Topographically anisotropic photonics for broadband integrated polarization diversity

Integrated polarimetric receivers have the potential to define a new generation of lightweight, high-performance instrumentation for remote sensing. To date, on-chip polarization-selective devices such as polarizing beam-splitters have yet to even approach the necessary performance, due to fundamental design limitations. Here, we propose, simulate and experimentally demonstrate a method for realizing spatially-mapped birefringence onto integrated photonic circuits, deemed topographically anisotropic photonics. With this robust and widely tolerant approach, devices can be constructed with strongly polarization-dependent modal properties and minimal wavelength dependence. An integrated polarizing beam-splitter (PBS) is realized with unprecedented performance: a record 0.52 octaves of fractional bandwidth (116 THz), maximum insertion loss of 1.4 +/- 0.8 dB, and a minimum extinction ratio of 16 +/- 3 dB, pushing it into the realm of wideband spectroscopy and imaging applications. Additionally, novel photonic structures such as polarization-selective beam-taps and polarization-selective microring resonators are demonstrated, enabling new on-chip polarimetric receiver architectures.