VCSELs, or vertical-cavity surface-emitting lasers, have two main application scenarios: consumer and communication. In consumer scenarios, VCSELs are used for sensing, such as lidar, and early applications used edge-emitting lasers for gesture recognition and somatosensory game sensors. Later, surface-emitting lasers were used for various types of machines in industrial intelligent manufacturing, motion recognition, facial recognition for mobile payment, and contactless access control identification after the epidemic. Communication applications focus on increasing bandwidth, differential gain, capacity, reducing noise, and improving reliability.
For VCSELs used for sensing, such as lidar, multi-junction design can increase electro-optic efficiency and improve reliability. VCSELs used for sensing are usually distributed in arrays using addressable technology to achieve true solid-state radar without MEMS. For VCSELs used in data communication, traditional designs are close to their limit, and mode control can improve effective mode bandwidth for multimode fiber, extend transmission distance, reduce mode noise, and reduce RIN. To increase bandwidth, designers usually need to reduce the RC constant and the junction capacitance c, which can be achieved by reducing the diameter of the P-type semiconductor, but this increases the risk of hidden reliability issues related to Joule heat and internal stress.
Lumentum provides VCSELs of several wavelengths, controlled at approximately 22dB, which are used for around 100G.
Lumentum suggests adopting the SWDM approach for higher-speed applications of 200Gbps and considering various factors such as substrate or surface emission, attenuation, dispersion, wavelength shift capability, and lens design for optical path control. For sensing applications, long wavelengths are preferred for safety reasons, while for communication applications, increasing bandwidth is necessary, and substrate light emission can help achieve this.
In summary, VCSELs have various applications in consumer and communication scenarios, and designers need to consider different factors depending on the specific application. Regarding VCSELs' package, ceramic components, such as DPC components, ceramic submount are commonly be used.
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