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A broad-band waveguide grating coupler with a subwavelength grating mirror

2005; Institute of Electrical and Electronics Engineers; Volume: 18; Issue: 1 Linguagem: Inglês

10.1109/lpt.2005.860037

1941-0174

Pavel Cheben, Siegfried Janz, Dan‐Xia Xu, B. Lamontagne, A. Delâge, Stoyan Tanev,

Photonic Crystals and Applications

A new diffractive device for light coupling between a planar optical waveguide and free space is proposed. The device utilizes a second-order waveguide grating to diffract the fundamental waveguide mode into two free propagating beams and a subwavelength grating (SWG) mirror to combine the two free propagating beams into a single beam. The finite-difference time-domain (FDTD) simulations show that the SWG mirror improves the coupling efficiency of the waveguide fundamental mode into the single out-coupled beam from about 30% to 92%. A high efficiency (>90%) is predicted for a broad wavelength range of 1520-1580nm. The proposed device is compact (/spl sim/80 μm in length) and it eliminates the need for blazing the waveguide grating.