Extra Loss-free Non-Hermitian Engineered Single Mode Laser Systems

TL;DR

This paper introduces a novel loss-free non-Hermitian method for single mode laser operation that enhances fundamental mode quality without added losses, improving power output and reducing design complexity.

Contribution

It presents the first loss-free non-Hermitian laser engineering approach that selectively enhances mode quality, enabling higher power and simpler cavity design compared to PT and SUSY methods.

Findings

Achieves single mode lasing without added optical losses.

Increases output power per cavity by enhancing fundamental mode.

Reduces the number of cavities needed in laser arrays.

Abstract

In a laser system non-Hermitian methods such as Parity-Time (PT) Symmetry and Supersymmetry (SUSY) have shown and demonstrated the ability to suppress unwanted lasing modes and, thus, achieved single mode lasing operation through the addition of lossy passive elements. While these approaches enable laser engineering versatility, they rely on the drawback of adding optical losses to a system tasked to produce single mode gain. Unlike PT and SUSY lasers, here we show an extra loss-free non-Hermitian laser engineering approach to realize single mode lasing operation for the first time. By selectively enhancing the fundamental modes quality factor, we obtain single mode operation with higher output power per cavity since all cavities in this system contribute to the laser output, in contrast to other non-Hermitian approaches. Furthermore, we show that this approach interestingly allows reducing the number of to-be-designed cavities in super-partner array as compared with, for example, the SUSY approach, thus leading to reduced design complexity upon coupled cavity scale up of laser arrays. In summary, the ability to engineer coupled laser systems where each laser cavity contributes to coherent light amplification opens up a new degree of laser-design freedom leading to increased device performance and simultaneous reduced design and fabrication complexity.