Silicon-based 2D slab nano photonic crystal TM polarizer in telecommunication wavelength

We report an extremely compact (15.4 μm x 8 μm) silicon-based 2D slab nano photonic crystal transverse magnetic (TM) polarizer which blocks propagation of the transverse electric (TE) polarized light around telecommunication wavelength (1,550 nm). TM polarization occurs in a length of mere 4.9 μm and it has a great potential to be integrated in a complex photonic integrated circuits. To our knowledge, this is the first ever demonstration of silicon-based TM polarizer in telecommunication wavelength. 2D and 3D finite difference time domain (FDTD) simulation was utilized to design a triangular array of air holes in silicon. Such photonic crystal TM polarizer was fabricated in silicon-on-insulator wafer using focused ion beam and reactive ion etch with air hole diameter of 170 nm and pitch distance of 347 nm for the TM polarizer and 371 nm for the input and output waveguide. The device was fully characterized using tunable lasers in the wavelength range of 1,528 nm ~ 1,604 nm. Transmitted light intensities of the TE and TM polarized lights were measured which clearly showed the TE polarized light is filtered out around 1.55 μm wavelength.