A 1550 NM phase change electro-optical shutter

This paper introduces a new electro-optical shutter with measured transmission loss of less than 1.3 dB in the shutter ON state and isolation of ~14 dB in the shutter OFF state. The shutter is composed of sub-wavelength metallic slits filled with germanium telluride (GeTe) phase change material (PCM). The slits serve both as waveguides for extra-ordinary transmission of optical signal and as nano-heaters for changing the phase of GeTe. This work focuses on thermal and optical characterization of the GeTe slits in both amorphous and crystalline states through Joule heating. As GeTe goes through its phase transition, its complex reflective index changes, resulting in a significant shift in the optical property of the shutter. In this work, the shutter is designed to have a strong peak in the transmission (with >75% transmission amplitude) at 1550 nm in the amorphous (OFF) state of GeTe. When GeTe crystalizes, the wavelength of transmission peak shifts and the transmission amplitude is modulated, resulting in only 4% transmission at 1550 nm. To the best of our knowledge, this work is the first demonstration of optical modulators using PCM and providing such a high contrast.