Emitter carrier injection and base hole recombination with base carrier transport (emitter to collector, EC) are fundamental to the operation of the transistor invented by Bardeen and Brattain in 1947. Carrier recombination has become the subject of intensive study and has established, over time, a basis for III-V compound semiconductor visible light emitting diodes by Holonyak in 1960, IR and visible diode lasers by Hall and Holonyak at in 1962, quantum-well diode lasers by Holonyak in 1977 and hetrojuction bipolar transistors (HBTs) by Kroemer in 1957. For high speed transistor operation (fT 500 GHz) by Feng in 2003, the HBT inevitably becomes a high-current-density nano-structure transistor. Hence, the HBT with quantum-wells inserted in the base and cavity modifications has made possible a three-port device called the transistor laser (TL) and patented by Feng and Holonyak in 2003. Subsequently, we have demonstrated the first low temperature CW transistor laser operation in 2004 and the first room temperature CW laser operation in 2005.