.

Main Methods:

• Generation of a 6th order Gaussian derivative for downstream (DS) UWB transmission using a directly modulated laser, chromatic dispersion, and a delay-line-interferometer (DLI).
• Wavelength reuse for upstream (US) baseband (BB) transmission via injection locking a colorless Fabry-Perot laser diode (FP-LD) using the other DLI output.
• Implementation of a dual-fiber transmission architecture to mitigate Rayleigh scattering noise.

Main Results:

• Successful symmetric transmission of 1.25 Gbps UWB signals over 60 km of single-mode fiber (SMF).
• Demonstration of wavelength reuse for efficient upstream signal generation.
• Bit-error-rate (BER) measurements and eye diagrams presented for both downstream and upstream transmissions, indicating system viability.

Conclusions:

• The proposed scheme effectively achieves bidirectional UWBoF transmission compatible with WDM.
• The system demonstrates efficient wavelength reuse and noise mitigation.
• The results validate the feasibility of the presented approach for high-speed optical communication.