  Achieving precise and adjustable control over laser frequency is an essential
requirement in numerous applications such as precision spectroscopy, quantum
control, and sensing. In many such applications it is desired to stabilize a
laser with a variable detuning from an atomic line. In this study, we employ an
offset-stabilization scheme by utilizing phase contrast spectroscopy in
microfabricated atomic diffractive elements vapor-cells. The spectroscopic
response of such a device generates oscillating optical fringes, providing
multiple optical frequency stabilization points across a bandwidth of tens of
gigahertz, centered around the absorption resonances of Rb. Using this device,
we demonstrate laser stabilization at various offset frequencies with
instabilities reaching sub-megahertz levels. We further explore the fundamental
limitations of our hybrid atomic-photonic device, drawing parallels to
birefringent and dichroic spectroscopy apparatuses, which are commonly employed
for offset stabilization. Our system showcases a broad offset lock bandwidth, a
highly compact footprint, scalability to chip-scale production, and the ability
to operate without reliance on magnetic fields. These attributes pave the way
for a multitude of applications in quantum technologies.
