Fig. 1. Micro-LED-based UWOC-NOMA system with 2 users.

Fig. 2. Experimental block diagram for UWOC based on the GaN-based MLA-NOMA. (a) The optical transmitter, (b) the laboratory 3-m water tank, (c) the optical receiver, and (d) the experimental system structure.

Fig. 3. Light emission source utilizing GaN-based micro-LED array. (a) The physical representation and (b) the design structure diagram.

Fig. 4. Comparison of the P-I characteristics between the GaN-based micro-LED and the conventional blue LED.

Fig. 5. Histogram and PDF of the optical power distribution obtained from turbulence simulation testing in the laboratory water tank.

Fig. 6. Variation of the BER for NOMA users with transmission rate under different turbulence intensities. (a) σ₁² = 0.013 and (b) σ₂² = 0.135.

Fig. 7. Variation of the average BER for NOMA users with transmission rate under different turbulence intensities: (a) σ₁² = 0.013 and (b) σ₂² = 0.135.

Fig. 8. Comparison of the average BER for GaN-based MLA-NOMA, DCO-NOMA, and OPD-NOMA at different transmission rates: (a) σ₂² = 0.013 and (b) σ₂² = 0.135.