A highly integrated 10 Gb/s transmitter optical sub-assembly was fabricated and characterized for XFP transceiver. As a
light source, uncooled 1.3 μm high-speed distributed feedback laser diode (DFB-LD) was fabricated and assembled on
AlN sub-mount with a monitoring PD, a matching-resistor, and a bias-Tee with spiral-inductor. A glass sealed metallic
low-loss TO-stem with in-line leads was newly presented. We developed a small-signal equivalent circuit model based
on measured S-parameters in order to verify RF characteristics of LD and passive components. The eye-diagram of 10
Gb/s NRZ patterns with a PRBS 2<sup>31</sup> -1 was opened clearly without mask violation. At 85°C, -3-dB bandwidth was
measured as high as 11 GHz and 75-km transmission was successfully achieved with very low penalty.