Realization of efficient electroabsorption using intersubband transitions in step quantum wells

TL;DR

This paper demonstrates efficient intersubband electroabsorption in step quantum wells, achieving significant modulation at low voltages and projecting high-speed operation suitable for integrated photonic devices.

Contribution

It presents a novel implementation of intersubband electroabsorption in step quantum wells with low voltage operation and high potential modulation speed.

Findings

6 dB absorption modulation at 6.0 μm wavelength

Low voltage swing of ±0.5 V achieves Stark shift

Projected modulation speed of approximately 120 GHz

Abstract

We have demonstrated efficient intersubband electroabsorption in InGaAs/InAlGaAs/InAlAs step quantum wells grown by metal-organic vapor phase epitaxy (MOVPE). An absorption modulation of 6 dB at $\lambda=6.0 \mu$m due to Stark shift of the IS absorption was achieved at a low voltage swing of $\pm 0.5$ V in a multipass waveguide structure. Based on the experimental results it is estimated that an electroabsorption modulator with a low peak-to-peak voltage of $V_{pp}=0.9$ V can yield a modulation speed of $f_{3dB} \approx 120$ GHz with the present material by using a strongly confining surface plasmon waveguide of 30 $\mu$m length.