Dual-etch apodised grating couplers for efficient fibre-chip coupling near 1310 nm wavelength

We present our recent work on fibre-chip grating couplers operating around 1310 nm. For the first time, we demonstrate the combination of dual-etch and apodization design approaches which may achieve a coupling efficiency of 85% (-0.7 dB). Subwavelength structures were employed to modify the coupling strength of the grating. -1.9 dB efficiency was measured from a first set of fabricated structures.