Broadband and low-cross talk mode multiplexer based on subwavelength-assisted phase matching.

Integrated mode multiplexers are key components in photonic networks and are crucial to achieving higher data density. Asymmetric directional couplers represent one of the most common multiplexing architectures, owing to their low losses and scalability, but further bandwidth enhancements are sought after. In this Letter, we demonstrate a multiplexer/demultiplexer link based on asymmetric directional couplers assisted by subwavelength grating metamaterials.

An Integrated Pump-Controlled Variable Coupler Fabricated by Ultrafast Laser Writing.

The design and fabrication of a integrated symmetric directional coupler dependent o the pumping power and operating at a 1534 nm wavelength is reported. The twin-core waveguide was inscribed into Er/Yb co-doped phosphate glass by a femtosecond laser direct writing technique. By optical pumping, the coupling ratio can be modulated due to the changes induced in the refractive index of the material.

Experimental demonstration of metamaterial anisotropy engineering for broadband on-chip polarization beam splitting.

Subwavelength metamaterials exhibit a strong anisotropy that can be leveraged to implement high-performance polarization handling devices in silicon-on-insulator. Whereas these devices benefit from single-etch step fabrication, many of them require small feature sizes or specialized cladding materials. The anisotropic response of subwavelength metamaterials can be further engineered by tilting its constituent elements away from the optical axis, providing an additional degree of freedom in the design.