Description
Optical tweezers have been used to trap micro- and nanoparticles varying in size from about 10nm up to many tens of microns. At the small end of this range, particles can be difficult to see, and it is possible for multiple particles to "invisibly" enter the trap. Generally, the higher the power of the trapping beam, the more likely it is that extra particles enter, which can change or corrupt measurements being made. However, if the trap power is too low, the probably of escape of a trapped particle through Brownian motion can become large. It will often be ideal to choose a trap power as a compromise between maximising the retention time of a single trapped particle within the trap, while minimising the probability of entry of additional particles. We model this entry/exit problem with two distinct methods: direct Monte Carlo simulation of particles in or near the trap, and solution of the time-dependent diffusion equation, and present results for some nanoparticle trapping problems of interest. Escape and entry of nanoparticles from or into the trap is particularly important when trying to use optically trapped nanodiamonds for quantum sensing.
| I am the presenting author | Yes |
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