Reduced Complexity, Low-Power Linear Modulator for DAC-Based Multilevel Coherent Transmitters

摘要

We present a simpler, power efficient, and cost-effective linear optical field modulator (LOFM) for digital-to-analog-based multilevel coherent transmitter. The new design has four advantages compared with the existing LOFM. First, it only uses one Mach–Zehnder modulator (with very short and broadband non-traveling waveguide phase modulators), which is configured for double-pass modulation to linearize the optical field response. Second, it has excellent linearity performance with a superior normalized deviation value of 0.8% when the power split ratio of the asymmetric coupler is set to 0.113. Third, it has inherent compensation functionality that mitigates the increased distortion when parameter is not optimized due to fabrication error. Finally, it reduces the radio frequency power consumption by one-half. Operational restrictions of the new device compared with current LOFM are also briefly noted.