INTEGRATED PHOTONIC DEVICES HAVING FOLDED DIRECTIONAL COUPLERS

摘要

An integrated photonic apparatus (200) that includes a glass substrate having a major surface (213), a first waveguide segment (221) and a second waveguide segment (223), and a folded evanescent coupler (284) connecting the first waveguide segment to the second. The folded evanescent coupler is formed by a first length of the first waveguide segment and an equivalent length portion of the second waveguide running parallel and adjacent to the first waveguide segment. The first length is substantially equal to one half of an evanescent-coupler length needed to transfer a first wavelength in a non-folded evanescent coupler. A reflector (251) (e.g., dielectric mirror that is highly reflective to light of the first wavelength and also highly transmissive to light of a second wavelength) is located at an end of the folded evanescent coupler. The first length is selected to transfer substantially all light of a first wavelength. The evanescent coupler (282) is used for transfering pump light (71) waveguide segment (222) into the other waveguide segment (224) for optical amplification of the signal light (91).