Abstract
New designs for electro-optical free-space and waveguided 2 x 2 switches are presented and analyzed at the 1.55 μm telecoms wavelength. The proposed devices employ a ~10 nm film of GeSe that is electrically actuated to transition the layer forth-and-back from the amorphous to the crystal phase, yielding a switch with two self-sustaining states. This phase change material was selected for its very low absorption loss at the operation wavelength, along with its electro-refraction Δn ~0.6. All switches are cascadeable into N x M devices. The free-space prism-shaped structures use III-V prism material to match the GeSe crystal index. The Si/GeSe/Si "active waveguides" are quite suitable for directional-coupler switches as well as Mach-Zehnder devices-all of which have an active length 16x less than that in the free-carrier art.
Highlights
The stoichiometric IV-VI compound GeSe has been identified as a phase-change material (PCM) having two stable, self-sustaining states: its amorphous and crystalline phases [1,2,3,4,5]
This PCM has the capability of high-speed reversible transition between phases, and a recent paper [1] reports experiments on electrically actuated transitions using a field of ~80 V/μm applied to the GeSe film
The optical contrast between the two states of GeSe can be exploited in a suitable wavelength range by incorporating a thin GeSe film within the electro-optical structures that are proposed and analyzed in this paper
Summary
The stoichiometric IV-VI compound GeSe has been identified as a phase-change material (PCM) having two stable, self-sustaining states: its amorphous and crystalline phases [1,2,3,4,5] This PCM has the capability of high-speed reversible transition between phases (occurring in 100 ns or less), and a recent paper [1] reports experiments on electrically actuated transitions using a field of ~80 V/μm applied to the GeSe film. Looking at refractive index data given in the literature, we see that a key feature of GeSe is its very low optical absorption loss in both phases at the important wavelength of 1550 nm. That fact affords an opportunity to develop specialized low-loss electro-optical (EO) switching components for telecommunication and optical wireless applications
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