A multichannel diffractive optic rotary joint was designed, fabricated by electron-beam lithography, and evaluated with regard to cross talk and to output signal power variations. High cross-talk margin (>25 dB) and low output signal power variations (<2 dB) were achieved. The sensitivity to input-light-beam wavelength uncertainty was investigated. Two design examples are presented. The first design eliminates cross talk due to unwanted diffraction orders and shows that for a ten-channel joint the wavelength uncertainty of an 850-nm emitting laser must be less than 8 nm. In the second design cross talk due to the second diffraction order is permitted, which results in a tolerance level that is three times better for wavelength uncertainty.
© 1999 Optical Society of America
(050.1970) Diffraction and gratings : Diffractive optics
(220.0220) Optical design and fabrication : Optical design and fabrication
(220.3740) Optical design and fabrication : Lithography
(230.0230) Optical devices : Optical devices
Mathias Johansson and Sverker Hård, "Design, Fabrication, and Evaluation of a Multichannel Diffractive Optic Rotary Joint," Appl. Opt. 38, 1302-1310 (1999)