A new any-point biasing scheme for Mach-Zehnder interferometer modulators which considers the complex phase is proposed. The Mach-Zehnder arm loss imbalance (imaginary part of the phase bias) is found by slightly perturbing the real and imaginary parts of the phase in each arm with low frequency pilot tones and monitoring and manipulating the spectral content at the output. This technique can be used to extend the possible extinction ratio, reduce the phase error, and better quantify the system chirp but also has some performance degradations which are also quantified and discussed. Simulation results indicate that the maximum extinction ratio of a typical modulator can be extended to ≳ 40 dB and maintained in the presence of ambient complex phase drift in the arms. Practical challenges for implementing this method with a silicon Mach-Zehnder modulator are discussed, but the analysis is general to other material platforms.

A new any-point biasing scheme for Mach-Zehnder interferometer modulators which considers the complex phase is proposed. The Mach-Zehnder arm loss imbalance (imaginary part of the phase bias) is found by slightly perturbing the real and imaginary parts of the phase in each arm with low frequency pilot tones and monitoring and manipulating the spectral content at the output. This technique can be used to extend the possible extinction ratio, reduce the phase error, and better quantify the system chirp but also has some performance degradations which are also quantified and discussed. Simulation results indicate that the maximum extinction ratio of a typical modulator can be extended to ≳ 40 dB and maintained in the presence of ambient complex phase drift in the arms. Practical challenges for implementing this method with a silicon Mach-Zehnder modulator are discussed, but the analysis is general to other material platforms.