TE optical switch with high extinction ratio based on slab photonic crystals

A transverse electric optical switch (TEOS) with a high extinction ratio (EXR) based on slab photonic crystals (PhCs), comprising:

• an upper slab photonic crystal (PhC) and a lower slab PhC connected as a whole;
• said upper slab PhC is a first square-lattice slab PhC, a unit cell of said first square-lattice slab PhC comprises a high-refractive-index first rotated-square pillar, three first flat dielectric pillars and a background dielectric, said three first flat dielectric pillars are arranged horizontally, the three first flat dielectric pillars make the upper slab PhC connected as a whole, and each of said three first flat dielectric pillars comprises a high-refractive-index dielectric pipe and a low-refractive-index dielectric in a pipe, or 1 to 3 high-refractive-index flat films;
• said lower slab PhC is a second square-lattice slab PhC with a complete band gap;
• a unit cell of said second square-lattice slab PhC comprises a high-refractive-index second rotated-square pillar, three second flat dielectric pillars and a background dielectric;
• said three second flat dielectric pillars are arranged horizontally, said three second flat dielectric pillars make the lower slab PhC connected as a whole, and said three second flat dielectric pillars are high-refractive-index dielectric pillars;
• said background dielectric is a low-refractive-index dielectric;
• and an normalized operating frequency (a/λ) of said TEOS is 0.4057 to 0.406, 0.4267 to 0.4329, or 0.44 to 0.479, wherein a is one lattice constant of the first and second square-lattice slab PhCs, and λ is a wavelength of incident wave.