Dual Wavelength Laser Designed for Locking to Cs-133 Atomic Transitions

In this paper, a phase locked dual wavelength laser (PLDWL) with a sampled Moiré sidewall grating operating at 894 nm is proposed. The beat frequency between the lasing lines is designed to be 9.19 GHz, equal to the difference frequency between two hyperfine energy levels in atoms of caesium-133. The PLDWL therefore has applications in miniature atomic clocks and room temperature magnetometers. Constructions of monolithic dual wavelength lasers with a phase locked beat frequency have been demonstrated [1] - [2] . However, because the wavelength spacing corresponding to the 9.19 GHz frequency separation is only 0.0245 nm, the difference in the periods of the dual gratings would be 0.0037 nm (assuming n =3.3412) which is beyond the limits of the technology used previously [1] - [2] . However, by utilizing a sampled Moiré grating, dual wavelength operation with a 9.19 GHz frequency separation can be achieved by setting the sampling periods of a laterally coupled dual grating laser.