Carbon-nanotube cathodes on optical fibers

Well-aligned carbon nanotubes (CNTs) arrays were synthesized on series of fibers with different diameters to serve as field-emission cathode. Because the CNTs emitters reach out from the fiber curved surface, the distance between emitters varies with the diameter of the fiber. With the fiber diameter decreasing, the field emission enhancement of CNTs array increased because the screen effect decreased with the distance between emitters increasing. While the fiber diameter decreased from 200μm to 40μm, the turn-on voltage of CNTs array decreased from 610V to 200V, at the same time the emission current dramatic increased. Our approach to fabricate this structure of CNT tip has a potential application for future vacuum micro- and nano-electronics devices, especially in constructing a photo-assisted field-emission cathode as a pulsed electron source.