Читать книгу VCSEL Industry - Babu Dayal Padullaparthi - Страница 29

A schematic of EEL manufacturing and testing processes is shown in Figure 1.10. The edge‐emitting lasers (such as FP and DFB lasers) require facet coatings after cleaving and often need regrowth of specific steps.

The FP‐EELs with cleaved laser mirrors have only 33% reflectivity. The reflectivity of the cleaved surface can be modified to be either higher or lower reflectivity by coating multi‐layer films that can be used to optimize the performance characteristics and to protect the surfaces of the EEL. The facet coatings are applied after the lasers are cleaved from the substrate and require extensive handling, which makes them more difficult to manufacture.

Another approach is to form the distributed reflectors through multiple epitaxial steps with intermediate fabrication steps. The regrowth and the intermediate processing result in a nonmonolithic epitaxial growth making this process very complex and not manufacturing‐friendly compared to a fully monolithic VCSEL fabrication.

Figure 1.10 The manufacturing processes of edge‐emitting lasers.

Source: Figure by K. Iga and J. A. Tatum [copyright reserved by authors].