# US 2021/0344170 A1 · Integrated laser detector > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0344170 A1 - Document ID: US20210344170A1 - Status: Published application - Kind: A1 - Application number: 17/228,706 - Filed: 2021-04-13 - Published: 2021-11-04 - Earliest claimed: 2020-05-01 - Assignees: Nexus Photonics LLC - Inventors: Tin Komljenovic - Web page: https://patentgrep.com/patent/US20210344170A1 ## CPC - H01S 3/0014: {Monitoring arrangements not otherwise provided for (photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003)} - H01S 5/1246: {plurality of phase shifts} - G01J 1/0414: {using plane or convex mirrors, parallel phase plates, or plane beam-splitters} - G01J 1/0425: {using optical fibers} - G01J 1/4228: {arrangements with two or more detectors, e.g. for sensitivity compensation} - G01J 1/4257: {applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam (monitoring arrangements for lasers in general H01S3/0014)} - G01J 11/00: Measuring the characteristics of individual optical pulses or of optical pulse trains - H01S 5/1231: {Grating growth or overgrowth details} - G01J 2001/4238: {Pulsed light} - G02B 6/12004: {Combinations of two or more optical elements} - G02B 6/124: Geodesic lenses or integrated gratings - G02B 6/4206: {Optical features (G02B6/4207, G02B6/421 take precedence)} - H01S 3/06704: {Housings; Packages} - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL - 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) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A PIC has first, second and third elements fabricated on a common substrate. The first element includes a structure supporting efficient coupling of one or more free-space optical modes of incident light into one or more waveguide guided optical modes. The second element includes an on-chip interferometer having an input optically coupled to the waveguide guided optical modes; one or more arms; one or more outputs; and a phase tuner configured to change optical path length in one or more of the arms. The third element includes one or more light detecting structures optically coupled to the one or more outputs of the second element, such that variation in optical power in the one or more outputs is detected, allowing an assessment of coherence characterizing the light incident on the first element of the PIC to be provided. ## Claims ### Claim 1 A PIC-based integrated laser detector comprising: first, second and third elements fabricated on a common substrate; wherein the first element comprises a structure supporting efficient coupling of one or more free-space optical modes of light incident on the first element into one or more waveguide guided optical modes; wherein the second element comprises an on-chip interferometer comprising: an input optically coupled to the waveguide guided optical modes; one or more arms; one or more outputs; and a phase tuner configured to change optical path length in one or more of the arms; and wherein the third element comprises one or more light detecting structures optically coupled to the one or more outputs of the second element, such that variation in optical power in the one or more outputs is detected, allowing an assessment of coherence characterizing the light incident on the first element to be provided. ### Claim 2 (depends on 1) The PIC-based integrated laser detector of claim 1: wherein key functionalities of the first and second elements are realized in dielectric materials; and wherein a key functionality of the third element is realized in a semiconductor material. ### Claim 3 (depends on 1) The PIC-based integrated laser detector of claim 1, additionally comprising: a fourth element; wherein the fourth element provides mode shaping functionality and enhances coupling efficiency between the free-space optical modes and the waveguide guided optical modes. ### Claim 4 (depends on 1) The PIC-based integrated laser detector of claim 1: wherein the first element comprises one or more optical gratings; and wherein the optical gratings provide filtering based on at least one of wavelength and angle of incidence. ### Claim 5 (depends on 4) The PIC-based integrated laser detector of claim 4, additionally comprising one or more control elements; wherein the first element comprises two or more optical gratings; and wherein the one or more control elements control coherent combining of power from different ones of the optical gratings. ### Claim 6 (depends on 4) The PIC-based integrated laser detector of claim 4, additionally comprising: a fifth element; wherein the fifth element provides polarization control functionality and enhances the coupling efficiency between the free-space optical modes and the waveguide guided optical modes, independent of polarization. ### Claim 7 (depends on 1) The PIC-based integrated laser detector of claim 1: wherein the first element comprises a corner reflector; and wherein the corner reflector provides broadband optical coupling between the free-space optical modes and the waveguide guided optical modes. ### Claim 8 (depends on 1) The PIC-based integrated laser detector of claim 1: wherein the first element comprises an edge coupler; and wherein the edge coupler provides broadband optical coupling between the free-space optical modes and the waveguide optical modes. ### Claim 9 (depends on 1) The PIC-based integrated laser detector of claim 1, connected to an electronic control circuit; wherein the electronic control circuit: provides control signals for the phase tuner; controls the one or more light detecting structures; and reads signals from the one or more light detecting structures. ### Claim 10 A PIC-based integrated laser detector comprising: two or more sub-systems and one or more phase tuners, the subsystems and the one or more phase tuners fabricated on a common substrate; wherein each sub-system comprises: first, second and third elements; wherein the first element comprises a structure supporting efficient coupling of one or more free-space optical modes of light incident on the first element into one or more waveguide guided optical modes; wherein the second element comprises an on-chip interferometer comprising: an input optically coupled to the waveguide guided optical modes; one or more arms; and one or more outputs; and wherein the third element comprises one or more light detecting structures optically coupled to the one or more outputs of the second element, such that variation in optical power in the one or more outputs is detected, providing a determination of coherence characterizing the incident light; wherein one of the one or more phase tuners is shared between two or more of the sub-systems, being configured to change optical path length in one or more of the arms in the corresponding two or more interferometers. ### Claim 11 A method of assessing coherence of incident light comprising one or more free space optical modes; the method comprising: intercepting the one or more free space optical modes with a PIC-based integrated laser detector comprising: first, second and third elements fabricated on a common substrate; wherein the first element comprises a structure supporting efficient coupling of the one or more free-space optical modes into one or more waveguide guided optical modes; wherein the second element comprises an on-chip interferometer comprising: an input optically coupled to the waveguide guided optical modes; one or more arms; one or more outputs; and a phase tuner configured to change optical path length in one or more of the arms; and wherein the third element comprises one or more light detecting structures optically coupled to the one or more outputs of the second element; operating the phase tuner, such that an optical path length of at least one arm of the interferometer is adjusted; receiving one or more signals from the one or more light detecting structures as the phase tuner is operated; and providing a measure of coherence of the incident light, based on analysis of the received one or more signals. ### Claim 12 (depends on 11) The method of claim 11, wherein operating the phase tuner comprises operating an electronic control circuit connected to the integrated laser detector, such that a control signal is generated and supplied to the phase tuner. ### Claim 13 (depends on 11) The method of claim 11, wherein providing a measure of coherence of the incident light comprises: analyzing the one or more signals received from the light detecting structures to yield a measure of fringe extinction ratio; and comparing the measure of fringe extinction ratio with a predetermined threshold of fringe extinction ratio. ### Claim 14 (depends on 13) The method of claim 13, wherein providing a measure of coherence of the incident light further comprises analyzing the one or more signals received from the light detecting structures to yield a measure of average power. ### Claim 15 (depends on 11) The method of claim 11, wherein providing a measure of coherence of the incident light comprises operating an electronic control circuit connected to the integrated laser detector. ### Claim 16 (depends on 11) The method of claim 11, wherein key functionalities of the first and second elements are realized in dielectric materials; and wherein a key functionality of the third element is realized in a semiconductor material. ### Claim 17 (depends on 11) The method of claim 11, wherein the integrated laser detector additionally comprises a fourth element, the fourth element providing mode shaping functionality and enhancing coupling efficiency between the free-space optical modes and the waveguide guided optical modes. ### Claim 18 (depends on 11) The method of claim 11: wherein the first element comprises one or more optical gratings; and wherein the optical gratings provide filtering based on at least one of wavelength and angle of incidence.