Parameter Range of Notes
parameter change
Main grating parameters
Type of a grating TBG
Resonant wavelength WL(nm) 400 ÷ 2700 Peak (central) wavelength
Diffraction efficiency DE 0 ÷ 99.9 Relative DE defined for
=Id/(Id+It) (%) plane monochromatic
wave
Additional grating parameters
Incident angle IA (θi, deg) -90 ÷ +90 In air
Exit angle EA(θd, deg) +90 ÷ -90 In air
Thickness T (mm) 0.5 ÷ 20
Width W (mm) 1 ÷ 35
Height H (mm) 1 ÷ 35
Antireflection coating AR (if not R<0.25% per Either broadband (BB)
specified – uncoated U) surface for BB or narrowband (NB)
R<0.1% per
surface for NB
Reference Parameters
Grating losses GL=(Ii-Id-It)/Ii (%) 0.1 ÷ 10 < 10% for uncoated(U) gratings;
< 2.5% for gratings with
AR coating
Angular selectivity AS (δθ, 0.1 ÷ 10 Full Width at Half
mrad) Maximum (FWHM)
Spectral selectivity WS (δλ, nm) 0.2 ÷ 20 Full Width at Half
Maximum (FWHM)
Grating period d (Λ, μm) 0.2 ÷ 20
Refractive index modulation 50 ÷ 1200 Amplitude of sinusoidal
RIM (δn, ppm) modulation
Grating slant angle in a glass -42 ÷ -90 Inside the grating
wafer SL φ +42 ÷ +90 medium
