AbstractWe propose a new linearization scheme in optical external modulator employing high‐pass filter characteristic of a gain saturated reflective semiconductor optical amplifier for an analog optical transmission system. The proposed scheme is based on power level relation between fundamental signal and IMD3 signal when a radio‐frequency tone is modulated, using an optical modulator at linearity region of transfer curve. Based on the proposed idea, a linearized optical transmitter module is implemented and evaluated. The proposed scheme is demonstrated and verified using a small scale test‐bed. Both carrier‐to‐interference ratio and spurious‐free dynamic range are improved. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2100–2103, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24545