This article presents the design and implementation of an Automatic Power Control (APC) loop in laser system which uses LMH13000 for driving the laser diode. The setup uses a laser diode which has an integrated back-facet photodiode for feedback. This application note will introduce ROHM's LD line-up and show how to design the drive circuits of ROHM LDs. 3), the driving circuit should act as a current source and. Laser diodes (LD) are semiconductor devices that convert electrical energy into high-power optical energy. If case temperature; Tc is 25 degrees Celsius, Po becomes about 6mW.