High Bandwidth Coherent Driver Modulator
The Lumentum high-bandwidth coherent driver modulator (HB-CDM) is an OIF-compliant integrated component for coherent applications and features a four-channel modulator driver integrated circuit, co-packaged with two nested modulators, designed to modulate amplitude and phase of the input light in both polarizations. The Mach-Zehnder (MZ) structures embed semiconductor optical amplifiers (SOAs) that can be used to reduce insertion loss or to balance power in the two polarizations. The device features two SOAs per polarization and are current controlled. This configuration allows the design of transceivers with a single laser split between transmitter and local oscillator. The temperature of the InP modulators is controlled by a thermoelectric cooler.
Control of the modulators is via analog voltage inputs to the module. Control of the driver is via SPI digital control interface, plus analog control signals. The device features monitoring photodiodes to detect power and provide feedback for control loops.
The module has one input fiber (from a CW laser) and one output fiber. The RF input contacts are located at the rear of the package (opposite the fibers) and use a GSSG pattern. 40 low-speed contacts located at the side of the package provide power supply, control signals, and the digital SPI interface.
The HB-CDM mechanical outline is the standard OIF Type 1 MSA size (30 mm x 12 mm x 6.5 mm). Electrical interfaces are provided through the 40-pin connector.