Method for manufacturing a photonic waveguide and photonic waveguide manufactured by said method

A method for manufacturing a photonic waveguide with low insertion losses between the photonic waveguide and an optical fiber, the method including the following steps:

• forming an optical waveguide on a first surface of a dielectric substrate;
• and
• thinning the dielectric substrate in order to form a photonic waveguide having a first end and a second end opposite the first end;
• wherein the thinning is carried out by cutting a second surface of the dielectric substrate, which surface is opposite the first surface, the thinning comprising forming a recess the profile of which is parallel to the optical waveguide, the depth of the recess varying continuously and gradually between a first point P1 of zero depth at the height of the second surface, and a maximum depth at a preset distance from the first end of the photonic waveguide, which end is intended to receive the optical fiber, the variation in the depth of the recess forming a vertical optical-mode transition zone of length between the photonic waveguide and the optical fiber.