US 11,815,784 B2
United states frequency conversion using interdigitated nonlinear crystal gratings
Yung-Ho Alex Chuang, Cupertino, CA (US); Yinying Xiao-Li, San Jose, CA (US); Elena Loginova, Milpitas, CA (US); John Fielden, Los Altos, CA (US); Baigang Zhang, San Jose, CA (US); Xuefeng Liu, San Jose, CA (US); and Kelly Ann Weekley Mauser, Santa Clara, CA (US)
Assigned to KLA Corporation, Milpitas, CA (US)
Filed by KLA Corporation, Milpitas, CA (US)
Filed on Dec. 22, 2022, as Appl. No. 18/087,236.
Application 18/087,236 is a continuation of application No. 17/555,404, filed on Dec. 18, 2021, granted, now 11,567,391.
Claims priority of provisional application 63/282,706, filed on Nov. 24, 2021.
Prior Publication US 2023/0161221 A1, May 25, 2023
Int. Cl. G02F 1/35 (2006.01); G02F 1/355 (2006.01)
CPC G02F 1/354 (2021.01) [G02F 1/3503 (2021.01); G02F 1/3507 (2021.01); G02F 1/3548 (2021.01); G02F 1/3551 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A laser assembly for generating a laser output light beam having an output frequency with a corresponding output wavelength in the range of approximately 125 nm to approximately 300 nm, said laser assembly comprising:
one or more fundamental lasers respectively configured to generate a fundamental light beam having a corresponding fundamental frequency;
one or more intermediate frequency conversion stages collectively configured to generate one or more intermediate light beams using said one or more fundamental light beams, each of said one or more intermediate light beams having an associated intermediate frequency and a corresponding intermediate wavelength;
a final frequency conversion stage configured to pass said one or more intermediate light beams pass through a nonlinear crystal grating assembly,
wherein said nonlinear crystal grating assembly includes an upright grating interleaved with an inverted grating in an interdigitated arrangement such that said one or more intermediate light beams pass through said upright and inverted gratings,
wherein each of said upright and inverted gratings comprises two parallel mesas separated by a groove, each of said upright and inverted gratings being configured such that:
a width of each said mesa in a propagation direction of the one or more intermediate light beams passing through said each mesa is substantially equal to an odd integer multiple of a critical length to achieve quasi-phase-matching (QPM) of said one or more intermediate light beams and said laser output light beam having said output frequency
a width of each groove is larger than the width of said each mesa, and
a first crystal axis of said upright grating is inverted with respect to a corresponding crystal axis of said inverted grating.