Gain Measurements using Multi-section device

Finally i have been able to measure Absorption of light using two sections of LASER device, by pumping sections independently and measure light intensity spectrum using OSA. Also by varying the pumping stripe length i am able to determine the gain of the device. It has been a rollercoaster weekend trying to make sense of all these measurements and apply Beer-Lambert Law to see the absorption spectrum..(aligning optical fiber to 350 micron facet is not trivial...)