We present a graphene-based optical leaky wave antenna (OLWA) with diamond-shaped perturbations. The leaky wave antenna is created by applying diamond-shaped graphene perturbations to a Si3N4 waveguide. The leaky wave behavior is observed by changing the graphene chemical potential. Results in the form of leakage power, normalized directivity, and reflectance, transmittance, leakage power, normalized directivity, and normalized E-field are presented. The half power beamwidth (HPBW) of 1.2° is achieved by this antenna. The reflectance and transmittance are in a very low wavelength range between 1.4 and 1.6 µm throughout. The leakage of power is more for the lower graphene chemical potential. The graphene-based design is also compared to a gold-based design and silicon-based design to show the leakage comparison. The designed graphene-based OLWA can be used in medical sensing devices.