can I make an optical lattice with a non Ti:Sapphire laser? I am currently at a small undergraduate institution that does not have access to workhorses like a Ti:Saphire laser, however I am very interested in trying to make an optical lattice with lower power lasers (HeNe, Ar ion) and hopefully do something cool with it (can't really do ultracold stuff either but might be able to use a decent vacuum chamber). Thoughts?
 A: The AC Stark effect, which is describes how atoms feel a potential energy shift from off-resonant light, is for alkali atoms (1):
$$U(r)=\frac{3\pi c^2}{2\omega_0^3} \frac{\Gamma}{\Delta}I(r)$$
where $\omega_0$ is the frequency at resonance, $\Delta$ is the frequency detuning of your laser from this resonance, $\Gamma$ is the natural linewidth of the transition, and $I$ is the laser intensity. The usual strategy is to make both $\Delta$ and $I$ large. This lets you have a strong force on the atoms without much heating (which scales as $\frac{1}{\Delta^2}$).
The point is, if you want a weaker laser, for the same force you have to get closer to the resonance. This will correspondingly make the heating for a given force stronger, although if your atoms are relatively hot anyway that might not matter to you.
So, a few things you need to ask yourself are:

*

*How strong an optical lattice would you need, given your expected temperature?


*Do you have a laser with the right combination of detuning and power to reach that strength?


*Would you have to be so close to the resonance that heating becomes an insurmountable problem?
Good luck!
