Abstract
The effect of the linewidth enhancement factor (LEF) or alpha-factor on two common routes to chaos (mainly period-doubling and quasi-periodic routes) in optically injected semiconductor laser is theoretically investigated using bifurcation diagrams. The value of the LEF is slightly modified to examine the sensitivity of routes to chaos to any variation in the LEF. Despite the fact that LEF en-hances chaos in the system, both routes are found to be highly insensitive to the variation in the LEF.