Frequency stabilization of a diode laser with a thin Cs-vapor cell

We propose a novel method of stabilizing laser oscillation frequency that uses a sub-Doppler spectrum of atoms in a thin vapor cell. An extended-cavity diode laser is frequency-locked to a hyperfine component of the Cs-D(2) line. In the Allan-variance measurements on the beat note between two lasers thus stabilized, a frequency stability of 6.6x10(-11) is achieved at an averaging time of 5.8 s. The frequency can be controlled even when the laser beam intensity is as small as 70 nW/cm(2).