# US 2013/0182729 A1 · Wavelength locker design for precise channel locking of a widely tunable laser > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0182729 A1 - Document ID: US20130182729A1 - Status: Published application - Kind: A1 - Application number: 13/349,513 - Filed: 2012-01-12 - Published: 2013-07-18 - Earliest claimed: 2012-01-12 - Assignees: Mars Technology - Inventors: Ruolin Li; Wenjun Fan - Web page: https://patentgrep.com/patent/US20130182729A1 ## CPC - H01S 5/0687: Stabilising the frequency of the laser - H04B 10/572: Wavelength control - H04J 14/02: Wavelength-division multiplex systems - H01S 5/0683: by monitoring the optical output parameters - 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 - H04B: TRANSMISSION - 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) ## Abstract In accordance with aspects of the present disclosure, a method is disclosed. The method includes controlling an operational wavelength of a wavelength tunable laser by receiving radiation from the laser at first photo-detector including a first optical element having a partially reflective coating on a front surface of the first optical element; receiving at least a portion of the radiation partially reflected from the front surface of the first optical element at an etalon; receiving radiation from the etalon at a second photo-detector including a second optical element having an anti-reflection coating on a front surface of the second optical element; determining, by processor, a control signal to be applied to the laser to control the operational wavelength of the radiation based on data from the first and the second photo-detectors; and transmitting the control signal to the laser to, control the operational wavelength of the radiation. ## Claims ### Claim 1 A method comprising: controlling an operational wavelength of a wavelength tunable laser by: receiving radiation from the laser at first photo-detector including a first optical element having a partially reflective coating on a front surface of the first optical element; receiving at least a portion of the radiation partially reflected from the front surface of the first optical element at an etalon; receiving radiation from the etalon at a second photo-detector including a second optical element having an anti-reflection coating on a front surface of the second optical element; determining, by processor, a control signal to be applied to the laser to control the operational wavelength of the radiation based on data from the first and the second photo-detectors; and transmitting the control signal to the laser to control the operational wavelength of the radiation. ### Claim 2 (depends on 1) The method according to claim 1, wherein the etalon is a solid state etalon. ### Claim 3 (depends on 2) The method according to claim 2, wherein the solid state etalon includes a solid state Fabry-Perot cavity. ### Claim 4 (depends on 1) The method according to claim 1, wherein the wavelength tunable laser is arranged to produce an optical signal for wavelength division multiplexing for optical communication. ### Claim 5 (depends on 1) The method according to claim 1, further comprising arranging each of the first and the second photo-detectors and the etalon on separate sub-assemblies. ### Claim 6 (depends on 1) The method according to claim 1, wherein the partially reflective coating on the first optical element reflects 50% of the incident light. ### Claim 7 The method according to claim wherein the anti-reflection coating on the second optical element permits a maxima transmission. ### Claim 8 (depends on 1) The method according to claim 1, wherein the second photo-detector includes an aperture that includes a dimension that is equal to or larger than an aperture of the first photo-detector. ### Claim 9 (depends on 1) The method according to claim 1, wherein the processor includes a digital signal processor. ### Claim 10 (depends on 1) The method according to claim 1, wherein the processor includes a memory that is arranged to store a known spectrum of the etalon. ### Claim 11 (depends on 1) The method according to claim 1, wherein the etalon is arranged to provide an absolute wavelength reference by being arranged to have a characteristic transmission spectrum with periodic peaks at desired wavelengths. ### Claim 12 A system comprising: a first photo-detector including a first optical element having a partially reflective coating on a front surface of the first optical element that is arranged to receive radiation from a wavelength tunable laser; an etalon arranged to receive at least a portion of the radiation partially reflected from the front surface of the first optical element; a second photo-detector including a second optical element having an anti-reflection coating on a front surface of the second optical element that is arranged to receive radiation from the etalon; and a digital signal processor arranged to receive and process data from the first and the second photo-detectors and to transmit a control signal to the laser to control the operational wavelength of the radiation in a feedback loop. ### Claim 13 (depends on 12) The system according to claim 12, wherein the etalon is a solid state etalon. ### Claim 14 (depends on 13) The system according to claim 13, wherein the solid state etalon includes a solid state Fabry-Perot cavity. ### Claim 15 (depends on 12) The system according to claim 12, wherein the wavelength tunable laser is arranged to produce an optical signal for wavelength division multiplexing for optical communication. ### Claim 16 (depends on 12) The system according to claim 12, wherein each of the first and the second photo-detectors and the etalon on arranged on separate sub-assemblies. ### Claim 17 (depends on 12) The system according to claim 12, wherein the partially reflective coating on the first optical element reflects 50% of the incident light. ### Claim 18 (depends on 12) The system according to claim 12, wherein the anti-reflection coating on the second optical element permits a maxima transmission. ### Claim 19 (depends on 12) The system according to claim 12, wherein the second photo-detector includes an aperture that includes a dimension that is equal to or larger than an aperture of the first photo-detector. ### Claim 20 (depends on 12) The system according to claim 12, wherein the processor includes a digital signal processor. ### Claim 21 (depends on 12) The system according to claim 12, wherein the processor includes a memory that is arranged to store a known spectrum of the etalon. ### Claim 22 (depends on 12) The system according to claim 12, wherein the etalon is arranged to provide an absolute wavelength reference by being arranged to have a characteristic transmission spectrum with periodic peaks at desired wavelengths.