Fig. 1. (a) Hybrid integrated CWDM TOSA module configuration. (b) Schematic structure of DML array subassembly. Insertion shows the alignment mark. (c) Optical coupling configuration.

Fig. 2. Model of RF circuit board with high frequency GCPW transmission line.

Fig. 3. Measured transmission response of the RF circuit board. Inset exhibits the electrical crosstalk between adjacent lanes.

Fig. 4. Measured transmission response and reflection response of the package body.

Fig. 5. Measured transmission response of the packaged TOSA module. Inset is the photograph of the module with a size of 11.5  mm×5.4  mm×5.4  mm, and the detailed inner distribution is also shown.

Fig. 6. Measured P-I characteristics of the TOSA module. Inset is the lasing optical spectrum (colored areas indicate CWDM grid).

Fig. 7. Experimental setup for the 112 Gb/s 10 km transmission system with direct detection. BPG, bit pattern generator; EA, electrical amplifier; OI, optical isolator; VOA, variable optical attenuator; PD, photodetector; TIA, transimpedance amplifer; DSO, digital sampling oscilloscope.

Fig. 8. Measured BER characteristics versus the ROP under 28  Gb/s operation for BTB 10 km with OI, 10 km without OI cases. Insets exhibit the eye diagram characteristics for various cases.

Fig. 9. Measured BER as a function of ROP for various cases under 25  Gb/s PAM-4 and OOK operations. Insets show the eye diagram characteristics.