Optical conductivity in orthorhombic d-wave superconductors

The large anisotropies observed in the in-plane transport properties of unt winned single crystals of YBa2Cu3O6.95 reside in the orthorhombic nature of its band structure which includes CuO chains as well as CuO2 planes. An in finite band model with distinct effective mass in a and b-direction is used to study the a.c. conductivity of a d-wave BCS superconductor. A subdomina nt s-wave admixture is also included in the gap because both symmetries bel ong to the same irreducible representation in an orthorhombic system. Param eters are fit to experimental data.