Compact slanted grating couplers

Abstract

We present a compact and efficient design for slanted grating couplers (SLGC's) to vertically connect fibers and planar waveguides without intermediate optics. The proposed SLGC employs a strong index modulated slanted grating. With the help of a genetic algorithm-based rigorous design tool, a 20microm-long SLGC with 80.1% input coupling efficiency has been optimized. A rigorous mode analysis reveals that the phase-matching condition and Bragg condition are satisfied simultaneously with respect to the fundamental leaky mode supported by the optimized SLGC.

Surface normal coupling to multiple-slot and cover-slotted silicon nanocrystalline waveguides and ring resonators

“…Although surface normal grating couplers exhibit potential advantages over angularly detuned gratings, previous surface normal couplers on silicon waveguides have required extreme fabrication complexity [17], an extensive bottom reflector [18], extra high resolution fabrication steps [19], or significant expansion of the device's footprint by simultaneously coupling to two counter-propagating waveguides [20]. Such elaborate workarounds are due to grating couplers often being designed solely from first principles with a single period and fill factor, effectively eliminating two of the most significant degrees of freedom available to a designer.…”

“…Such elaborate workarounds are due to grating couplers often being designed solely from first principles with a single period and fill factor, effectively eliminating two of the most significant degrees of freedom available to a designer. To circumvent the difficulty of relaxing first-principle design, previous works have employed a genetic algorithm to slightly vary a traditionally designed grating in order to obtain marginal efficiency increases [17,19,21]. However, entirely departing from an initial first-principle design could manifest new structures that enable high performance coupling across many platforms, specifications, and fabrication constraints.…”

Laser beam shaping and mode conversion in optical fibers

“…This method showed an improvement in coupling efficiency from fiber to a waveguide, but 5-micron mode field diameter is still very large in comparison with mode filed diameters of many integrated optical waveguides. Several configurations have been proposed for improving fiber-to-waveguide coupling efficiency in very small size waveguides such as grating coupler [16][17][18], micro-ring vertical coupler [19], parabolic reflector [20], and tapered waveguides [21][22][23][24][25].…”

Lasing from dye-doped photonic crystals with graded layers in dichromate gelatin emulsions

“…1 Among the many unique properties of photonic crystals, the control of the photonic density of states has a direct effect on the spontaneous emission of photons, which is an important capability in optoelectronics devices such as lasers, 2 light emitting diodes, 3 microwaveguides, 4 and many other promising photonic devices. 5 It has been proposed that the enhancement of the spontaneous emissions in one-dimensional ͑1D͒ photonic crystals doped with gain materials is possible because of the localization at the band gaps and the high density of states at the band edges.…”