Mitigating end-to-end nonlinearity in LED-based VLC transceivers via an optical intensity feedback

Area of Science:

• Electrical Engineering
• Optical Communications
• Nonlinear Systems

Background:

• Intensity Modulation and Direct Detection (IM/DD) transceivers suffer from holistic nonlinearity.
• Existing pre-distortion methods address nonlinearity primarily at the transmitter, with limitations.
• Minimizing nonlinearity is crucial for enhancing the performance and reliability of optical communication systems.

Purpose of the Study:

• To propose a novel intensity-modulation transmitter with an optical intensity feedback (OIF) loop.
• To mitigate holistic nonlinearity in IM/DD transceivers from the transmitter side.
• To develop an analytical model and implementation scheme for the OIF loop.

Main Methods:

• Implementation of a negative feedback loop connecting the optical intensity of light-emitting diodes (LEDs) to a sensor.
• Utilizing the feedback loop for nonlinearity perception and suppression across all physical devices.
• Analytical modeling and experimental validation of the proposed OIF loop.

Main Results:

• Significant improvement in total harmonic distortion (THD) and power gain flatness.
• Bipolar Junction Transistor (BJT)-based OIF transceiver achieved an average THD of -49.4 dB (0.37%).
• Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET)-based transceiver achieved an average THD of -52.42 dB (0.25%).

Conclusions:

• The OIF loop effectively suppresses nonlinearity in IM/DD transceivers.
• The proposed method offers lower complexity and better applicability due to its reliance on negative feedback.
• The OIF transmitter demonstrates superior linearity and stability compared to control groups.