Method for designing diffractive device and method for manufacturing diffractive device

Patent metadata

Field	Value
Publication number	US-2026099042-A1
Application number	US-202219101780-A
Country	US
Kind code	A1
Filing date	Aug 9, 2022
Priority date	Aug 9, 2022
Publication date	Apr 9, 2026
Grant date	—

Abstract

An embodiment is a method including calculating an electric field distribution of an emission light on an emission plane of the diffractive element with respect to the incident light, the incident light being a Gaussian beam, calculating an electric field distribution obtained by multiplying an electric field distribution of emission light from the emission plane by a Gaussian window in a plane parallel to the emission plane located at a predetermined distance from the emission plane, as an electric field distribution of a beam approximated by a Bessel Gaussian beam, calculating a first electric field distribution as an electric field distribution on the emission plane of the diffractive element with respect to the electric field distribution of the emission light on the plane, and determining a depth of an unevenness on a surface of the diffractive element.

First claim

1 - 5 . (canceled)

6 . A method for designing a diffractive element for modulating a phase of incident light, using a computer, the method comprising:
calculating an electric field distribution of an emission light on an emission plane of the diffractive element with respect to the incident light, the incident light being a Gaussian beam; calculating an electric field distribution obtained by multiplying an electric field distribution of emission light from the emission plane by a Gaussian window in a plane parallel to the emission plane located at a predetermined distance from the emission plane, as an electric field distribution of a beam approximated by a Bessel Gaussian beam; calculating a first electric field distribution as an electric field distribution on the emission plane of the diffractive element with respect to the electric field distribution of the emission light on the plane, on the basis of a principle of Kirchhoff's diffractive integral; and determining a depth of an unevenness on a surface of the diffractive element, on the basis of the electric field distribution on the emission plane of the diffractive element.

7 . The method for designing the diffractive element according to claim 6 , further comprising:
calculating a second electric field distribution in which a positive square root of the light intensity distribution imaged on the plane is set as an intensity; and calculating an electric field distribution on the emission plane of the diffractive element according to a convolution integral of the second electric field distribution and the first electric field distribution.

8 . The method for designing the diffractive element according to claim 6 ,
wherein in a Cartesian coordinate system in which the emission plane is orthogonal to a z-axis, when calculating the electric field distribution of the emission light on the emission plane of the diffractive element, an electric field distribution E Ax (x, y) on the emission plane with respect to the incident light is calculated using equation (A), and when calculating the electric field distribution obtained by multiplying the electric field distribution of emission light from the emission plane, an electric field distribution E BG, z1 (x, y) of the emission light on the plane is calculated by equation (B), using an electric field distribution E B, z1 (x, y) calculated using a diffractive integral of Kirchhoff.

E
Ax

(

x
,
y

)

=

e

-

(

r
xy

w
in

)

2

⁢

e

j
⁡
(

ar
xy

)

(
A
)

wherein, r xy =√{square root over ( )}(x 2 +y 2 ), win is a radius of a Gaussian beam,
α=k sin φ B , moreover, φ B is represented by following equation,

φ
B

=

sin

-
1

2.252728

2
⁢

r
B

⁢
k

=

sin

-
1

2.252728

4
⁢

r
B

⁢
π

λ

here, 2r B is a diameter of a Bessel beam, k is a wavenumber of the incident light or the emission light,
λ is a wavelength of the incident light or the emission light in the vacuum.

E

BG
,

z
1

(

x
,
y

)

=

e

-

(

r
xy

w

)

2

⁢

E

B
,

z
1

(

x
,
y

)

Assignees

• Ntt Inc

Inventors

• Ueno Masahiro
• KAWAMURA Sohan
• Sakamoto Takashi
• Tsuda Masayuki

Classifications

• G02B5/18

  Diffraction gratings {(holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44)} · CPC title

• G02B27/0012 Primary

  Optical design, e.g. procedures, algorithms, optimisation routines · CPC title