PHASE-ENGINEERED III-V MQW MACH-ZEHNDER MODULATORS

We have optimized the negative frequency chirp while maintaining a hig h extinction ratio in an InP-InGaAsP multiple-quantum-well (MQW) Mach- Zehnder modulator. Our procedure is to elongate one modulator arm such that a pi phase shift is produced at zero bias relative to the opposi ng arm. The resulting de extinction ratio is improved to approximate t o 16 dB from 10 dB relative to a symmetric design. The frequency chirp of the modulator at the rising edge is about -3 GHz enabling excellen t transmission performance over a 95 km of conventional fiber.