Tunneling Modulation of Transistor Lasers: Theory and Experiment

The coherent photons generated at the base quantum wells in the transistor laser (TL) interact with the collector field and “assist” electron tunneling from the valence band of the base to the conduction band states of the collector. The cavity coherent photon intensity effect on photon-assisted tunneling in the TL has resulted in the realization of a novel photon-field enhanced optical absorption. This intra-cavity photon-assisted tunneling (ICPAT) in the TL or the light-emitting transistor is the unique property of voltage (field) modulation and the basis for ultrahigh speed direct tunneling photon modulation and switching. In addition, a new tunneling current modulation gain in a “new form” of transistor is discovered based on the collector tunneling holes feedback to the base and dielectric relaxation base transport. The TL, owing to its unique three-terminal configuration and the complementary nature of its optical and electrical collector output signals, enables fast base recombination, collector tunneling, and OEO feedback, which has resulted in the realization of compact electro-optical applications, such as non-linear signal-mixing, frequency multiplication, OE tunneling transistor, and electrical and optical bistability.