High-density photonic and optoelectronic integration is a natural alternative to electronic infrastructure and is a rapidly growing field.[1] Compared to traditional electrical transmission, optical transmission has a very large bandwidth (information capacity) and high speed. Central to progress in this area has been the development of materials and structures that can provide flexibility in connecting various nanophotonic elements. Conventionally, nanoscaled optical fibers are fabricated using a physical drawing process, and have been shown to be promising materials for low-loss optical guiding [2] and fast detection [3] . Admirable results presented by Yang and coworkers [4] demonstrate that single-crystalline semiconducting nanoribbons can be successfully used for passive and active photonic integrations. In addition, Lieber's group [5] reported that active nanowires have unique advantages in combination with electronics. Therefore, the fabrication of 1D single-crystal nanomaterials is of great scientific interest and technological significance, which will bring about the impetus of photonic integration and promote the development of optical information technology.Divanadium pentoxide (V 2 O 5 ), the most stable form in the vanadium oxide family, has been at the forefront of applied research due to its unique physical and chemical properties. For example, Gu and coworkers [6] showed that sheets made of entangled vanadium oxide nanofibres behave like artificial muscles (actuators) that contract reversibly under an electrical signal. In addition to its electromechanical properties, V 2 O 5 also exhibits excellent photochromic or electrochromic behavior [7] upon light irradiation or electrochemical reactions. A number of enabling mechanical and optical properties show that the low-dimensional nanostructures of V 2 O 5 are candidate materials for applications in photonics. In this regard, the optical properties of individual V 2 O 5 nanoribbons are desirable and significant for our study.There are several approaches available for synthesizing nanostructures of vanadium oxides. [8] It is important to develop a new method with desirable practical attributes, such as simplicity, catalyst-free, and not requiring extreme pressure conditions. [9] In this contribution, we have synthesized divanadium pentoxide nanoribbons using a simple thermal vapor deposition technique under ambient conditions. Representative dark-field optical images (Fig. 1a) revealed that nanoribbons with a typical length of several hundred micrometers, and even up to millimeters, were produced in high yield. The typical topography of the as-grown products was examined using field-emission scanning electron microscopy (SEM, JEOL JSM-6700F), as shown in Figure 2a. The ribbons have a rectangular cross-section with a typical width and height of %300 nm and %100 nm, respectively, giving a length-to-width or length-to-height aspect ratio of well over 1000. These nanostructures have excellent cross-section uniformity and smooth surfaces without pron...

No abstract