PC waveguide switches on and off magnetically

In a photonic-crystal (PC) waveguide switch developed by scientists at Michigan Technological University, Integrated Photonics, and the Russian Academy of Sciences, the photonic bandgap is controlled magnetically, allowing switching via an external electromagnet.

Mar 1st, 2010

In a photonic-crystal (PC) waveguide switch developed by scientists at Michigan Technological University (Houghton, MI), Integrated Photonics (Hillsborough, NJ), and the Russian Academy of Sciences (Moscow, Russia), the photonic bandgap is controlled magnetically, allowing switching via an external electromagnet. The PC material contains bismuth, gadolinium, lutetium, iron, and oxygen and is grown on a gadolinium-gallium-garnet substrate.

The waveguide is 1.2 mm long, 2.75 µm thick, and about 5 µm wide with a 200 µm long one-dimensional PC section that has a 343.4 nm grating period and a 700 nm grating depth. Light with a 1550 nm wavelength is coupled into a 900 µm long feeder section connected to the waveguide. Although the waveguide is multimode, about 95% of the input light is coupled into the fundamental mode. The small stress birefringence in the feeder is largely offset by its geometrical birefringence, enabling TE-TM coupling for the fundamental mode (and which is suppressed for higher modes). Switching the magnetization direction rotates the optical polarization, switching the light off or on. Insertion loss for the device is 5.4 dB; the on-to-off transmission ratio is about 9. Contact Miguel Levy at mlevy.mtu.edu.

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