Patent ID: 11971431
Assignee: KABUSHIKI KAISHA NIHON MICRONICS
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An optical probe communicating an optical signal with an optical device, the optical probe comprising:
a first region; and
a second region connected to have a continuous optical waveguide in which a transmission mode is a single mode, the optical waveguide including a core part and a clad part arranged at a circumference of the core part;
wherein the first region connected to a tip-end surface opposed to the optical device includes a region in which a mode field diameter that is maximum at the tip-end surface is gradually decreased toward a boundary between the first region and the second region;
wherein the tip-end surface is a curved surface and has a radius of curvature set so that an advancing direction of the optical signal entering through the tip-end surface approximates in parallel to a central-axis direction of the optical waveguide; and
wherein the radius of curvature R at the tip-end surface, a numerical aperture NA at the tip-end surface, a first MF diameter Ce that is the mode field diameter at the tip-end surface, a radiation angle 2αm of the optical signal entering the tip-end surface, a refractive index nr of the core part at an incident point at which the optical signal enters the tip-end surface, a central semi-angle ω at the incident point of the tip-end surface, a refraction angle (β+ω) of the optical signal at the incident point, and a numerical aperture sin(α0) at the tip-end surface on an assumption that the tip-end surface is flat fulfil the following relational expressions:

R=Ce/sin(ω);

NA=sin(αm);

αm=sin−1[nr×sin(β+ω)]−ω; and

β=sin−1[sin(α0)/nr].