894 D1 Collaborators: Gerginov, Tanner, Calkins.

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894nm laser--overhead view

Tanner's Graudate student (Calkins) and Postdoc (Gerginov).

Various Laser Components

894nm laser--angled view

P_½ lifetime is 34.894 ns (P_3/2 is 30.473 ns).

Natural linewidth (Lorentzian) is gamma/2pi where tau=1/gamma, so 10⁹/(35•2\pi)=4.56 MHz.

Doppler width, if not in a beam, 7.16×10^-7v₀ sqrt(T/M) 416 MHz.

Velocity of atoms: use derivative of Maxwell distribution to find mode of sqrt(2kT/M) or 1/2Mv^2=3/2kT to find rms with root 3 instead. Gives 220 m/s or 270 m/s (less than speed of sound). Mean is root(8/pi) factor instead or 250 m/s.

Doppler width (Gaussian) of 12 mrad beam is about 2.5 MHz. Use tan z=x/y=.006 z=6mrad=.35degrees so 1.5 m/s instead 250. Thus scale down the 416MHz.

Can ignore? pressure broadening since maybe 30 MHz/torr (sodium D) and 1.33•10^-4 Pa is 1.9•10^-8psi=.2millitorr? so 3 kHz. The shift might be 1/30 as much or 0.1 kHz. There is also Dicke narrowing especially in infra-red when doppler width is larger than the pressure-broadening.

Zeeman may be about 1 kHz. AC Stark is less than 0.1 kHz.

We are so slow that the second order doppler shift (higher order term in the expansion of gamma) is very ignorable. (1-beta²)^-½=1-½beta²+3/8beta⁴-15/48beta⁶...

Relative strength of each of the F-F' transitions (due to sublevel degeneracies, in order 3,4): S_FF': (1/12)(3 9/7 5).

Free spectral range: c/(4L)=299792458 m/s/0.4 m = 750 MHz. If whole? pathlength (back to diode): 250 MHz.

All pictures taken February 20, 2004.