A volume grating focusing waveguide coupler has been designed, fabricated, and tested. The volume grating is designed to couple a 633-nm wave guided in a single-mode polyimide waveguide preferentially into the air cover. The beam is outcoupled normally to the surface of the waveguide and focused to a line 25 mm above the waveguide. The slanted-fringe volume grating is holographically recorded by the interference of two coherent 364-nm ultraviolet waves focused with a cylindrical lens to produce the chirped grating. The 1-mm-long volume grating coupler exhibits a preferential-coupling ratio of 0.98, a coupling efficiency of 95%, and an almost diffraction-limited focal line with a full width at half-maximum of 10.49μm.
© 1999 Optical Society of America
(050.0050) Diffraction and gratings : Diffraction and gratings
(050.1950) Diffraction and gratings : Diffraction gratings
(050.1970) Diffraction and gratings : Diffractive optics
(090.7330) Holography : Volume gratings
(130.0130) Integrated optics : Integrated optics
Stephen M. Schultz, Elias N. Glytsis, and Thomas K. Gaylord, "Volume grating preferential-order focusing waveguide coupler," Opt. Lett. 24, 1708-1710 (1999)