All-optical nano modulator, sensor, wavelength converter, logic gate, and flip flop based on a manipulated gold nanoparticle

Asaf Shahmoon, Yoed Abraham, and Ofer Limon, Liora Bitton and Aviad Frydman, Ron Unger, Zeev Zalevsky
We developed a device in which one can shift and control the position of a gold nanoparticle by using special type of optical tweezers realized by guiding and confining light in a nanosize void structure in which the nanoparticle is placed. The nanosize void is positioned inside a multimode interference (MMI) region of a silicon waveguide. The coupling of light from two opposite sides of the optical device generates standing interference waves in the MMI region. The relative phase between the two coupled beams is controllable and therefore also the position of the fringes of the standing waves. Evanescent tails coming from the guided standing waves interfere in the void and allow control the position of the trapped nanoparticle. A nanoparticle with diameter of 30 nm was experimentally implanted in the void. The particle was trapped by one of the high intensity evanescent fringes. Changing the relative phase between the two inputs to the chip allowed us experimentally to modify the location of the fringes and the position of the particle (similarly to what happens in optical tweezers). This experimentally demonstrated capability may be useful for all-optical nano modulators, sensors, wavelength converters, logic gates and even a state machine (e.g. a flip flop).

DOI