# US 12,003,073 B2 · Femtosecond pulse laser apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,003,073 B2 - Document ID: US12003073B2 - Status: Granted - Kind: B2 - Application number: 18/198,520 - Filed: 2023-05-17 - Published: 2023-09-14 - Granted: 2024-06-04 - Earliest claimed: 2020-12-04 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics and Telecommunications Research Institute - Inventors: Dong Hoon Song; Hong-Seok Seo; Chul Huh - Web page: https://patentgrep.com/patent/US12003073B2 ## CPC - H01S 3/1115: using intracavity saturable absorbers - H01S 3/0816: {having 4 reflectors, e.g. Z-shaped resonators} - H01S 3/094096: {Multi-wavelength pumping} - H01S 3/09415: {the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping} - H01S 3/10053: {Phase control} - H01S 3/102: by controlling the active medium, e.g. by controlling the processes or apparatus for excitation (H01S3/13 takes precedence) - H01S 3/1068: {using an acousto-optical device} - H01S 3/1305: {Feedback control systems} - H01S 3/1307: {Stabilisation of the phase} - H01S 3/1312: {by controlling the optical pumping} - H01S 3/1625: {titanium} - H01S 3/1636: {Al2O3 (Sapphire)} - H01S 2301/03: Suppression of nonlinear conversion, e.g. specific design to suppress for example stimulated brillouin scattering [SBS], mainly in optical fibres in combination with multimode pumping - 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 A femtosecond pulse laser apparatus includes a pump light source configured to provide a pump light, a gain medium configured to obtain a gain of a laser light using the pump light, a first curved mirror and a second curved mirror, which are provided at both sides of the gain medium, an output mirror configured to transmit a portion of the laser light and reflect the other portion of the laser light to the gain medium, a mode locking portion configured to generate a femtosecond pulse of the laser light, and an acoustic wave generator configured to provide an acoustic wave into the gain medium so as to adjust self-phase modulation of the laser light. ## Claims ### Claim 1 A femtosecond pulse laser apparatus comprising: a pump light source configured to provide a pump light; a gain medium configured to obtain a gain of a laser light using the pump light; a first curved mirror and a second curved mirror, which are provided at both sides of the gain medium to reflect the laser light into the gain medium; an output mirror configured to transmit a portion of the laser light reflected by the second curved mirror and reflect the other portion of the laser light to the gain medium; a mode locking portion configured to generate a femtosecond pulse using a locking mode of the laser light reflected by the first curved mirror; an acoustic wave generator connected to the gain medium and configured to provide an acoustic wave into the gain medium so as to adjust a self-phase modulation of the laser light; a wavefront sensor configured to detect a first wavefront of the laser light; an adaptive window provided between the pump light source and the first curved mirror and configured to partially adjust a second wavefront of the pump light; and a controller connected to the wavefront sensor and the adaptive window to distinguish the first wavefront of the laser light, the controller configured to adjust the second wavefront of the pump light in the adaptive window based on the first wavefront. ### Claim 2 (depends on 1) The femtosecond pulse laser apparatus of claim 1, further comprising a first pad electrode and a second pad electrode, which are provided on and under the gain medium to connect the acoustic wave generator into the gain medium. ### Claim 3 (depends on 1) The femtosecond pulse laser apparatus of claim 1, wherein the adaptive window comprises a liquid crystal panel. ### Claim 4 (depends on 1) The femtosecond pulse laser apparatus of claim 1, further comprising a convex lens disposed between the first curved mirror and the adaptive window to focus the pump light to the gain medium. ### Claim 5 (depends on 1) The femtosecond pulse laser apparatus of claim 1, further comprising a first flat mirror provided between the second curved mirror and the wavefront sensor. ### Claim 6 (depends on 1) The femtosecond pulse laser apparatus of claim 1, wherein the first curved mirror comprises a dichroic curved mirror. ### Claim 7 (depends on 1) The femtosecond pulse laser apparatus of claim 1, wherein: the gain medium and the mode locking portion generate a positive self-phase modulation, and the acoustic wave generator provides the acoustic wave into the gain medium to generate a negative self-phase modulation that compensates the positive self-phase modulation. ### Claim 8 (depends on 1) The femtosecond pulse laser apparatus of claim 1, wherein the pump light source comprises: a first laser diode configured to generate first pump light; a second laser diode configured to generate second pump light having a wavelength shorter than that of the first pump light; and a third laser diode configured to generate third pump light having a wavelength shorter than that of the second pump light. ### Claim 9 (depends on 8) The femtosecond pulse laser apparatus of claim 8, wherein: the first pump light has a wavelength of 525 nm, the second pump light has a wavelength of 491 nm, and the third pump light has a wavelength of 471 nm. ### Claim 10 (depends on 8) The femtosecond pulse laser apparatus of claim 8, wherein the pump light source further comprises: a first beam splitter between the first laser diode and the second laser diode; and a second beam splitter between the second laser diode and the third laser diode. ### Claim 11 (depends on 10) The femtosecond pulse laser apparatus of claim 10, wherein the pump light source further comprises aspherical lenses between the first to third laser diodes and the first and second beam splitters. ### Claim 12 (depends on 8) The femtosecond pulse laser apparatus of claim 8, wherein the pump light source further comprises cylindrical lenses adjacent to the third laser diode. ### Claim 13 (depends on 12) The femtosecond pulse laser apparatus of claim 12, wherein the cylindrical lenses comprise: a concave cylindrical lens configured to enlarge the pump light; and a convex cylindrical lens configured to collimate the pump light. ### Claim 14 (depends on 1) The femtosecond pulse laser apparatus of claim 1, wherein the gain medium comprises a titanium sapphire crystal. ### Claim 15 (depends on 1) The femtosecond pulse laser apparatus of claim 1, further comprising a second flat mirror provided between the second curved mirror and the output mirror. ### Claim 16 (depends on 1) The femtosecond pulse laser apparatus of claim 1, further comprising a third curved mirror provided between the first curved mirror and the mode locking portion. ### Claim 17 (depends on 1) The femtosecond pulse laser apparatus of claim 1, wherein the mode locking portion comprises a saturated absorber. ### Claim 18 A femtosecond pulse laser apparatus comprising: a pump light source configured to provide a pump light; a gain medium configured to obtain a gain of a laser light using the pump light; a first curved mirror and a second curved mirror, which are provided at both sides of the gain medium to reflect the laser light into the gain medium; an output mirror configured to transmit a portion of the laser light reflected by the second curved mirror and reflect the other portion of the laser light to the gain medium; a mode locking portion configured to generate a femtosecond pulse using a locking mode of the laser light reflected by the first curved mirror; and an acoustic wave generator connected to the gain medium and configured to provide an acoustic wave into the gain medium so as to adjust a self-phase modulation of the laser light, wherein the pump light source comprises: a plurality of laser diode configured to provide the pump light; and cylindrical lenses adjacent to one of the plurality of the laser diode, wherein the cylindrical lenses comprise: a concave cylindrical lens configured to enlarge the pump light; and a convex cylindrical lens configured to collimate the pump light.