Broadband Bias-Magnet-Free On-Chip Optical Isolators with Integrated Thin-Film Polarizers

Most on-chip optical isolators utilize nonreciprocal magneto-optic (MO) garnet-materials that require an external bias magnetic field to operate. The magnetic field is applied through incorporation of either a permanent magnet or an active electromagnet. Permanent magnets add significantly to device bulk and electromagnets increase fabrication complexity and power consumption. Hence, it is highly desirable to reduce or eliminate the magnetizing component in these devices. Here, we experimentally demonstrate a first of its kind bias-magnet-free (BMF) on-chip waveguide optical isolator with integrated Polarcor UltraThin polarizers. The BMF isolator device obviates the need for magnetizing components while possessing superior performance, relative to other on-chip isolators, with ≥25 dB of isolation ratio (IR), and ≤3.5 dB of insertion loss (IL) across the entire infrared optical C-band.