Vertical-Cavity Surface-Emitting Laser Technologies for Optical Communication

Vertical-cavity surface-emitting lasers (VCSELs) are semiconductor devices that emit light perpendicular to the wafer surface, combining low threshold currents, compact size and high modulation bandwidth. They have become foundational to short-reach datacentre interconnects, optical fibre links and free-space sensing, including LiDAR. Progress in epitaxial growth and cavity engineering has extended modulation speeds into the tens of gigahertz while retaining single-mode operation, enabling data-rates of 100 Gbps and beyond. Multijunction cascaded designs now approach and exceed the efficiency of traditional edge-emitting lasers, and antireflective cavity architectures reduce beam divergence for long-distance applications. High-contrast metastructure mirrors and oxide-defined apertures suppress higher-order modes and support stable single-mode lasing over wide current ranges. Integration with single-mode fibres and silicon photonic platforms further secures VCSELs’ role as scalable, cost-effective light sources. Remaining challenges include thermal rollover at high drive currents, achieving millimetre-wave modulation and balancing power density against beam quality. Given their reliability, manufacturability and versatile performance, VCSELs continue to drive innovation across telecom, data communications, automotive sensing and emerging photonic systems.

Research from Nature Portfolio

Recent studies have introduced an antireflective cavity concept for multijunction VCSELs that integrates a light reservoir to suppress unwanted reflections and shorten the effective cavity length. By tailoring the antireflective layer, single-longitudinal-mode operation is preserved while divergence angles are halved and brightness is trebled relative to conventional designs. Experimental arrays ranging from six to seven junctions achieved divergence as low as 8° (D86) and single-transverse-mode output exceeding 28 mW, demonstrating a path to cost-effective long-distance LiDAR illumination and inspiring new cavity-engineering strategies across photonic devices.

Vertical-Cavity Surface-Emitting Laser Technologies for Optical Communication publication trend

The graph below shows the total number of articles in vertical-cavity surface-emitting laser technologies for optical communication across all publications each year (not limited to Nature Index journals).

Technical terms

Vertical-Cavity Surface-Emitting Laser (VCSEL): A semiconductor laser in which the optical cavity is formed perpendicular to the wafer surface, offering low threshold current and high modulation speed.

Differential quantum efficiency: The ratio of the increase in emitted photons to the increase in injected carriers above the lasing threshold, indicating device efficiency.

Side mode suppression ratio (SMSR): The power ratio between the primary lasing mode and the strongest competing mode, measuring single-mode purity.

Antireflective cavity: A laser cavity design that incorporates an antireflective layer or reservoir to control feedback, reduce divergence and preserve single-mode operation.

High-contrast metastructure (HCM): A subwavelength-engineered mirror with spatially varying reflectivity, used to favour fundamental mode lasing and suppress higher-order modes.

References

1. Multi-junction cascaded vertical-cavity surface-emitting laser with a high power conversion efficiency of 74%. Light: Science & Applications (2024).
2. Antireflective vertical-cavity surface-emitting laser for LiDAR. Nature Communications (2024).
3. Single-mode chirped high-contrast metastructure VCSEL for 106 Gbps PAM4 transmission. Optica (2024).