# US 10,483,714 B2 · Q-switched laser with stabilized output energy > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,483,714 B2 - Document ID: US10483714B2 - Status: Granted - Kind: B2 - Application number: 16/083,685 - Filed: 2016-03-30 - Published: 2019-05-02 - Granted: 2019-11-19 - Earliest claimed: 2016-03-30 - Assignees: Saab AB - Applicants: Saab AB - Inventors: Peter Bane; Marcus Gustafsson - Web page: https://patentgrep.com/patent/US10483714B2 ## CPC - H01S 3/136: by controlling devices placed within the cavity - H01S 3/115: using intracavity electro-optic devices - H01S 3/117: using intracavity acousto-optic devices - H01S 3/1305: {Feedback control systems} - H01S 3/1306: {Stabilisation of the amplitude} - H01S 3/131: by controlling the active medium, e.g. by controlling the processes or apparatus for excitation - H01S 3/137: for stabilising of frequency - H01S 3/061: {with elliptical or circular cross-section and elongated shape, e.g. rod} - H01S 3/0941: of a laser diode - H01S 3/1608: {erbium} - H01S 3/1611: {neodymium} - H01S 3/1643: {YAG} - H01S 3/17: amorphous, e.g. glass - 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 ## Abstract The present disclosure relates a laser arrangement (1) and a method of the laser arrangement, arranged to output energy in the form of laser emission, for emitting controlled Q-switched laser emission. The laser arrangement comprises a gain medium (2) arranged to be excited when pumped, an optical resonator (3), an active Q-switch (4) arranged in the optical resonator, said active Q-switch (4) being controllable between at least a high loss state and a low loss state, and being arranged to introduce loss in the optical resonator to prevent lasing in the high loss state and to affect lasing minimally in the low loss state, a photo detector (5) arranged to detect the presence of a free running pulse (1′) generated by the optical resonator and which occurs when a lasing threshold is reached and a processing circuitry (6) arranged to control (S4) of the state of the active Q-switch based on the detection of the free running pulse. ## Claims ### Claim 1 A laser arrangement (1), arranged to output energy in the form of laser emission, for emitting controlled Q-switched laser emission, the arrangement comprising: a gain medium (2) arranged to be excited when pumped; an optical resonator (3); an active Q-switch (4) arranged in the optical resonator, said active Q-switch (4) being controllable between at least a high loss state and a low loss state, and being configured to introduce loss in the optical resonator to prevent lasing in the high loss state and to affect lasing minimally in the low loss state; a photodetector (5) configured to detect the presence of a free running pulse (1′) generated by the optical resonator and which occurs when a lasing threshold is reached; and a processing circuitry (6) configured to control (S4) of the state of the active Q-switch based on the detection of the free running pulse. ### Claim 2 (depends on 1) The laser arrangement according to claim 1, wherein the active Q-switch (4) is either an acousto-optic Q-switch or an electro-optic Q-switch. ### Claim 3 (depends on 1) The laser arrangement according to claim 1, wherein the photodetector (5) is arranged in the optical resonator (3). ### Claim 4 (depends on 1) The laser arrangement according to claim 1, wherein the photodetector (5) is arranged outside of the optical resonator (3). ### Claim 5 (depends on 1) The laser arrangement according to claim 1, wherein the optical resonator (3) comprises a mirror (3a, 3b) that reflects part of the emission in the optical resonator towards the photodetector (5). ### Claim 6 (depends on 1) The laser arrangement according to claim 1, wherein the processing circuitry (6) is configured to control (S4) the state of the active Q-switch to the high loss state for a predetermined amount of time and thereby adding a predetermined amount of energy to the laser arrangement. ### Claim 7 (depends on 1) The laser arrangement according to claim 1, wherein the processing circuitry (6) is configured to control the state of the active Q-switch to the low loss state. ### Claim 8 A method in a laser arrangement (1) for emitting controlled Q-switched laser emission, the method comprising the steps of: providing a laser arrangement comprising: a gain medium (2); an optical resonator (3); an active Q-switch (4) arranged in the optical resonator, said active Q-switch (4) being controllable between at least an high loss state and a low loss state, and being configured to introduce loss in the optical resonator to prevent lasing in the high loss state and to affect lasing minimally in the low loss state; a photodetector (5); and a processing circuitry (6); initiating pumping (SI) of the gain medium (2); detecting (S3), using the photodetector (5), the presence of a free running pulse (1′) generated by the optical resonator and which occurs when a lasing threshold is reached; and controlling (S4), using the processing circuitry (6), the state of the active Q-switch based on the detection of the free running pulse. ### Claim 9 (depends on 8) The method according to claim 8, wherein the controlling (S4) step comprises to control (S41) the state of the active Q-switch to the high loss state. ### Claim 10 (depends on 8) The method according to claim 8, wherein the controlling (S4) step comprises to control (S42) the state of the active Q-switch to the high loss state for a predetermined amount of time and thereby adding a predetermined amount of energy to the laser arrangement. ### Claim 11 (depends on 8) The method according to claim 8, further comprising the step of controlling (S2) the state of the active Q-switch to a high loss state, using the processing circuitry, said controlling (S2) step occurring before detection (S3) of the free running pulse. ### Claim 12 (depends on 8) The method according to claim 8, further comprising the step of controlling (S2) the state of the active Q-switch to an intermediate high loss state, using the processing circuitry, said controlling (S2) step occurring before detection (S3) of the free running pulse. ### Claim 13 (depends on 11) The method according to claim 11, wherein the controlling (S4) step comprises control (S43) of the state of the active Q-switch to the low loss state. ### Claim 14 (depends on 8) The method according to claim 8, further comprising a step of stopping pumping (S5) the gain medium at the same time as the state of the active Q-switch is controlled to the low loss state. ### Claim 15 (depends on 8) The method according to claim 8, wherein: the active Q-switch is an acousto-optic Q-switch; and controlling (S4) the state of the active Q-switch comprises controlling a radio frequency (7′) directed at the active Q-switch. ### Claim 16 (depends on 8) The method according to claim 8, wherein: the active Q-switch is an electro-optic Q-switch; and controlling (S4) the state of the active Q-switch comprises controlling a voltage (7′) directed at the active Q-switch.