US 12,253,785 B2
Apparatus and method for measuring and controlling chirp of ultrafast laser pulse
Jingdi Zhang, Hong Kong (CN); Xiaoyue Zhou, Hong Kong (CN); and Richard Douglas Averitt, San Diego, CA (US)
Assigned to The Hong Kong University of Science and Technology, Hong Kong (CN); and The Regents of the University of California
Filed by The Hong Kong University of Science and Technology, Hong Kong (CN); and The Regents of the University of California, Oakland, CA (US)
Filed on Mar. 2, 2023, as Appl. No. 18/177,748.
Claims priority of provisional application 63/326,284, filed on Apr. 1, 2022.
Prior Publication US 2023/0318244 A1, Oct. 5, 2023
Int. Cl. G02F 1/35 (2006.01); G01J 11/00 (2006.01); G02F 1/355 (2006.01); G02F 1/37 (2006.01); H01S 3/00 (2006.01)
CPC G02F 1/3501 (2013.01) [G01J 11/00 (2013.01); G02F 1/3551 (2013.01); G02F 1/37 (2013.01); H01S 3/0057 (2013.01); G02F 2203/13 (2013.01); H01S 3/0092 (2013.01)] 12 Claims
OG exemplary drawing
 
1. An optical apparatus for measuring and controlling chirp of an ultrafast laser pulse, comprising:
a chirp control module configured to receive an ultrafast laser pulse and tune a pulse duration of the ultrafast laser pulse, so as to convert the ultrafast laser pulse into a chirped pulse;
a beam splitter optically coupled with the chirp control module and configured to divide the chirped pulse from the chirp control module to a first pulse portion and a second pulse portion;
a nonlinear medium generation module optically coupled with the beam splitter and configured to receive the first pulse for generation of at least one terahertz electromagnetic wave using a nonlinear medium, wherein the nonlinear medium serves as a medium for nonlinear interaction of an intense driving laser field to promote frequency-down-conversion enabled by four-wave mixing process;
a terahertz wave detection module comprising an electro-optic crystal, photo-diode and a lock-in amplifier and configured to guide the terahertz electromagnetic wave and the second pulse portion to the electro-optic crystal, photo-diode and then to the lock-in amplifier;
a terahertz collection module optically coupled between the nonlinear medium generation module and the terahertz wave detection module and comprising:
a pair of parabolic mirrors configured to perform beam collimation and refocusing; and
a filter optically coupled between the nonlinear medium generation module and the pair of parabolic mirrors and configured to permit terahertz radiation to pass therethrough;
a time delay stage optically coupled between the beam splitter and the terahertz wave detection module and configured to receive the second pulse portion from the beam splitter, wherein the nonlinear medium generation module and the time delay stage are respectively positioned in a first optical path and a second optical path which are separated from each other; and
a beam combiner optically coupled both between the terahertz collection module and the terahertz wave detection module and between the time delay stage and the terahertz wave detection module, so as to combine the terahertz electromagnetic wave which is from the nonlinear medium generation module and guided by the terahertz collection module with the second pulse portion propagated from the time delay stage.