Fig. 1: Photon-momentum transfer and optical force in a nanofibre-based optomechanical system.
From: Ultra-long-range optical pulling with an optical nanofibre
a Schematic of pushing a droplet along a silica nanofibre by a 980-nm-wavelength light guided along the nanofibre. After penetrating the droplet, the tightly confined driving light (horizontal black arrows) diverges into the far-field (divergent black arrows), resulting in a positive momentum transfer (i.e. Δp > 0) and an optical pushing force (i.e. Fz > 0). b Calculated electric field |E| mapping of the HE11 mode (λ0 = 980 nm) of a 400-nm-diameter silica nanofibre penetrating through a 20-μm-diameter silicone-oil droplet. The grey dashed line indicates the profile of the droplet. Scale bar, 5 μm. c Schematic of pulling a droplet along a silica nanofibre by a 1550-nm-wavelength light guided along the nanofibre. After penetrating the droplet, the loosely confined driving light (horizontal black arrows) is focused into the nanofibre (focused black arrows) in the near-field, resulting in a negative momentum transfer (i.e. Δp < 0) and an optical pulling force (i.e. Fz < 0). d Calculated |E| mapping of the HE11 mode (λ0 = 1550 nm) penetrating through a 20-μm-diameter silicone-oil droplet. Scale bar, 5 μm. e Calculated λ0-dependent Fz with D = 400 nm (orange line) and D-dependent Fz with λ0 = 1550 nm (blue line), respectively.
