# US 12,181,278 B2 · Measuring apparatus, on-chip instrumentation device and measuring method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,181,278 B2 - Document ID: US12181278B2 - Status: Granted - Kind: B2 - Application number: 17/800,612 - Filed: 2020-02-25 - Published: 2023-03-09 - Granted: 2024-12-31 - Earliest claimed: 2020-02-25 - Assignees: Nippon Telegraph and Telephone Corporation - Applicants: Nippon Telegraph and Telephone Corporation - Inventors: Katsumasa Yoshioka; Masayuki Hashisaka; Koji Muraki; Norio Kumada - Web page: https://patentgrep.com/patent/US12181278B2 ## CPC - G01B 9/02051: {Integrated design, e.g. on-chip or monolithic} - G01N 21/3581: using far infrared light; using Terahertz radiation - G01B 9/02003: using beat frequencies - G01B 9/02069: {Synchronization of light source or manipulator and detector} - G01R 15/24: using light-modulating devices - G01R 19/0007: {Frequency selective voltage or current level measuring (measuring frequency G01R23/00; testing attenuation in line transmission systems H04B3/48; monitoring testing in transmission systems H04B17/00)} - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract This application discloses a measurement apparatus that does not use a femtosecond laser light source and a delay stage. The measurement apparatus mixes a first laser light from a first CW laser light source and a second laser light from a second CW laser light source to generate an interference light having a beat in a range from GHz to THz and demultiplexes the interference light into a pump light and a probe light. A generating photoconductive antenna is irradiated with the pump light, and a detecting photoconductive antenna is irradiated with the probe light. A current value of an electromagnetic wave propagating through a waveguide connecting the generating photoconductive antenna and the detecting photoconductive antenna is measured using a current system connected to the detecting photoconductive antenna. ## Claims ### Claim 1 A measurement apparatus comprising: a first CW laser light source; a second CW laser light source; a photomixer configured to mix a first laser light from the first CW laser light source and a second laser light from the second CW laser light source to generate an interference light having a beat in a range from GHz to THz; an optical demultiplexer configured to demultiplex the interference light to output a pump light and a probe light; and an on-chip measurement device including a generating photoconductive antenna, a detecting photoconductive antenna, a waveguide connecting the generating photoconductive antenna and the detecting photoconductive antenna, and an ammeter connected to the detecting photoconductive antenna, wherein the generating photoconductive antenna is irradiated with the pump light, the detecting photoconductive antenna is irradiated with the probe light, and the ammeter is configured to measure a current value of an electromagnetic wave that propagates through the waveguide and reaches the detecting photoconductive antenna. ### Claim 2 (depends on 1) The measurement apparatus according to claim 1, wherein at least one of the first CW laser light source or the second CW laser light source is modulable in wavelength. ### Claim 3 (depends on 2) The measurement apparatus according to claim 2, wherein the waveguide includes a set of a first waveguide, a second waveguide, and a third waveguide, the second waveguide is divided into a first portion and a second portion, and a gap is provided between the first portion and the second portion, and the gap serves as a filter configured to cut noise of a DC component included in the electromagnetic wave. ### Claim 4 (depends on 1) The measurement apparatus according to claim 1, wherein the waveguide includes a set of a first waveguide, a second waveguide, and a third waveguide, the second waveguide is divided into a first portion and a second portion, and a gap is provided between the first portion and the second portion, and the gap serves as a filter configured to cut noise of a DC component included in the electromagnetic wave. ### Claim 5 (depends on 4) The measurement apparatus according to claim 4, wherein the first waveguide is divided into a first portion, a second portion, and a third portion, the generating photoconductive antenna is disposed between the first portion of the first waveguide and the second portion of the first waveguide, and the detecting photoconductive antenna is disposed between the second portion of the first waveguide and the third portion of the first waveguide. ### Claim 6 An on-chip measurement device comprising: a generating photoconductive antenna; a detecting photoconductive antenna; and a waveguide connecting the generating photoconductive antenna and the detecting photoconductive antenna, wherein the generating photoconductive antenna is irradiated with a pump light, the detecting photoconductive antenna is irradiated with a probe light, and an electromagnetic wave propagates through the waveguide from the generating photoconductive antenna to the detecting photoconductive antenna, and the waveguide includes a set of a first waveguide, a second waveguide, and a third waveguide, the second waveguide is divided into a first portion and a second portion, and a gap is provided between the first portion and the second portion, and the gap serves as a filter configured to cut noise of a DC component included in the electromagnetic wave. ### Claim 7 A measurement method comprising: mixing two CW laser lights to generate an interference light having a beat in a range from GHz to THz; demultiplexing the interference light into a pump light and a probe light; irradiating a transmitting photoconductive antenna with the pump light, and irradiating a detecting photoconductive antenna with the probe light; and measuring a current value between a pair of electrodes included in the detecting photoconductive antenna. ### Claim 8 (depends on 7) The measurement method according to claim 7, further comprising Hilbert-transforming the current value measured.