We have studied the effect of design parameters on the performance of non-biased optical bistable (NOB) devices fabricated with non-resonant multiple quantum wells nipi-diode structures. This device made of extremely shallow quantum wells as intrinsic regions allows both a large low-field electroabsorption change and exciton ionization, and consequently, ensures both large electric field swing and strong Light absorption without external bias voltage. By optimizing stack pairs of non-resonant nipi-structures, the performance of the NOB device was significantly enhanced with a large signal contrast ratio, low heat power dissipation, and low drive voltage, while maintaining low switching energy, high signal difference, and layout simplification. (C) 1998 Elsevier Science BN. All rights reserved.