Anisotropic optical conductivity of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>n</mml:mi></mml:math>-doped type-II three-dimensional Dirac semimetal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>PtTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

We analyze theoretically the anisotropic optical conductivity of the $n$-doped type-II three-dimensional (3D) Dirac semimetal (DSM) ${\mathrm{PtTe}}_{2}$. With the effective Hamiltonian, which describes the anisotropic and tilted 3D Dirac cone in bulk ${\mathrm{PtTe}}_{2}$, the optical conductivities induced by the linearly polarized light are evaluated using the energy-balance equation derived from the Boltzmann equation. The in-plane optical conductivity ${\ensuremath{\sigma}}_{xx}(\ensuremath{\omega})$ is similar to that of isotropic and nontilted Dirac systems, whereas a unique out-of-plane optical conductivity ${\ensuremath{\sigma}}_{zz}(\ensuremath{\omega})$ has been found due to the tilt of the Dirac cone of ${\mathrm{PtTe}}_{2}$ along the ${k}_{z}$ direction. Both ${\ensuremath{\sigma}}_{xx}(\ensuremath{\omega})$ and ${\ensuremath{\sigma}}_{zz}(\ensuremath{\omega})$ are contributed by intraband and interband electronic transitions, where the interband transitions show more distinct anisotropic properties. We show that both ${\ensuremath{\sigma}}_{xx}(\ensuremath{\omega})$ and ${\ensuremath{\sigma}}_{zz}(\ensuremath{\omega})$ depend sensitively on energy relaxation times, temperature, and electron density, which enables their broad tunability in ${\mathrm{PtTe}}_{2}$, and promotes tailored applications of this and similar type-II 3D DSMs.