Optoelectronic oscillator stabilized to an intra-loop atomic filter with a coherent population trapping resonance

Abstract

We report the construction and characterization of an optoelectronic oscillator stabilized to an intra-loop 85Rb cell with a 3.036-GHz coherent population trapping (CPT) resonance. We use an extended-cavity diode laser (ECDL) as a light source and directly modulate its injection current by using the beating signal filtered by the CPT resonance. Use of the ECDL guarantees stability of the carrier frequency and eliminates a bulky and power-consuming external modulator. We also adjust the cavity length and operate the ECDL in multimode in order to achieve a high modulation efficiency. To further improve the oscillator's frequency stability, we incorporate a negative feedback system based on a CPT dispersion. The Allan deviation of the oscillator frequency is 3 x 10(-10) at a 100-s integration time.