Optical Modulators

Fiber Optical DP-QPSK (I-Q) Modulator 128Gbps

The DPSK series fiber optical modulator supports high-speed modulation up to 128 Gbps using the DP-QPSK (Dual-Polarization Quadrature Phase Shift Keying) transmission format. It integrates four independently driven Mach-Zehnder Interferometer (MZI) modulators—each with a low Vπ of 3.5 V, ~30 GHz bandwidth, dedicated DC bias ports, and monitor photodiodes for auto bias control—all in a single package. Two MZI pairs form dual I/Q modulators for the X and Y polarizations. A single-polarization CW laser is input into the device, split into two orthogonal polarization paths, modulated independently, and then recombined into a dual-polarization optical output. The system achieves 128 Gbps by combining a 30 Gbaud symbol rate, QPSK modulation (2 bits per symbol), and dual-polarization, effectively utilizing all four MZIs to deliver a 4× data rate increase over a single-modulator setup.