Demonstration of an Ultra-Compact and Broadband TM-Pass Polarizer Using Nano-Elliptical Holes

An ultra-compact and large-bandwidth transversal magnetic (TM) polarizer is proposed and demonstrated. Low-loss propagation of TM modes is enabled by the creation of a bandgap using nano-elliptical holes, while transverse electric (TE) modes are effectively suppressed. Theoretical analysis results show that the proposed devices have a bandwidth (BW) over 305 nm (1394 nm~1699 nm) with a polarization extinction ratio (PER) above 20 dB and an insertion loss (IL) less than 1.0 dB. This wide BW covers the S-, C-, L- and U-bands, as well as part of the O-band, within a compact total device length of only <tex-math notation="LaTeX">3.996 ~μ m </tex-math> . Experimental results show IL < 1.0 dB and PER more than 20 dB in a BW of 220 nm. To our knowledge, this is currently the most compact TM polarizer on the 220 nm SOI platform, measuring <tex-math notation="LaTeX">3.996\,\,μ m\,\,× 0.58\,\,μ m </tex-math> , while delivering the same level of performance.