Injection locking and coupling the emitters of large VCSEL arrays via diffraction in an external cavity

TL;DR

This paper demonstrates a scalable 22-VCSEL array with individual control, achieving mutual and external injection locking via diffraction in an external cavity, advancing photonic neural networks and complex system studies.

Contribution

It introduces a scalable VCSEL array with independent control and demonstrates mutual and external injection locking through diffractive coupling.

Findings

Mutual injection locking of 22 lasers achieved

Simultaneous phase locking to an external laser demonstrated

Scalability suggests potential for larger laser networks

Abstract

Networks of optically coupled semiconductor lasers are of high interest for fundamental investigations and for enabling numerous technological applications in material processing, lighting and information processing. Still, experimental realizations of large networks of such elements employing a scalable concepts have so far been been lacking. Here, we present a network 22 of the vertical-cavity surface-emitting lasers in a $5 \times 5$ square lattice array via. Crucially, the array allows individual control over each laser's pump current, which we leverage spectrally align the array. Leveraging diffractive coupling through an external cavity, 22 lasers are mutually injection locked, and, furthermore, we demonstrate their simultaneous phase locking to an external injection laser. The VCSEL network is a promising platform for experimental investigations of complex systems and has direct applications as a photonic neural network. The scalability of the concept opens future possibilities for systems comprising many more individual lasers.