A　polarization-stabilized　fundamental　mode　vertical　cavity　surface　emitting　laser　(VCSEL)　was　developed　for　a　coherent　population　trapping　(CPT)　Cs　atomic　clock.　The　VCSEL　achieved　a　single　stabilized　polarization　state　through　a　directly-etched　surface　grating　structure　on　the　surface.　The　device　polarization　characteristics　of　different　surface　grating　parameters　were　analysed　using　the　finite-difference　time-domain　(FDTD)　method.　For　the　fundamental　transverse　mode　condition,　the　lasing　wavelength　corresponded　to　the　Cs　atom＇s　D-1　line.　Owing　to　the　polarization-dependent　reflectivity　of　surface　gratings,　the　VCSEL＇s　orthogonal　polarization　suppression　ratio　(OPSR)　exceeded　20　dB.　Since　the　surface　grating　eliminated　the　degeneracy　of　the　two　orthogonal　linear　polarization　fundamental　modes,　a　linewidth　of　approximately　53　MHz　for　the　VCSEL　could　be　obtained　using　the　delayed　self-homodyne　method.　A　7.6　GHz　modulation　bandwidth　satisfied　the　atomic　clock＇s　bandwidth　requirement.　We　introduced　the　directly-etched　surface　grating　VCSEL　to　the　Cs　atomic　clock,　and　measured　the　CPT　resonance　signal.