an er of 15 db over a change in v ce third terminal control of only 0 8 v a low voltage swing with a high er is especially advantageous for making highly efficient low power voltage controlled lightwave modulators fig6 shows the modulation characteristics of a common emitter tj tl at two different biases the biases are chosen so as to maintain the same photon densities in each case a resonance constrained modulation response with photon carrier relaxation oscillation at frequency f r is obtained with the bc junction forward biased in fig6 a and b in this mode of operation the tj tl is biased in saturation i e two forward biased p n junctions as is identified in the regime before the u201c knee u201d of the i v characteristics of fig3 and operating region 1 of fig4 however when operated in the forward active mode region 2 of fig4 the modulation response is free of resonance extending the usable bandwidth to its greater 3 db bandwidth f 3 db the u201c tilt u201d in the base charge population imposed by the boundary condition at the reverse biased bc junction removes the saturated charge u201c pile up.