Aiming at the stability requirement of SLD output luminous power, based on analyzing the temperature control circuit of the light source, the electric filed coupling model was built between SLD constant current loop and TEC, and the influence of TEC on its internal electric field was discussed. The distributed capacitance among different components of the light source was analyzed. The results show that the AC component coming from temperature control circuits acts on TEC, thus generates time-varying electric field, then it is coupled to the constant current circuit by the distributed capacitance. The case of SLD light source grounds well, which can reduce the distributed capacitance, thus reduce the effect of electric field coupling on the optical output power.
