Optical frequency response analysis of light-emitting transistors under different microwave configurations

Abstract

In this report, the optical frequency responses of InGaP/GaAs heterojunction bipolar light-emitting transistors are measured and analyzed using electrical small-signal equivalent circuit models under common-emitter, common-base, and common-collector configurations. Different optical modulation amplitudes and bandwidths, f3 dB, are obtained due to different input impedances and electrical transfer functions. The optical response of light-emitting transistors is able to be “tuned” by different input ports due to unique three-terminal characteristics along with carrier-photon conversion in the base region. From microwave analyses, identical “intrinsic” optical responses can be determined under three configurations at same DC bias condition.

Theory for voltage modulation of transistor lasers using Franz-Keldysh absorption in the presence of optoelectronic feedback

“…The measured optical response does depend on these parasitic elements. These analytical techniques are often adopted for light-emitting diodes (LEDs) or LETs [21,22]. In our case of TLs, a theoretical model composed of the intrinsic optical response and an electrical transfer function which is fed back by this optical response is proposed to elucidate the true behavior of voltage modulation in TLs.…”

Quantum Well Saturation Effect on the Reduction of Base Transit Time in Light-Emitting Transistors

“…With forward-active operation of transistors and unique bias-dependent carrier transit characteristics, an electrical RF measurement followed by de-embedding parasitics can result more direct and detailed carrier dynamics. Recently, we have constructed both electrical and optical small-signal equivalent circuit of the LET and developed a method to determine τ cap and τ esc by utilizing electrical microwave S-parameters measurement followed by small-signal model analysis to obtain the τ t of both the LET and the heterojunction bipolar transistor (HBT), in which the information of τ cap and τ esc can be directly determined without entangling optical and electrical signal processes like TRPL [8], [19]. The additional τ cap and τ esc related to the base transit time of the LET can be expressed as follows [8]:…”