Table 2.

Peak CE and 1 dB bandwidth comparison of CGA optimized gratings for combinations of different SiN slab thickness and claddings.

tSiN (nm)	Air cladding						SiO2 cladding
	Peak Coupling (dB)			Bandwidth-δλ1dB (nm)			Peak Coupling (dB)			Bandwidth-δλ1dB (nm)
	Si sub	2 DBR	4 DBR	Si sub	2 DBR	4 DBR	Si sub	2 DBR	4 DBR	Si sub	2 DBR	4 DBR
300	−3.4	−0.66	−0.56	27	35	36	−3.0	−0.56	−0.48	32	44	45
40	−2.2	−0.56	−0.5	33	39	40	−2.5	−0.38	−0.31	35	42	43
500	−1.47	−0.5	−0.46	31	33	33	−2.4	−0.33	−0.26	33	43	43
600	−1.2	−0.5	−0.48	24	26	26	−3.13	−0.36	−0.28	26	38	39
700	−1.65	−0.5	−0.46	22	23	23	−2.8	−0.46	−0.36	20	30	30

The figures are provided for 3 cases which are gratings with a bare Si substrate at optimal BOX height (Si sub), and those with a 2 and 4 layer DBR stack.