Microresonator-based all-optical transistor

We present theoretical estimates for a low-loss, all-optical transistor using a microresonator device whose fields interact evanescently with rubidium vapor. We use a four-level, electromagnetically induced absorption scheme to couple the light fields of the transistor. We show results indicating that a weak control beam with less than single-photon intensities can switch a much stronger signal beam with switching contrast of greater than 25 dB and loss less than 0.5 dB.