US 11,906,387 B2Granted

Test method and test device for mode field diameter

AssigneeNippon Telegraph and Telephone Corporation

InventorsAtsushi Nakamura, Daisuke Iida, Hiroyuki Oshida

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Abstract

The purpose of the present disclosure is to provide a mode field diameter test method and test device that enable acquisition of a mode field diameter for an arbitrary higher-order mode. The present disclosure is a mode field diameter test method including: a test light incidence procedure for selectively causing test light to be incident in a mode subject to measurement, on one end of an optical fiber 10 under test; a far-field pattern measurement procedure for measuring a far-field pattern of the mode subject to measurement, with respect to a divergence angle θ at the other end of the optical fiber under test, by a far-field scanning technique; and a mode field diameter calculation procedure for calculating, using an equation, a mode field diameter from information about incident mode orders in the test light incidence procedure and the far-field pattern measured in the far-field pattern measurement procedure.

Claims3

Dependent claims

A mode field diameter test device comprising:

test light incidence means for selectively causing test light to be incident in a mode subject to measurement, on one end of an optical fiber under test;
far-field pattern measurement means for measuring a far-field pattern of the mode subject to measurement, with respect to a divergence angle θ at the other end of the optical fiber under test, by a far-field scanning technique;
and
mode field diameter calculation means for calculating, using a first equation, a mode field diameter from information about incident mode orders in the optical fiber under test by the test light incidence means and the far-field pattern measured by the far-field pattern measurement procedure, or mode field diameter calculation means for calculating an electric field distribution in a near field from the far-field pattern and further calculating a mode field diameter using a second or third equation;
wherein the first equation is Equation (C4),
[
Math
.
C
⁢
4
]
MFD
=
v
+
2
⁢
μ
-
1
⁢
λ
π
⁢
2
⁢
∫
0
π
/
2
❘
"\[LeftBracketingBar]"
F
v
⁢
μ
(
θ
)
❘
"\[RightBracketingBar]"
2
⁢
sin
⁢
θ
⁢
cos
⁢
θ
⁢
d
⁢
θ
∫
0
π
/
2
❘
"\[LeftBracketingBar]"
F
v
⁢
μ
(
θ
)
❘
"\[RightBracketingBar]"
2
⁢
sin
3
⁢
θcos
⁢
θ
⁢
d
⁢
θ
(
C4
)
where ν is the order in a circumferential direction, μ is the order in a radial direction, λ represents a wavelength of the test light, θ is the divergence angle, Fνμ(θ) is an electric field distribution in a far field, and |Fνμ(θ)|2 represents the far-field pattern.

85 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/636,930Filed 10 Sep 2019
Published: US 2022/0276123 A11 Sep 2022
Granted: 20 Feb 2024
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01M 11/02
Testing of optical apparatus; Testing structures by optical methods not otherwise provided for: testing optical properties
G01M 11/332
With a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face: using discrete input signals
G01M 11/33
Testing of optical devices, constituted by fibre optics or optical waveguides: with a light emitter being disposed at one fibre or waveguide…
G01M
Testing static or dynamic balance of machines or structures

Family

US 2022/0276123 A1Pre-grant publication · published 1 Sep 2022
US 11,906,387 B2This patent

From the US filing history. Foreign family members aren’t listed.

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