Transistor laser

Abstract: This letter reports the direct observation of the radiative recombination in the graded base layer of InGaP/GaAs heterojunction bipolar transistors (HBTs). For a 1 μm×16 μm emitter HBT, we demonstrate the change of the spontaneous light emission intensity (ΔIout) as the base current (Δib) of the HBT is varied from 0 to 5 mA, i.e., an HBT operating as a light-emitting transistor. We also demonstrate output light modulation from the base layer at 1 MHz with the base current modulated at 1 MHz in normal transistor mode operation of the HBT.

Abstract: This letter reports the enhanced radiative recombination realized by incorporating InGaAs quantum wells in the base layer of light-emitting InGaP/GaAs heterojunction bipolar transistors (LETs) operating in the common-emitter configuration. Two 50 A In1−xGaxAs (x=85%) quantum wells (QWs) acting, in effect, as electron capture centers (“traps”) are imbedded in the 300 A GaAs base layer, thus improving (as a “collector” and recombination center) the light emission intensity compared to a similar LET structure without QWs in the base. Gigahertz operation of the QW LET with simultaneously amplified electrical output and an optical output with signal modulation is demonstrated.

Abstract: A research team at the University of Illinois at Urbana-Champaign has developed a new, more powerful kind of device, called the transistor laser. The transistor puts out both electrical signals and a laser beam, which can be directly modulated to send optical signals at the rate of 10 billion bits per second. With some further modification, the transistor laser will eventually send a staggering 100 billion bits per second or more. Instead of using relatively slow wires to connect chips stacked together in packages, transistor lasers can be used as optical interconnects, which would let data flow instantaneously to and from memory chips, graphics processors, and microprocessors. There is much work ahead, but unlike the host of self-assembling, blue-sky nanotechnologies currently being touted as the next big thing in optoelectronics, transistor lasers do not need an entirely new fabrication infrastructure for further development or even to go into production.

Abstract: A quantum well (160A) transistor laser with a 400μm cavity length that achieves the large 3dB modulation bandwidth of 13.5GHz is described. The fast base recombination (transport determined, τBL 1∕2), resulting in a resonant peak magnitude of unity and consequently a resonance frequency of ∼0GHz (no peak) in the small-signal response. Quantum well band filling and bandwidth saturation are observed on the ground state (λ=1000nm), and increase with operation on the first excited state (λ=980nm).