Optical coupler, optical coupling member, light source module and optical engine
A Y-branch type optical coupler includes an optical coupling part to which a plurality of input-side optical waveguides through which the plurality of lights propagate, and one output-side optical waveguide are connected, wherein the optical coupling part has an isosceles trapezoid shape of which the width is narrowed in a taper shape at a first angle α from the input side to the output side (a traveling direction of light) in a plan view, at least two input-side optical waveguides among the plurality of input-side optical waveguides are disposed symmetrically with respect to a symmetry axis of the isosceles trapezoid, are inclined at a second angle θ that is different from the first angle α, and are connected to a lower bottom portion of the isosceles trapezoid, and the difference between the first angle and the second angle is 0.9° or more and 14.8° or less.
1 . An optical coupler that couples a plurality of lights with different wavelengths, comprising:
an optical coupling part to which a plurality of input-side optical waveguides through which the plurality of lights propagate, and one output-side optical waveguide are connected,
wherein the optical coupling part has an isosceles trapezoid shape of which a width is narrowed in a taper shape at a first angle from an input side to an output side in a plan view,
at least two input-side optical waveguides among the plurality of input-side optical waveguides are disposed symmetrically with respect to a symmetry axis of the isosceles trapezoid, are inclined at a second angle that is different from the first angle, and are connected to a lower bottom portion of the isosceles trapezoid, and
a difference between the first angle and the second angle is 0.9° or more and 14.8° or less.
2 . The optical coupler according to claim 1 , wherein the plurality of input-side optical waveguides include four or more input-side optical waveguides disposed symmetrically with respect to the symmetry axis, and two input-side optical waveguides adjacent to each other without sandwiching the symmetry axis are connected to the lower bottom portion of the isosceles trapezoid with one inclined at the second angle with respect to the other.
3 . The optical coupler according to claim 1 , wherein the plurality of input-side optical waveguides include an input-side optical waveguide that extends along the symmetry axis and that is connected to the lower bottom portion of the isosceles trapezoid shape.
4 . The optical coupler according to claim 2 , wherein the plurality of input-side optical waveguides include an input-side optical waveguide that extends along the symmetry axis and that is connected to the lower bottom portion of the isosceles trapezoid shape.
5 . The optical coupler according to claim 1 , wherein the number of the plurality of input-side optical waveguides is two, and a length of the optical coupling part is 6 μm or more and 303 μm or less.
6 . The optical coupler according to claim 2 , wherein the number of the plurality of input-side optical waveguides is four, and a length of the optical coupling part is 16 μm or more and 238 μm or less.
7 . The optical coupler according to claim 3 , wherein the number of the plurality of input-side optical waveguides is three, and a length of the optical coupling part is 9 μm or more and 490 μm or less.
8 . An optical coupling member comprising:
a substrate made of a material different from lithium niobate; and
an optical coupling functional layer made of a lithium niobate film and formed on a main surface of the substrate,
wherein the optical coupler according to claim 1 is formed in the optical coupling functional layer.
9 . A light source module comprising:
the optical coupling member according to claim 8 ; and
a plurality of laser light sources configured to emit lights that are coupled by the optical coupling member.
10 . An optical coupling member with an optical modulation function, comprising:
the optical coupling member according to claim 8 ; and
a Mach-Zehnder type optical modulator connected to the optical coupling member and configured to guide a plurality of lights emitted from a plurality of laser light sources to the optical coupling member.
11 . A light source module comprising:
the optical coupling member with a light modulation function according to claim 10 ; and
a plurality of laser light sources configured to emit lights to be coupled by the optical coupling member with a light modulation function.
12 . An optical engine comprising:
the light source module according to claim 9 ; and
a light scanning mirror configured to reflect the light emitted from the light source module by changing an angle to display an image.
13 . An optical engine comprising:
the light source module according to claim 11 ; and
a light scanning mirror that reflects the light emitted from the light source module by changing an angle to display an image.