Читать книгу VCSEL Industry - Babu Dayal Padullaparthi - Страница 39

In the fourth stage of VCSEL history, from 2010 to 2020, the true scaling of VCSEL production has been realized. In data communication, highly reliable 850 nm VCSELs are made using InGaAs quantum wells with 3 dB bandwidths exceeding 25 GHz and operated above 70 Gb/s NRZ. New modulation (PAM‐4) standards are made for higher speeds to meet the continued network demand. This is also supported by development of short wavelength WDM VCSELs (in the 850–980 nm band).

In the optical sensing area, high‐power 940 nm VCSELs arrays have been made with optimized designs with power conversion efficiency > 50%, slope efficiency = 1.0 W/A, and with new trends of using multi‐tunnel junctions that offer a power conversion efficiency > 60%, slope efficiency = 3.0 W/A, with power densities of 1 kW/mm². This facilitated the use of VCSEL arrays in consumer devices (mobile/smart phones/smart homes), infrastructure and transport applications incorporating LiDAR, surveillance and night vision products, robots, drones, IoT, and so on. Further applications include multi‐mode VCSEL arrays in LiDARs at 905 nm, 850 nm, and 1060 nm; large‐scale 940 nm arrays in industrial heating systems. On the other hand, single‐mode VCSELs are being applied to optical coherence tomography (1060 nm) and atomic clocks. Details and references can be found in related chapters.

The multi‐function ability of VCSELs further expanded manufacturing bases across the world with investments prompting high market demands never seen before. This also triggered high‐volume manufacturing from 4" (100 mm) to 6" (150 mm) for optical sensor products. All these items will be discussed in Chapters 3–9.