GRATING-ASSISTED COUPLING OF LIGHT BETWEEN SEMICONDUCTOR AND GLASS WAVE-GUIDES

Floquet-Bloch theory is used to calculate the electromagnetic fields i n a leaky-mode grating-assisted directional coupler (LM-GADC) fabricat ed with semiconductor and glass materials. One waveguide is made from semiconductor materials (refractive index approximate to 3.2) while th e second is made from glass (refractive index approximate to 1.45). Th e coupling of light between the two waveguides is assisted by a gratin g fabricated at the interface of the glass and semiconductor materials , Unlike typical GADC structures where power is exchanged between two waveguides using bound modes, this semiconductor/glass combination cou ples power between two waveguides using a bound mode (confined to the semiconductor) and a leaky mode (associated with the glass). The chara cteristics of the LM-GADC are discussed, Such LM-GADC couplers are exp ected to have numerous applications in areas such as laser-fiber coupl ing, photonic integrated circuits, and on-chip optical clock distribut ion. Analyses indicate that simple LM-GADC's can couple over 40% of th e optical power from one waveguide to another in distances less than 1 .25 mm.