Mitsubishi introduces modulators

Fiber Optics Weekly Update, Nov 22, 2002

The Electronic Device Group of Mitsubishi Electric & Electronics USA Inc., announced a 40 Gbps electro-absorption (EA) modulator chip and module that demonstrate an input power tolerance of up to 15 dBm, the industry's highest, combined with low chirp. Designed for C Band, the devices' high input power tolerance enables them to offer a significant transmission distance boost to 40 km without an optical amplifier when using dispersion-shifted fiber--double the distance of previous-generation devices. The new EA modulator products represent a significant cost and space advantage for DWDM applications compared to lithium-niobate alternatives.

Developed using InGaAsP(4) technology, the ML9XX38 EA modulator chip uses an asymmetric quantum well absorption layer that is deposited on a semi-insulating indium-phosphide substrate. This layer prevents degradation of the optical waveform by photocarrier buildup, which normally occurs when an EA modulator is operated with high input power. As a result, the ML9XX38 chip attains a high input power of 15 dBm with a chirp parameter of less than 0.5 (at -0.5 volts). The chip occupies a tiny 0.3-mm x 0.3-mm footprint, making module integration easier.