Nanofabrication on optical resonators using optical tweezers

We use an optical positioning and linking (OPAL) platform based on optical tweezers to fabricate a grating coupler on a microtoroid-shaped optical resonator for highly efficient coupling of light into the resonator, which acts as a chemical sensor. Light is coupled into and out of the microtoroid through a grating fabricated from 0.5 µm polystyrene particles on the rim of the microtoroid, which acts as a fiber-free coupler. Unlike a tapered fiber coupler, this particle grating is highly robust and not susceptible to mechanical and vibrational noise, paving the way for field-portable sensing devices.