Correct for: ...of the mirror coatings on gravitational wave dectors a tight focusleads-> focus leads ...fits into a cuvette which for convenient -> which provides convenient ...external translation state,before mirror -> external translation stage, before the mirror ...far detuned form -> far detuned from CQED -> cavity QED Add reference for LG basis Add this paragraph to the conclusion, but I'm not sure if it is convincing. At this cavity length, we observe the transverse-mode fre- quency spacing of 40(5) MHz, which is within the same order of magnitude as the estimated atom-cavity cou- pling strength of 20 MHz. As a result, the presented cavity design can be employed to probe the atomic dy- namics in the regime of multi-mode strong coupling cav- ity QED