Compact polarization splitter based on silicon grating-assisted couplers

Abstract

Compact polarization beam splitter (PBS) based on grating-assisted couplers is proposed by utilizing contra-directional coupling between two corrugated strip waveguides. The co-directional coupling in the device is greatly suppressed by the designed asymmetric structure. The phase matching condition is only satisfied for TE polarization at the central wavelength of 1550 nm by a spatially periodic refractive-index perturbation. Due to the contra-directional coupling, the device breaks the limit of the precise control of the coupling strength and length. The simulation results show that the presented PBS, with a coupling length of only 19 μm, has a broad working bandwidth (∼40 nm) for a crosstalk below -12 dB. A large fabrication tolerance (±40 nm) for the waveguide width is also achieved.

Nanophotonic Polarization Routers Based on an Intelligent Algorithm

“…[ 3,4 ] As an essential component of on‐chip integrated photonic devices, polarization router can separate and steer light with different polarizations of transverse electric (TE) and transverse magnetic (TM) modes into different output ports, so as to realize polarization division multiplex of channels. In the past few years, polarization routers are generally realized based on gratings, [ 5–8 ] optical waveguides, [ 9–12 ] photonic crystals, [ 13–16 ] plasmonic structures, [ 17–20 ] metamaterials [ 21–23 ] or some other structures. [ 24–27 ] Polarization routers based on gratings or waveguides usually possess simple configurations and high extinction ratio, but the large size restricts the practical applications for on‐chip dense integration.…”

“…[ 24–27 ] Polarization routers based on gratings or waveguides usually possess simple configurations and high extinction ratio, but the large size restricts the practical applications for on‐chip dense integration. [ 5,7–10 ] The routers based on photonic crystals possess high transmittance, but the bandwidth is narrow and the crosstalk is relatively large. [ 13,16 ] The plasmonic polarization routers are broadband and have smaller size, but usually possess large loss.…”

High-extinction-ratio silicon polarization beam splitter with tolerance to waveguide width and coupling length variations

“…The PER of the DC-based PBS decreased from 20 dB to 12 dB as the coupling length varied from 6.5 μm to 5.5 μm [23]. A compact PBS based on asymmetrical grating-assisted contradirectional couplers (GACCs) was theoretically proposed [24]. An advantage of such PBS is that it does not require stringent phase matching and coupling length conditions.…”

“…In theory the optical coupling between the two waveguides is monotonically dependent on the coupling length. To realize a single etch and simple fabrication process, a symmetrical vertical structure is used in our design, which differs from that in [24]. The upper cladding of both waveguides is air.…”

High Extinction Ratio and Broadband Silicon TE-Pass Polarizer Using Subwavelength Grating Index Engineering

“…High refractive index contrast makes silicon waveguides highly polarization dependent. To address this issue, various types of passive polarization management components have been reported recently, including polarization splitters [2,3], rotators [4][5][6][7][8][9][10] and polarizers [11][12][13][14][15][16]. Among them, polarizers which simply filter the undesired polarization state are suitable for many applications.…”