Table 1.

Summary of the theoretical (CE_T) and experimental (CE_E) coupling efficiencies for different GC reported in the literature. Results are ordered with respect to the thickness of the Silicon layer. Devices that required the use of a back reflector (BR) are reported in italics, while those relating to this work are shown in bold. All the values are reported with the number of significant figures provided by the authors.

Si [nm]	Description	CET [dB]	CEE [dB]	Ref.	Si [nm]	Description	CET [dB]	CEE [dB]	Ref.
220	GA	−2.15	—	11	250	fully-etched PhC	−1.8	−1.74	23
220	poly-Si overlay	−1.08	—	12	250	lag effect in etching	−1.31	−1.9	18
220	poly-Si overlay	—	−1.6	13	250	linear apodization	−2.3	−2.7	22
220	linear apodization	−2.6	−2.7	21	250	BR: Aluminum	−0.26	−0.62	16
220	GA	−1.9	—	20	250	BR: Aluminum	−0.43	−0.58	17
220	BR: Gold	−1.43	−1.61	15	260	GA	−1.0	—	20
220	BR: DBR	−0.36	—	11	260	linear apodization	−0.8	−0.9	*
220	BR: DBR	−0.86	−1.58	14	340	200-nm deep etching	−0.8	−1.2	19
220	linear apodization	−1.6	—	*	340	GA	−0.5	—	20