# US 2014/0153862 A1 · Polarization rotator assembly including a subwavelength composite portion > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153862 A1 - Document ID: US20140153862A1 - Status: Published application - Kind: A1 - Application number: 14/092,569 - Filed: 2013-11-27 - Published: 2014-06-05 - Earliest claimed: 2012-11-27 - Assignees: Teraxion Inc. - Applicants: Teraxion Inc. - Inventors: Marie-Josée PICARD; Yves PAINCHAUD - Web page: https://patentgrep.com/patent/US20140153862A1 ## CPC - G02B 6/126: using polarisation effects {(G02B6/1226 takes precedence)} - G02B 6/1228: {Tapered waveguides, e.g. integrated spot-size transformers (for coupling with fibres G02B6/305)} - G02B 6/2766: {Manipulating the plane of polarisation from one input polarisation to another output polarisation, e.g. polarisation rotators, linear to circular polarisation converters} - G02B 2006/12107: {Grating} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A polarization rotator assembly for rotating a polarization mode of an electromagnetic signal is provided. The polarization rotator assembly has a waveguiding structure of co-extensive first and second layers defining, successively, an input portion, a subwavelength composite portion and a polarization rotating portion. The subwavelength composite portion is formed by the first and second layers, where the second layer defines a subwavelength pattern. The polarization rotator portion is geometrically configured to rotate the polarization mode of the electromagnetic signal. ## Claims ### Claim 1 A polarization rotator assembly for rotating a polarization mode of an electromagnetic signal, the polarization rotator assembly comprising: a waveguiding structure having co-extensive first and second layers and having a first height corresponding to the first layer and a second height corresponding to a superposition of the first and second layers, the waveguiding structure having a waveguiding axis and comprising successively therealong: an input portion formed by the first layer; a subwavelength composite portion formed by the first and second layers, where the second layer defines a subwavelength pattern having a characteristic feature size which is less than half an effective wavelength of the electromagnetic signal when propagating therein; and a polarization rotator portion comprising at least the first and second layers and geometrically configured to rotate a polarization mode of the electromagnetic signal. ### Claim 2 (depends on 1) The polarization rotator assembly according to claim 1, wherein the polarization rotator portion is configured to rotate the polarization mode of the electromagnetic signal by 90 degrees. ### Claim 3 (depends on 1) The polarization rotator assembly according to claim 1, wherein the polarization rotator portion is configured to rotate the polarization mode of the electromagnetic signal from a TM polarized mode to a TE polarized mode. ### Claim 4 (depends on 1) The polarization rotator assembly according to claim 1, wherein the first and second layers are made of silicon, silicon nitride, silicon carbide, indium phosphide, gallium arsenide, a high-index polymer or a combination thereof. ### Claim 5 (depends on 1) The polarization rotator assembly according to claim 1, wherein the subwavelength pattern comprises a series of corrugations formed by said second layer and extending transversally to the waveguiding axis, said series of corrugations being interleaved with a series of gaps. ### Claim 6 (depends on 5) The polarization rotator assembly according to claim 5, wherein the gaps of the subwavelength pattern are filled with air or with a cladding material. ### Claim 7 (depends on 5) The polarization rotator assembly according to claim 5, wherein the series of corrugations has a fixed period. ### Claim 8 (depends on 5) The polarization rotator assembly according to claim 5, wherein the series of corrugations has a variable period. ### Claim 9 (depends on 5) The polarization rotator assembly according to claim 5, wherein the series of corrugations has a fixed duty cycle. ### Claim 10 (depends on 5) The polarization rotator assembly according to claim 5, wherein the series of corrugations has a variable duty cycle. ### Claim 11 (depends on 5) The polarization rotator assembly according to claim 5, wherein the series of corrugations has an aperiodic distribution. ### Claim 12 (depends on 1) The polarization rotator assembly according to claim 1, wherein the subwavelength pattern comprises a series of corrugations formed by said second layer and extending parallel to the waveguiding axis. ### Claim 13 (depends on 1) The polarization rotator assembly according to claim 1, wherein the subwavelength pattern comprises an array of pillars formed by said second layer. ### Claim 14 (depends on 1) The polarization rotator assembly according to claim 1, wherein the subwavelength pattern comprises an array of holes extending through said second layer. ### Claim 15 (depends on 1) The polarization rotator assembly according to claim 1, wherein the subwavelength pattern comprises a wedge-shaped section forming a longitudinally widening taper along said waveguiding axis. ### Claim 16 (depends on 1) The polarization rotator assembly according to claim 1, wherein the subwavelength composite portion tapers down from a first width to a second width. ### Claim 17 (depends on 1) The polarization rotator assembly according to claim 1, wherein the waveguiding structure further comprises a buffer zone between the subwavelength composite portion and the polarization rotator portion. ### Claim 18 (depends on 1) The polarization rotator assembly according to claim 1, wherein the polarization rotator portion is formed by the first and second layers and the rotation of the polarization mode of the electromagnetic signal based on a level difference between the first and the second heights. ### Claim 19 (depends on 17) The polarization rotator assembly according to claim 17, wherein the polarization rotation portion has an input end and an output end, and wherein a width of the second layer along the waveguiding axis decreases from the input end to the output end. ### Claim 20 (depends on 18) The polarization rotator assembly according to claim 18 wherein a width of the first layer along the waveguiding axis increases from the input end to the output end of the polarization rotating portion. ### Claim 21 (depends on 1) The polarization rotator assembly according to claim 1, wherein the polarization rotating portion comprises a polarization-rotating path and a polarization-maintaining path, said polarization rotating portion being geometrically configured to split the electromagnetic signal into two signal polarization components respectively guiding along the polarization rotating and maintaining paths.