# US 10,374,704 B2 · Raman amplifier system and method with integrated optical time domain reflectometer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,704 B2 - Document ID: US10374704B2 - Status: Granted - Kind: B2 - Application number: 15/705,834 - Filed: 2017-09-15 - Published: 2018-01-18 - Granted: 2019-08-06 - Earliest claimed: 2012-09-19 - Assignees: Ciena Corporation - Applicants: Ciena Corporation - Inventors: Jean-Luc Archambault; Jun Bao; Balakrishnan Sridhar - Web page: https://patentgrep.com/patent/US10374704B2 ## CPC - H04B 10/0797: {Monitoring line amplifier or line repeater equipment} - G01M 11/3109: {Reflectometers detecting the back-scattered light in the time-domain, e.g. OTDR} - G01M 11/319: {Reflectometers using stimulated back-scatter, e.g. Raman or fibre amplifiers} - H01S 3/302: {in an optical fibre} - H04B 10/071: using a reflected signal, e.g. using optical time domain reflectometers [OTDR] - H04B 10/0731: {Testing or characterisation of optical devices, e.g. amplifiers} - H04B 10/2916: {using Raman or Brillouin amplifiers} - H04J 14/0227: {Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation} - H04Q 9/00: Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom - G01M 11/3136: {for testing of multiple fibers} - H01S 3/094042: {of a fibre laser} - H01S 3/094046: {of a Raman fibre laser} - H01S 3/1312: {by controlling the optical pumping} - H04B: TRANSMISSION - G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR - 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 - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) ## Abstract An optical module includes an optical amplifier configured to amplify Wavelength Division Multiplexing (WDM) channels transmitted on a fiber; and an optical time domain reflectometer (OTDR) configured to transmit an OTDR signal on the fiber and detect a back-scattered signal based thereon to test the fiber, wherein a wavelength of the OTDR signal is one of i) between one or more wavelengths associated with the optical amplifier and one or more wavelengths associated with the WDM channels and ii) greater than the one or more wavelengths associated with the WDM channels, for in-service operation of the OTDR. ## Claims ### Claim 1 An optical module, comprising: an optical amplifier contained in the optical module and configured to amplify Wavelength Division Multiplexing (WDM) channels transmitted on a fiber; and an optical time domain reflectometer (OTDR) contained in the optical module and configured to transmit an OTDR signal on the fiber and detect a back-scattered signal based thereon to test the fiber, wherein a wavelength of the OTDR signal is one of i) between one or more wavelengths associated with the optical amplifier and one or more wavelengths associated with the WDM channels and ii) greater than the one or more wavelengths associated with the WDM channels, for in-service operation of the OTDR, wherein the optical amplifier comprises a Raman amplifier, wherein the wavelength of the OTDR signal experiences gain when the Raman amplifier is on, and wherein the OTDR operates with the Raman amplifier on and off to determine gain. ### Claim 2 (depends on 1) The optical module of claim 1, wherein the wavelength of the OTDR signal is between 1470 nm and 1527.5 nm. ### Claim 3 (depends on 1) The optical module of claim 1, wherein the wavelength of the OTDR signal is greater than 1567 nm. ### Claim 4 (depends on 1) The optical module of claim 1, wherein the wavelength of the OTDR signal is substantially close to the one or more wavelengths associated with the WDM channels to experience similar gain from the optical amplifier. ### Claim 5 (depends on 1) The optical module of claim 1, wherein the OTDR comprises a tunable transmitter configured to transmit the wavelength of the OTDR signal at a plurality of wavelengths. ### Claim 6 (depends on 5) The optical module of claim 5, wherein the optical amplifier comprises a Raman amplifier, wherein the tunable transmitter is configured to tune the wavelength of the OTDR signal to a first wavelength which experiences gain from the Raman amplifier and tune the wavelength of the OTDR signal to a second wavelength which does not experience gain from the Raman amplifier, to determine a gain of the Raman amplifier in-service. ### Claim 7 (depends on 1) The optical module of claim 1, wherein the OTDR comprises a configurable pulse generator for the OTDR signal which is adjusted to change an operating mode of the OTDR. ### Claim 8 (depends on 7) The optical module of claim 7, wherein the optical amplifier comprises a Raman amplifier, and wherein the configurable pulse generator is configured to set pulse width to detect back reflection close to the Raman amplifier. ### Claim 9 An optical amplifier module, comprising: a Raman amplifier with one or more Raman pumps contained in the optical amplifier module and configured to transmit at Raman wavelengths on a fiber to amplify Wavelength Division Multiplexing (WDM) channels transmitted thereon; and an optical time domain reflectometer (OTDR) contained in the optical amplifier module and configured to transmit an OTDR signal on the fiber and detect a back-scattered signal based thereon to test the fiber, wherein a wavelength of the OTDR signal is one of i) between one or more wavelengths associated with the one or more Raman pumps and one or more wavelengths associated with the WDM channels and ii) greater than the one or more wavelengths associated with the WDM channels, for in-service operation of the OTDR, wherein the wavelength of the OTDR signal experiences gain when the Raman amplifier is on, and wherein the OTDR operates with the Raman amplifier on and off to determine gain. ### Claim 10 (depends on 9) The optical amplifier module of claim 9, wherein the wavelength of the OTDR signal is between 1470 nm and 1527.5 nm. ### Claim 11 (depends on 9) The optical amplifier module of claim 9, wherein the wavelength of the OTDR signal is greater than 1567 nm. ### Claim 12 (depends on 9) The optical amplifier module of claim 9, wherein the wavelength of the OTDR signal is substantially close to the one or more wavelengths associated with the WDM channels to experience similar gain from the optical amplifier. ### Claim 13 (depends on 9) The optical amplifier module of claim 9, wherein the OTDR comprises a tunable transmitter configured to transmit the wavelength of the OTDR signal at a plurality of wavelengths. ### Claim 14 (depends on 13) The optical amplifier module of claim 13, wherein the tunable transmitter is configured to tune the wavelength of the OTDR signal to a first wavelength which experiences gain from the Raman amplifier and tune the wavelength of the OTDR signal to a second wavelength which does not experience gain from the Raman amplifier, to determine a gain of the Raman amplifier in-service. ### Claim 15 (depends on 9) The optical amplifier module of claim 9, wherein the OTDR comprises a configurable pulse generator for the OTDR signal which is adjusted to change an operating mode of the OTDR. ### Claim 16 (depends on 15) The optical amplifier module of claim 15, wherein the configurable pulse generator is configured to set pulse width to detect back reflection close to the Raman amplifier. ### Claim 17 A method implemented by an optical module, comprising: amplifying, by an optical amplifier in the optical module, Wavelength Division Multiplexing (WDM) channels transmitted on a fiber; transmitting an optical time domain reflectometer (OTDR) signal by an OTDR in the optical module on the fiber, wherein the OTDR is integrated in the optical module with the optical amplifier, wherein the transmitting is performed both with and without the amplifying; detecting a back-scattered signal based on the OTDR signal to test the fiber for the transmitting performed both with and without the amplifying; and determining Raman gain of the optical amplifier based on comparing at least two detected back-scattered signals with and without the amplifying, wherein a wavelength of the OTDR signal is one of i) between one or more wavelengths associated with the optical amplifier and one or more wavelengths associated with the WDM channels and ii) greater than the one or more wavelengths associated with the WDM channels, for in-service operation of the OTDR.