Multiple-wavelength VCSEL arrays on patterned substrates

The lasing wavelength of a VCSEL is primarily determined by the effective cavity thickness which can be varied by changing the thickness of the /spl lambda/-spacer or the DBR layers. There have been many efforts in making MW-VCSEL arrays, where different methods of varying the effective cavity thickness were explored. Among all these methods, patterned-substrate MBE growth presents a very attractive approach since only a single growth is necessary and wide and accurate wavelength spans can be achieved with in-situ monitoring. In this paper, we review two patterned substrate methods. Both lead to simultaneous achievements of wide /spl lambda/ spacing, high yield and high performance. The comparison between the two methods is discussed.