Yq. Fu et al., Diffractive optical elements with continuous relief fabricated by focused ion beam for monomode fiber coupling, OPT EXPRESS, 7(3), 2000, pp. 141-147
The design, microfabrication and testing of diffractive optical elements (D
OE's) with continuous relief used for fiber coupling are discussed in detai
l. DOE's with diameters as small as 50 mm are fabricated by means of focuse
d ion beam (FIB) technology. A focused Ga+ ion beam is used to mill a conti
nuous relief microstructure at a 50 kV acceleration voltage. The optical pe
rformance of DOE's made in this way was compared with that of DOE's fabrica
ted by other methods. The focusing performance of DOE's fabricated with thr
ee and six annulus by FIB milling was investigated. Testing of the system w
hich has a coupling efficiency of -1.25 dB (75%) shows that the design meet
s the application's requirement for fiber coupling, and that DOE's manufact
ured by our FIB technology are practicable. Compared with a conventional fi
ber coupling system that uses a plano - convex lens, our system has the adv
antages of simplicity, short focal length, low cost for the lens and high c
oupling efficiency. (C) 2000 Optical Society of America.