High‐speed LED/PD arrays for optical parallel interface

Optical parallel transmission is an effective technique for various interconnections, e.g., the interface between computer equipment. Monolithically integrated optoelectronic arrays for this purpose are very promising to realize compact, low power-consuming, highly reliable, and low-cost systems. In this paper various devices are examined and compared in terms of the forementioned requirements. As the most suitable optical devices, a 12-channel, 1.3-μm mesa-structure planar LED array with high output power at low drive current and a low crosstalk InGaAs pin-PD array with separated-unit structure have been developed. Coupled with the GI 62.5 multimode optical fiber, the output power, rise time and fall time of the LED array were -16 dB, 2.7 and 1.5 ns, respectively, at 12-mA drive current. Because of the low-current operation, the interaction among channels due to heat generation was negligible. A separated-unit structure was used for PD array to suppress crosstalk. As a result, the capacitance between two channels was as low as 0.05 pF, leading to the measured crosstalk lower than -40 dB until hundreds of megahertz 7-mm thick compact modules with 1.5-W power consumption have been fabricated and optical parallel transportation of 12-channel, 150-Mbit/s/ch for 100-m distance has been realized with the modules.