John Michael Dallesasse
University of Illinois, USA
Title: The transistor-injected quantum cascade laser: A novel three-terminal device for Mid-IR wavelengths through THz frequencies
Biography
Biography: John Michael Dallesasse
Abstract
The quantum-cascade laser (QCL) has emerged as an important device for the generation of coherent light over operating bands from mid-IR wavelengths through THz frequencies. Wide-ranging applications in chemical detection and security have been enabled by the availability of these devices. At the same time, the device has certain limitations that are fundamental to its two-terminal nature and reliance on engineered quantum states that depend strongly on electric field, and as a consequence bias voltage. A promising enhancement to the QCL will be discussed that utilizes the transistor effect in a novel three-terminal n-p-n transistor structure to separate the field control from the current amplitude. This separation is achieved through placing the device cascade region in the reverse-biased base-collector junction of a heterojunction bipolar transistor (HBT), where the amplitude of the current flowing through the cascade region is controlled by the emitter-base bias. The ability to separately modulate the amplitude (emitter-base) and frequency (base-collector) creates unique opportunities for novel applications. The device design also allows a reduction of the doping level in and around the cascade region, which is ultimately expected to reduce free carrier absorption and improve wall-plug efficiency.