Broadband and CMOS-compatible polarization splitter and rotator built on a silicon nitride-on-silicon multilayer platform

Abstract

A broadband and CMOS-compatible polarization beam splitter and rotator (PSR) built on the silicon nitride-on-silicon multilayer platform is presented. The PSR is realized by cascading a polarization beam splitter and a polarization rotator, which are both subtly constructed with an asymmetrical directional coupler waveguide structure. The advantage of this device is that the function of PSR can be directly realized in the SiN layer, providing a promising solution to the polarization diversity schemes in SiN photonic circuits. The chip is expected to have high power handling capability as the light is input from the SiN waveguide. The use of silicon dioxide as the upper cladding of the device ensures its compatibility with the metal back-end-of-line process. By optimizing the structure parameters, a polarization conversion loss lower than 1 dB and cross talk larger than 27.6 dB can be obtained for TM-TE mode conversion over a wavelength range of 1450 to 1600 nm. For TE mode, the insertion loss is lower than 0.26 dB and cross talk is larger than 25.3 dB over the same wavelength range. The proposed device has good potential in diversifying the functionalities of the multilayer photonic chip with high integration density.

Design and analysis of a compact and broadband polarization beam splitter on silicon nitride on silicon-on-insulator multilayer platform using a partially overlapped vertical asymmetrical directional coupler

“…Taking advantage of the advancements in both the back-end-of-line or front-end-of-line processes, layer-by-layer integration can already be realized ideally with simple process flow in some commercial foundries 16 – 18 Compared with the devices fabricated in single layer, only a few more steps are required, which are fully compatible with the available CMOS technology. In our case, special attentions should be paid for the planarization of SiO2 layer (step 6), as it determines Hs, as well as the quality of SiN layer deposited later.…”

“…In this paper, we propose a PBS with a vertical ADC structure based on Si nitride (SiN)-on-SOI platform. On this platform, the devices or circuits fabricated in SiN and Si layers can work in many complementary ways due to the different material properties, thus offering much more functional flexibility with higher integration density 16 , 17 . Devices, such as interlayer coupler, 18 grating coupler, 19 polarization handling devices, 20 – 23 optical switches, 24 or Bragg grating filter, 25 have been demonstrated on this platform.…”

“…On this platform, the devices or circuits fabricated in SiN and Si layers can work in many complementary ways due to the different material properties, thus offering much more functional flexibility with higher integration density. 16,17 Devices, such as interlayer coupler, 18 grating coupler, 19 polarization handling devices, [20][21][22][23] optical switches, 24 or Bragg grating filter, 25 have been demonstrated on this platform. Different from the planar DC scheme, there exists extra freedom of the relative location between SiN and Si waveguides in the vertical ADC structure, which could break its horizontal and vertical symmetries simultaneously.…”

Chemical design of barium titanate thin films for nanophotonic devices

“…Theoretically, modulation at 1 GHz frequency is achievable in silicon-based modulators. 1,4,5 However, the modulation speed is below satisfactorily level, not comparable to the speed of the modulators which are made from III-V semiconductor compounds or EO materials such as LiNbO 3 . 6,7 Additionally, its operating voltage is not compatible with complementary metal-oxidesemiconductor (CMOS), which is a critical requirement for all chip-scale EO modulators in the future photonic system.…”

“…One of the key constraints for Si‐based photonic material is the low speed of silicon optical modulators as it is limited by the charge‐carrier lifetimes in reversed‐biased devices. Theoretically, modulation at 1 GHz frequency is achievable in silicon‐based modulators 1,4,5 . However, the modulation speed is below satisfactorily level, not comparable to the speed of the modulators which are made from III–V semiconductor compounds or EO materials such as LiNbO 3 6,7 .…”