Multichannel Generations of Orbital Angular Momentum Modes with On‐Demand Characteristics on a Chip

• Published in: Advanced optical materials Vol. 9; no. 24
• Main Authors: Fu, Pan, Ni, Pei‐Nan, Wang, Qiu‐Hua, Liu, Yu‐Fei, Wu, Bo, Chen, Pei‐Pei, Kan, Qiang, Wang, Shuang‐Peng, Chen, Hong‐Da, Xu, Chen, Xie, Yi‐Yang
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.12.2021
• Subjects: Angular momentum; Communications systems; Demultiplexing; Emitters; Lasers; Materials science; metasurfaces; Multiplexing; on‐chip integration; optical vortex; Optics; Optoelectronics; orbital angular momentum; Orthogonality; Power efficiency; Topology; Vertical cavity surface emission lasers; vertical cavity surface‐emitting lasers
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202101308

The orthogonality among optical beams with different orbital angular momentum (OAM) modes presents a new perspective as independent data‐carrying channels for multiplexing and demultiplexing. In particular, the theoretically infinite topological charge of OAM beam promises the unbounded capacity in communication systems. As a key part for the advancement of OAM technologies, OAM source has attracted considerable interest and experienced a rapid development. Nevertheless, conventional approaches to create OAM modes mainly rely on the use of bulky optical devices and external laser source, preventing their implementation into a miniaturized system. As a contrast, on‐chip generation of OAM beams with a built‐in source stands out with several advantages, including small footprint, compactness, portability, and high‐power efficiency. In this work, a versatile approach to directly produce OAM modes with on‐demand characteristics on a chip is demonstrated. Featuring the judicious combination of the emerging dielectric metasurface with the standard vertical cavity surface‐emitting laser (VCSEL) platform, the approach represents a feasible solution to the wide implementation of wafer‐level OAM emitters for optoelectronic integrations. Prototype laser chips for the generation of both individual OAM beam and OAM array with novel functionalites, such as controllable directionality and spatially varying topological charge and distribution, are systematically presented. Wafer‐level optical vortex sources are demonstrated via monolithic integration of metasurfaces with vertical cavity surface‐emitting lasers (VCSELs). This approach features versatile capabilities to on‐chip convert the Gaussian beam of a VCSEL into any given orbit angular mode (OAM) with on‐demand characteristics, including multichannel generation and well‐defined directionality.