If the laser intensity increases, the photodiode responds by generating a higher current, which in turn creates a larger voltage drop across R1. This reduces the output voltage of the op-amp, subsequently decreasing the laser intensity. The opposite behavior is seen with a. Semiconductor laser diodes (SLDs) are often packaged with a photodiode. SLDs, however, are prone to pathological drifts, such as temperature variations and mode-hopping, that can. Photodiodes measure laser power by using a semiconductor to convert light directly into an electric signal. The term photodiode can be broadly defined to include even solar batteries, but it usually means sensors that accurately detect changes in light level.