Abstract: Provided is a chip-scale atomic clock having a folded optic configuration or physics package. In particular, the physics package includes a vapor cell for containing gaseous alkali atoms and a VCSEL for generating a laser light One or more heating elements are positioned to simultaneously heat both the vapor cell and VCSEL to the required operating temperature. A micro-lens element, positioned between the VCSEL and a reflector, is used to first expand the beam of light, and then to subsequently collimate the light after it is once reflected. Collimated, reflected light passes through the vapor cell wherein the alkali atoms are excited and a percentage of the reflected light is absorbed. A detector, located opposite the reflector and micro-lens array, detects light passing through the cell. An error signal is generated and the output voltage of a local voltage oscillator is successively stabilized.

Abstract: Provided is a chip-scale atomic clock having a folded optic configuration or physics package. In particular, the physics package includes a vapor cell for containing gaseous alkali atoms and a VCSEL for generating a laser light. One or more heating elements are positioned to simultaneously heat both the vapor cell and VCSEL to the required operating temperature. A micro-lens element, positioned between the VCSEL and a reflector, is used to first expand the beam of light, and then to subsequently collimate the light after it is once reflected. Collimated, reflected light passes through the vapor cell wherein the alkali atoms are excited and a percentage of the reflected light is absorbed. A detector, located opposite the reflector and micro-lens array, detects light passing through the cell. An error signal is generated and the output voltage of a local voltage oscillator is successively stabilized.