Yq. Fu et Nka. Bryan, Hybrid microdiffractive-microrefractive lens with a continuous relief fabricated by use of focused-ion-beam milling for single-mode fiber coupling, APPL OPTICS, 40(32), 2001, pp. 5872-5876
The design, microfabrication, and testing of a hybrid microdiffractive-micr
orefractive lens with a continuous relief that is used with a laser diode f
or monomode fiber coupling is discussed. The hybrid microlens with a diamet
er as small as 65 mum and a numerical aperture of 0.25 is fabricated direct
ly onto a spherical surface by use of focused-ion-beam milling technology.
A focused Ga+ ion beam is used to mill the continuous relief microstructure
at an acceleration voltage of 50 kV. From the test results a coupling effi
ciency of 71% (-1.49 dB) was achieved at room temperature. A diffraction ef
ficiency of the main diffractive order, -1, was measured to as high as 90.5
% at a wavelength of 635 nm. This indicates that the hybrid microlens was s
uitably designed within the application requirements and satisfactorily man
ufactured with focused-ion-beam milling. (C) 2001 Optical Society of Americ
a.