# US 12,184,326 B2 · Free space optical communications using a spectrally-equalizing amplifier > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,184,326 B2 - Document ID: US12184326B2 - Status: Granted - Kind: B2 - Application number: 18/743,973 - Filed: 2024-06-14 - Published: 2024-10-03 - Granted: 2024-12-31 - Earliest claimed: 2023-02-06 - Assignees: Attochron, LLC - Applicants: Attochron, LLC - Inventors: Thomas M. Chaffee; Wayne H. Knox - Web page: https://patentgrep.com/patent/US12184326B2 ## CPC - H04B 10/11: Arrangements specific to free-space transmission, i.e. transmission through air or vacuum - H04B 10/1121: {One-way transmission} - H04B 10/25073: {using spectral equalisation, e.g. spectral filtering} - H04B 10/2519: using Bragg gratings - H04B 10/2941: {using an equalising unit, e.g. a filter (H04B10/296 takes precedence)} - H04B 10/524: Pulse modulation - H04B: TRANSMISSION ## Abstract Systems and methods are described for transmitting information optically. For instance, a system may include an optical source configured to generate a beam of light. The system may include at least one modulator configured to encode data on the beam of light to produce an encoded beam of light/encoded plurality of pulses. The system may include a spectrally-equalizing amplifier configured to receive the encoded beam of light/encoded plurality of pulses from the at least one modulator and both amplify and filter the encoded beam of light/encoded plurality of pulses to produce a filtered beam of light/filtered plurality of pulses, thereby spectrally equalizing a gain applied to the encoded beam of light. In some cases, the system may slice the beam of slight, to ensure a detector has impulsive detection. In some cases, the system may include a temperature controller to shift a distribution curve of wavelengths of the optical source. ## Claims ### Claim 1 An optical system, the optical system comprising: an optical source configured to generate a first beam of light; and a spectrally-equalizing amplifier configured to produce a second beam of light based on the first beam of light, wherein the spectrally-equalizing amplifier spectrally equalizes a spectrum of the second beam of light, wherein the optical system is configured to transmit the second beam of light through a variably refractive medium to a target. ### Claim 2 (depends on 1) The optical system of claim 1, wherein the optical system is a lidar system. ### Claim 3 (depends on 1) The optical system of claim 1, wherein the optical system is a beacon system. ### Claim 4 (depends on 3) The optical system of claim 3, wherein the spectrally-equalizing amplifier is a gain-flattened amplifier that flattens a gain of the spectrum of the second beam of light, and the gain-flattened amplifier is a fiber amplifier comprising at least a core and a cladding surrounding the core, wherein the cladding comprises a transition metal ion compound, and the core of the gain-flattened amplifier is configured to both amplify and filter the spectrum of the second beam of light. ### Claim 5 (depends on 1) The optical system of claim 1, wherein, based on spectrally equalizing the spectrum of the second beam of light, amplified output wavelengths within a range are made to have substantively equal spectral power density. ### Claim 6 (depends on 1) The optical system of claim 1, wherein the optical source is a superluminescent diode (SLED), and the spectrally-equalizing amplifier is a nonlinear filter that amplifies the spectrum of the second beam of light and reduces high frequency noise. ### Claim 7 (depends on 1) The optical system of claim 1, wherein: photons, of the second beam of light, travel along a plurality of ray paths having different lengths to the target; the photons, of the second beam of light, arrive at the target according to a temporal distribution curve that depends, at least in part, on the different lengths of the plurality of ray paths; and a full width at half maximum (FWHM) value of the temporal distribution curve is at least three times as large as a coherence time value equal to a coherence length of the second beam of light divided by a speed of light through the variably refractive medium. ### Claim 8 (depends on 1) The optical system of claim 1, wherein the spectrally-equalizing amplifier includes one or more of: long-period fiber grating, a MEMs equalizer, or a thin film coating. ### Claim 9 (depends on 1) The optical system of claim 1, wherein the spectrally-equalizing amplifier is a Raman amplifier. ### Claim 10 (depends on 1) The optical system of claim 1, wherein the spectrum of the second beam of light is flattened to produce a distribution curve of wavelengths, wherein the distribution curve has a variance less than ±1 dB over a center range of wavelengths of the spectrally-equalizing amplifier. ### Claim 11 A method, the method comprising: generating, by an optical source, a first beam of light; producing, by a spectrally-equalizing amplifier, a second beam of light based on the first beam of light, wherein the spectrally-equalizing amplifier spectrally equalizes a spectrum of the second beam of light; and transmitting the second beam of light through a variably refractive medium to a target. ### Claim 12 (depends on 11) The method of claim 11, wherein the second beam of light has a measured quality of less than one in one million over a free space optical distance for a measurement period of at least sixty seconds. ### Claim 13 (depends on 11) The method of claim 11, wherein the spectrally-equalizing amplifier is a gain-flattened amplifier that flattens the spectrum of the second beam of light. ### Claim 14 (depends on 13) The method of claim 13, wherein the gain-flattened amplifier is a fiber amplifier comprising at least a core and a cladding surrounding the core, wherein the cladding comprises a transition metal ion compound and the core of the gain-flattened amplifier is configured to both amplify and filter the spectrum of the second beam of light. ### Claim 15 (depends on 11) The method of claim 11, wherein, based on spectrally equalizing the spectrum of the second beam of light, amplified output wavelengths within a range are made to have substantively equal spectral power density. ### Claim 16 (depends on 11) The method of claim 11, wherein the optical source is a superluminescent diode (SLED), and the spectrally-equalizing amplifier is a nonlinear filter that amplifies the spectrum of the second beam of light and reduces high frequency noise. ### Claim 17 (depends on 11) The method of claim 11, wherein: photons, of the second beam of light, travel along a plurality of ray paths having different lengths to the target; the photons, of the second beam of light, arrive at the target according to a temporal distribution curve that depends, at least in part, on the different lengths of the plurality of ray paths; and a full width at half maximum (FWHM) value of the temporal distribution curve is at least three times as large as a coherence time value equal to a coherence length of the second beam of light divided by a speed of light through the variably refractive medium. ### Claim 18 (depends on 11) The method of claim 11, wherein the spectrally-equalizing amplifier includes one or more of: long-period fiber grating, a MEMs equalizer, or a thin film coating. ### Claim 19 (depends on 11) The method of claim 11, wherein the spectrally-equalizing amplifier is a Raman amplifier. ### Claim 20 (depends on 11) The method of claim 11, wherein the spectrum of the second beam of light is flattened to produce a distribution curve of wavelengths, wherein the distribution curve has a variance less than 1 dB over a center range of wavelengths of the spectrally-equalizing amplifier.