Write expression for threshold gain - loss, that will be equal to zero, in terms of the following variables: A, a_i (internal loss), L (length) and Bb where A=gA where is the confinement factor and g is the gain , and Bb=ln(R1R2) where R1 is the power reflectivity of the first facet and R2 is the power reflectivity of the second facet. You should structure your answer so that you have threshold gain - loss in your math expression. This expression will be equal to zero. The correct answer uses the variable "a" and not the word "alpha" to indicate alpha