In this work, for the first time a novel heptagonal photonic crystal fiber has been designed and analyzed. The proposed design has been introduced with a new type of glass material $Si7N3$. It has been numerically studied. The designed model has been rigorously investigated by ensuring the finite element method (FEM). By taking the advantages of above mentioned glass material ultrahigh nonlinearity is made. It offers ultra-high level nonlinearity of $48,850W-1km-1$ and high level of numerical aperture (NA) of 0.85 simultaneously at the wavelength $\lambda =1\mu m$. Moreover, some fundamental optical behaviors such as power fraction, confinement loss (CL) and scattering loss of the proposed PCF have also been mentioned. Leveraging all these advantages, such type of fiber is a great prospect for efficient high nonlinear applications, optical coherence tomography (OCT), super continuum generations and all optical signal processing applications