  We describe a high-performance, compact optical frequency standard based on a
microfabricated Rb vapor cell and a low-noise, external cavity diode laser
operating on the Rb two-photon transition at 778 nm. The optical standard
achieves an instability of 1.8x10$^{-13}$/$\sqrt{\tau}$ for times less than 100
s and a flicker noise floor of 1x10$^{-14}$ out to 6000 s. At long integration
times, the instability is limited by variations in optical probe power and the
AC Stark shift. The retrace was measured to 5.7x10$^{-13}$ after 30 hours of
dormancy. Such a simple, yet high-performance optical standard could be
suitable as an accurate realization of the SI meter or, if coupled with an
optical frequency comb, as a compact atomic clock comparable to a hydrogen
maser.
