# US 2022/0045753 A1 · Free Space Optical Communication Terminal with Dispersive Optical Component > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2022/0045753 A1 - Document ID: US20220045753A1 - Status: Published application - Kind: A1 - Application number: 17/394,287 - Filed: 2021-08-04 - Published: 2022-02-10 - Earliest claimed: 2020-08-04 - Assignees: SA Photonics, Inc. - Applicants: SA Photonics, Inc. - Inventors: James F. Coward; Greg G. Mitchell - Web page: https://patentgrep.com/patent/US20220045753A1 ## CPC - H04B 10/112: Line-of-sight transmission over an extended range - H04B 10/1125: {using a single common optical path} - H04B 10/114: Indoor or close-range type systems - H04B 10/1143: {Bidirectional transmission} - H04B 10/25: Arrangements specific to fibre transmission - H04B 10/29: Repeaters - H04B 10/50: Transmitters - H04B 10/614: {comprising one or more polarization beam splitters, e.g. polarization multiplexed [PolMux] X-PSK coherent receivers, polarization diversity heterodyne coherent receivers (H04J14/06 takes precedence)} - H04B 10/66: Non-coherent receivers, e.g. using direct detection - G02B 6/32: having lens focusing means {positioned between opposed fibre ends (with lens being an integral part of the single fibre end G02B6/262)} - H04B: TRANSMISSION - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract Embodiments relate to a local free space optical (FSO) terminal that transmits and receives optical beams. The FSO terminal includes a fore optic and a dispersive optical component. A receive (Rx) optical beam from a remote FSO terminal is received and focused by the fore optic to a Rx spot at a focal plane of the fore optic. A transmit (Tx) optical beam with a different wavelength forms a Tx spot at the focal plane and is collimated and projected by the fore optic to the remote FSO terminal. The dispersive optical component is positioned along optical paths of both the Rx beam and the Tx beam. Among other advantages, a wavelength dependence of the dispersive optical component laterally separates the Rx spot and the Tx spot at the focal plane. ## Claims ### Claim 1 A local free space optical (FSO) communication terminal configured to transmit optical beams to and receive optical beams from a remote FSO communication terminal, the local FSO communication terminal comprising: a fore optic having a focal plane, wherein a receive (Rx) optical beam from the remote FSO communication terminal is received and focused by the fore optic to a Rx spot at the focal plane and a transmit (Tx) optical beam forms a Tx spot at the focal plane and is collimated and projected by the fore optic to the remote FSO communication terminal; and a dispersive optical component that is positioned along optical paths of both the Rx optical beam and the Tx optical beam, wherein the Rx and Tx optical beams are different wavelengths and a wavelength dependence of the dispersive optical component laterally separates the Rx spot and the Tx spot at the focal plane. ### Claim 2 (depends on 1) The FSO communication terminal of claim 1, wherein the dispersive optical component is a refractive optical component. ### Claim 3 (depends on 2) The FSO communication terminal of claim 2, wherein the dispersive optical component is a wedge. ### Claim 4 (depends on 1) The FSO communication terminal of claim 1, wherein the dispersive optical component has transmission losses below 2 dB at the Tx and Rx wavelengths. ### Claim 5 (depends on 1) The FSO communication terminal of claim 1, wherein the dispersive optical component is a window of the FSO communication terminal. ### Claim 6 (depends on 1) The FSO communication terminal of claim 1, wherein the dispersive optical component is a diffractive optical component. ### Claim 7 (depends on 6) The FSO communication terminal of claim 6, wherein the diffractive optical component is a diffraction grating. ### Claim 8 (depends on 1) The FSO communication terminal of claim 1, wherein optical paths of the Rx optical beam and of the Tx optical beam in the local FSO communication terminal are circulator-less. ### Claim 9 (depends on 1) The FSO communication terminal of claim 1, wherein the lateral separation of the Rx spot and the Tx spot at the focal plane is not a result of a beam splitter positioned along optical paths of the Rx optical beam or the Tx optical beam. ### Claim 10 (depends on 1) The FSO communication terminal of claim 1, wherein the Rx optical beam is coupled from the Rx spot into an Rx fiber and the Tx optical beam is coupled from a Tx fiber to the Tx spot. ### Claim 11 (depends on 10) The FSO communication terminal of claim 10, wherein the Rx beam has a first wavelength, and the FSO communication terminal further comprises: a second Tx fiber on a laterally opposite side of the Rx fiber relative to the Tx fiber; and a Tx optical source, the Tx optical source coupled to the second Tx fiber and configured to produce a second Tx optical beam with the first wavelength. ### Claim 12 (depends on 10) The FSO communication terminal of claim 10, wherein the Tx beam has a first wavelength, and the FSO communication terminal further comprises: a second Rx fiber on a laterally opposite side of the Tx fiber relative to the Rx fiber; and an Rx optical detector, the Rx optical detector coupled to the second Rx fiber, the Rx optical detector configured to receive a second Rx beam with the first wavelength. ### Claim 13 (depends on 10) The FSO communication terminal of claim 10, wherein the Rx fiber and the Tx fiber are single mode fibers. ### Claim 14 (depends on 1) The FSO communication terminal of claim 1, further comprising a multi-core fiber with a first core and a second core, wherein the Rx optical beam is coupled from the Rx spot into the first core and the Tx optical beam is coupled from the second core to the Tx spot. ### Claim 15 (depends on 1) The FSO communication terminal of claim 1, wherein the Rx spot and the Tx spot are laterally separated by at least 125 micrometers. ### Claim 16 (depends on 1) The FSO communication terminal of claim 1, wherein the Rx spot and the Tx spot are laterally separated enough to reduce interference between the Tx and Rx beams at the focal plane below a threshold level. ### Claim 17 (depends on 1) The FSO communication terminal of claim 1, wherein the Tx and Rx wavelengths are selected from wavebands covered by ITU (International Telecommunication Union) channels. ### Claim 18 (depends on 17) The FSO communication terminal of claim 17, wherein the Tx and Rx wavelengths are selected from ITU publication G.694.1 or G.694.2. ### Claim 19 (depends on 17) The FSO communication terminal of claim 17, wherein either or both the Tx and Rx wavelengths are within 100 nm wavelength of 1064 nm. ### Claim 20 (depends on 1) The FSO communication terminal of claim 1, wherein the dispersive optical component has an index of refraction larger than 1.5 and smaller than 4.2.