A novel one step integration of edge-emitting laser diode with micro-elliptical lens using focused ion beam direct deposition

An edge-emitting laser diode (LD) integrated with a microlens on its emitting surface for the purpose of collimating and fiber coupling is introduced in detail in this paper. A micro-elliptical lens is adopted for the integration in terms of divergence angle in both parallel and transverse directions. The lens with dimensions of 50 /spl mu/m/spl times/30 /spl mu/m/spl times/4 /spl mu/m is microfabricated on the emitting surface of the laser diode with operating wavelength of 635 nm directly by focused ion beam (FIB) deposition function. The SiO/sub 2/ deposition is realized by programming of the FIB machine. It is shown by test results that the focused spot size in the parallel and transverse propagation directions are 7.9 and 9.1 /spl mu/m (at site of 1/e/sup 2/), respectively, and the coupling efficiency of the compact and miniaturized system can reach as high as 71%. Measured far-field angles (full angle) with the microlens in both parallel and transverse directions are 2.2/spl deg/ and 1.2/spl deg/, respectively. Compared with the original divergence angles of 31/spl deg/ and 14/spl deg/ without the micro-elliptical lens, they were greatly reduced by this method.