Electrically Parallel Three-Element 980 nm VCSEL Arrays with Ternary and Binary Bottom DBR Mirror Layers

Area of Science:

• Optoelectronics and Photonics
• Optical Wireless Communication (OWC)
• Semiconductor Lasers

Background:

• Fifth-generation (5G) and future sixth-generation (6G) systems demand high-performance lasers for optical wireless communication (OWC) and sensing.
• Existing laser technologies face limitations in cost, reliability, and compactness for meeting future OWC and sensing system requirements.
• Free-space optical communication requires lasers capable of transmitting infrared beams over various distances with high data rates.

Purpose of the Study:

• To develop low-cost, reliable, and compact laser arrays for 5G/6G OWC and sensing systems.
• To achieve high data rates (5-20 Gb/s, ideally up to 100 Gb/s) for infrared beams over free-space line-of-sight.
• To explore the use of vertical cavity surface-emitting laser (VCSEL) arrays for short-distance OWC applications.

Main Methods:

• Design, epitaxial growth (metal-organic vapor phase epitaxy), fabrication, and testing of 980 nm top-emitting triple VCSEL arrays.
• Development of novel p-metal and top mesa inter-VCSEL connectors for electrically parallel, optically uncoupled arrays.
• On-wafer high-frequency probe testing to evaluate array performance characteristics.

Main Results:

• Achieved record bandwidths of 20-25 GHz in the VCSEL arrays.
• Demonstrated optical output powers ranging from 20-50 mW.
• Successfully transmitted data error-free at rates up to 40 Gb/s, exceeding single VCSEL performance.

Conclusions:

• The developed VCSEL arrays are highly suitable for 5G short-reach OWC and sensing applications.
• Novel connector designs enable parallel electrical operation while minimizing optical coupling and speckle.
• These arrays represent a significant advancement towards meeting future high-speed free-space optical communication demands.