# US 10,120,263 B2 · Low-duty-cycle continuous-wave photoconductive terahertz imaging and spectroscopy systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,120,263 B2 - Document ID: US10120263B2 - Status: Granted - Kind: B2 - Application number: 15/318,347 - Filed: 2015-06-12 - Published: 2017-05-04 - Granted: 2018-11-06 - Earliest claimed: 2014-06-13 - Assignees: The Regents of the University of California - Applicants: The Regents of the University of California - Inventors: Mona Jarrahi - Web page: https://patentgrep.com/patent/US10120263B2 ## CPC - G02F 1/3534: {Three-wave interaction, e.g. sum-difference frequency generation (G02F1/3532 takes precedence)} - G02F 2203/13: involving THZ radiation - 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 ## Abstract Systems and methods for plasmonics enhanced photomixing for generating continuous-wave (CW) frequency-tunable terahertz radiation in accordance with embodiments of the invention are disclosed. A photomixing system configured to generate continuous-wave terahertz frequency signals can include an optical pump configured to generate at least two beams, where the at least two beams are utilized to create a frequency-offset and operate below a 50% duty cycle, where the duty cycle includes an operation cycle and a sleep cycle. The photomixing system can also include a photomixer that includes a radiating element configured to receive the frequency-offset and to generate a terahertz radiation utilizing the received frequency-offset and the radiating element, where the radiating element includes at least one plasmonic contact electrode. ## Claims ### Claim 1 A photomixing system configured to generate continuous-wave terahertz frequency signals comprising: an optical pump configured to: generate at least two beams, where the at least two beams are utilized to create a frequency-offset; and operate below a 50% duty cycle, where the duty cycle includes an operation cycle and a sleep cycle, wherein the optical pump operates with an average optical pump power of less than or equal to 150 mW; and a photomixer comprising a radiating element configured to receive the frequency-offset and to generate a terahertz radiation utilizing the received frequency-offset and the radiating element, wherein the radiating element includes at least one plasmonic contact electrode. ### Claim 2 (depends on 1) The photomixing system of claim 1, wherein the radiating element is an antenna capable of broadband radiation. ### Claim 3 (depends on 2) The photomixing system of claim 2, wherein the radiating element is selected from the group consisting of a logarithmic spiral antenna, a dipole antenna, a bow-tie antenna, a log-periodic antenna, and a folded dipole antenna. ### Claim 4 (depends on 1) The photomixing system of claim 1, wherein the photomixer is fabricated on a substrate that is capable of absorbing photons in the optical pump's operating wavelength range. ### Claim 5 (depends on 4) The photomixing system of claim 4, wherein the photomixer is fabricated on an ErAs compound substrate. ### Claim 6 (depends on 4) The photomixing system of claim 4, wherein the photomixer is fabricated on an InGaAs compound substrate. ### Claim 7 (depends on 4) The photomixing system of claim 4, wherein the photomixer is fabricated on a substrate selected from the group consisting of GaAs, InGaAs, Ge, InP, Graphene, and GaN substrates. ### Claim 8 (depends on 1) The photomixing system of claim 1, wherein the generated terahertz radiation has a 0.25-2.5 THz frequency range. ### Claim 9 (depends on 1) The photomixing system of claim 1, wherein the generated terahertz radiation has a frequency range greater than 2.5 THz. ### Claim 10 (depends on 1) The photomixing system of claim 1, wherein the generated terahertz radiation has a frequency range less than 0.25 THz. ### Claim 11 (depends on 1) The photomixing system of claim 1, wherein the generated terahertz radiation is frequency-tunable. ### Claim 12 (depends on 1) The photomixing system of claim 1, wherein the generated terahertz radiation is a non-tunable radiation. ### Claim 13 A method for generating continuous-wave terahertz frequency signals using a photomixing system comprising: generating at least two beams using an optical pump, where the at least two beams are utilized to create a frequency-offset; operating the optical pump below a 50% duty cycle, where the duty cycle includes an operation cycle and a sleep cycle, wherein the optical pump operates with an average optical pump power of less than or equal to 150 mW; receiving the frequency-offset using a photomixer, where the photomixer comprises a radiating element, wherein the radiating element includes at least one plasmonic contact electrode; and generating a terahertz radiation based upon the received frequency-offset and the radiating element. ### Claim 14 (depends on 13) The method of claim 13, wherein the radiating element is an antenna capable of broadband radiation. ### Claim 15 (depends on 14) The method of claim 14, wherein the radiating element is selected from the group consisting of a logarithmic spiral antenna, a dipole antenna, a bow-tie antenna, a log-periodic antenna, and a folded dipole antenna. ### Claim 16 (depends on 13) The method of claim 13, wherein the photomixer is fabricated on a substrate that is capable of absorbing photons in the optical pump's operating wavelength range. ### Claim 17 (depends on 16) The method of claim 16, wherein the photomixer is fabricated on an ErAs compound substrate. ### Claim 18 (depends on 16) The method of claim 16, wherein the photomixer is fabricated on an InGaAs compound substrate. ### Claim 19 (depends on 16) The method of system of claim 16, wherein the photomixer is fabricated on a substrate selected from the group consisting of GaAs, InGaAs, Ge, InP, Graphene, and GaN substrates. ### Claim 20 (depends on 13) The method of claim 13, wherein the generated terahertz radiation has a 0.25-2.5 THz frequency range. ### Claim 21 (depends on 13) The method of claim 13, wherein the generated terahertz radiation has a frequency range greater than 2.5 THz. ### Claim 22 (depends on 13) The method of claim 13, wherein the generated terahertz radiation has a frequency range less than 0.25 THz. ### Claim 23 (depends on 13) The method of claim 13, wherein the generated terahertz radiation is frequency-tunable. ### Claim 24 (depends on 13) The method of claim 13, wherein the generated terahertz radiation is a non-tunable radiation.