Voltage and Current Modulation at 20 Gb/s of a Transistor Laser at Room Temperature

Abstract

Data are presented showing open-eye 20-Gb/s transmission for a quantum-well transistor laser operating at room temperature (25°C). The fast spontaneous recombination lifetime (∼30 ps) in the base region results in a resonance-free frequency response allowing demonstration of 20-Gb/s transmission with an I/I TH = 3. It is shown that higher temperature hastens the transition to the first excited state and improves bandwidth and eye-opening at low bias levels (I/I TH = 2). In addition, room temperature 20-Gb/s transmission through voltage modulation of a transistor laser via intracavity photon-assisted tunneling in the base-collector junction is reported.

Effect of Collector Voltage on the Large and Small Signal Modulation Characteristics of 980 nm Transistor Laser

“…With the introduction of optical cavities , the light emitting transistor (LETs) eventually turned into transistor laser (TL) 2 . Feng group 3,4 invented the TL having a quantum well (QW) in the base region of a HBT. Under forward bias, the electrons in the emitter are diffused, and the carriers are injected sufficiently into the base to create population inversion.…”

Microwave photonic links based on transistor lasers: Voltage modulation versus current modulation

“…In particular, in the common emitter configuration one can modulate either the base current or the collector-emitter voltage. Both schemes have been investigated for digital applications [11]. Voltage modulation is potentially of interest given the higher impedance of the collector-emitter port in tunnel-junction devices [11].…”

Effect of the energy barrier in the base of the transistor laser on the recombination lifetime

“…9 More recently, the edge emitting transistor laser has shown, through process optimization and stabilization, room temperature (up to 25 C) open-eye data transmission at 20 Gb/s utilizing both conventional current modulation (I B ) as well as voltage modulation (V CE ) through photon assisted tunneling. 10 The TL has proved to be a promising three-port optoelectronic device both with regards to high-speed operation as well as the ability for monolithic electronic-photonic integration.…”

“…The epitaxial structure is as described earlier, 10 and additionally there is present a 100 Å heavily doped p-type Al x Ga 1Àx As layer (acting as the energy barrier) in the GaAs base region at the collector interface. For the crystals used in this work, the values of the aluminum mole fraction x are 0.05 (sample A) and 0.10 (sample B) which correspond to a conduction band energy barrier (DE C,B ) of 41 meV and 82 meV, respectively.…”

“…This is a direct consequence of the reduced lifetime in the base region as we have claimed previously. 4,10,18 The absence of a large resonance peak in the transistor laser's frequency response results in an improvement in signal integrity.…”