Design and performance analysis of nitride quantum well-based electroabsorption modulators for visible light communication

Abstract

Visible light communication (VLC) technology utilizes visible light for high-speed wire- less communication facilitating a secure and energy-efficient data transmission. This study focuses on the design and performance analysis of nitride Multiple Quantum Well (MQW)- based Electro-Absorption Modulators (EAMs) for visible light communication (VLC) sys- tems. Nitride semiconductors offer unique advantages, such as wide bandgap and high carrier mobility, making them suitable for VLC applications. The proposed EAM design in- corporates MQWs to harness the quantum-confined Stark effect (QCSE) for efficient mod- ulation of visible light signals. Based on the envelope function approximation, incident light energy, and E-field dependent absorption characteristics are evaluated using the self- consistent numerical method. A substantial modulation bandwidth of approximately 75 THz is achieved. The study findings suggest that the highest level of performance can be achieved by adjusting the electric field from 250 V/µm to 340 V/µm, which corresponds to the the ’ON’ and ’OFF’ states at a wavelength of 450 nm. The verification of the existence of confined mode is conducted, and an examination of the characteristics of the fundamental mode is performed using Finite Element Method (FEM)-based modal analysis. The study revealed that confined power percentage varies from 3.13 % for a single QW to 62.4 % for a QW count of 30. Implementing the modulator as a multi-state frequency-dependent s- parameter component, the modulation characteristics are observed. Quantitative analysis of the modulated signal distortion was performed based on the commonly employed Figure of a Merit (FoM), Extinction Ratio (ER) and Quality Factor (Q-factor). The normalized Power amplitude of ON and OFF states was observed as ≈ 89 % and 5 % exhibiting ER of 20 and Q − factor of 484. The proposed EAM design presents a potential solution for achieving efficient modulation of visible light signals. For a specific free space lossy channel, the maximum error-free transmissible distances are 2.31 m, 4.123 m, and 4.8882 m for input powers of 1 W, 5 W, and 10 W for transmission. With the input power level of 1W, the error-free transmission distance obtained are 1.945 m and 2.345 m, respectively for 10 Gbps and 5 Gbps data speed. We conducted an investigation to confirm the inherent trade-off between the demand for input Power and the achievement of high-speed communication. Our findings indicate that a 30 Gbps increase in speed can be achieved at the expense of a 1000 mW power enhancement. These findings will pave the way for the realization of high-performance nitride quantum well-based EAMs, enabling the deployment of efficient and reliable VLC systems for various applications.