This work proposed two promising architectures over multi input multi output free-space optics (MIMO-FSO) channel, namely hybrid and non-hybrid optical modulators, aiming to improve the capacity of fronthaul connectivity for cloud radio access network networks in case of severe weather conditions utilizing end-to-end Gamma–Gamma turbulence channel. A proposed hybrid transmitter design combined a vertical-cavity surface-emitting laser (VCSEL) pumping an external Mach–Zehnder modulator (MZM) whereas the non-hybrid system utilized only MZM. To compensate atmospheric losses, both designs employ a wideband travelling-wave semiconductor optical amplifier (WTWSOA) to improve the received signal intensity. The hybrid scheme utilized to leverages the VCSEL’s low-threshold efficiency and MZM’s chirp control. Based on the simulation results obtained by Optisystem 21 simulator, the hybrid optical modulator demonstrated significant performance improvement compared with the counterpart non-hybrid modulator. Thus in severe rain condition with 19.275 dB km−1 attenuation, the hybrid MIMO-FSO technique works quite well, with Q-factor values of 29.8 at the link length of 1.9 km, while the non-hybrid architecture (MIMO-MZM FSO), achieves Q-factor of 10 at the same range. The simulation results report that the hybrid VCSEL–MZM modulator has a 2.1–2.8 average Q-factor gain over a single MZM transmitter about 35% drop in bit error rate at 50 dB km−1 attenuation. Under mild turbulence, MIMO diversity increases the possible link distance by 1.5–2 km. Considering strong turbulence the hybrid modulator achieves a peak Q-factor of approximately 27 at strong attenuation (around 40 dB km−1), maintaining Q-factor >6 even when attenuation increases to 55 dB km−1. Meanwhile at weak turbulence condition the reported Q-factor is 43 at attenuation of 40 dB km−1 and remains acceptable Q-factor ⩾ 6 up 60 dB km−1. These results show that the suggested hybrid modulator along with WTWSOA are crucial techniques in improving the transmitted signal over FSO fronthaul especially in cities where there is a lot of fog and turbulence.