# US 11,442,235 B1 · Optical system including optical devices having in-situ capacitive structures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,442,235 B1 - Document ID: US11442235B1 - Status: Granted - Kind: B1 - Application number: 17/444,000 - Filed: 2021-07-29 - Granted: 2022-09-13 - Earliest claimed: 2021-07-29 - Assignees: Hewlett Packard Enterprise Development LP - Applicants: Hewlett Packard Enterprise Development LP - Inventors: Di Liang; Sudharsanan Srinivasan - Web page: https://patentgrep.com/patent/US11442235B1 ## CPC - G02B 6/4286: {Optical modules with optical power monitoring} - G01J 1/0209: {Monolithic} - G01J 1/0407: {Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings} - G01J 1/0425: {using optical fibers} - G01J 1/46: using a capacitor - H04B 10/0799: {Monitoring line transmitter or line receiver equipment} - H04B 10/50: Transmitters - H04B 10/69: Electrical arrangements in the receiver - H10F 30/10: the devices being sensitive to infrared radiation, visible or ultraviolet radiation, and having no potential barriers, e.g. photoresistors - H10F 77/413: {directly associated or integrated with the devices, e.g. back reflectors (directly associated or integrated with photovoltaic cells H10F77/42)} - H10F 77/703: {of the semiconductor bodies, e.g. textured active layers} - G02B 6/12007: {forming wavelength selective elements, e.g. multiplexer, demultiplexer} - G02B 6/29338: {Loop resonators} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) - H04B: TRANSMISSION - H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION ## Abstract Examples described herein relate to an optical system. In some examples, the optical system may include a light-conducting medium and a first optical device to transmit an optical signal over the light-conducting medium. Further, the optical system may include a second optical device coupled to the light-conducting medium to receive an optical signal transmitted by the first optical device. In some examples, at least one of the first optical device, the light-conducting medium, and the second optical device may include an in-situ capacitive structure to detect light intensity. Moreover, the optical system may include a monitoring circuit electrically coupled to the in-situ capacitive structure to generate an electrical signal indicative of the light intensity detected by the in-situ capacitive structure. ## Claims ### Claim 1 An optical system, comprising: a light-conducting medium; a first optical device to transmit an optical signal over the light-conducting medium; a second optical device coupled to the light-conducting medium to receive the optical signal transmitted by the first optical device, wherein at least one of the first optical device, the light-conducting medium, and the second optical device comprises a capacitive structure to detect light intensity; and a monitoring circuit electrically coupled to the capacitive structure to cause generation of an electrical signal via the capacitive structure indicative of the light intensity detected by the capacitive structure; wherein, the capacitive structure comprises: a waveguide region comprising a first-type doping and carrying the optical signal, wherein the waveguide region comprises one or more defect sites causing generation of free charge carriers relative to an intensity of the optical signal in the waveguide region resulting in a change in a conductance of the waveguide region; a buffer semiconductor region comprising a second-type doping; and an insulating layer disposed between the waveguide region and the buffer semiconductor region. ### Claim 2 (depends on 1) The optical system of claim 1, wherein the first optical device comprises one of a light source, an optical amplifier, an optical modulator, an optical splitter, an optical combiner, an optical coupler, an optical filter, an optical resonator, or a photodetector. ### Claim 3 (depends on 1) The optical system of claim 1, wherein the second optical device comprises one of an optical amplifier, an optical modulator, or a photodetector. ### Claim 4 (depends on 1) The optical system of claim 1, wherein the capacitive structure further comprises a first contact region comprising the first-type doping and disposed in contact with the waveguide region. ### Claim 5 (depends on 4) The optical system of claim 4, wherein the capacitive structure further comprises a second contact region comprising the second-type doping and disposed in contact with the buffer semiconductor region. ### Claim 6 (depends on 5) The optical system of claim 5, wherein the monitoring circuit is electrically coupled to the first contact region and the second contact region via respective metal contacts to: apply a reference variable voltage signal to the first contact region; and measure an electrical current flowing through the second contact region. ### Claim 7 An optical system, comprising: an optical modulator; a coupling waveguide disposed adjacent to the optical modulator and comprising a first capacitive structure formed along at least a portion of the coupling waveguide to detect light intensity inside the coupling waveguide; and a monitoring circuit electrically connected to the first capacitive structure at a first monitoring site and at a second monitoring site to cause generation of a first electrical signal and a second electrical signal via the first capacitive structure indicative of the light intensities at the first monitoring site and the second monitoring site, respectively, wherein the optical modulator is optically coupled to the coupling waveguide between the first monitoring site and the second monitoring site and the monitoring circuit determines an insertion loss of the optical modulator based on the first electrical signal and the second electrical signal. ### Claim 8 (depends on 7) The optical system of claim 7, wherein the optical modulator comprises a second capacitive structure to detect light intensity inside the optical modulator. ### Claim 9 (depends on 7) The optical system of claim 7, further comprising one or more additional optical modulators optically coupled to the coupling waveguide between the first monitoring site and the second monitoring site forming a bank of optical modulators comprising the optical modulator and the one or more additional optical modulators. ### Claim 10 (depends on 9) The optical system of claim 9, wherein the monitoring circuit determines an insertion loss of the bank of optical modulators based on the first electrical signal and the second electrical signal. ### Claim 11 (depends on 9) The optical system of claim 9, wherein the first capacitive structure comprises a waveguide region comprising a first-type doping and carrying an optical signal, wherein the waveguide region comprises one or more defect sites causing generation of free charge carriers relative to an intensity of the optical signal in the waveguide region resulting in a change in a conductance of the waveguide region. ### Claim 12 (depends on 11) The optical system of claim 11, wherein the first capacitive structure further comprises a buffer semiconductor region comprising a second-type doping. ### Claim 13 (depends on 12) The optical system of claim 12, wherein the first capacitive structure further comprises an insulating layer disposed between the waveguide region and the buffer semiconductor region. ### Claim 14 (depends on 12) The optical system of claim 12, wherein the first capacitive structure further comprises: a first contact region comprising the first-type doping and disposed in contact with the waveguide region; and a second contact region comprising the second-type doping and disposed in contact with the buffer semiconductor region. ### Claim 15 (depends on 14) The optical system of claim 14, wherein the monitoring circuit is electrically coupled to the first contact region and the second contact region via respective metal contacts to: apply a reference variable voltage signal to the first contact region; and measure an electrical current flowing through the second contact region. ### Claim 16 A method, comprising: applying, by a monitoring circuit, reference variable voltage signals to a monitoring site of a first capacitive structure and a monitoring site of a second capacitive structure, wherein the first capacitive structure is formed in a coupling waveguide and the second capacitive structure is formed in an optical device optically coupled to the coupling waveguide; measuring, by the monitoring circuit, electrical signals generated at the monitoring site of the first capacitive structure and the monitoring site of the second capacitive structure; and determining, by the monitoring circuit, at least one of an amplification gain and an insertion loss caused by the optical device based on the measured electrical signals. ### Claim 17 (depends on 16) The method of claim 16, further comprising tuning an operating wavelength of the optical device based on the measured electrical signals.