Efficient 4.95 µm–8.5 µm dual-band grating coupler with crosstalk suppression capability

Abstract

In many integrated optics systems, grating couplers are a key component of interfacing the external light source with in-plane photonic devices. Grating couplers with dual-band capability are often desired for expanding the operation spectrum of photonic systems. Here, we propose and theoretically investigate, for the first time, a 4.95 µm–8.5 µm dual-band grating coupler on a Ge-on-SOI platform. In addition to conventional structures, Bragg gratings are introduced to two wavelength division directions for crosstalk suppression. With this design, the simulated coupling efficiencies have respectively reached 59.93% and 46.38% for the 4.95 µm and 8.5 µm bands. This mid-infrared dual-band grating coupler may be useful for defense and environmental monitoring applications.

Efficient 1.55 and 2 μm Dual‐Band SOI Grating Coupler for Light Coupling and On‐Chip Wavelength Division (De)multiplexing

“…The simulated CEs at the opposite grating port are below −20 dB for the whole operating window from 1400 to 2100 nm, and can be further suppressed by introducing the subwavelength grating structure [ 37 ] or additional Bragg gratings. [ 38 ] Moreover, the fabrication tolerances are investigated via calculating the CEs with variations in the grating pitch, DC, and etch depth. As can be seen from Figure , the CEs of the 2 μm waveband are sensitive to the change of DCs and the maximum CE will decrease.…”