Optically trapped non-linear particles as probes for scanning near-field optical microscopy

We use the frequency doubled light from an optically trapped lithium niobate particle for non-intrusive scanning near-field optical microscopy. The detected power from this 50–100 nm diameter probe is currently tens of pW and is expected to approach nW with an improved detection system. The current experimental resolution is approximately 0.5 μm, while the ultimate theoretical resolution is 70–90 nm. An acoustic trap which potentially allows higher resolution imaging is briefly described.