A Scalable THz Photonic Crystal Fiber with Partially-Slotted Core That Exhibits Improved Birefringence and Reduced Loss

A photonic crystal fiber (PCF) based on high resistivity silicon is reported that exhibits high birefringence, low loss, and flat dispersion characteristics across a wide bandwidth in the THz regime. Except for the center region, which remains the background dielectric, its core is occupied by a set of rectangular air slots. The material and configuration lead to high birefringence and low loss. The simulation results, which include the material losses, indicate that a birefringence value of 0.82 and a total loss of 0.011 cm^-1, including the effective material loss and confinement losses, are achieved at 1.0 THz. These values are a factor of ten times higher and four times lower, respectively, than many recent designs. The numerical analyses also demonstrate that the reported PCF can be scaled to any desired portion of the THz regime, while maintaining a similar birefringence, simply by changing the lattice constant. This 'scalable' characteristic is shown to be applicable to other PCF designs. It could facilitate a novel way of testing THz fibers, i.e., it suggests that one only needs to test the preform to validate the performance of the fiber at higher frequencies. This outcome would significantly reduce the design complexity and the costs of PCF testing.