Planar gratings and holograms are normally readout-wavelength insensitive. We show, however, that a binary phase surface-relief hologram can be transparent at one wavelength (λ) yet diffract efficiently at another (λ′), provided that the phase delay is an integer number of waves (e.g., 3) at λ and a half-integer number of waves (e.g., 2.5) at λ′. We fabricated a 7.9-μm-deep binary phase grating in BK7 glass that separates the standard telecommunications wavelengths, 1.3 and 1.55 μm, with 80% efficiency (neglecting Fresnel losses) and greater than 30:1 contrast.
© 1996 Optical Society of America
Joseph E. Ford, Fang Xu, and Yeshayahu Fainman, "Wavelength-selective planar holograms," Opt. Lett. 21, 80-82 (1996)