Gain-assisted optical tweezing of plasmonic and large refractive index microspheres

We have theoretically investigated optical tweezing of gain-functionalized microspheres using a highly focused single beam in the nonparaxial regime. employ Mie-Debye theory tweezers to calculate force acting on homogeneous and core-shell Mie with gain. demonstrate that gain plays crucial role manipulation, especially optimize restoring thus allowing for trapping large refractive index plasmonic particles. Indeed we one can trap such particles, which is usually not possible case passive media, by functionalizing them an material. show varying value gain, be realized changing pump power, only achieve but also manipulate equilibrium position tweezed particle. Altogether our findings open new venues gain-assisted optomechanics, where functionalized systems could facilitate manipulation nanoparticles particular, potential applications self-assembling nanoparticle suspensions chip.