Thermomagnetic Recording On Silicon Waveguide

Researchers have demonstrated, for the first time, light-induced thermomagnetic recording in a magnetic thin-film on silicon waveguides. The new writing technique is poised to enable miniature high-performance magneto-optical memories that don’t require bulky optics or mechanical rotation. The devices are nonvolatile — meaning that data is saved even when no power is supplied to the device — and can withstand many cycles of writing and rewriting.

On-chip magneto-optical memories could enable all-optical alternatives to the electronic packet routers used in today’s telecommunications infrastructure. They would eliminate the energy and expense required for optical-electrical-optical conversions and enable flexible communication for each data packet. Magneto-optical memories could also offer bit-level storage for optical computers, which use light for processing, storing, and transferring data.

Magneto-optical memory devices use heat to demagnetize a small spot on a magnetic film above a critical temperature known as the Curie point. A locally applied magnetic field then determines the direction in which the spot is magnetized when it cools. Performing this type of thermomagnetic recording in a photonic integrated circuit requires controlling the magnetic state of a magnetic film inside a waveguide using light propagating in the waveguide.

The researchers used light propagating in the waveguide to reverse the magnetization direction by heating the magnetic recording film to near the Curie temperature. Their approach allows the material’s magnetization to be easily aligned along the direction of the applied external magnetic field.

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