OPTICAL HEAD

摘要

PURPOSE:To independently optimize coeffts. of radiation loss by means of an input grating coupler which inputs the laser beam from a laser beam source into a waveguide layer and a condenser grating coupler which radiates the guided light and condenses the light to the point outside the waveguide layer. CONSTITUTION:A buffer layer 2 of a low refractive index is formed on a substrate 1 and the optical waveguide layer 20 is formed in the annular band region having its central axis at L on the buffer layer 2. A buffer layer 21 of a low refractive index is formed in the annular band region having its central axis at L on the buffer layer 2 and the outer peripheral part thereof overlaps on the inner peripheral part of the optical waveguide layer 20. The optical waveguide layer 22 is formed to a circular shape having its central axis at L in the form of covering a part of the inner peripheral side of the optical waveguide layer 20 and a part of a transparent layer 21 and a transparent layer 2. The outer peripheral part thereof is formed by etching to a taper shape. A concentrical grating 23 having its central axis at L is formed in the annular band region having its central axis at L on the optical waveguide layer 20 and a concentrical grating 24 having the central axis at L is formed on the optical waveguide layer 22.