Nano-structured top contact with low optical polarization dependence for THz generation using photodiodes

Uni-travelling carrier photodiode (UTC-PD) with different top optical and electrical accesses are proposed towards optical polarization sensitivity reduction. With the optimized structure, only 1 percent dependence in optical polarization is obtained while ensuring good RF access. Measurements up to 110 GHz are presented at -1V bias and 25.3 mW optical power.