Description
We are working towards building a coherent population trapping (CPT) based Rubidium-87 atomic vapor-cell microwave-clock with a fractional frequency uncertainty <5×10⁻¹0 @1s integration/averaging time, as shown in the schematic and block diagrams on the right. Further we also intend to miniaturize this clock to chip-scale. Note that CPT is a coherent interference phenomenon. To create side bands, we modulate vertical cavity surface emitting laser’s (VCSEL’s) injection current at 3.42 GHz. And for locking laser to the central 795nm, we modulate VCSEL’s dc-bias current at e.g., 10 kHz as shown in the block diagram on the right.
