Fabrication of 1x2 optical switch devices based on semiconductor-to-metallic phase transition characteristics of VO_2 smart coatings

摘要

We have successfully fabricated two types of optical switch devices, namely, all-optical switch (VO_2/quartz) and electro-optical switch (VO_2/TiO_2/ITO/glass) based on semiconductor-to-metallic phase transition characteristic of vanadium dioxide (VO_2) smart coatings. The VO_2 active layer, the TiO_2 buffer layer, and the ITO transparent conductive electrode used in these devices, were achieved by reactive pulsed laser deposition. The optical switching of the fabricated devices was investigated at λ = 1.55 μm. The semiconductor (on) to metallic (off) phase transition was controlled by photoexcitation of VO_2 in the case of the all-optical switch, and by an external electric-field between the ITO and the VO_2 layer in the case of the electro-optical switch. The extinction ratio (on/off) is found to be much higher for the all-optical switch than for the electro-optical switch. For the all-optical switch, extinction ratio of about 22 dB and 12 dB are obtained in the transmission and reflection modes respectively. In the case of the electro-optical switch, the extinction ratio is about 12 dB in the transmission mode and 5 dB in the reflection mode.