VCSEL Industry. Babu Dayal Padullaparthi

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СКАЧАТЬ Stage V: VCSEL Industry

      In the fifth stage (2020 onward) VCSELs will continue to expand in global volume production and find new application areas. The ever‐increasing demand for data communication and emerging technologies in machine vision, artificial intelligence (AI), augmented reality (AR), mixed reality (MR), and the Internet of Things (IoT) will drive global demand for VCSELs [52]. In this stage, VCSELs will affect nearly all aspects of human life. Details on computer vision (AR, MR, VR) will be introduced in Chapter 5. The application to automotive LiDARs and autonomous shuttles will be covered in Chapter 6.

1.4 Timeline and Milestones

      1.4.1 Milestones of VCSEL Research and Development

In Table 1.2 we show a list of key benchmark events based on 44 years of basic research and commercial product developments on semiconductor lasers and VCSELs.

      1.4.2 Single‐Mode and Multi‐Mode Behavior

Semiconductor lasers oscillate in different modes (power radiation patterns) that depend on the dimensions of the optical resonator. Especially for VCSELs, the mode structure or pattern depends on the size and shape of the oxide aperture (mode) diameter used for current and optical confinement [53, 54]. Several kinds of modes appear in the emission spectra, namely longitudinal, transverse, single, and multi‐modes. In Figure 1.16 we show how the behavior of VCSEL in single longitudinal and multi‐transverse (and longitudinal) operation. More details on the VCSEL mode structure will be discussed in Chapter 2.

Table 1.2 Milestones of surface emitting laser research and development.

1977	Surface‐emitting laser concept proposed
1979	First device demonstrated (77 K, pulsed)
1988	First RT CW operation
1988	Semiconductor DBR
1989	QW VCSEL
1989	Micro‐post QW laser RT CW (Bell Labs)
1989	Periodic gain proposed (UCSB)
1990	AlGaAs hydro‐oxidization (UIUC)
1992	VCSEL mechanical tuning demonstrated
1995‐	Low threshold device competition Ith < 0.1 mA
1995	MEMS tunable VCSEL (USB)
1996	VCSEL commercialization (Honeywell)
1999	VCSEL LAN
2000	Oxide aperture device reliability
2001	VCSEL printer (Fuji, Xerox),
2001	Computer mouse (HP)
2002	10G Ethernet standard IEEE802.3ae
2003	4Gb/s VCSELs (Honeywell)
2006	High‐contrast grating for VCSEL (UC Berkeley)
2010	100G Ethernet standard IEEE802.3ba
2011‐	VCSEL photonics
2016	VCSEL arrays for sensing
2016	VCSEL SWDM in datacom
2017	VCSEL face ID 3D sensor (iPhone X from Apple)
2018	400G AOC (Finisar/II–VI)
2020	LiDAR scanner (iPhone 12 Pro, iPad Pro 11″/12″ from Apple)
2021‐	VCSEL Industry

      Italic: From K. Iga’s group.

      RT CW: Room‐temperature continuous wave

      QW: Quantum well.

Figure 1.16 Origin of single‐mode and multi‐mode behavior in VCSELs.

      Source: [55, 8]. Figure by K. Iga [copyright reserved by author].

      The origin of multi‐mode operation in a VCSEL is not from longitudinal mode behavior but multiple transverse mode oscillation. When the lateral extent of the optical resonator diameter is extended to larger than several microns, multi‐transverse with multispectral‐mode operation is achieved. On the other hand, small diameters lead to single‐transverse and single spectral‐mode operation.

      1.4.3 Major Features of VCSELs

VCSELs have become the light source of choice for many applications and are rapidly replacing edge‐emitting lasers (EELs) and LEDs in many more every day. The inherent advantages in manufacturing and the ability to tailor the VCSEL properties to different applications has been key to their success. The ability to scale the optical power and emission pattern with 2D arrays of emitters has enabled the widespread adoption of 3D sensors. Table 1.3 summarizes the typical operating characteristics of VCSELs and EELs. Even with the long list of advantages, there are still many applications where EELs offer a better solution. Some areas where EELs are still dominant are single‐mode fiber optic communications and extremely high‐power applications.

The authors rearranged Table 1.3 to provide a simple picture of advantageous and key characteristics along with performance attributes into Table 1.4.

      1.4.4 VCSELs as Major Optical Components

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