We have designed evanescent semiconductor active optical isolators to realize lower forward transparent current in transverse electric (TE) mode integrable semiconductor active optical isolators with 9.3 dB/mm optical isolation. Evanescent semiconductor active optical isolators are composed of a semiconductor optical amplifier waveguide with an InGaAsP waveguide layers having an Fe layer at its sidewall upon an MQW active layer, allowing TE-mode optical isolation to be realized without etching the MQW active layer unlike conventional TE-mode semiconductor active optical isolators. Evanescent-mode optical isolators enable higher internal quantum efficiency and lower transparent current, compared with conventional TE-mode optical isolators. Furthermore, it was found that the evanescent-mode optical isolators had higher 3 dB saturation output power.