# US 8,787,768 B2 · Method and apparatus for synthesizing and correcting phase distortions in ultra-wide bandwidth optical waveforms > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,768 B2 - Document ID: US8787768B2 - Status: Granted - Kind: B2 - Application number: 12/793,028 - Filed: 2010-06-03 - Published: 2011-12-08 - Granted: 2014-07-22 - Earliest claimed: 2010-06-03 - Assignees: Raytheon Company - Applicants: Matthew J. Klotz; Jean-Paul Bulot - Inventors: Matthew J. Klotz; Jean-Paul Bulot - Web page: https://patentgrep.com/patent/US8787768B2 ## CPC - H04B 10/073: using an out-of-service signal (H04B10/071 takes precedence) - H04B 10/676: {for all-optical demodulation of the input optical signal} - H04B: TRANSMISSION ## Abstract In accordance with various aspects of the disclosure, a method, an apparatus and a system for characterizing and compensating for deterministic phase nonlinearities and distortion inherent in radio frequency and optical components utilized to synthesize a single sideband suppressed carrier optical waveform in the presence of random phase noise generated by an optical carrier source is disclosed. The method comprises mixing a modulated optical signal with a continuous wave optical signal in an optical coupler; optically heterodyning the mixed signal output from the optical coupler in a detector to produce a radio frequency waveform; and analyzing the produced radio frequency waveform in a processor based on a phase history of a preselected continuous wave signal to measure distortion characteristics of the radio frequency modulated optical signal. ## Claims ### Claim 1 A method for characterizing, in the presence of optical carrier phase noise, and compensating for deterministic phase nonlinearities and distortion inherent in radio frequency and optical components to modify time-bandwidth properties of a radio frequency waveform and synthesize a single sideband suppressed carrier optical waveform in the presence of random phase noise generated by an optical carrier source, the method comprising: mixing a modulated optical signal with a constant frequency optical signal in an optical coupler; optically heterodyning the mixed signal output from the optical coupler in a detector to produce a radio frequency waveform; digitizing the radio frequency waveform by an analog to digital converter to produce one or more digital waveform representations of the radio frequency waveform; comparing the digitized radio frequency waveform in a processor to known, theoretical phase history of a preselected continuous wave signal to measure distortion characteristics of the radio frequency modulated optical signal; and transforming the measured distortion characteristics to a baseband signal bandwidth by input-referred mapping by a bandwidth based scaling coefficient; wherein analyzed, characterized and transformed waveform distortion components of the digitized radio frequency waveform are used to pre-compensate the radio frequency waveform. ### Claim 2 (depends on 1) The method according to claim 1, further comprising: digitally mixing the one or more digital waveform samples with a preselected waveform to extract one or more waveform distortion components from the digitized radio frequency waveform. ### Claim 3 (depends on 2) The method according to claim 2, further comprising: using the processor to analyze and characterize the one or more waveform distortion components using Legendre Polynomials. ### Claim 4 A system for characterizing, in the presence of optical carrier phase noise, and compensating for deterministic phase nonlinearities and distortion inherent in radio frequency and optical components to modify time-bandwidth properties of a radio frequency waveform and synthesize a single sideband suppressed carrier optical waveform in the presence of random phase noise generated by an optical carrier source, the system comprising: an optical coupler configured to mix a modulated optical signal with a constant frequency optical signal; an optical detector configured to receive the mixed signal output from the optical coupler and optically heterodyne the mixed signal to produce a radio frequency waveform; an analog to digital converter configured to digitize the radio frequency waveform to produce one or more digital waveform samples of the radio frequency waveform; and a processor in communication with a memory having instructions stored therein which, when executed compare the digitized radio frequency waveform to a known, theoretical phase history of a preselected continuous wave signal and measure distortion characteristics of the radio frequency modulated optical signal, and wherein the processor transforms the measured distortion characteristics to a baseband signal bandwidth by input-referred mapping by a bandwidth based scaling coefficient, wherein analyzed, characterized and transformed waveform distortion components of the digitized radio frequency waveform are used to pre-compensate the radio frequency waveform. ### Claim 5 (depends on 4) The system according to claim 4, wherein the processor is configured to digitally mix the one or more digital waveform samples with a preselected waveform to extract one or more waveform distortion components from the digitized radio frequency waveform. ### Claim 6 (depends on 5) The system according to claim 5, wherein the processor is configured to analyze and characterize the one or more waveform distortion components using Legendre Polynomials. ### Claim 7 A computer-readable physical medium including instructions that, when executed by a processor, cause the processor to carry out functions related to compensating for deterministic phase nonlinearities and distortion in a radio frequency and optical components to modify time-bandwidth properties of a radio frequency waveform and synthesize a single sideband suppressed carrier optical waveform, the functions comprising: generating a first waveform comprising a linear frequency modulated chirp; determining a distortion component from a received second waveform; transforming the measured distortion component to a baseband signal bandwidth by input-referred mapping by a bandwidth based scaling coefficient; and modifying the first waveform using the transformed distortion component to pre-compensate for the deterministic phase nonlinearities and distortion of the received second waveform produced by the radio frequency components and the one or more optical components. ### Claim 8 (depends on 7) The computer-readable medium according to claim 7, further comprising repeating the determining and modifying until the first waveform is substantially free of the phase nonlinearities and the distortion. ### Claim 9 (depends on 7) The computer-readable medium according to claim 7, wherein the distortion component is determined by using Legendre Polynomials. ### Claim 10 (depends on 7) The computer-readable medium according to claim 7, further comprising modifying a bandwidth of the received second waveform to conform to a bandwidth of the first waveform.