Optical probe, probe card, measuring system, and measuring method

An optical probe comprising a core part and a clad part arranged along an outer circumference of the core part, the optical probe having an incident surface through which an optical signal from an optical semiconductor element enters, the incident surface having a radius of curvature R,

• wherein the radius of curvature R and a central half angle ω at an incident point of the optical signal on the incident surface fulfil the following formulae using a radiation angle γ of the optical signal, an effective incident radius Se of the optical signal transmitted in the core part without penetrating into the clad part on the incident surface, a refractive index n(r) of the core part at the incident point, and a refracting angle β at the incident point, wherein:
• β=sin−1[sin(γ/2)/n(r)]
• R=Se/sin(ω)
• ω=±sin−1{[K22/(K12+K22)]1/2}
• where K1=n(r)×cos(β)−cos(γ/2) and K2=n(r)×sin(β)−sin(γ/2).