How Does the Gradient Force Arise in Lasers?

[rida]

how come there is an electrical gradient in lasers? i means lasers are just monochromatic photons so how come a particle feels an electrical force there

 

[Drakkith]

A laser emits coherent electromagnetic waves. That's what light is; an electromagnetic wave. This wave consists of electric and magnetic fields that constantly alternate from + to - and back. The higher the intensity of the light, the greater the electric and magnetic forces felt by a particle in the beam path.

Also, depending on the size of the particle and the wavelength, the particle can experience radiation pressure by absorbing or reflecting light, taking some of the lights momentum and being accelerated away from the source.

 

[rida]

in polystyrene bead placed in lase, only the refracted wave is responsible for electrical gradient not the reflected one. how come it is so

 

[Andy Resnick]

how come there is an electrical gradient in lasers? i means lasers are just monochromatic photons so how come a particle feels an electrical force there

Because the intensity varies in spatial extent.