Linearity enhancement of analog optical transmitter using gain saturated reflective semiconductor optical amplifier

We 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.