wavelength, nm - waveguide  width 400		420		430		440		450 nm
1250	-1.5198	1250	-1.4348	1250	-1.397	1250	-1.3622	1250	-1.3304	
1275	-1.533	1275	-1.4448	1275	-1.4058	1275	-1.3698	1275	-1.3366	
1300	-1.5462	1300	-1.4548	1300	-1.4146	1300	-1.3774	1300	-1.3428	
1325	-1.5618	1325	-1.4674	1325	-1.4258	1325	-1.3872	1325	-1.3516	
1350	-1.5776	1350	-1.48	1350	-1.437	1350	-1.3972	1350	-1.3604	
1375	-1.596	1375	-1.4952	1375	-1.4508	1375	-1.4096	1375	-1.3716	
1400	-1.6164	1400	-1.5128	1400	-1.4668	1400	-1.4244	1400	-1.3854	
1425	-1.6344	1425	-1.528	1425	-1.4806	1425	-1.4372	1425	-1.3968	
1450	-1.6546	1450	-1.5454	1450	-1.4968	1450	-1.452	1450	-1.4104	
1475	-1.6738	1475	-1.5624	1475	-1.5128	1475	-1.4668	1475	-1.424	
1500	-1.695	1500	-1.5816	1500	-1.531	1500	-1.4838	1500	-1.44	
1525	-1.715	1525	-1.6004	1525	-1.5488	1525	-1.5004	1525	-1.456	
1550	-1.7308	1550	-1.6158	1550	-1.5636	1550	-1.5146	1550	-1.469	
1575	-1.747	1575	-1.6326	1575	-1.5798	1575	-1.5304	1575	-1.484	
1600	-1.7604	1600	-1.6478	1600	-1.595	1600	-1.5454	1600	-1.4986	
1625	-1.7738	1625	-1.6612	1625	-1.609	1625	-1.5594	1625	-1.5124	
	--	1650	-1.6746	1650	-1.623	1650	-1.5734	1650	-1.5262