US 12,261,405 B2
Apparatus and method for spectrally shaping a laser beam
Mitchell Underwood, III, Hamden, CT (US)
Assigned to Nufern, East Granby, CT (US)
Filed by Nufern, East Granby, CT (US)
Filed on Jun. 30, 2021, as Appl. No. 17/364,315.
Prior Publication US 2023/0006407 A1, Jan. 5, 2023
Int. Cl. H01S 3/10 (2006.01); G02B 5/30 (2006.01); H01S 3/00 (2006.01)
CPC H01S 3/0057 (2013.01) [G02B 5/3025 (2013.01); G02B 5/3083 (2013.01); H01S 3/0085 (2013.01); H01S 3/10015 (2013.01); H01S 3/10053 (2013.01); H01S 3/10061 (2013.01)] 19 Claims
OG exemplary drawing
 
1. An optical apparatus for spectrally shaping a laser beam, comprising:
a birefringent optic having orthogonal first and second polarization axes, the birefringent optic arranged to receive and transmit the laser beam, the laser beam received by the birefringent optic being linearly polarized and having an electric-field vector oriented at an oblique angle ϕ to the first polarization axis; and
a linear polarizer having a polarizing direction, the polarizer arranged to receive the laser beam transmitted through the birefringent optic and to transmit a portion thereof, the polarizing direction oriented at an oblique angle θ to the first polarization axis, the portion of the laser beam transmitted through the polarizer having a more-uniform power spectral density than the laser beam received by the birefringent optic;
wherein transmission through the birefringent optic induces a wavelength-dependent phase shift between a component of the laser beam parallel to the first polarization axis and a component of the laser beam parallel to the second polarization axis, the wavelength-dependent phase shift producing a wavelength-dependent polarization state of the laser beam transmitted through the birefringent optic, thereby modulating power spectral density in the portion of the laser beam transmitted through the polarizer;
wherein angles ϕ and θ are in a range between 19° and 30°; and
wherein the birefringent optic causes a phase delay between the component of the laser beam parallel to the first polarization axis and the component of the laser beam parallel to the second polarization axis, and the phase delay is in a range between 7π/8 and 9π/8 radians.