LOW-VOLTAGE VERTICAL DIRECTIONAL COUPLER SWITCH WITH SUPPRESSED ELECTROABSORPTION

We have studied the performance of a vertical directional coupler in w hich a multiple quantum well and a bulk semiconductor material act as the cores of the two guides in two arms. The power output of the devic e is expected to be unaffected by the electroabsorption effect in a di rectional coupler based on quantum confined Stark effect even when ope rated very close to excitonic absorption edge, The above principle is utilized in realizing low-voltage switching and almost equal power in bar and cross states in a multiple-quantum-well (MQW) vertical directi onal coupler. Our calculation for a vertical coupler composed of InGaA sP bulk and InGaAsP-InP MQW's show switching voltages comparable to th at of a similar coupler composed of a more complex barrier reservoir a nd quantum well electron transfer (BRAQWET) structure, with a slightly lower value of power output.