In a time-division-multiplexing (TDM) fiber optic sensor system, a continuous-wave laser source can be externally modulated by an intensity modulator to generate an optical pulse. To enhance sensor system performance, an optical pulse with a high extinction ratio (ER) is highly desirable. The high ER increases sensor sensitivity and reduces sensor crosstalk. For optimum TDM operation, it is important not only to select an intensity modulator with a high ER, but to operate the modulator at its most optimum operating point. We provide a way to achieve these goals. We demonstrate a control to maintain the output optical pulse from an optical guided-wave (OGW) intensity modulator at its maximum ER bias point. Our unique control methodology uses a reference value obtained after the process of amplifying, digitizing and averaging the input signal of the optical pulse. Results are analyzed and processed, using a custom software program and algorithm of our own design, and used to control the OGW, electronics maintaining the optimum bias point for best ER. Our experimental results show that this control scheme can be used to satisfactorily operate an OGW at high sensitivity with output optical pulse light intensity variation of less than 15 nW, which provides for improved TDM fiber optic sensor system response and operation.