SEMICONDUCTOR OPTICAL MODULATION WAVEGUIDE

摘要

PROBLEM TO BE SOLVED: To realize stable motion by solving a problem associated with occurrence of variation of a core layer voltage in a semiconductor optical modulation waveguide such as a nin type InP/InGaAsP optical modulator.

SOLUTION: A voltage is applied between an n-type InPn cladding layer 11 and a layer 16-1 of an optical modulation part composed on an n-type InP by inputting an electric signal to an electrode 18 in a state in which light is propagated in a direction vertical to a cross section of a mesa structure. Since an InP barrier layer 15 is p-type and acts as a potential barrier toward electrons, electron injection from the layer 16-1 is suppressed, and optical phase modulation based on an electrooptic effect is carried out by applying voltage to a core layer 13 in the state of little generation of a leak electric current. Since an electric potential of a p-type InP region 16-2 (a separation region) is lower than that of the depleted barrier layer 15, holes flow into the region 16-2 and accumulation of the holes in the barrier layer 15 is suppressed.

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