Contents I. Introduction
The optical switch is an important device because of its wide application in optical networks and photonic integrated circuits (PIC). A lot of optical switches with various structures have been reported, such as the directional coupler [1], the Mach–Zehnder interference [2], the total-internal-reflection (TIR) optical switch [3], [4], and the microring resonators [5]. The TIR switch has tremendous potentials for the planar lightwave circuit (PLC) due to its small size, polarization independence, and capability to be monolithically integrated with other optical and electrical devices. Employing the electrical-current-induced carrier effect, TIR switches have been designed and fabricated on InP, SiGe, and silicon-on-insulator (SOI) materials [3], [6], [7]. However, they commonly suffer from heat problem caused by current injection. Since the heat generated by the photon injection is smaller, using the photon-induced carrier effect to replace the current-induced effect can resolve this problem. It has been observed and proved that the photon-induced carrier effect can also generate significant refractive-index changes [2], [8]. Meanwhile, since both the electron and the hole are excitated in pairs when photons are injected, the velocity of carrier recombination is faster than that in the case of electrical-current injection, which means that the response speed of the photon-induced carrier effect is faster than that of the electrical-current-induced carrier effect. The ultrafast optical switches controlled by light pulses have been researched widely in recent years [9]–[11]. In this letter, a photon-induced TIR optical switch is designed and fabricated on GaAlAs/GaAs. The principle of this TIR optical switch is presented first. Then it is fabricated and characterized.
