Farzin Emami - Associate Prof. of Optoelectronic: dept. Electrical and Electronic Shiraz University of Technology , SUTECHShiraz, Iran
Masoumeh Mehboudi - M.SC Student of electronic: dept. Electrical and Electronic Shiraz University of Technology , SUTECHShiraz, Iran

Vertical-Cavity Surface-Emitting Lasers (VCSELs)are a relatively recent type of semiconductor lasers, which haveobtained an incredible reputation as a unique technology to beexploited in a tremendously wide range of applications like fiberchannel,Ethernet and intra-systems links, etc. In this paper, athorough numerical simulation is performed to investigate theeffects of DBR radius and active region radius on severalimportant VCSEL parameters such as lateral modediscrimination, threshold current, maximum gain of thefundamental mode and the first higher order mode and peakoutput power. The obtained results show both parts radiusreduction yields better mode selectivity, however the DBR is moreeffective. Besides, the active region reduction face several tradeoffsbetween advantages and disadvantages. We also investigatedseveral obstacles limiting radius reduction like happening modehopping,slope efficiency decay and kink power decreasing.

laser; VCSEL; transverse mode discrimination; kink; mode-hopping