Application of reduced light shift optical pumping method to chip scale atomic clock

In a chip scale atomic clock (CSAC), a laser beam with a higher intensity is usually used to achieve a good contrast of the clock transition signal. Thus the light shift (AC Stark shift) is of great importance to the performance of a CSAC device. Here we apply the reduced light shift optical pumping method to a micro-machined ⁸⁷Rb vapor cell in order to reduce the sensitivity of the measured clock frequency to various operational parameters. The preliminary result shows the improved short term stability.