# US 2021/0278610 A1 · Polarization splitter and rotator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0278610 A1 - Document ID: US20210278610A1 - Status: Published application - Kind: A1 - Application number: 17/330,772 - Filed: 2021-05-26 - Published: 2021-09-09 - Earliest claimed: 2019-09-24 - Assignees: MACOM Technology Solutions Holdings, Inc. - Applicants: MACOM Technology Solutions Holdings, Inc. - Inventors: Yunchu Li; Austin G. Griffith; Rich R. Grzybowski - Web page: https://patentgrep.com/patent/US20210278610A1 ## CPC - G02B 6/4213: {the intermediate optical elements being polarisation selective optical elements (G02B6/27 takes precedence)} - G02B 6/1228: {Tapered waveguides, e.g. integrated spot-size transformers (for coupling with fibres G02B6/305)} - G02B 6/126: using polarisation effects {(G02B6/1226 takes precedence)} - G02B 6/2726: {in or on light guides, e.g. polarisation means assembled in a light guide} - 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 6/2773: {Polarisation splitting or combining} - G02F 1/01: for the control of the intensity, phase, polarisation or colour (G02F1/29, G02F1/35 take precedence) - H04B 10/50: Transmitters - G02B 6/274: {based on light guide birefringence, e.g. due to coupling between light guides (G02B6/105, G02B6/024 take precedence; mechanically induced birefringence G02F1/0134)} - G02B 6/2793: {Controlling polarisation dependent loss, e.g. polarisation insensitivity, reducing the change in polarisation degree of the output light even if the input polarisation state fluctuates} - G02B 6/2813: {based on multimode interference effect, i.e. self-imaging} - G02B 2006/12116: {Polariser; Birefringent} - G02F 1/025: in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - H04B: TRANSMISSION ## Abstract Example polarization splitter and rotator devices are described. In one example, an optical apparatus includes a splitter configured to split a light signal into a first signal having a first polarization and a second signal having a second polarization, a polarization rotator configured to rotate the second polarization of the second signal into a third polarization, and a polarization mode converter configured to convert the third polarization of the second signal into the first polarization. In certain aspects of the embodiments, the splitter can be a curved multi-mode inference (MMI) polarization splitter, and the polarization rotator comprises input and output ports, with the output port being wider than the input port. The polarization mode converter can be an asymmetrical waveguide taper mode converter. The devices described herein can overcome the deficiencies of conventional devices and provide low insertion loss, flat and/or wide wavelength response, high fabrication tolerance, and compact size. ## Claims ### Claim 1 A method of transmitting a plurality of optically modulated signals for output to a fiber system, the method comprising the steps of: providing a first laser source configured to emit light of a first wavelength having a first polarization and a second laser source configured to emit light of a second wavelength having the first polarization, the second wavelength being different than the first wavelength; receiving a first portion of the light emitted by the first laser source with a first modulator and a second portion of the light emitted by the first laser source with a second modulator; receiving a first portion of the light emitted by the second laser source with a third modulator and a second portion of the light emitted by the second laser source with a fourth modulator; outputting a first modulated optical signal from the first modulator, the first modulated optical signal having the first polarization; outputting a second modulated optical signal from the second modulator, the second modulated optical signal having the first polarization; outputting a third modulated optical signal from the third modulator, the third modulated optical signal having the first polarization; outputting a fourth modulated optical signal from the fourth modulator, the fourth modulated optical signal having the first polarization; multiplexing the first modulated optical signal and the third modulated optical signal to provide a first multiplexed optical signal having the first polarization; multiplexing the second modulated optical signal and the fourth modulated optical signal to provide a second multiplexed optical signal having the first polarization; altering the second multiplexed optical signal to have a second polarization, the second polarization being different from the first polarization; and combining the first multiplexed optical signal having the first polarization and the second multiplexed optical signal having the second polarization into a third optical signal. ### Claim 2 (depends on 1) The method of claim 1, further comprising the step of providing the third optical signal to a fiber system. ### Claim 3 (depends on 1) The method of claim 1, wherein the first laser source and the second laser source are each laser diodes. ### Claim 4 (depends on 1) The method of claim 1, wherein the step of altering the second multiplexed optical signal to have the second polarization includes the step of passing the second multiplexed optical signal having the first polarization through a waveguide polarization rotator. ### Claim 5 (depends on 1) The method of claim 1, wherein the first polarization is a TE mode polarization. ### Claim 6 (depends on 1) The method of claim 1, wherein the first polarization is a TE mode polarization and the second polarization is a TM mode polarization. ### Claim 7 A method of detecting a plurality of optical signals at a plurality of wavelengths, the method comprising the steps of: receiving an optical signal including a plurality of polarization mixed optical signals, each of the polarization mixed optical signals being at a respective wavelength; splitting the plurality of polarization mixed optical signals into a first portion optical signal having a first polarization and a second portion optical signal having a second polarization; demultiplexing the first portion optical signal into a first wavelength optical signal at a first wavelength having the first polarization and a second wavelength optical signal at a second wavelength having the first polarization; routing the first wavelength optical signal to a first photodetector and the second wavelength optical signal to a second photodetector; converting the second portion optical signal having the second polarization into a third portion optical signal having the first polarization; demultiplexing the third portion optical signal into a third wavelength optical signal at the first wavelength having the first polarization and a fourth wavelength optical signal at the second wavelength having the first polarization; and routing the third wavelength optical signal to the first photodetector and the fourth wavelength optical signal to the second photodetector. ### Claim 8 (depends on 7) The method of claim 7, wherein the step of converting the second portion optical signal having the second polarization into a third portion optical signal having the first polarization includes the steps of: passing the second portion optical signal through a waveguide polarization rotator to produce a fourth portion optical signal having a third polarization; and altering the polarization of the fourth portion optical signal to the first polarization to produce the third optical signal having the first polarization. ### Claim 9 (depends on 7) The method of claim 7, wherein the first polarization is a TE mode polarization. ### Claim 10 (depends on 7) The method of claim 7, wherein the first polarization is a TE mode polarization and the second polarization is a TM mode polarization. ### Claim 11 (depends on 8) The method of claim 8, wherein the first polarization is a TE0 mode polarization, the second polarization is a TM mode polarization, and the third polarization is a TE1 mode polarization. ### Claim 12 An optical apparatus comprising: a splitter configured to split a light signal into a first signal having a first polarization and a second signal having a second polarization; a waveguide polarization rotator configured to rotate the second polarization of the second signal into a third polarization; and a polarization mode converter configured to convert the third polarization of the second signal into the first polarization. ### Claim 13 (depends on 12) The optical apparatus of claim 12, wherein the splitter is a multi-mode inference (MMI) polarization splitter. ### Claim 14 (depends on 13) The optical apparatus of claim 13, wherein the splitter is curved. ### Claim 15 (depends on 12) The optical apparatus of claim 12, wherein the polarization rotator comprises an input port and an output port, wherein the output port is wider than the input port. ### Claim 16 (depends on 15) The optical apparatus of claim 15, wherein the input port is at or about 420 nm wide, and the output port is at or about 1000 nm wide. ### Claim 17 (depends on 12) The optical apparatus of claim 12, wherein the polarization rotator comprises a rib layer and a ridge layer. ### Claim 18 (depends on 17) The optical apparatus of claim 17, wherein the rib layer is at or about 90 nm thick. ### Claim 19 (depends on 17) The optical apparatus of claim 17, wherein the ridge layer is at or about 220 nm thick. ### Claim 20 (depends on 17) The optical apparatus of claim 17, wherein the rib layer is at or about 1000 nm wide. ### Claim 21 (depends on 12) The optical apparatus of claim 12, wherein the polarization mode converter is an asymmetrical waveguide taper mode converter. ### Claim 22 (depends on 12) The optical apparatus of claim 12, wherein the first polarization is a zero order transverse-electric (TE) mode polarization and the second polarization is a zero order transverse-magnetic (TM) mode polarization. ### Claim 23 (depends on 12) The optical apparatus of claim 12, wherein the third polarization is a first order transverse-electric (TE) mode polarization. ### Claim 24 (depends on 12) The optical apparatus of claim 12, wherein the first signal having a first polarization and the second signal having the first polarization are output to one or more receivers. ### Claim 25 A method of light transmission comprising: splitting a light signal into a first signal having a first polarization and a second signal having a second polarization; rotating the second polarization of the second signal into a third polarization with a waveguide polarization rotator; and converting the third polarization of the second signal into the first polarization. ### Claim 26 (depends on 25) The method of claim 25, wherein the first polarization is a zero order transverse-electric (TE) mode polarization and the second polarization is a zero order transverse-magnetic (TM) mode polarization. ### Claim 27 (depends on 25) The method of claim 25, wherein the third polarization is a first order transverse-electric (TE) mode polarization. ### Claim 28 (depends on 25) The method of claim 25, wherein the first signal having a first polarization and the second signal having the first polarization are output to one or more receivers. ### Claim 29 An optical apparatus comprising: a polarization mode converter configured to convert a first polarization of a first light signal into a second polarization; a waveguide polarization rotator configured to rotate the second polarization of the first light signal into a third polarization; and a combiner configured to form a combined light signal by combining the first light signal having a third polarization with a second light signal having the first polarization. ### Claim 30 (depends on 29) The optical apparatus of claim 29, wherein the combined light signal is input into one or more optical transmission fibers. ### Claim 31 (depends on 29) The optical apparatus of claim 29, wherein the first light signal and the second light signal are generated by a laser light source.