Interferometric measurement of Van Hove singularities in strained graphene

This study presents a method based on the total internal reflection and phase-shifting interferometry for measuring the Van Hove singularities in strained graphene. A linearly polarized light passes through some quarter- and half-wave plates, a hemi-cylindrical prism, and a Mach-Zehnder interferometer. The Van Hove singularities manifest themselves as some sharp dips or peaks in the spectrum of the final phase difference of the two interference signals. The numerical analysis demonstrates that the number of Van Hove singularities is independent of the modulus of the applied stress, but their position shifts as the strength of the tension increases. Moreover, the number and location of singularities strongly depend on the stress direction relative to the zigzag axis in the graphene lattice. We also show that the location of singularities is independent of the tension direction relative to the tangential component of the electric field of the incident radiation.