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Electrically pumped topological laser with valley edge modes.

Yongquan Zeng¹, Udvas Chattopadhyay², Bofeng Zhu²

¹Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering & The Photonics Institute, Nanyang Technological University, Singapore, Singapore.

|February 14, 2020

Summary

This study presents the first electrically pumped terahertz quantum cascade laser utilizing topologically protected valley edge states. This compact topological laser bypasses defects, paving the way for practical applications in driven laser sources.

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Area of Science:

Photonics
Condensed Matter Physics
Quantum Cascade Lasers

Background:

Quantum cascade lasers (QCLs) are vital mid-infrared and terahertz light sources.
Topological concepts have extended to photonics, enabling robust lasing modes.
Previous topological lasers required external optical pumping and operated at optical frequencies.

Purpose of the Study:

To demonstrate an electrically pumped terahertz quantum cascade laser using topological protection.
To develop a compact topological laser design leveraging valley edge states.
To explore the practical application of topological protection in semiconductor lasers.

Main Methods:

Fabrication of an electrically pumped terahertz quantum cascade laser.
Implementation of a compact photonic crystal design utilizing valley degrees of freedom.
Utilizing topologically protected valley edge states in a triangular cavity for lasing.

Main Results:

Successful demonstration of lasing in an electrically pumped terahertz QCL.
Topologically protected valley edge states enabled lasing in a compact, sharp-cornered triangular cavity.
Lasing modes exhibited robustness against perturbations and circulated without localization.

Conclusions:

This work introduces the first electrically driven topological laser in the terahertz regime.
The compact design based on valley edge states offers a novel approach to topological photonics.
The developed laser technology holds promise for practical applications of topological protection in semiconductor devices.