A horizontally asymmetric transverse magnetic (TM) pass polarizer is presented. The device passes only TM mode and rejects transverse electric (TE) mode. The proposed device has an asymmetricity in the horizontal direction comprising a direction coupler region with a silicon waveguide, silicon nitride waveguide, and an air gap, all residing on silica. Between three equal width Si waveguides, we have one region filled with air and the other with SiN with unequal optimized widths. The device with its optimal dimensions yields an extremely low insertion loss (IL) of 0.16 dB for TM→TM, while TE is rejected by an IL of >48 dB. The proposed polarizer is operated between C&L bands with a high extinction ratio and broadband width of about 110 nm.
A Grating Based hybrid-Plasmonic-waveguide with subwavelength optical-confinement is
proposed which exhibits large-propagation-length with low-modal-propagation-loss. The Grating is
formed in Si region by varying the grating period and duty cycle. The thickness of the grating region
is 600 nm and the grating period is 700 nm. The mode is confined in the 10 nm SiO<sub>2</sub> region. The Si
layer below the SiO<sub>2</sub> provides the large propagation length of 4 mm with low modal propagation loss
of 1 dB/mm with subwavelength mode confinement 0.00079/ μm<sup>2</sup> is obtained.