Fig. 1. The basic principle of the optical module

Fig. 2. Direct modulation optical module link

Fig. 3. The basic principle of the electrical-optical conversion circuit used in this paper

Fig. 4. Schematic diagram of the equivalent internal circuit of VCSEL

Fig. 5. Transient response curve of laser model

Fig. 6. The schematic diagram of the PRBS31 differential voltage signal directly driving the VCSEL

Fig. 7. The eye diagram of the output optical signal at dif-ferent transmission rates

Fig. 8. Test schematic diagram of scheme 1

Fig. 9. Test schematic diagram of scheme 2

Fig. 10. The typical signal eye diagram of the TOSA terminal output in scheme 1

Fig. 11. The BER under different differential voltage and bias current driving in scheme 1

Fig. 12. The eye diagram at the differential voltage of 500 mV and the bias current of 15 mA for scheme 1

Fig. 13. The typical signal eye diagram of the TOSA terminal output in scheme 2

Fig. 14. The BER under different differential voltage and bias current driving in scheme 2

Fig. 15. Variation of S parameters with frequency at two transmission distances