US 11,923,655 B2
Light emission device
Kazuyoshi Hirose, Hamamatsu (JP); Yuu Takiguchi, Hamamatsu (JP); Takahiro Sugiyama, Hamamatsu (JP); and Yoshitaka Kurosaka, Hamamatsu (JP)
Assigned to HAMAMATSU PHOTONICS K.K., Hamamatsu (JP)
Appl. No. 17/269,313
Filed by HAMAMATSU PHOTONICS K.K., Hamamatsu (JP)
PCT Filed Aug. 27, 2019, PCT No. PCT/JP2019/033568
§ 371(c)(1), (2) Date Feb. 18, 2021,
PCT Pub. No. WO2020/045453, PCT Pub. Date Mar. 5, 2020.
Claims priority of application No. 2018-158242 (JP), filed on Aug. 27, 2018.
Prior Publication US 2021/0226412 A1, Jul. 22, 2021
Int. Cl. H01S 5/026 (2006.01); H01S 5/11 (2021.01); H01S 5/183 (2006.01); H01S 5/185 (2021.01); H01S 5/343 (2006.01)
CPC H01S 5/026 (2013.01) [H01S 5/18305 (2013.01); H01S 5/185 (2021.01); H01S 5/11 (2021.01); H01S 5/34313 (2013.01); H01S 5/34353 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A light emission device configured to output light forming an optical image along a normal direction of a main surface of a substrate, an inclination direction intersecting the normal direction, or both the normal direction and the inclination direction, the light emission device comprising:
a light emission portion; and
a phase modulation layer provided on the substrate, the phase modulation layer being optically coupled to the light emission portion,
wherein the phase modulation layer includes a base layer and a plurality of modified refractive index regions provided in the base layer so as to be distributed in a two-dimensional shape on a plane perpendicular to the normal direction, the plurality of modified refractive index regions having a refractive index different from a refractive index of the base layer,
in a state in which a virtual square lattice is set on the plane, the plurality of modified refractive index regions is arranged in a state of being separated from lattice points corresponding to centers of gravity of the plurality of modified refractive index regions by a predetermined distance, and a rotation angle being around each lattice point in the virtual square lattice is set according to a phase distribution for forming the optical image, the rotation angle being a rotation angle of a line segment connecting the center of gravity of each of the plurality of modified refractive index regions and the corresponding lattice point with respect to the virtual square lattice,
a lattice spacing a of the virtual square lattice and an emission wavelength λ, of the light emission portion are set so as to satisfy an oscillation condition at an M point of symmetric points in a reciprocal lattice space corresponding to a wavenumber space of the phase modulation layer, and
a magnitude of at least one first in-plane wavenumber vector, out of first in-plane wavenumber vectors in four directions formed in the reciprocal lattice space of the phase modulation layer, is smaller than 2π/λ.